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WILLOUGHBY WALKE.
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A Lieutenant, 2d U. S. Artillery.
3. A copy should be issued every officer of the Corps of Engineers
on his application for it, and upon his signing a memorandum
receipt therefor. These copies to be returned at the option of the
officers, and to be at all times kept from unauthorized persons.
N $ * * * * * 3. *
§§ i 5. No copy, except as above, should be issued except upon the
ºr special order of the Chief of Engineers. -
- BY COMMAND OF BRIG.-GENERAL DUANE; i.
(Signed) THOMAS TURTLE, º
\, Captain of Engineers. ..
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(CONFIDENTIAL.)
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MATH) H. I H) L
SUBMARINE \||NIN(, SERWI('E
UNITED STATES ARMY.
WITH A MANUAL FOR ITS
USE IN COAST DEFENSE.
st BM ITTED To
BRIG-GENERA. J. C. DUANE, CHIEF of ENGINEERs,
BY
(Jolo NEI, HENRY L. ABBOT, Corps of ENGINEERs,
131&ICV ET BRIGADIER-GENERAL, U. S. A.
1 88 7.
——- ~<}< Prº-- ~~~~
PRINTED ON THE PRESS OF THE BATTALION OF ENGINEERS.
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HEADQUARTERs CoRPS OF ENGINEERs,
Washington, D. C., March 24, 1887.
The following system for the Matériel of the Submarine
Mining Service, with a Manual for its Use in Coast Defense,
prepared under the orders of the Chief of Engineers by
Colonel Henry L. Abbot, Corps of Engineers, is, with the
approval of the Secretary of War, hereby determined and es-
tablished for the Engineer Service of the Army.
J. C. DUANE,
Brig.-General, Chief of Engineers.
LETTER OF TRANSMISSION.
ARMY BUILDING, WEST IIouston STREET,
New York, January 22, 1887.
Brig.-General J. C. Duane, p
Chief of Engineers, U. S. A., +.
(Through the Board of Engineers.)
GENERAL: • • ,
In 1875 it devolved upon me, as the Commanding Officer of
the Battalion of Engineers, to prepare a Manual for the instruc-
tion of the Engineer troops in the application of the system of
submarine mining which, during the preceding six years, I had
devised and, with the efficient assistance of the officers and en-
listed men, had developed for the defense of the harbors and
rivers of the United States.
The experiments upon which this system was based had been
thorough and extensive; covering investigations with every
class of trodern explosive, with every form of igniting agent,
with several different patterns of mines, insulated torpedo cable
and minor appliances, and with original apparatus for operating
the system by electricity.
The details of these investigations are contained in my Report
to the Board of Engineers; of which Part I has been published
as Professional Paper No. 23 of the Corps of Engineers, while
Part II forms a portion of the confidential course of instruc-
tion at the Engineer School of Application at Willets Point.
The first edition of the Manual, printed on the press of the
Battalion of Engineers between the years 1875 and 1877, was
intended partly to meet the immediate needs of the service,
and partly to undergo the careful experimental revision which
seemed to be expedient before any authorized edition was
(2) - *
vi L ET'T' E I? O H' T R A WS MISS TO W.
issued. The book consisted of three separate parts: electricity
as applied in submarine mining; the approved matériel of the
service; and a drill book for its use in war.
After a practical experience of about eight years with this
Manual as a text book for the instruction of the officers and en-
listed men of my command, I undertook the preparation of a
second and thoroughly revised edition. This work, delayed by
reasons beyond my control, I now submit, through the Board
of Engineers, for your decision as to its fitness to receive the
formal approval of the Department.
One important modification of the original Manual has been
made. Part I of that edition, designed as a text book and
aïde memoire in electricity, has been extended to cover other
applications to the special duties of the Corps of Engineers,
and is now in press as an independent work. It should always
accompany the Manual now submitted; because, often referred
to therein, familiarity with its contents is assumed.
Very respectfully, your obedient servant,
HENRY L. ABBOT,
Colonel of Engineers,
Bot. Brig.-General, U. S. A.
TABLE OF CONTENTS.
CIIAPTETR I. I.) EFENCE BY SU BMATRINE MIN ES.
Elements of modern coast defence.—General conditions to be fulfilled by
Submarine mines.—Approved dispositions of mines; grand groups;
skirmish lines; detached groups; self-acting mines.—Buoyant and
ground mines compared; explosive energy and distance.—Different
electrical systems for operating mines.
CHAPTER II. IAIBORATORIES AND PERSONNEL.
The mining casemate.—The loading room.—The personnel when planting
the mines; the personnel when operating the mines.
CIIAPTER III. SUBMARINE MINING MATERIEL.
MATſºn IEL of TIIE CASEMATE: The operating boxes; the disconnector; the
judgment firing key; the resistance coils; the firing battery; the sig-
mal battery; the testing battery; permanent earth plates; the detector;
the Bradley galvanometer; the Siemens universal galvanometer; the
bridge rheostat; the reversing key; switch keys and switches; case-
mate cable tags; Wheatstone dial telegraph; tool box A for casemate
use.—MATſiri EI, OF THE LOADING ROOM: the buoyant torpedo; the
ground mine buoy; the ground torpedo; the self-acting torpedo; charge
bags for buoyant torpedoes; the circuit closer; the circuit regulator;
electrical fuzes; the switch box; utensils for the loading room; in-
sulated wire; insulated joint supplies; special supplies, etc.—MATÉ-
RIEI, OF THE BOAT SERVICE: vessels and boats; the mine anchor; the
wire mooring rope; the shackles; the cable stop; insulated cable;
turks head collars; single junction boxes; the triple junction box; the
grand junction box; the junction box buoy; the planting buoy; drum
frames; boat earth plates; special tools.—The explosive: suitable ex.
plosives and their relative efficiency; properties of nitro-glycerine;
properties of explosive gelatine; properties of forcite gelatine; prop-
erties of Atlas powder; properties of gun-cotton; properties of dyna-
mite No. 1; proof tests; needful precautions.—Shipping dimensions
and weights of the Imatériel of the casemate; same of the matériel of
the loading room; same of the matériel of the boat service.
CIIAPTER IV. PREPARATORY SHORE DUTIES.
DUTIES OF THE COMMANDING ENGINEER: locus of the circuit regulators; use
of deteriorated cable; requisitions; local administration.—DUTIES OF
THE EI.ECTRICIAN: the leading wires; adjusting the testing apparatus;
T' A ſ? I, E! O H' CO N T ENT'S.
Time
Setting up the batteries; adjusting the disconnector; adjusting the
judgment firing key; adjusting the operating boxes; adjusting the
plates for sea cell tests; testing the fuzes; adjusting circuit closers
and circuit regulators; testing the loaded mines; testing the insulated .
cable; adjusting dial telegraphs.--DUTIES IN THE LOADING ROOM:
buoyant mines, to prepare the compound plug, to charge the torpedo;
ground mines; to prepare the compound plugs, to charge the torpedo;
Self-acting mines, to make safety rings, to prepare a safety break, to
encase the battery, to charge the torpedo; to charge a main line switch
box; to charge a skirmish line switch box; to charge a switch box for
judgment firing; insulated cable, jointing the core, making a turks
head, completing the joint; the moorings, to insert thimbles in wire
rope, to attach a cable stop; time required for loading room duties.
CHAPTER V. PLANTING THE MINEs.
required for planting mines.—DUTIES OF THE COMMANDING EN-
GINEER.—DUTIES OF THE ELECTRICIA.N.—DUTIES OF BoAT PARTIES:
to place a grand junction box; to place triple junction boxes; to plant
a buoyant mine; to plant a ground mine; to raise single mines; to
plant mines in grand groups; to raise or repair mines in grand groups;
to plant skirmish mines; to raise skirmish mines; to plant self-acting
mines; to raise self-acting mines.—The automatic flanking guns.
CHAPTER WI. OPERATING THE SYSTEM.
Electrical tests of the firing battery; of the signal battery; of the automatic
apparatus; of the disconnector; of the judgment firing key; of the
mines and cables; occasional tests; repairing injuries to the system.
—Drill of the detachment: automatic system drill; mapping drill;
judgment firing drill. —Defence of the mines: attacks by daylight;
attacks by night or in fogs, fouling lines, flanking guns, electric light,
movable torpedoes; injuries from friends; attempted passage by force.
LIST OF PLATES.
I. Defence by submarine mines.
II. Electrical circuits for submarine mines.
III. Mining casemate.
IV.
VI.
VII.
VIII.
IX.
Buoyant torpedo, ground torpedo, buoys in use.
Anchor, switch box, cable stop, shackle.
Grand junction box, triple junction box, single junction box.
Drum for torpedo cable; diagram for flotation computations.
Diagram of casemate connections.
Jointing a core, charging compound plugs, turks head, electrical
fuze, loading wires. .
ER RATA,
Page V. Last line. For “be” read “me.”
Page VI. 16th line from top. Insert “being ” before “after.”
Page VII and page VIII. Wording should be identical with headings of
Chapters.
Page 9. 9th line from bottom. Strike out “as well.”
Page 10. 4th line from top. Insert “the moorings” before “and.”
Page 12. Last line. For “matériel ” read “insulated cable.”
Page 15, 21st line from top. Insert “a” after “of.”
Page 16, 14th line from top. For “is” read “has been.”
Page 16, 9th line from bottom. For “tension” read “potential.”
Page 17, 21st line from bottom. For “circuit” read “circuits.”
Page 24. 8th line from bottom. For “especial " read “special.”
Page 25, 15th line from top. For “especial" read “special.”
*Page 31. 14th line from top. For “zinc " read “carbon.”
Page 41. 10th line from top. For “plug" read “break.”
Page 41. 14th line from top. For “two ring” read “two-ring.”
Page 46. Last line. For “formulae'' read “formula.”
Page 47. 22d line from top. Change comma to semicolon.
*Page 48. 26th line from top. Insert sign of equality between “cos 9)” and
4 & 7.2.”
*Page 49. 3d line from top. For “ll "read “ll,”. - - - -------- - - - - - - - -
*Page 49. 24th line from top. For “ W 1 – 081" read “ V 1 – 0.81.”
*Page 50. 3d line from top. For “2 [(1616 – 827-- 100 + 100)]” read
“2 [1616 – (827-- 100 + 100)].”
Page 64. 4th line in table. For “cut-off” read “switch.”
Page 68. 3d line from top. For “their "read “switch.”
*Page 68, 4th line from top. For “iron" read “steel.”
*Page 68. 11th line from top. For “1}" read “3.”
Page 68, 13th line from top. For “cut-off” read “switch.”
*Page 72. 6th line from bottom. Insert “ANCHOR” after “MINE.”
Page 100 and all even pages to 134. Change heading to “PREPAIRATORY
SHORE DUTIES.”
*Page 109. 10th line from top. Insert “ ( page 23)” after “Electrician ".
Page 116. 11th line from bottom. Insert “the base’’ before." is.”
*Page 135. 5th line from top. Insert “, slipped into its receptacle, ” after
“battery.”
*Page 135. 11th line from top. For “slip " read “wedge.”
*Page 135. 12th line from top, Strike out ‘‘, and wedge it in place.”
*Plate IX. In figure 2, add letter A to wire emerging from compound plug.
In figures 2 and 3, add letter C to wire at base of circuit regulator
plug. In figure 3, add earth wire to fuze can, as in figure 2; add
letter D to shore wire; add letter E to buoy wire emerging from
ground mine compound plug; add letter F to wire emerging from
buoy compound plug.
sk Important to meaning-should be corrected by hand.
(JIIAPTER I.
DEFENCE EY STU BMA FINE MINES.
Elements of modern coast defence.—General conditions to be fulfilled by
submarine mines.—Approved dispositions of mines; grand groups;
skirmish lines; detached group8; self-acting mines.—Buoyant and
ground mines compared; explosive energy and distance.—Different
electrical systems for operating mines.
One frequent problem in coast defence is how to best close
the water approaches to the port to be defended. The days
have gone by when this can be accomplished by artillery fire
alone; a more complex system is now demanded.
Such a system comprises: (1) stationary torpedoes which,
while allowing free passage for friendly ships, shall bar the
channel effectively against any hostile attempt to run past,
whether by day or by night; (2) land defences affording facil-
ities for operating the torpedoes, security against assault, and
substantial cover for the artillery; (3) high power guns of suf-
ficient calibre to keep at a distance all armored vessels whose
draft and armament would otherwise permit them to approach
and destroy the land defences; (4) smaller cannon, aided by
machine and rapid firing guns, to open a heavy flanking fire
upon launches or other vessels operating against the mines
anywhere within the mined zone; (5) bullet proof movable
torpedoes, under control from the shore, for the offensive de-
fence of the mined area against countermining operations; (6)
powerful electric lights to sweep the entire obstructed zone; (7)
picket boats pushed well to the front to guard against surprise.
This duty should be performed by regular torpedo boats of the
navy, able as well to act offensively whenever occasion permits.
Stationary torpedoes in modern coast defence thus constitute
one fundamental element in a complex system, no part of which
can safely be neglected. They are simply channel obstructions
—the most formidable which science has thus far been able to
devise.
With respect to nomenclature, when a torpedo is fixed in
position to defend a channel against the approach of an enemy,
it differs from a land countermine only in being submerged.
(3)
1() DEFENCE B Y S UB MARINE MIN ES.
The name torpedo will therefore be restricted to the case itself;
while the whole apparatus, including the case, the explosive, the
fuzes, the circuit regulator (for causing the contact of the enemy
to explode the mine), and the anchor will be called a submarine
mine, or simply a mine. -
GENERAL CONDITIONS TO BE FULFILLED.
Considering the general conditions to be fulfilled by this sys-
tem of channel obstruction: -
First. The mines must be so arranged as to admit of the
safe passage of our own vessels, while they can instantly be
rendered dangerous to the enemy. This condition can only be
attained by employing electricity as the igniting agent. When
there are several parallel channels, it may be admissible to close
some of them by self-acting mines; but such instances are ex-
ceptional, not the rule.
Second. Mines which can be exploded only by the act of an
operator on shore have a very limited application. In the night,
or a fog, or the smoke of a bombardment, or when several ves-
sels are approaching abreast, or when the water is deep, or when
the channel is wide, the chances of failure are very great. In-
deed, the destructive range of practicable charges is so limited
that if the ship be constructed with double cellular bottom and
water-proof compartments, judgment firing has become nearly
obsolete for any but very narrow channels. In general, there-
fore, the system must be automatic, the explosion occurring in
consequence of the touch of the enemy; but it should also
admit of judgment firing by groups when desired.
To meet the contingency of interference by our own vessels,
or the use of defensive outriggers by the enemy, provision must
be made to delay the explosion, after contact, until the order to
fire can be given by the officer directing the defense. Since the
apparatus must be operated in a casemate, from which no view
of the channel can be had, this condition implies not only an
arrangement of the apparatus by which a contact may report
itself without firing the mine, but also a telegraphic communi-
cation with the ramparts. As a vessel moving at a high rate of
speed will remain only for a few seconds within dangerous
range of a mine, a perfect code system is essential. -
Third. The mines should be so disposed as to cover a large
A PP R O V E D D IS POSITI O WS. 11
area of the channel. It is not enough to oppose a narrow belt
of danger. The waters well to the front of the forts, under
their close fire, and far to the rear, must be dreaded by the
enemy.
Fourth. Since the mines may remain in position for long
periods, the system must provide effective electrical tests, by
which the condition of every part may often be verified in
detail; and it must also be arranged to admit of easy repairs,
in case of need. -
Fifth. All the mechanical arrangements of the torpedo must
be simple, enduring, and strong enough to resist shocks from
friendly vessels and from the explosion of neighboring mines;
and special precautions against twisting and undue depression
by currents, must be taken for all floating parts.
Sãath. Every practicable auxiliary expedient should be
adopted. . Movable torpedoes controlled from the shore, and
the electric light, have already been mentioned. In addition,
the operating apparatus should be arranged to provide for the
automatic firing of flanking guns in case of any disturbance of
the system by the enemy, under cover of night or fog. The
electric cable should have sufficient weight to sink into the
mud in favorable localities—thus increasing the difficulty of
boat grappling; strong hemp cables, weighted at short intervals,
should be anchored in front of the mines with the same object
in view; and, lastly, dummy mines and false buoys should not
be neglected.
APPROVED DISPOSITIONS OF MINES.
Mines for obstructing the approaches of an important posi-
tion (Plate I) will be disposed upon one or more of four
systems—grand groups, skirmish lines, detached groups, and
self-acting mines. The last class absolutely closes the channel
against all comers; the others offer a safe passage to friends,
either through a narrow unobstructed pass or (with certain pre-
cautions) over the mines themselves.
Grand Groups. On each of several main lines intersecting
the zone to be defended, and so laid out as to be well flanked
from the forts, grand groups of 21 mines are planted. These
mines are separated from each other by intervals of about one
hundred feet, and therefore cover a front of 700 yards. They
are all operated through a seven-core multiple cable, each core
12 I) E, FE WO E) J3 Y S Uſ B MA I? IN /; MIN E S.
serving three mines. When set for automatic firing, only the
mine struck by the enemy explodes; when fired by judgment,
the three mines on the selected core are exploded simultaneously.
When the line of a grand group crosses the track of the
enemy at right angles, a second group is disposed in quincunx
to reduce the intervals between mines to fifty feet; when the
intersection is very oblique this second group may be un-
necessary.
The following description, with Plate I, will explain the de-
tailed arrangements of a grand group.
From the mining casemate, the multiple cable containing
seven separate cores, extends to a grand junction box planted
one hundred feet in rear of two-thirds of the proposed mines.
At the grand junction box, the cores diverge into seven single
conductor cables, radiating like a fan toward the enemy. These
branch cables terminate, upon the line proposed for two-thirds
of the mines, in triple junction boxes three hundred feet apart.
At each of these triple junction boxes, the cable again radiates
through a switch box into three single conductor cables, each
terminating at a distance of one hundred feet in a mine—ground
or buoyant according to the depth of water. Two of these
mines are planted on the line of triple junction boxes, and the
third perpendicularly in front of it, toward the enemy.
The total cost of a grand group ready for service varies, with
the depth of water and strength of current, from six to nine
thousand dollars, plus about $1600 per mile of multiple cable
required between the group and the casemate. -
Skirmish Lines. This method of planting consists in
stringing several single mines (not exceeding twenty in num-
ber) upon one single conductor cable, at approximate intervals
of about two hundred and fifty feet; both ends of the cable
are in the casemate, or one of them enters the mining casemate
of a coöperating fort—thus affording facilities for telegraphic
communication, as well as other important advantages. Near
each proposed mine the cable is jointed, through a switch box,
to a branch cable about one hundred feet in length—at the end
of which a torpedo is planted, loaded for automatic firing only.
This system bears a relation to the regular groups not unlike
that of a skirmish line to a line of battle. Its proper function
is to augment the number of mines in the channel, by a com-
paratively small expenditure of matériel; to fill spaces between
A PPI, O V E D D IS PO SITI () WS. 13
different main lines; and, finally, to extend the area of danger
throughout a wide zone in front.
By such an arrangement, the enemy is forced to begin oper-
ations at a considerable distance from the principal lines of
defence—which should always be kept under the effective fire
of flanking guns; and to waste time and incur risks in removing
outlying mines so widely scattered as not to be readily dis-
covered.
An apparent objection to the system is that by cutting the
cable at any point, the automatic apparatus must be rendered
inoperative; and the cutting may even destroy all the mines
beyond that point. But both ends of the cable enter the same
or coöperating forts, and by keeping an enduring and powerful
firing battery applied to each of them, the mines would usually
remain as dangerous as before. Indeed, the only certain effect
of such an injury would be to compel the electrician to operate
them upon this more troublesome plan.
Of course, no judgment firing would be possible with such a
system, nor could an injured or exploded mine be located and
replaced. The application of skirmish lines is therefore re-
stricted to reinforcing grand groups, or to defending harbors of
minor importance.
The cost of a skirmish line in our ordinary channels is about
six thousand dollars, plus $350 per mile for all insulated cable
beyond the terminal mines.
Detached Groups. This system consists of a few large
mines to be fired by judgment; they are therefore preferably
ground mines without buoys, when the depth of water will
permit. Such mines may be served by insulated cable too much
deteriorated for use with an automatic system.
Detached groups are used when the enemy is restricted by
the conformation of the shore to a few contracted positions for
his preliminary distant bombardment; or they may be planted
at any time during the siege in rear of the mined zone, to assail
him unexpectedly should he succeed in forcing a passage.
Self-acting Mines. This system is used to close channels
not needed for our own use—especially when they cannot be
covered by a close flanking fire from the forts.
There are many cheap and temporary varieties of this class
which, in cases of emergency, may be improvised for the ob-
struction of rivers and other land locked channels. The manner
(4)
14 I) E FE WOJ) J3 Y S U B MA R IN E MIN ES.
of planting such devices will depend upon the principle upon
which they are to be exploded; and the work, dangerous at
best, will be done according to the views of the officer preparing
them. - -
The service pattern of self-acting mine is designed for closing
such of the entrances of our larger harbors as may be sacrificed
without serious loss, while others parallel to them are kept open
to our vessels by using only electrical mines under control from
the shore. They may also be very useful in a desperate siege,
for obstructing by night passages in our mined zone which the
enemy has succeeded in opening and buoying.
The cost of the service self-acting mine (complete) may be
estimated for ordinary channels at about two hundred and fifty
dollars.
I3UOYANT AND GROUND MINES COMPAREI).
With respect to locus, there are two classes of mines—the
buoyant and the ground; their characteristics and relative
merits next call for attention.
In the ordinary buoyant mine, the torpedo, containing charge,
fuzes, and circuit regulating apparatus has sufficient flotation to
remain at any desired distance above the bottom, being held
down, and in position, by an anchor and mooring of suitable
character.
In the ground mine, the torpedo, containing the charge and
fuzes, rests upon the bottom; and the circuit regulator, placed
in a separate buoy, is moored either over it—or, if the use of
defensive outriggers by the enemy be apprehended, enough in
rear of it to be struck when the ship is over the mine.
The latter precaution is not peculiar to the ground mine;
since the charge and fuze may be placed in a buoyant torpedo
and moored just below the level of the ship's bottom, while
the circuit regulating apparatus, in a separate buoy, is placed
slightly in rear of its position, as before.
When the channel to be defended is sufficiently shallow to
allow the charge to rest upon the bottom, and yet to act destruc-
tively upon the vessel, the following advantages result from
disposing it in that manner. -
A%rst. Absolute fixity of position, which largely increases the
probability of success in judgment firing.
J3 UO YA N T A W D G R O U W D. 15
Second. Increased lightness in the arrangements needful for
automatic firing—since the weight of the charge is not to be
supported, and the size of the buoy for carrying the circuit
regulator, its mooring rope, etc., may be reduced to the mini-
mum. In strong currents this is a matter of no small importance,
as will soon appear.
Third. Less complex arrangements for placing the charge
in the best position, relative to the circuit regulator, to baffle
defensive outriggers. -
Fourth. Absolute security to friendly vessels against accidents
resulting from mechanical injuries done by them to the torpedo.
On the other hand, the ground mine offers certain important
disadvantages, viz.:
Fºrst. Larger and hence more expensive charges, are needful
for the ground torpedo, owing to the increased distance from
the hull.
Second. The loading and planting of the mines are more
complicated.
Third. The hostile vessel, being at a greater distance from
the charge, has a better chance of escaping a deadly blow by
virtue of strong construction.
In fine, the advantages seem to be in favor of the ground
pattern for shallow water, and in favor of the buoyant pattern
for deep channels; but the exact depth at which the former
should give place to the latter, governed largely by the weight
adopted for the charge, can only be decided by a knowledge of
the mathematical law connecting the destructive energy of an
explosion with the distance.
Explosive Energy and Distance. A long series of
experiments has been conducted at the Engineer School of
Application at Willets Point, to determine this law for every
variety of explosive. They have resulted (Professional Paper
No. 23, Corps of Engineers) in the following formula, in which
the extreme destructive range against the hull of a modern ship
of war is denoted by A ; the angle included between the ver.
tical through this charge and a right line drawn to the point of
attack, reckoned from the nadir and expressed in degrees, is
denoted by 3; E is a constant depending upon the nature of
the explosive; and C is the weight of the charge in pounds.
A submergence of three or four feet for 100 pounds, and pro-
portionally more for larger charges, is assumed.
16 D F FE W (J E J Y S UIR MAI. IN J. MIN JES.
*******-*-*-*-*-****
(1) - - - A = 8
This formula, which will be more fully considered in Chapter
III, has led to the important practical conclusion that it is
usually inexpedient to employ mines requiring very large
charges. For instance, to increase the destructive energy ten
times, it is needful to increase the charge one hundred times;
or, in other words, 10 000 pounds is only ten times more ef-
fective than 100 pounds. For this reason ground mines are
usually charged with only 200 pounds of dynamite, and are
not used when the depth at high tide exceeds thirty feet; the
charge of buoyant mines is fixed at 100 pounds. Upon these
figures the dimensions of the system have been established;
but provision for increasing the charges, whenever desirable,
is made.
IDIFFERENT ELECTRICAI, SYSTEMS FOR OPER-
ATING THE MINES.
It remains to consider the character of the electrical circuit
to be chosen for operating a system of mines. Three are avail-
able—an open circuit, a closed circuit of high resistance, and a
closed circuit of low resistance. All three are used in the
United States service; and an officer, especially if called upon
to improvise a defence by mines, should thoroughly understand
the advantages and disadvantages of each of them.
The following tabular statement, with Plate II, sufficiently
indicates the principles upon which operating apparatus have
been devised, when, as is generally the case, the earth is used
for the return circuit. Three kinds of fuzes are available—low
tension, medium tension and high tension. Although some-
times interchangeable, the first class (now preferred) pertains
more particularly to voltaic currents; the second class, to mag-
neto-electric machines; and the third class, to frictional ap-
paratus. g *-. -
Open circuit. I. Operator applies electricity of high
tension.
Patano ſº circuit, II. Operator applies voltaic, magneto-
Purely Judgment. (high or low). electric or frictional electricity—
according to the nature of the
U fuze.
Open circuit. III. Enemy closes the circuit.
Closed circuit, IV. Enemy closes a derived circuit of
(high resist.). much less resistance than the
primary.
Purely Automatic.
JD TFF EIR JEW T E L E G T R ICA I, SYST'Jº MS. 17
ſ Open circuit. V. Combine (I) and (III) by using
two fuzes, one high tension and
the other low tension, placed in
derived circuit.
Closed circuit, VI. Enemy breaks the circuit and
(low resist. ). then re-closes it.
Closed circuit, VII. Combine (II) and (III) by using
(low resist.). a small normal resistance to be
shunted out by the enemy, and
a low tension fuze—both in the
primary circuit.
Closed circuit, VIII. Combine (II) and (IV) by using
(high resist.). a resistance coil in the primary
circuit, to be shunted out by the
enemy ; and a medium tension
fuze in a second derived circuit.
This is the old English system ;
the new system with the Arm-
strong relay is too complex for
consideration here—see Abbot's
confidential School of Applica-
tion Paper No. VII.
Closed circuit, IX. Combine (II) and (IV) by using
(high resist.). Abbot's circuit regulator and a
\. low tension fuze.
In deciding between these several systems the advantages
peculiar to each circuit should be carefully considered. For the
open or high resistance circuit these are:
JFirst. Accidental firing of mines by blundering is usually
impossible when an open circuit or a closed circuit of high
resistance is used; but such an accident may occur on a closed
circuit of low resistance if the operator happen to be negligent
or stupid.
Second. A circuit closer can be made much less sensitive to
the explosion of neighboring mines than a circuit breaker; and
the operating of the system is therefore simpler with open
circuits, or closed circuits of high resistance, than with those of
low resistance.
Third. In the matter of testing the condition of the mines,
the open circuit is the more simple; because most faults reveal
themselves instantly by the passage of a current, while with a
closed, circuit, unless the apparatus be very delicately adjusted,
measurements are needful to detect the variations in the flow
by which alone trouble is indicated. It need hardly be added
that the larger the resistance in the closed circuit, the more does
it approximate to the open circuit in this advantage.
Fourth. Since on an open circuit no work is performed by
the signal battery except at the instant of firing, a few cells
JWither Judgment
or Automatic.
4
(5)
18 I) EF E W C E /3 Y S Uſ.JP MA R IN J. MIN ES.
may be used of a type which will stand for months without
deterioration and without renewal. In this respect any closed
circuit is inferior, since its signal battery always exacts attention
whether the external resistance be high or low.
Indeed, with a low external resistance and an automatic sys-
tem, so much work will be demanded that many separate and
powerful signal batteries will be required; and even with a
high external resistance, calling for only a feeble current through
each fuze, a constant type of cell must be used, and the com-
bined work with many mines will still be so considerable that
this condition must receive careful consideration.”
The advantages peculiar to the closed circuit are the follow-
ing: w
Jºrst. Tension fuzes and breaks, and special apparatus nec-
essary for judgment firing with an open or highly resisting
* To fix ideas upon this important point, the size of a signal battery to
work on a system with high external resistance will be considered—the in-
sulation of the cables being assumed to be perfect, and the resistance of the
several groups to be identical. - -
Allowing 80 ohms for the magnet of the operating apparatus, a ohms for
the cable, 3 ohms for the fuzes and cut-offs, 4200 ohms for the regulator,
and 3 ohms for each torpedo earth, the total resistance of the part of the
circuit between the zinc pole of the battery and earth at a triple group of
mines, 18 :
80-- a + **** = 1482 -- a.
But for each grand group there are seven of these circuits attached to the
1482–H a
—; º
battery in multiple arc, giving a joint resistance of Hence allow-
ing 3 ohms for the home earth, and denoting the number of cells by n, and
of grand groups by N, the constant current (C,) to be supplied by the bat-
tery is given by the equation:
7) E
(2) - - -- * C = --_ --
f £ 1482 -- a
n R, + 3 + “” 7 N
Evidently, to operate the system with a single signal battery, a type of
cell of suitable dimensions to supply this current steadily must be selected.
This is the first requisite.
But the signal battery must also fulfill a second condition. To operate the
apparatus automatically, when any torpedo or buoy is struck by the enemy,
an increased current (C,) must flow through that particular circuit. Hence,
denoting the resistance of the latter circuit by B, and the joint resistance of
a grand group, *** , by A the following equation may be stated, from
the laws of derived circuits.
Af
I) / FFJ; IP JJ W T JE L // (ſ T'Jº ICA. J., S. Y S TJW, M S. 19
circuit are not required with a closed circuit of low resistance.
This materially simplifies the manipulations in the casemate.
Second. A closed circuit of low resistance permits a restricted
use of insulated cable which has deteriorated to such an extent
as to be worthless for an open circuit—because the mine can be
exploded through a very defective cable.
For example, suppose the insulation resistance of a cable to
be only 90 ohms, while the metallic resistance of the circuit
through the fuze is 10 ohms. Then, by the law of derived cir-
cuits, nine-tenths of the current of the firing battery would
still traverse the fuze; and, with the usual allowance of surplus
power, explosion would be certain.
Such a cable, however, could not be used for automatic firing,
A
C, - m E A. x·x = º
+x B --B
n R,+3+-R
* +B
Whence, solving with respect to m :
(3) n = , 9.4° 3-B) tº NB (A + AB+3 Nº .
A*(E–C, R, ) + NB(AE–2 AC, R,-C, R, NB)
Equations (2) and (3) are general formulae applicable to the matériel of
the United States Service, and in practice they may be simplified. Thus, if
one of many common forms of the sulphate of copper cell be selected, the
Watson for example, E becomes 1.0 volt, and R, may safely be assumed at 5
ohms; with the approved operating apparatus, C, is 0.03 ampères; since the
range of the firing battery is five miles (largely in excess of probable re-
quirements) that of the signal battery may have the same limit, giving a =
60. Making these substitutions, A becomes 220.3; B becomes 80+60 + 6
= 146; and Equation (3) can be put under the form: -
70, t 1+0.68 N-H 0.000N *
0.19-1-0.1 N = 0.015 N*
From this equation it appears that the number of cells increases as the
number of grand groups is increased, at first slowly, and then very rapidly.
Thus:
1 grand group requires 6 Watson cells.
2 4 & {{ { % 7 { { & 4
3 { { { % 4 4 9 § { § {
4 t & & £ & 11 4 4 { %
5 { % § { & 4 15 { { { {
6 4 & { { { { 22 { { { %
7 £ 4 4 & £ 4 39 { { { %
8 $ 4 $ $ {{ 234 4 4 & &
9 4 4 £ 4 & 4 Cº) £ 4 & &
Reverting now to the first requisite, let the foregoing values of all the
Constants, except of a, be substituted in Eq. (2); and let a have its most un-
favorable (theoretical) value, zero. Then:
20 D EFE WO E. B. Y S UIR MA R TWE. MIN ES.
because abnormal action of the signal battery would be caused
by the leakage through the cable. This subject will receive a
mathematical analysis in Chapter IV.
Th?rd. A closed circuit either of high or low external re-
sistance, renders it easy to detect one class of faults which,
occurring in an open circuit, can only be discovered by mechan-
ically closing the circuit closer; viz., such a break in the
continuity of the conductor as leaves the home end insulated.
This injury is unlikely to occur naturally in a submerged cable,
but it may be caused by night operations of the enemy.
In fine, after much experimental research involving the inven-
tion and successive improvement of many varieties of apparatus,
the systems marked (II), (III) and (IX) in the foregoing table
have been adopted for the United States service; the approved
apparatus, however, admits of adjustment for some of the other
methods.
C, = -* wis te
5n + 3 + TNT
If the corresponding values of n and N as given in the foregoing table, be
substituted in this formula, the following values result for the normal flow
required from the assumed battery. When the external equals the internal
resistance, i. e., when it is working to the best advantage, its current is
0.100 ampères.
1 grand group requires 0.025 amperes.
2 4 & { { { { 0.049 & 4
3 & 4 4 & { { 0.075 § {
4 { % £ (, § { 0.099 & 4
5 4 & { { { % 0.125 $ 4
This discussion shows very clearly that the ordinary form of sulphate of
copper cell is only powerful enough to operate, automatically, four or five
grand groups in perfect condition. If a larger number be required, or if the
cables contain slight faults, either a stronger constant cell must be chosen or
more than one signal battery must be employed.
To illustrate the enormous gain resulting from using a stronger cell, the
sulphate of copper variety will be supposed to be replaced by an ordinary
Grove or Bunsen cell. The electromotive force then becomes 1.9 volts, and
the internal resistance Bay 0.3 ohms. Substituting these values in Eq. (3),
and reducing as before, it becomes:
, 1+0.68N +0.000 N*
0.42–H 0.28 N - 0.0009 N2
By solving this equation numerically, it will be seen that from 1 to 15
grand group8 may be operated by 3 cells; and from 16 to 36 grand groups
by 4 cells. In other words, 3 nitric acid cells are ample for all ordinary
purposes. º
In fine, this discussion sufficiently proves that the question of the signal
battery, although very simple for an open circuit, becomes complex when
any form of closed circuit is preferred
(JIIAPTER II.
I, A BORATORIES AND PERSONNEL.
The mining casemate.—The loading room.—The personnel when planting
the mines; the personnel when operating the mines.
To operate electrical submarine mines successfully, large
voltaic batteries and delicate apparatus of various kinds are in-
dispensable. To expose this matériel to boat attacks, or even to
distant bombardment, would be inadmissible—for even a slight
injury here might open the channel to the enemy. The opera-
ting apparatus is the most vulnerable part of the system, and all
the resources of engineering and the whole military force of the
defenders must be combined in its protection; hence the ac-
cepted principle that for important harbors the mines must be
operated from strong land fortifications.
THE MINING CASEMATE.
When practicable some well covered casemate in an existing
fort will be prepared for use in operating the mines; the floor
space should at least equal 12 × 16 feet, and larger dimensions
are to be preferred.
The following project for defensive arrangements built speci.
ally for the purpose, was prepared by the Board of Engineers;
and in 1874 it received the official approval of the War Depart-
ment, subject to such changes in detail as might be ordered by
the Chief of Engineers. It was assumed that the structure
would be covered against direct fºre by its location. When this
condition cannot be fullfilled, much more substantial protection
is necessary.
“The room for the operators, instruments, etc., may be in
any sheltered part of the main work, out-works, or even in a
detached structure built for the purpose; such room being so
located that the cables leading from it may be sheltered in the
best possible way from an enemy's fire till deep water (say three
fathoms, at least, when practicable) shall be reached.
“From the operating room the cables, when practicable,
should be laid to the proper point on the shore line through a
gallery large enough to permit a man to crawl through, such
(6) -
22 LA 13 O I: A TO RI ſº S A N D PE IR SO N N J. L.
gallery being covered with a sufficient thickness of earth to
protect it from an enemy’s shots. It will generally be imprac-
ticable to place the bottom of the gallery at its shore extremity,
at a level lower than one foot below mean low water, without
serious expense; and it has been represented at that reference
in the drawings. Wherever it may be practicable to go lower
without much increase of cost, it would be well to do so. These
galleries should be prepared without waiting till the necessity
for their use arises.
“From the shore end of the gallery the cables should be led
to deep water, by the shortest line, in as deep a trench as can
be made with the means at command. It is not to be prepared
beforehand, but only in time to be ready for the cables. It is
thought that in most of our harbors and rivers where torpedoes
will be employed, one or more dredges may be had to excavate
these trenches.
“The cables being laid, the trenches should be filled up and
further covered over with earth (in sand bags when necessary
to prevent the leveling action of the sea) to protect them from
injury from our own fire and that of the enemy.
“When, as will often be the case, it is either impracticable
or too expensive to lead the cables from the fort or its outworks,
a special structure should be provided—a general design for
which (Plate III) is simply a concrete arched room, covered
with a thickness of earth which makes it bomb-proof. The
clear dimensions of the room are 12" x 16", which is believed to
be sufficient for the purposes of the operators, the instruments
and such chemicals as are needed. From the table, which is
placed in the centre of the room, the cables are led down
through a rectangular shaft, 4' × 2' 6", to the gallery below, which
is 2' 6" × 3' 6"—these dimensions being large enough to allow a
man to crawl through. In low sites it will be carried only to
the foot of the slope of earth covering of the structure, as
represented in the drawings. From this point to the water, its
extension is simply a rectangular trough of concrete, 1 × 2' 6"
interior dimensions, which is to be covered up with earth till the
occasion for its use arises—when the earth is to be removed, the
cables laid, and afterwards covered up with a sufficient thick-
ness of earth to secure them from injury from shot and shell.
When the ground has sufficient height (ten feet or more) the
T II Jº M I WING! (! A SJ; M.A T'J'. 23
gallery may be extended to the farthest point at which the
needful cover can be had.
“As the best form of table for the electrician and his instru-
ments has not yet been fully decided upon, the exact arrange-
ment of the cover for the shaft has not been determined, and is,
therefore, not given. For the present, the hole may be left
covered with a simple trap-door of boards.
“When the room is to be in the fort or an outwork, any suita-
bly situated casemate may be taken for the purpose; from which
the gallery for the cables will be carried out according to the
principles already laid down.”
Since this project was prepared by the Board of Engineers,
all the minor details have been settled. As a rule, this work
will be done after the party arrives, and the electrician will
therefore need the assistance of a few intelligent and instructed
Engineer soldiers at once. .
His first duty will be to provide a raised platform and table
suitable for the operating apparatus, some battery shelves, and
two stout tables—one for the testing apparatus and one for the
dial telegraph instrument. A small work bench adapted to the
tools contained in box A will also be needed.
The platform (Plate VIII) should rise 6 inches above the
floor, covering the shaft. In its top is a hinged trap door
affording ready access to the latter. Around three of its edges
is placed a table 12 inches wide, with the top 42 inches above
the platform. The running length should be sufficient to ac-
commodate the operating boxes, allowing 24 inches measured
on the inner edge, for each. The cables will pass out through
holes in the vertical sides of the platform, under the table, to
the boxes, where each will be labeled with a casemate tag.
The battery shelves are placed by the side of the casemate.
They are made of 2-inch plank 15 inches wide, and allow 30
running inches for each 10-cell box. The clear space between
shelves is 18 inches. The boxes rest on beveled strips thickly
coated with paraffine.
The dial telegraph table, which on account of the magnets
must be remote from the testing apparatus, should be 24 inches
by 30 inches by 40 inches high; it should have a shelf or two
under it.
The table for the testing apparatus should be 18 inches wide,
24 I, A B O R A T' O B J // S. A. W. D. P. Jº Jº S () W W // I, .
42 inches high, and at least 6 feet long; drawers and shelves
under it are convenient.
THE I/O AIDING ROOM.
A light wooden building distant from the main fortifications
and magazines and convenient to the wharf, should be prepared
for loading the torpedoes. A floor space of 10 × 10 feet should
be allowed for loading a torpedo; and about as much more for
the corresponding Squad engaged in loading plugs, switch boxes,
etc., and inserting thimbles. The dimensions of the building
may be fixed by this rule; i. e. allow 10 × 10 feet of floor space
for each four men available.
Kings to receive the blocks and falls for slinging torpedoes
and buoys in loading, should be attached to substantial beams
overhead. Under each ring two strips of 5-inch scantling, about
3 feet long, are spiked to the floor parallel to each other and 3
inches apart; the middle of the support thus formed is hollowed
to roughly fit the curvature of the torpedoes; a crow-bar passed
through the lowering ring and laid between the strips, will
prevent rotation when withdrawing and inserting the plugs in
loading. Stout tables and benches must be provided for the use
of the other squads.
Good ventilation and a moderate temperature are important;
and to Secure the latter in inclement weather, a stove must be
supplied—well removed from the explosives. Smoking is to be
prohibited by formal orders.
TILE PERSONNEL.
Two periods are to be considered—the planting of the mines,
and the operating of them after they have been placed in
position. -
Planting the Mines. When a maritime war occurs, many
harbors will have to be simultaneously defended; to plant the
mines successfully care, intelligence and especial training are
essential; the numbers of Engineer soldiers are now, and prob-
ably will continue to be, insufficient to do the entire work in a
satisfactory manner; and, lastly, in every large harbor an ample
Supply of tugs and row-boats, with skillful crews accustomed to
handling them, can be obtained. Care has, therefore, been
taken to assign to Engineer soldiers only such duties as require
special training at the School of Application; and which should
*
T'JJ Jº JP Jº I? S () W W ſº I, . 25
not be trusted to men, no matter how intelligent, without such
training, long continued. Hence the figures given below are to
be regarded as the mºnºmum consistent with a reſ/sonable
prospect of 80/60688.
As a convenient unit, the minimum force required for prop-
erly planting one grand group of 21 mines is adopted ; with
drilled men, a good outfit, and favorable conditions this work
should be done in one day. The number of Engineer troops
necessary at any harbor may be computed from these data, by
deciding how imany such groups must be placed in position
simultaneously.
For planting one grand group, two commissioned officers are
essential—one to exercise a general supervision on the water,
and the other to act as electrician. The duties of the latter are
too important, and require too much especial knowledge and
familiarity with the system, to be safely trusted to civilians.
Three non-commissioned officers of Engineers are necessary
—one to take station on the boat containing the grand junc-
tion-box, and from it to command the parties in the skiffs
containing the triple junction-boxes; another to take post in the
tug and Supervise the planting of the mines; and a third to
superintend the loading of the mines on shore.
Twenty-four privates of Engineers are needed—two in the
grand junction-box boat, six in the three triple junction-box
skiffs, four in the tug planting the mines, and twelve in the
loading room.
About forty sailors, laborers, etc., must be procured to man
the boats, to transport and place on the tug the torpedoes and
other apparatus, and to assist generally.
Hence, for each grand group the minimum Engineer detail
will be the following (the number of commissioned officers
usually admitting of some reduction when several groups are
laid simultaneously):
2 Commissioned officers.
3 Non-commissioned officers.
24 Engineer privates.
40 Sailors, laborers, etc.
Operating the Mines. In operating a system of electrical
mines, the duties of the mining casemate are of vital importance
to success. Electricity is an agent which allows no margin ror
ignorance, carelessness or neglect. The Engineer in charge must
(7)
26 I, A B O I? A T'O R T J'S A W D P E JP SO W W /? I, .
now be his own electrician, and will be held responsible for
every detail.
His principal assistant must be exercised in manipulating, and,
if necessary, in repairing the electrical apparatus; in making and
interpreting the electrical tests; and in obtaining so thorough
and exact an understanding of every part of the system, that
no excitement of action can prevent the proper performance
of duties demanding great coolness and presence of mind in
emergencies.
As to the size of the detachment, the following is an extract
from a project of the Board of Engineers which, in 1874, re-
ceived the formal approval of the War Department.
“The minimum force required at a fort or battery for opera-
ting the system of torpedoes, consists of four men—one officer,
who stations himself at Some good point of observation on the
work to direct the conduct of the electrician; one private, having
with him a telegraphic instrument connected with the operating
room; one non-commissioned officer in the operating room as
electrician; and one private, also in the operating room, in charge
of a telegraph instrument connected with the one on the work.
This number makes no allowance for casualties, and should be
increased if practicable by one non-commissioned officer and
one private. If three reliefs are provided, there will be required
for each work, three commissioned officers, six non-commissioned
officers and nine privates.”
This estimate requires some reduction when the difficulty of
obtaining instructed men renders it necessary to fix upon an
absolute mºnºmºum.
At the more important stations one Engineer officer to com-
mand the party and be the responsible electrician, is indispensable;
and if one or two other officers who have passed through the
special course of instruction in submarine mining at the En-
gineer School of Application can be spared, their assistance
will be highly desirable. If not, well instructed non-commis-
sioned officers of Engineers must be assigned to act as assistant
electricians.
As the channel cannot be seen from the operating room, tele-
graphic communication must be established between it and a
look-out, placed in the most suitable part of the fort. Dial
telegraph instruments, connected by insulated cable laid where
least exposed to injury from the enemy's fire, will be employed;
T'II E P E R S () W NEI, . 27
and two privates of the battalion will be required as operators.
The service may have to be kept up night and day; occasional
repairs may be needed; and an allowance for sickness and cas-
ualties must be made. Hence, at least three reliefs should be
provided. The minimum personnel when operating the mines
will, therefore, consist of:
1 Commissioned officer of Engineers.
3 Non-commissioned officers of Engineers.
6 Privates of Engineers.
If the larger force of trained men contemplated by the Board
estimate can be spared, it certainly should be supplied; but
this minimum detachment is absolutely essential to justify any
eſcpectation of success.
The whole party, acting under the orders of the Command-
ing officer of the post, will be able while serving the mines to
incidentally determine ranges for the use of the artillery in
action.
() || A PTE R III.
SU F3 MIA ERIN HE MINING MATERIEL.
MATſºrTEL OF THE CASEMATE: The operating boxes; the disconnector; the
judgment firing key; the resistance coils; the firing battery; the sig-
mal battery; the testing battery; permanent earth plates; the detector;
the Bradley galvanometer; the Siemens universal galvanometer; the
bridge rheostat; the reversing key; switch keys and switches; case-
mate cable tags; Wheatstone dial telegraph; tool box A for casemate
use.—MATÉRIEL OF THE LOADING ROOM: the buoyant torpedo; charge
bags for buoyant torpedoes; the self-acting torpedo; the ground mine
buoy; the ground torpedo; the circuit closer; the circuit regulator;
electrical fuzes; the switch box; utensils for the loading room; in-
sulated wire; insulated joint supplies; special supplies, etc.—MATſº-
RIEI, OF TIIE BOAT SERVICE: vessels and boats; the mine anchor; the
wire mooring rope; the shackles; the cable stop; insulated cable;
turks head collars; single junction boxes; the triple junction box; the
grand junction box; the junction box buoy; the planting buoy; drum
frames; boat eartly plates; special tools.--THE EXPLOSIVE: suitable
explosives and their relative efficiency; properties of nitro-glycerine;
properties of explosive gelatine; properties of forcite gelatine; prop-
erties of Atlas powder; properties of gun-cotton; properties of dyna-
mite No. 1; proof tests; needful precautions.—SIIIPPING DIMENSIONS
AND WEIGHTS: Inatériel of the casemate; matériel of the loading
room; matériel of the boat service.
The matériel pertaining to our submarine mining service
is classified according to locality, as that of the mining case-
mate, that of the loading room, and that of the boat service.
Explosives, from their importance, are accorded a separate
sub-division of the chapter.
MATERIEL OF THE CASEMATE.
This matériel includes the electrical operating apparatus, the
voltaic batteries, the testing apparatus, the dial telegraph, and
the tools and supplies necessary for their adjustment and repair.
The electrical operating apparatus consists of the operating
boxes, the disconnector, the firing key, and the resistance coils.
The essential features of this mechanism were devised in the
winter of 1871–72; but successive improvements were made
until the year 1877, when the patterns were finally approved.
The voltaic batteries are three in number—the firing battery,
the signal battery and the testing battery. The testing apparatus
comprises a detector, a four-coil Bradley galvanometer, a Siemens
MA 7'ſ I; J JJ L OF TII R' ('A SEMA TJJ. 29
universal galvanometer, a bridge rheostat, a reversing key and
four switches for changing circuits.
The Operating Boxes. These are of two kinds—multiple
cable boxes and key-board boxes. One of the former is required
for each grand group of mines. Only one of the latter is needed
at each station, to operate the entire system and to receive the
cables leading to skirmish mines.
Both patterns are of the same size, 22 inches by 74 inches by
7% inches, and they each weigh 24 pounds. When set for ser-
vice they may be closed and locked—thus excluding dust and
preventing unauthorized handling.
Multiple cable boxes contain seven magnets, each to operate
the three mines upon each core of the multiple cable. Two in-
sulated wires traverse the box longitudinally, with binding
posts at each terminal to permit adjacent boxes to be united in
series. One of these wires carries the current of the signal
battery, and the other that of the firing battery. Seven shunt
circuits in each box connect the signal battery wire with seven
binding posts to receive the seven cores of the multiple cable
leading to the mines of its grand group. These shunt circuits
each include one of the magnets, and a mercury cup at which
the circuit is broken when the armature of the magnet is at-
tracted by the flow of current caused by closing the circuit at
the torpedo. If set for automatic action, this motion of the ar-
mature after breaking the circuit of the signal battery closes the
circuit of the firing battery to the torpedo, and thus explodes
the charge; if not set for automatic action, the armature re-
mains vibrating and thus sounding an alarum until the circuit at
the torpedo is broken. This vibrating motion also drops a num-
ber shield, and thus indicates which group has been struck. If
any given gun plug be removed, and a wire leading to the
proper flanking guns be inserted in the corresponding binding
post, an enemy disturbing that part of the system will, without
exploding the mines, draw upon himself a discharge of canister
or case shot.
Key-board boxes contain six magnets arranged for the skir-
mish mines exactly as just described. The seventh magnet is
replaced by two permanent switches, one for the firing battery
and the other for the signal battery, to the zinc poles of which
their levers are respectively connected by leading wires. Each
(8)
30 S UJ; M.A R IN E MINING MA 7'ſ RIE. L.
switch has two circuits, to either of which its lever may be
turned.
Two of these circuits, designed for automatic action, connect
their respective batteries to the longitudinal wires traversing the
boxes. When thus connected the mines are set for automatic
action, as above described. When the signal battery circuit only
is closed, if a mine be struck the fact is reported by the sound
of the vibrating armature and the fall of its number shield, but
no explosion ensues. When both switches are open, the system
is entirely inert.
The other two circuits at the switches are designed for test-
ing. That for the firing battery opens a route for the current
through a piece of platinum wire (the counterpart of the bridge
of a service fuze) and thence through the resistance coils to
home earth. The number of ohms through which it reddens
the wire indicates the condition of the battery. The signal bat-
tery testing circuit conducts the current to the testing table,
where after traversing the desired instruments it returns to the
box and flows through the automatic circuit, as before.
For convenience in making sea-cell tests, a wire (under the
base board) unites the automatic post of the firing battery with
the testing post of the signal battery. One important fact must
be borne in mind in connection with this part of the sea-cell cir-
cuit—it shunts out the resistance (80 ohms) of the magnets.
This is necessary in order to secure a good galvanometer deflec-
tion with so feeble a current; but if the signal battery has too
low an internal resistance to be safely introduced into such a
circuit, the gun plugs must be removed before making insula-
tion tests with the signal battery, especially at the planting of
the mines. If this matter be neglected, and if an accidental
contact making good earth beyond the fuzes inside the torpedo
exists, the lever of the magnet in the operating box may vibrate
when the galvanometer circuit is closed at the testing table, and
thus by sending the signal battery current through this shunt
route may fºre the mºne. The removal of the gun plugs in
making these tests is therefore imperative; it does away with any
possibility of such an accident.
Mine numbers are nickle-plated discs with large figures
stamped thereon; they are issued separately from the boxes,
and are to be slipped over the brass shields in the operating
boxes, according to the system of numbering adopted.
MA. TAE I: TJ L OF T'JI E (JASE MA. T E. 31
Each switch and binding post of the operating boxes must
have a distinct label pasted on or near it. Printed slips are
supplied; they are to be attached with flour paste, and im-
mediately covered with shellac varnish.
The Disconnector. The object of this apparatus is: (1)
to break the circuit of the signal battery about one-tenth of a
Second after a mine is fired, in order to prevent neighboring
mines from being endangered by the shock transmitted to their
circuit regulators through the water—the circuit remains open
about six or eight Seconds and then automatically closes; (2)
to inform the operator that an explosion has occured, by the
continuous ringing of a bell so long as the signal battery circuit
remains open.
The zine poles of both batteries are connected to the home
earth through this apparatus. The firing battery simply trav-
erses the coils of an electro-magnet of low resistance. The
signal battery circuit includes two platinum tips, which are held
in contact by a projection from a wheel connected to a clock
movement. The motion of the armature of the electro-magnet,
caused by the passage of the firing battery current, releases this
wheel, sets the clockwork in action, and thus opens the circuit
of the signal battery until the wheel has completed one revolu-
tion. During this revolution the clockwork rings a bell
continuously. A cam on the wheel restores the armature to its
original position in time to engage the stop, and check the revo-
lution at the point necessary to again close the circuit of the
signal battery.
The Firing Key. This is a reversing key, held in position
by a stiff spring which may be overcome at pleasure by pressing
a lever. The leading wires from the firing battery traverse it
before reaching any other part of the apparatus. Depressing
the proper armature in the operating box, and reversing the
current by this lever, will explode the corresponding triple
group of mines. This apparatus (which is simply a current
reverser) was designed to permit firing by judgment with all
possible promptitude.
The Resistance Coils. This apparatus is a box of re-
sistance coils arranged to allow any desired number of ohms less
than 160, to be unplugged at pleasure. The wire of the coils is
sufficiently coarse to permit them to carry the current of the
firing battery without injurious heating.
32 S UB MA 1: I W H MINING MA. T ſº I, II, L.
The Firing Battery. Most of those in depot are of the
Leclanché type—fluid, a Saturated Solution of ammonium chlo-
ride; positive plate, cast zinc in the form of a hollow cylinder,
with six vertical cuts to increase the exposed surface and facili-
tate the motion of the fluid; negative plate, a carbon slab
embedded in a mass of peroxide of manganese and crushed car-
bon, contained in a flannel bag.
A later pattern contains a cylinder of rolled zinc, and a cen-
tral carbon hexagon grooved on each side to fit a cylinder of
compressed peroxide of manganese and carbon, 6 inches long
and 0.9 of an inch in diameter. These cylinders are held in
position by a couple of thick rubber bands, which also serve to
prevent contact with the zinc plate. Each cell is of ebonite, 4
inches in diameter and 74 inches high.
The battery is put up in stout boxes each containing ten
cells coupled permanently in series, with two terminals outside.
These boxes each weigh 110 pounds, being 27 × 12 × 11 inches
in size. Ten of them constitute the battery for an ordinary
station. They should stand on narrow strips of wood nailed
to shelves and coated with paraffine. The power of such a
battery in good order is represented by the following formula;
in which C represents the current in ampéres, and R, the ex-
ternal resistance in ohms:
C = ...”. .
30 + R,
For further details respecting firing batteries see Abbot’s
Moſes on Flectricity, especially pages 47, 52 and 72.
The Signal Battery. Any form of sulphate of copper
battery with an internal resistance not exceeding 5 or 6 ohms
per cell, will suffice. At large stations it is advantageous to re-
duce this resistance—which may be done by using the following
form devised by Captain de Wolski of the Royal Engineers.
The jars are of glass, holding about two and a half quarts of
fluid. There are two porous cups, one within the other. The
zinc, in the shape of a stout rod, is set in a dish of mercury in
the inner cup. The solution is dilute sulphuric acid, one part
to twelve of water. The copper plate and the sulphate of
copper are contained in the outer glass compartment. Every
two or three days, the solution between the porous cups is with-
drawn and replaced by fresh fluid, thus preventing infiltration of
cupric sulphate to the zinc compartment. By this devise great
MA 7'ſ I: IEL OF TIII) CASF, MA. T. E. * Q Q
* } .
constancy of action is secured; with large copper plates the
internal resistance can easily be reduced to one ohm.
Any copper appearing on the porous cups should be covered
with marine glue at once.
For further details respecting signal batteries, see Abbot's
Notes on Electricity, pages 63 and 72; also consult the foot note
on page 18 above. *
The Testing Battery. A small and portable pattern of
Leclanché cell is in store at the Willets Point depot for issue.
The battery is contained in a box 9 × 4 × 6 inches in size; with six
triangular ebonite cells connected to seven exterior binding posts
So that any of them, or any number of them, may be used at
pleasure. The internal resistance is about 10 ohms per cell. The
boxes are issued charged ready to receive pure water; about a
fluid ounce should be poured into each cell through its filling
hole, which should then be loosely corked, The formation in
store of troublesome oxychloride crystals on the zincs, may ren-
der the cleaning of this battery necessary when first received.
Another and perhaps better form of testing battery is the
chloride of silver pattern (6 cells) described in Abbot's Motes
on Electricity, page 57.
Earth Plates. The home earth at a torpedo station must
receive very careful attention. Experience * has shown that
there is danger that an earth plate connected with the casemate
by a single wire, in the usual manner, may be partially or com-
pletely detached by rust or accident; and such an occurrence
(not always easily detected ) would be fatal to efficiency, since
it would introduce so great a resistance into the circuit that the
firing battery could not explode the mines.
* For example, in September, 1875, the home earth at Willets Point con-
sisted of a slab of cast iron, exposing 250 square inches of surface, buried in
the mud near a pile of the wharf, and connected with the laboratory by a No.
10 B. W. G. galvanized iron wire. The connection to the slab was a large mass
of solder holding a short piece of the wire, which was joined to the land line
by a good telegraph joint spiked to the pile just above low water mark. This
had been in position for two or three years, (giving a normal resistance of
three or four olims) when some obscure difficulty appeared in the Fort
Schuyler circuit. At times everything was right, but at others a large re-
sistance was noted. Investigation showed that the state of the tide exerted
a marked influence; and finally it was discovered that the telegraph joint on
the pile had rusted to such an extent as to give a resistance of 80 ohms when
wet, and of 50,000 olyms when dry. This joint was well made with fourteen
turns of the wire.
(9)
34 S UJ; MA R IN E MINING MA 7'ſ. R T E L.
It is recommended that the shore ends of the armor of one
or more of the submerged multiple cables be soldered together
and used as the main plate at torpedo stations. The armor of a
mile of submerged single conductor cable has a resistance of
only about 1% ohms, and that of a multiple cable has less.
The home earth plates used in sea-cell tests should be placed
in the sea at the nearest and, most secure point, where frequent
inspection can be made. The plates should be about 6 inches
by 6 inches, and they should be kept clean.
The following experiments upon the resistance of copper and
tin earth plates in salt water, were made at Willets Point in
April, 1876. The plates were placed in the sea. One was 2
feet by 2 feet in area, giving 576 square inches of active sur-
face. The other was varied in size, giving the following results
for the joint resistance.
Active surface of 18 square inches gave a resistance of 3.51 ohms.
g
{ { & 4 72 “ . . . . & g 1.88 “
“ 126 “ . . . . ( & 1.57 “
“ . . 252 “ . . . . & © 1.42 “
“ “ 576 “ . . . . 6 & 1.07 “
“ 1152 “ . . . . & & 0.50 “
Two copper plates (3 inches by 3 inches) each having an
active surface of 9 square inches, opposed at twenty yards dis-
tance, in sea water, gave a joint resistance of 20 ohms (10 to
each). Such a plate is used for boat tests in planting mines.
The earth resistance of service mines planted in salt water
has been repeatedly measured, and its normal value is about an
ohm. º
The end of a torpedo cable left in the sea after an explosion,
usually shows a clean cut exposing but little copper, and gives
a resistance which often exceeds 100 ohms. The following
numerical values of this resistance are derived from measure-
ments made upon the cables of service mines immediately after
explosion: 130 ohms; 37 ohms; 6 ohms; 107 ohms; 118 ohms;
104 ohms; 133 ohms. º
The Detector. This instrument is designed to verify the
continuity of circuits. It consists of a galvanoscope with a
couple of small Leclanché cells in a compartment at the base
of the case. The needle is weighted in a vertical position. The
resistance of the coils is about 120 ohms. The circuit between
the terminals includes the galvanoscope and the battery.
To prepare it for use, open the back slide and remove the
MA. Tſº R TE I, O If TII R' ('A SEMA TE. 35
battery; charge each cell with about half a fluid ounce of pure
water; replace the corks; see that the connections are made;
and return the battery to its place in the case. If sluggish,
open the cells and clean the Zincs.
In using the instrument, avoid tºpping it and see that the
easterior circuit is kept open except when in use. Always raise
the detector by the ring on top.
The Bradley Galvanometer. This instrument is a four-
coil tangent galvanometer of peculiar construction, which has
been modified at Willets Point for use in ordinary rough test-
ing in the operating casemate. It is fully described in Abbot's
Notes on Electricity, page 92.
Siemens Universal Galvanometer. This instrument is
a sensitive galvanometer, combined with a Wheatstone bridge
having one fixed and two variable sides. It is used for the deli-
cate testing at torpedo stations, and is fully described in Abbot’s
Motes on Electricity, page 89.
The Bridge Rheostat. The form of bridge rheostat issued
to our torpedo stations is that used in the Post Office service in
England, and the instruments now on hand (1887) indicate B.
A. ohms. To transform a reading to the legal or Paris ohm,
multiply by 0.9888. The instrument as made in England con-
tains no binding post between the A and B sides. This post
is a great convenience, but must be especially ordered in all
purchases for our service. The instrument belongs to the class
in which two sides are fixed while one varies. It is so arranged
that the A and B sides may be either 10, 100 or 1000 ohms at
pleasure; while in the set of coils representing the R side, any
number of ohms from 1 to 11,110 may be unplugged.
For full details see Abbot's Wotes on Electricity, page 109.
The Reversing Key. The form of reversing key supplied
to torpedo stations is that used in transmitting telegrams through
submarine cables; although more complex than necessary for
simple reversing, this pattern is convenient for other uses.
The stand is of ebonite, carrying two transverse strips to
which the poles of the battery are connected. Two contact
pieces are kept pressing by their elastic force under one of these
strips; by their binding posts they may be connected to the
bridge rheostat in such a manner as to render unnecessary its
right hand contact key. By pressing upon the ebonite head of
either of these contact strips, the other remaining as before, the
36 S UIR MA. I. IN 1) M IN ING MA. T ſº Jº II) L.
battery circuit is closed. The direction of the current, of
course, depends upon which is depressed; rapid reversals may
thus be made. The circuit of the galvanometer is closed, as
usual, by the left hand key of the bridge rheostat.
Switch Keys and Switches. The object of these devices
is to control the route of the testing currents in the simplest and
most expeditious manner. Their construction requires no special
description.
Casemate Cable Tags. These tags are cylinders of lead
about three inches long, cast with a hole through the axis,
which will allow a 4% inch leading wire to pass easily. They
are bevelled slightly at the ends, and are painted red with
French varnish. They are numbered consecutively by figures,
printed with black varnish, ranging from one to the whole num-
ber of mine leading wires leaving the casemate. This form of
tag slipped over the ends of the mine leading wires, and wedged
fast at a convenient distance between the table and floor, can
never be displaced ; and its weight is handy in detaching cables
in testing.
Wheatstone Dial Telegraph. This instrument is used
to connect the mining casemate with the station of the com-
manding Engineer in action; and, in general, for telegraphing
wherever noise might interfere with conversation by telephone.
For a description of its internal mechanism, with directions for
its adjustment and ordinary repairs, consult Abbot's Notes on
Electricity, Chapter VI. The directions for ordinary manipu-
lation there given are repeated here, together with a special code
for use in submarine mining. *
MANIPULATION. When using the apparatus, one terminal is
put to earth and the second to an insulated wire extending to
the other station, where a duplicate instrument is arranged in
like manner. -
When the apparatus is thus connected, each operator has only
four movable parts of mechanism to control; understanding
them, practice will soon make any one proficient.
The four movable parts are: first, the crank, which is to be
kept revolving uniformly and with but moderate rapidity in
the direction of the hands of a watch, during the whole time
of signaling. An alternating current of electricity is thus gen-
erated, which follows one of three routes. If the index be held
fast by any depressed button, the current is confined to the
MA. T.I., R TEL OF T II E' ('A S E MA. T E. 37
instrument itself and traverses neither its receiver, its bell, nor
the line. If the button be raised, the index moves and the
current passes to the line through one of the other two routes,
depending upon the position of the switch. If the switch lever
be up, the receiver magnet is thrown into the circuit and its
index moves; if the switch lever be down, the bell magnet is
thrown into the circuit and the bell rings. The effect at the
distant station depends entirely on the position of the switch
there; if its lever be up the receiving index moves; if down,
the bell rings. The sender has no control or knowledge of this
matter.
The second movable part is the switch. It must always be
either hard up or hard down; the effect of these positions upon
the circuits has been explained above. The lever must be
handled delicately to avoid distortion, and the contact points
must be kept bright. In a word, good contacts must be made
by the lever, or the circuit is broken and communication
becomes impossible. Stupidity here causes much trouble; and
if no circuit be indicated (the bell or receiving index remain-
ing mute when the transmitting index revolves), the switches
should always be examined first.
The third movable part is the system of buttons; before the
revolution of the crank ceases, the button opposite the + should
always be depressed, and the index be left at rest against it.
To send any letter or figure, depress its button and wait until
the index is stopped there. If both switches are up and the in-
struments are in unison, both of the receiving indices will point
to the desired letter or figure. Sometimes in damp positions a
slight shock may be received on touching a button; this will be
prevented by wearing a dry glove, or by interposing any insulator
between the finger and button.
The fourth movable part is the small lever under the receiving
dial. This is designed by a gentle backward and forward move-
ment to mechanically advance the receiving index step by step,
and thus bring it into unison with the index of the transmitter.
. The receiving index being also under the control of the distant
operator, is liable to move through his agency; its position
therefore should not be shifted except as prescribed below for
getting into unison. -
INSTRUMENTS AT REST. The instruments should always be
left with both indices at the +, and ordinarily with the switch
(10)
38 SU B MA RIVE MINING MA. T.K. R.I.E.L.
lever depressed; but if they are to be watched, time is saved by
leaving the switch levers up. The motion of the receiving in-
dex makes sufficient noise to attract attention at two or three
feet distance, and no shifting of circuits will be needed.
To CALL THE DISTANT STATION. Raise the + button, revolve
the crank about half a dozen times, depress the + button, and
when the index comes to rest, stop turning the crank and await
a reply. If the circuit be good, the home bell has rung or the
home receiving index has revolved, according to the position of
the home switch.
At the distant station the effect will be governed by the
position of the switch there. So soon as the sound ceases, the
distant operator exactly follows the above directions. The
return signal being received, the caller has again the right of
way; but he should wait long enough not only to raise his
switch and see that his two indices are in unison, but also to
give ample time for the distant operator to do likewise. IIaste
causes loss of time. The next step is to get in unison.
To PLACE TIIE INSTRUMENTS IN UNISON. The calling oper-
ator sends the sign + twice. At the distant station the receiving
index may stop twice at any place on the dial; if this be else-
where than at the +, the operator brings his index there by the
small lever, and then sends back the sign + twice. If the
caller receives this signal at the +, the instruments are in unison ;
if not, he repeats. So soon as unison is obtained he has the
right of way.
With instruments once correctly adjusted, unison should never
be lost if the operators take care always to turn the crank uni-
formly ; to leave the index of the transmitter at the + in
passing from the bell to the sending circuit; and after inter-
rupting to stop at the + and to bring the receiving index to
the same by the lever. If, therefore, in sending a message
unison be suddenly lost, it indicates that something is wrong in
the apparatus. The difficulty will usually be caused by a dirty
switch, which a little polishing will correct; but if not, the fact
should be reported to the officer in charge who should be able
to detect and correct the trouble after examining the internal
mechanism. Experience has shown that only after long wear,
or clumsiness in repairs, is an interruption of this kind likely to
OCCIII".
MA. T 16 RIAE L OF T H E G A S E M A T'J'. 39
When first set up it may be impossible to place the instru-
ments in unison, one always lagging one letter behind the other.
This is corrected by interchanging the earth and line wires of
the instrument at the subordinate station.
After unison is established the message may be sent either by
code signals or by the alphabet; when by the alphabet (except
messages acknowledged) the first letter must always be preceded
by the signs + + +. The receiver is thus informed in advance
that the message is to be spelled letter by letter.
To TELEGRAPH BY ALPIIABET. Messages (preceded by a triple
+ as above) are sent by revolving the crank steadily and press-
ing down successively the buttons opposite the proper letters,
taking care to wait until the index of the transmitter comes to
rest before touching the next button, To send the same letter
twice in succession, touch a preceding button and then the right
one before the index has had time to arrive. To mark the ends
of words, stop at the + ; and at the end of the message stop
twice at the same character. As soon as a message is received
and understood, signify the fact by sending back the letters O K.
If the thread of the message be lost by the receiver, it be-
comes necessary to interrupt the sender and make him repeat.
This is done by revolving the crank, seeing that no button is
down. The effect is to give a continuous revolution to the re-
ceiving index at both stations; which will soon attract the
attention of the sender, as will appear by his ceasing to signal.
The instruments are then placed in unison by the sender as
above described (he having the right of way), and the message
is repeated, beginning with the sentence which was interrupted.
In transmitting messages containing many numerals, it may
be convenient to use the inner circles on the dial plates, where
the right hand figures are to be used to denote numbers (the
left hand figures are reserved for code combinations). The
intention to pass from the outer to the inner characters is signi-
fied by stopping four times at the + ; and to return to the outer
characters, by stopping three times at the +.
After a little practice abbreviations will suggest themselves,
but the details are so easily arranged between the operators
that no directions are needed here. -
Messages may be sent by the alphabet with considerable
speed; but in action, and in the preparatory drill, greater
40 S UB MA R IN E M IN ING MA. T ſº I, IE L.
promptness is needful. This is secured by the use of a special
code.
To TELEGRAPH BY THE SERVICE Copſ. The instruments must
have been put carefully in unison; and, with the switches up,
the operators fix their eyes on the receiving dials. All signals
now refer to the inside characters—the right hand figures
denote the mine groups, each being designated by its number;
the left hand figures are used for the abbreviated code given
below. After sending a message the stop is always to be made
at the +.
Should either operator desire to send a message not provided
for in the code he will stop three times at the +, after which
his signals will be read on the alphabet; but every message so
sent must be preceded by a triple stop at the +.
In every case whether in action or at drill, all code messages
must be instantly repeated by the receiver for verification.
The following is the regular code for action. By a further
combination of numbers it may be extended indefinitely; but,
to avoid complexity it should be restricted to urgent messages.
THE COI) E FOR ACTION.
11. See that circuit of firing battery is broken at its switch.
22. Report number of any group struck, and prepare to fire it.
33. No vessel near—find out difficulty and report.
44. Friend—let pass.
555. Enemy is over the mine—fire.
666. (Adding number in right hand figures). Prepare to fire group
No. When I am ready, message 555 or 44 will be sent, accord-
ing to circumstances.
777. Automatic adjustment to fire flanking guns if torpedoes or cables be
disturbed.
888. Automatic adjustment to fire the mines—enemy approaching.
121. Trouble here requires your presence.
131. My message was not understood—I now repeat it.
141. Your message is not understood—please repeat.
151. Leak in torpedo.
161. Loss of insulation in cable.
171. The circuit is broken—end of core insulated.
181. The cable has parted—end of core in water.
Tool Box A for Casemate Use. To repair the apparatus
in use in the casemate, and to enable the electrician to perform
his special duties in planting the mines, “tool box A* is pro-
vided—the following are its contents.
MA. T. ſ. It IEL OF T'ſſ E L OA DIW (; R O O M. 41
T()() L I3() X A.— MININ (; CASEMA'ſ' E.
1, back saw. 1 glue pot.
1 hatchet. 1 rule.
1 mallet. 1 oiler.
1 riveting hammer. 1 oil stone.
2 Screw-drivers. 12 camels' hair pencils, assorted.
1 4-inch chisel. 1 dust brush for apparatus.
1 shears. 1 mercury bottle.
1 Stevens vise, 1 safety ring mould for self-acting mines.
1 hand vise. 1 safety plug wrench for ditto.
1 monkey wrench. 1 blow pipe. -
1 S wrench. 1 nest small evaporators.
3 files, flat, triangular and round. 1 spirit lamp. jº
2 die sinker's files. 1 two ring stand for spirit lamp.
3 cutting plier8. 1 Wedgewood mortar and pestle.
4 gimlets. Resin.
1 brad-awl set of 20 tools. Shellac.
1 soldering copper. Solder, 4 oz.
There are many supplies such as marine glue, resin and bees-
wax cement, etc., needed occasionally in the casemate ; they
will be drawn from the loading room.
MATERIEL OF THE LOADING ROOM.
As already stated the word mine technically includes the
metallic case containing the charge, its contents, its wire mooring
rope and its anchor; the word torpedo is restricted to the
metallic case containing the charge.
The matériel of the loading room includes buoyant torpedoes,
charge bags, self-acting torpedoes, circuit closer buoys, ground
torpedoes, circuit closers, circuit regulators, electrical fuzes, ex-
plosives, switch boxes, and the various tools and supplies used
in loading. Each will now be described in turn.
The Buoyant Torpedo. A good buoyant torpedo must
fulfill certain conditions, which will be recapitulated here to
assist in improvising matériel when necessary so to do. They
a PG :
First. The power of enduring long continued exposure to
the action of sea water, the attacks of marine animals and con-
stant motion. Experience has shown that wood soon becomes
water-logged, and is liable to be rendered leaky by worms; that
if the material be metallic and not homogeneous, voltaic action
induces rust—even rivets are objectionable in this respect; that
screws either inside or outside the torpedo, if not clamped by
(11)
42 S Uſ? MA R IN E MINING MA TÉIRIE L.
set screws, are frequently loosened by the continued oscillation
due to waves and currents; lastly, that few if any paints will
long resist submergence in sea water. Upon the whole, open
hearth steel galvanized, or primed with red lead and painted
with two coats of good white lead and raw oil, toned down to a
neutral grey with lamp black, combines economy, endurance
and strength better than any other material. The painted sur-
face soon becomes coated with rust, marine shells, etc., after
which the progress of corrosion is slow. For instance, a sub-
mergence of a ſº-inch torpedo for about five years at Willets
Point, did not occasion any leakage.
Second. The strength to resist unavoidable blows from
friendly vessels. In time of war such blows would, of course,
be reduced to the minimum by requiring all vessels to slow
down their speed to the lowest limit necessary for steerage way
when passing the mines, but with every care severe shocks could
not be avoided.
Third. The strength to resist the explosion of a neighboring
mine, after allowance for slight errors in planting which might
reduce their normal distance apart. Experiment has established
that the approved pattern of buoyant torpedo is unaffected by
countermine explosions of 100 lbs. of dynamite at a distance of
40 feet, or of 500 lbs. at 80 feet, both torpedoes being 10 feet
or more below the water surface. This strength is ample, the
normal distance between mines being 100 feet.
Fourth. A form which shall combine the following merits—
1st, a symmetrical shape with respect to a vertical axis, in order
to eliminate so far as possible all tendency to twist the moor-
ings; 2nd, the maximum attainable displacement, the minimum
weight and cross section, and a smooth surface to resist the de-
pressing effects of currents; 3rd, freedom from rivets, or other
causes of leaks; 4th, convenience in handling and loading.
ſºft/. An arrangement by which the electric cable can be
Securely attached by its iron armor, leaving the short exposed
end of the core encased in a box that will protect it against
stresses or mechanical injuries,
Sºwth. Internal arrangements which : (1) shall protect the
fuze wires against stresses from movements of the charge
caused even by severe concussions; (2) shall ensure the prim-
ing against dampness; (3) shall hold the circuit regulator
firmly in position ; and (4) shall facilitate electrical tests.
MA. T J R TJJJ, O F T'JI E L () A D IN (; Jº O O M. 43
Seventh. A judicious economy of construction.
All these conditions, with others of minor importance, are
fulfilled in the following approved patterns.
THE SERVICE 32-INCII PATTERN. The material for our adopted
32-inch pattern (Plate IV, figure 1) is 10-pound open hearth
steel (4 of an inch thick) of great toughness and elasticity. The
shell consists of two hemispheres ribbed and welded together at
the equator, thus avoiding all rivets. Every torpedo before it
is accepted, is to be tested with an internal hydraulic pressure
of 120 pounds per square inch.
The top hemisphere is provided with an external manoeuvring
ring; the bottom hemisphere is pierced at the pole by a hole
5% inches in diameter. The edge of this hole is reinforced by a
welded ring 1.5 inches thick; and near it are four bosses, also
welded, carrying screw bolts which project 24 inches outside to
secure the cap.
The uses of the cap are to clamp the turk's head of the elec-
tric cable; to cover and protect the portion of the core exposed
outside the torpedo; and to serve as an attachment for the wire
mooring rope. The cap consists of a hemisphere of 15-pound
wrought iron ($ inches thick) flanged and dished at the base to
fit the torpedo—to which it is attached by the four bolts already
mentioned. They pass through slots in the flange, which is then
held in position by four screw nuts, keyed down. The water,
of course, has free admittance to the chamber inside the cap.
The end of the electric cable is thrust through a hole at the
pole of the cap, and a turk's head is made upon it, and secured
by the clamp—which consists of two jaws, one movable and the
other fixed, held together by two screw bolts and nuts. In a
few torpedoes a second clamp is provided in the side of the cap,
for use when the circuit regulator is placed in a separate buoy.
The mooring attachment consists of a ring of inch and a half
wrought iron, having a clear hole 24 inches in diameter. It is
attached to the cap by three bales of one inch wrought iron,
permanently doubly riveted to the sides. -
The large hole in the torpedo, covered by the cap, is closed
by a wrought iron annular plug screwed into the bossing. The
joint is made water tight by a lead washer jammed between the
plug head and shell, and by a coating of red lead upon the screw
threads. Inside the torpedo, the annular plug carries a shank
to which a canvas bag to receive the charge is lashed by marline
44 SUB MA R IN J. MINING MA T'ſ, R J E J.
or wired. A hole three inches in the clear, cut with a screw
thread, is made through the middle of the annular plug. After
the charge has been inserted through this small hole, it is closed
by what is known as the compound plug.
The uses of the compound plug are; 1st, to close the loading
hole against leakage: 2nd, to protect the fuzes bedded in a loose
charge of dry dynamite, against mechanical injuries to their
connections; 3rd, to hold the circuit regulator firmly in position,
near the middle of the torpedo; 4th, to introduce the core of
the electric cable without also admitting water; 5th, to form
part of the torpedo earth plate.
To accomplish these objects, the compound plug consists of a
wrought iron plug screwed tightly into the small hole in the
annular plug, with a lead washer and a smearing of red lead to
exclude water; of a cylinder of stout brass, large enough to
contain about a pound of dynamite, the fuzes, etc.; and of the
circuit regulator. These parts are either brazed together, or
Screwed together and held fast with set screws—as experience
has shown that the continual motion of the torpedo will ulti-
mately loosen any simple screw coupling. The insulated wire
for carrying the electric current passes through a hole in the
wrought iron plug to the fuze can, and thence to the circuit
regulator—its whole length being thus protected against injury.
Where it enters the torpedo, and where it enters the fuze can,
it passes through stuffing boxes to exclude water. Lastly, from
its intimate connections with the torpedo, the compound plug
makes an earth plate, of which the electrical resistance in Salt
water does not exceed about an ohm.
When the buoyant torpedo is used with a detached circuit
regulator, a cap having a second cable clamp (many do not have
them) and a plug which will allow the electric current to pass
in to the fuze and out to the regulator, are needful. The
plug belonging to the ground mine serves the latter purpose,
and is made to fit either torpedo.
LARGER SIZEs. In the strong currents and deep water of
Some harbors, more buoyancy than is possessed by the 32-inch
torpedo is required. This is obtained by inserting a cylinder of
20-pound wrought iron between the hemispheres, stiffened by
extra welded ribs for the larger sizes; all other details remain
unchanged. Such torpedoes are designated by the diameter in
inches of spheres having the same buoyancy. Thus a No. 40
MA. Tſº RIE L OF TIIE, L O A D IN G R O O M. 45
torpedo is a 20-pound wrought iron cylinder with hemispherical
ends of 10-pound steel 32 inches in diameter, having a displace-
ment equal to that of a spherical torpedo 40 inches in diameter.
The following table exhibits the dimensions and weights of
buoyant torpedoes, complete except the charges and moorings.
For each pattern now in store, the mean of ten measured weights
is given. The actual free buoyancy when planted, will be the
difference between the displacement and weight as given in the
table, reduced by 100 pounds for the charge and by 1 pound
per running foot for the moorings and electric cable.
T)IMIENSIONS OF HUOY ANT TORPEIOO ES.

--- --------
+3 Ł £ + |
ſº ºf 2, rc Q, ; :
Q9 3 = £ 3
B 23 d5 - G) 3 : |
NO. Qi.) P- - (A) , e. a; RCInarks.
: 33 #: £º: ;
p-4 O tº-1 & *n ºf
ź &# z; # =
3. : 2 | *
lbs lbs lbs feet H
32 635 297 300 0 || All are about 33% inches in outside -
33 695 353 • * 4 • 0.17 diameter, the extreme length in
* each case is 4.3 feet plus the length
34 762 384 * e º e 0.35 Of the cylinder.
35 | 829 || 416 . . . . . 0.54 |
36 904 || 451 | . . . . . 0.75
37 982 487 . . . . . 0.96
38 1064 527 | . . . . 1.20
39 1149 567 | . . . . 1.43
40 | 1242 | 610 614 | 1.70 |
41 || 1341 || 654 . . . . 1.96
42 1436 || 701 | . . . . . 2.24 !
43 1540 777 748 2.53
44 1652 || 831 ... . . 2.77 | One extra welded rib. i
45 1767 865 . . . . 3.17 ‘‘ ‘ ‘ & & & |
i
$ 888 | Lot of 1879; one extra welded rib.
46 | 1887 | 941 3.50 |}}.} 1884; “ “ 4 * 4 &
47 2013 || 1000 tº a º e 3.85 One extra welded rib.
48 2144 1062 1026 4.20 ‘‘ ‘‘ & & & &
CoMPUTATIONS IN ORDERING TorpEDOEs. Buoyant torpedoes
of varying sizes are necessary to suit the requirements of our
different channels, and before ordering a supply for any harbor
it is needful to compute the proper dimensions from local data,
which will be furnished by the Engineer Department. The
weights of certain parts are constant for all approved patterns
(12)
46 S U B M A R T W ſº M IN ING MA. T ſº I. Iſ L.
of torpedoes, and these and other dimensions will now be stated
in a manner to facilitate such computations. sº
J%rst. The simple spherical shell, exclusive of all projections
and attachments. Denoting by r the radius in feet, and by s
(usually 10) the weight in pounds of a square foot of the steel
employed in the construction, the weight of this portion of the
torpedo (w'), and the area of a great circle in square feet (a (),
are expressed by the following equations:
70' = 4 T 72 &.
a ’ = 7: 7.2.
Second. The projections and movable attachments, which
are sensibly unvarying for all sizes of torpedo. Some of these
parts, such as the internal bosses (5 lbs.), the compound plug
(17 lbs.), the annular plug (11 lbs.), and the canvas bag (2 lbs.),
are inside the torpedo, and hence experience no diminution of
weight when submerged. Their total weight is 35 lbs. Other
parts, such as the cap and its attachments (34 lbs), the welded
ring (say 15 lbs), and the manoeuvring ring (1 lb.) lose about
one seventh of their weight in air, when placed in water; that
is, their total weight of 50 pounds in air should be taken at 43
pounds in buoyancy computations. Hence, the constant weight
(w”) to be added to that of the spherical shell is 35+43 = 78
pounds.
For the plane surface exposed to the current by the cap,
bales, etc., (a"), an allowance of 0.5 square feet is sufficient.
Hence for the weight empty (w), the total displacement (B),
and the section exposed to the current (a), we have:
(4) . . . w = w' + w” = 4t r*& + 78.
(5) . . . B = 64 × 47 r 3.
(6) . . . a = a + a” = t r* + 0.5.
When considering the problem of submarine defence at any
particular locality, it is needful (see Plate VII, fig. 3) to know
the minimum draft (d) of hostile vessels to be stopped by the
mines; the tidal range (T); the tidal level above low water (t)
corresponding to the known tidal currents (w); the depressing
effect (a) of those currents upon the torpedo; and the mini-
mum submergence (d") needful for water tamping and for
concealment. From these quantities, the overlap of the ship
upon the torpedo (d"), upon which its efficiency as an obstruc-
tion depends, may be computed for any known values of t and
w by the formulae:
MA T'ſ R IT, I, O F TH E L O A D J N (; 18 O O M. 47
(7) . . . . d" = d – (d" + 0 + t ).
The greater the arithmetical difference between the two
terms in the second member, the larger will be d" and the
better will be the chance of a contact; when these terms are
equal the vessel will only graze the torpedo, and a must if pos-
sible be reduced by providing more buoyancy. If d' +2+ t >d
a simple solution of the problem is impossible, and the defence
must include different systems of mines—the more advanced
adjusted for low water, and those in rear for high water.
A few words respecting the different quantities entering this
formula are not out of place.
The numerical value of d' is governed by the clearness of
the water and the size of the charge. In most of our impor-
tant harbors the neutral color of the torpedo renders it invisible
when submerged three feet, and this depth affords sufficient
tamping for a 100-pound charge.
The effect of currents to depress torpedoes (a) was studied
experimentally at Hell Gate in 1874, with results fully detailed
in Part II, Professional Papers No. 23 of the Corps of En-
gineers. Two kinds of oscillation are communicated by currents,
one a rapid vibratory movement about the position of equilib-
rium, the other, a gradual movement dependent upon the
variation in strength of currents at different tidal phases. The
former is rather advantageous for the defence in properly mined
zones; because several torpedoes must be passed, and each one is
as likely to be above as below the normal level when encoun-
tered. The latter oscillation is governed by local conditions;
but, in general, slack water occurs at the turns of the tide, and
the strongest currents occur after the ebb has been flowing for
a considerable time. Of course, no tidal depression of the tor-
pedo (a) is of importance unless it exceed the corresponding
tidal fall of water surface (T — t). In considering the subject
for any given channel, the local conditions favoring accumula-
tions of sea grasses upon the mooring rope, and animal and
vegetable growth upon the torpedo, must not be overlooked.
The following formulae (units: foot, pound and second) re-
sulted from the Hell Gate investigations, and are fully explained
in Part II of General Abbot's Report above named. In them
(Plate VII, figure 13) a denotes the tidal depression; y, the
tidal swing; }, the angle included between the mooring rope
(assumed to remain straight) and a vertical through the anchor;
48 SUR MA RINE MINING MA. Tſº RIE.L.
l, the length of the mooring rope (the depth of water at low
tide, less the length of the torpedo increased by the value adopted
for d’); a, the area of the mid cross section of the torpedo;
a", the sum of the diameters of the mooring rope and electric cable
(about 0.13 feet); B, the displacement of the torpedo; w”, the
weight of the mooring rope and electric cable, which may be
estimated at one pound for each foot of /; v, the velocity of the
current; and C the weight of the charge.
(s) . . tan 9–gºt "º")".,.
2[B — (70 + C + w”)]
(9) . . . . a = l (1 — cos ?).
(10) . . . . . y = 'sin Ö.
These formulae must always be applied before purchasing
torpedoes for any special locality, to determine whether the
proposed pattern has suitable buoyancy. --
JEXAMIPLE.
Let them be applied to the 32-inch service torpedo (4.3 feet long) made of
10-pound steel, charged with 100 pounds of dynamite, and anchored by
moorings 80 feet long in a harbor where the least draft of the hostile vessels
to be excluded (d) is 18 feet, where the tidal range is 8 feet, and where the
most unfavorable current occurs on the ebb at 2 feet above low water, when
the velocity is 3 feet per second.
(By Eq. 4) . . n-4-(;) io-is-so lbs.
(By Eq. 5) . . B=4x4-(; "=635 lbs.
(By Eq. 3) . . a = tr (#) +0.5 =0.1 Square ft.
6.1 + 0.13 × 80 cos 9) × 9 gº
By Eq. 8) tan & = (*! -H".” X***)^* = 0.178-1-0.304 cog 9.
(***) "" = gºfiºſº + 0.304 cos
Hence, S =24° 27'.
(By Eq. 9) . . . a = 80 (1 — cos & )7.2 feet.
(By Eq. 10) . . . y = 80 sin 9 = 33.1 feet. .
(By Eq. 7) d" = 18 — (3+7–H2) = 6 feet (most unfavorable).
(do.) . d" = 18 — (3+8) = 7 feet (high tide slack).
(do.) . d" = 18 – 3 = 15 feet (low tide slack).
These computations show that the normal overlap of the ship on this tor-
pedo will never be less than six feet, and that its extreme horizöntal distance
from the vertical (only important from its effect on judgment firing) will not
exceed aljout 33 feet. In other words, this pattern is well suited to the lo-
cality in question.
Conversely, the dimensions needful to fulfill certain desired
conditions may be computed by the following formulae—of
which a demonstration is given in Part II of General Abbot's
Teport referred to above.
MA. T 16 RIEL OF THE LOADING ROOM. 49
(11) . . . . r? – Ar” = A'.
(12) . . A = 0.0469 3 + *–
170.7 W 1–72
as 2 /// / Y
(13) . Aſ = " l, (0.5 +a" l!') +- C+88-|-l
536.2 VT-72 268.1
(14) . . . . . /, = ºr.
As this computation (unless the one indicated above shows it
to be unnecessary) is always to be made before ordering tor-
pedoes for a special locality, an example will be given. The
charge (C) is usually assumed at 100 pounds; but if it should
ever be desirable to vary this weight, the formulae provide for
so doing.
EXAMPLE: NARROWS, NEW YORK.
DATA: The minimum draft of the hostile armored ships is assumed at 18 feet;
the extreme tidal range is 7 feet; the most unfavorable currents occur on the
ebb within a foot of low water, when the velocity is 5 feet per second; a
minimum water cushion of 3 feet over the torpedo is here admissable; the
greatest low water depth in mid channel is 108 feet, giving: l = 108 – (4.3+.
3) = say 100 feet; the minimum normal overlap of the ship upon the tor-
pedo may be taken at 4 feet; such a value of 8 should be assumed as will
make the computed weight about equal to that of the service torpedo of
corresponding equivalent radius, or say in this case at 15 to be subsequently
revised. Hence;
(By Eq. 7) . . . a = 18 — (3 + 4 + 1) = 10 feet.
100 — 10
• – 'YY “Y = 0.9.
(By Eq. 14) ' 100
25 X 0.9
(By Eq. 12) . A = 0.0489.15+ → *== 1.006.
- 170.7 4/1 – 081
25 × 0.9 (0.5–1–0. 13 × 100 × 0. 00
(By Eq. 18) A = ** (0.5–H 8x10 ׺), ºf = 2.249.
536.2 4/1 – 0.81 º -
(By Eq. 11) . . . r" — 1.006 r? = 2.249.
q = 1.74 feet.
Next verify the correctness of assuming the value of 8 to be 15, as above.
(By Eq. 4) . . w = 4t (1.74) * 15 + 78 = 649 lbs.
The tabular weight (page 45) of a torpedo 41.8 inches in diameter (radius
1,74 feet) is about 690 pounds—showing that too small a value of 8 was
assumed. Repeating the computation with s = 18 gives:
(By Eq. 11) . . . r" — 1.146 rº = 2.249.
q = 1.82 feet. .
(By Eq. 4) . . w = 4r (1.82) * 18 + 78 = 827 lbs.
The tabular weight (page 45) of a torpedo 44 inches in diameter (radius
1,83 feet) is 881 pounds. Hence this size is plainly indicated by the com-
putations as demanded at this locality. Solving the above equations we have
for the characteristics of such a torpedo:
(13)
50 SUB MARINE MINING MA T'ſ, R.I.E.L.
(By Eq. 6) a = t (1.82)” ––0.5 = 10.9 square feet.
(By Eq. 5) B = 64 × 4 + (1.82)* = 1616.
_ (10.9–1–0.13 × 100 cos & ).25 R rac,
(By Eq. 8) tan 19 = 2[(1616–827–1–100-E100).] T 0.231 + 0.275 cos 9.
Hence, & = 25° 36'.
(By Eq. 9) a = 100 (1 — cos & ) = 9.8 feet.
(By Eq. 10) 3) = 100 sin 9 = 43.2 feet.
(By Eq. 7) d" = 18 – (3+ 10–1–1) = 4 feet (most unfavorable).
(do.) d" = 18 – (3-H 7) = 8 feet (high tide slack).
(do. ) d" = 18 – 3 = 15 feet (low tide slack).
The large value of y is noteworthy; it clearly demonstrates that judgment
firing must not be attempted with buoyant torpedoes planted in so deep water,
The following table contains data useful for reference in
making such computations. The results are first approxima-
tions (not revised for exact value of 8).

IDIMENSIONS ANI) ACTION UNI) ER V ARYING CONIOITIONS.
| common R. . #
* 3 # # | # 3.
# #3 || 5 c | #~ | g = | #~
# # 3 & # ſa | #3 & #5 s
‘; a. Q) S ää | # 3 S- || @ 3 : S-
3 3 à || 3: § § ºr.
= ſº * ſº <!
feet. feet. feet. lb.8. inches. lbs. lbs. O feet.
40 9 5 10 31.1 283 433 39 25
{ % 9 6 10 32.9 308 539 39 25
50 {) 3 10 29.3 259 327 35 29
& 4 9 5 10 32.6 304 514 35 29
& 4 9 5 20 39.0 734 988 35 29
{ { 9 6 10 34.8 337 658 35 29
& & 9 6 20 41.3 818 1208 35 29
£ 6. 8 8 20 48.2 1088 2017 33 27
60 9 5 20 40.4 785 1108 32 32
“ 9 6 20 43.1 885 1386 32 32
70 9 5 10 35.5 347 688 29 34
“ 9 ſj 20 || 41.8 834 || 1232 29 34
“ 9 6 10 38.2 394 918 29 34
{ { 9 6 20 44.8 949 1565 29 34
80 9 5 : 10 36.6 364 '760 28 37
{ % 9 5 20 43.1 881 1361 27 37
£ 4 9 6 1() 40.2 425 1070 28 37
& & 9 (; 20 46.5 1018 1765 27 37
© g 8 8 20 56.2 1447 3245 26 35
100 9 3 10 33.1 311 493 24 41
« g 9 5 10 39.6 414 994 24 41
{ { 9 5 20 45.6 980 1630 24 41
120 9 5 20 48.0 1078 1914 22 44
300 9 9 20 101.5 4980 20280 14 69
MA. T K R II, L OF TH E L O A D ING ROOM 51
Charge Bags for Buoyant Torpedoes. These bags are
used to hold the explosive loosely about the priming charge, and
to separate it from direct contact with the metallic case. They
are made of No. 10 canvas for the bottom, sides and top; the
neck and top ring are reinforced by No. 1 canvas. All seams
are inside and must be of thoroughly good workmanship.
The bottom consists of a circle of canvas 19 inches in diameter
(when sewed); the top consists of a circle of canvas 9 inches in
diameter (when sewed); these parts are united by a cone of
canvas 20 inches long, measured on the sewed side.
The top is centrally pierced by the neck, 2 inches high and
44 inches in diameter, designed to closely fit the neck of the
annular plug of the torpedo; which is conical, sloping from a
diameter of 44 inches to 3% inches in a length of 14 inches—a
ring below the smaller end, 4} inches in diameter, supports the
marline lashing. The canvas neck has a longitudinal slit to ad-
mit of being closely fitted to this surface.
The Self-Acting Torpedo. The self-acting class of mines
is used (1) to block all passage through channels not needed for
our own use; and (2), when admissable, to obstruct under cover
of night or fogs such buoyed passages in a mined zone as the
enemy may have succeeded in opening by countermines.
To accomplish these objects, the best improvised patterns, al-
though perhaps serviceable in rivers or quiet waters, should not
be trusted on the sea coast. Simplicity demands that so far as
possible the approved matériel of the service shall be inter-
changeable. Hence, the pattern of the ordinary buoyant torpedo
has been adopted for self-acting mines; and special parts needful
to equip it for use without shore connections, have been devised.
Beside the ordinary requirements of a good buoyant mine,
the following must be fulfilled by the self-acting class.
First. Entire safety in handling and planting—which im-
plies an automatic removal of the safety device after the mine
7s in place. Trustworthy certainty of action when this removal
has been effected is of course implied.
Second. The greatest possible difficulty in removal. Sooner
or later the enemy will learn the secret of any mechanism, and
what we can recover with ease cannot be made difficult for him
to remove or destroy. Hence, easy raising is incompatible with
efficiency, and must be sacrificed.
Third. Any buoyant torpedo is liable to be set adrift by the
52 S U B MA R IN E MINING MA TF RIE L.
rusting off of the mooring rope, and then to be swept by the
tide among our own vessels. Effective provision must be made
against this chance, which with self-acting mines might involve
great dangers.
These three special requirements are met in the adopted pat-
tern: (1) by a special cap containing a battery and safety break,
which takes the place of the ordinary cap; (2) by an inverted
circuit closer in lieu of the usual pattern; and (3) by anchoring
the torpedo by its usual lowering ring—thus inverting its
normal position. .
The special cap has the form of a truncated cone, 94 inches
in diameter at the torpedo, 8 inches in diameter at the top; and 94
inches in height—not including a lowering ring which adds 34
inches more. The weight complete in air is 50 pounds, in water
43 pounds. The mode of attachment to the torpedo is identical
with that of the usual cap; and the weight and shape are so
similar that no recomputations for flotation are needful.
As above stated, this cap contains a battery and a safety break.
The battery consists of two chloride of silver cells, described
in Abbot's Motes on Electricity, page 59. They are packed in
paraffine and sealed inside a brass case, which in its turn is en-
closed in a water tight battery box of iron bolted to the inside
of the cap (see Chapter IV for full directions for inserting).
One terminal wire of this battery is connected inside the cap
to an insulated wire leading through the single fuze to the cir-
cuit closer and (when the latter is closed) to the metal of the
torpedo; the other terminal is connected to the metal of the cap
through the safety break. The circuit of the battery is thus
complete except at two breaks; when both are closed the tor-
pedo is fired, but so long as either is open no explosion is
possible.
The safety break consists of a brass case screwing into the
boss of the cap; a stiff brass spring; a sliding cylinder pressed
down by the latter; a soluble safety ring; * a brass closing ring;
* Many trials were made to determine the best composition and mode of
preparation of the soluble rings. All attempts at casting them in a mould
failed to give good results. Pulverizing, mixing with a thick solution of gum
arabic in a mould and then drying was finally adopted. Rings made in this
manner with loaf sugar or common salt, keep the circuit open for about 10
minutes; rings of alum or zinc sulphate soften and yield irregularly by com-
pression when wetted. Potassium bichromate so readily forms a saturated
solution that in a confined space the time of closing the circuit varies from
MA T13 IRIE L OF THE J O A D IN G R O O M. 53
and, carried by the latter, a brass-ebonite plug containing a plat.
inized terminal and a platinized tip forming the end of the
second battery leading wire. The hole through this plug is
secured by rubber packing against infiltration of water. The
platinized terminal is attached to the brass-ebonite plug by a
piece of rubber tubing, which although it permits a slight
motion excludes water. So long as the soluble ring remains in-
tact no contact can occur between the platinized terminal and
the platinized tip; but when the ring dissolves (in from one to
two hours after submergence) the spring presses the sliding
cylinder down upon the platinized terminal and thus perma-
nently closes the break. -
These devices permit the mine to be planted in absolute safety,
and thus fulfill the first of the above conditions; so soon as the
ring is dissolved, any contact of a vessel with the torpedo will
close the circuit closer and thus fire the mine.
The second of the above conditions (difficulty of removal) is
fulfilled (1) by placing the battery in the cap, where no part of
its circuit can be reached until the torpedo is raised and opened;
and (2) by inverting the usual position of the torpedo, which
causes the charge (100 lbs.) to hang from the top. If, there-
fore, the mooring rope be severed by the enemy, the torpedo
shoots upward by virtue of its buoyancy (say 200 lbs.); and,
revolving at the same time to seek a position of equilibrium,
the circuit closer acts and the charge explodes—probably at or
near the surface of the water, sending fragments of iron in
every direction among the parties engaged in countermining.
This inversion of the torpedo also perfectly fulfills the third
condition (Security against drifting among our own vessels);
one to twenty-four hours. Cupric sulphate forms good rings which keep the
circuit open from one to two hours; but they are not easy to prepare. Mixed
with sugar this difficulty is overcome. One part by weight of sugar to two
parts of cupric sulphate give the best results. It is important to use the
minimum amount of gum arabic, because an excess causes the ring to warp
in making and to dissolve irregularly.
The adopted formula for the soluble rings (see Chapter IV for full direc-
tions for making) is 2 drachms of loaf sugar, 4 drachms of cupric sulphate,
and 1 scruple of an aqueous solution of gum arabic as thick as honey. This
makes one ring—which may be trusted to keep the circuit open after sub-
mergence for about an hour, and to close it within two hours; out of a series
of 24 trials in fresh water, the shortest observed time was 58 minutes, and
the longest 1 hour and 49 minutes, the mean being 1 hour and 22 minutes.
In Sea water, 14 trials gave an average time of 1 hour and 38 minutes.
(14)
54 S U B MA R IN E MINING MA TERIEL.
because, when the mooring rope rusts off, the mine destroys it-
self, as above, and therefore cannot endanger friendly shipping.
In fine, this pattern of self-acting mine is absolutely safe to
plant when care is observed in the tests given in Chapter IV;
it remains inert for about an hour after planting, and it becomes
active before the lapse of two hours. This range in time is
ample for most purposes. If a longer time be needed in any
special case, the Safety ring may be replaced by an ordinary
clock work set to close the circuit after any desired interval
—but the greater complexity of this arrangement would prob-
ably increase the chances of accident.
The Ground Mine Buoy. The external form and attach-
ments are identical with those of the buoyant torpedo, the
latter being interchangeable between the two models. The
same proof test is also exacted.
The internal arrangements are different, since no charge is to
be carried by the buoy. The annular plug and canvas bag are
omitted. The compound plug consists simply of the 3-inch
wrought iron plug, and of a pipe tinned into it carrying a
brass socket to hold the circuit regulator near the middle of the
buoy. Where the core of the electrical cable enters, a double
stuffing box is used to give additional Security against leakage.
For buoyancy computations, the same formulae are applicable
as for the buoyant torpedo, the only difference being in the
value of w”, which is 14 + 42 = 56 pounds.
The ordinary size of buoy adopted for our harbors, is 28
inches in diameter—giving a weight (cap, etc., in water), of
171 + 56 = 227 lbs. ; a free buoyancy exclusive of moorings of
426 – 227 = 199 lbs. ; and a plane section of 4.3 + 0.5 = 4.8 sq.
feet. The extreme length from the anchoring ring to the top
of the buoy is 4.0 feet.
Such a buoy anchored by moorings 30 feet long—correspond-
ing to a high water depth of 40 feet, a tidal range of 3 feet,
and a submergence at low water of 3 feet—would be deflected
by a 5-foot current 31 degrees, giving a depression of 4.3 feet
and a horizontal swing of 16 feet in any direction determined
by the set of the current. -
If the current be too strong for this size of buoy, a buoyant
torpedo may be substituted with a partial charge, live or inert
as preferred. The former would make the mine exceedingly
destructive in its effects. s
MA. Tſ’ RIEL OF THE LOAD ING ROOM. 55
The Ground Torpedo. The conditions to be fulfilled by a
good pattern of ground torpedo differ in so many respects from
those of the buoyant class, that a different model and another
material have been selected. These conditions are:
First. The capacity to endure long exposure to the corroding
action of sea water, and to the attacks of marine animals. Cast
iron is so much superior to wrought iron in this respect, and is
so much cheaper, that it has been adopted.
Second. Sufficient strength to resist the explosion of its neigh-
bors. This can be given by a suitable thickness with internal
bracing, and a rounded shape with no sharp internal angles; as
has been experimentally established at Willets Point. A thick-
ness of # of an inch, the other conditions being fulfilled, is
sufficient to resist the explosion of 200 pounds of dynamite at
60 feet, or of 500 pounds at 77 feet, both torpedoes resting on
the bottom in 20 feet of water.
Third. A low flat form which will oppose a great resistance
to any rolling by the current, and will not obstruct shallow
channels against our own vessels. Since the ground mine serves
as an anchor to the buoy, it may be subjected to stresses that
will demand considerable absolute weight. The exterior should
be free from projections, so as to offer the minimum hold to the
grappling irons of the enemy. Lastly, convenience in handling
and loading should not be overlooked.
Fourth. A convenient arrangement for protecting the ex-
posed core where the electric cable enters and leaves the tor-
pedo. In this respect it resembles the buoyant mine.
Fifth. Internal arrangements which : 1st, shall protect the
'fuzes and a small priming charge of dry dynamite, against any
possible infiltration of water—a danger which the greatly in-
creased pressure acting upon the ground torpedo, renders more
probable than with buoyant types. Since dynamite thoroughly
soaked with water may be exploded by a dry priming, a leak
in the torpedo is of minor consequence provided the latter can
be kept dry; for the loss of buoyancy which would be fatal to
a floating charge, has no significance for one resting upon the
bottom; 2nd, a provision for revealing by electrical tests any
presence of water in the fuze can.
Sºath. Proper economy of construction.
The form and details of construction adopted for the U. S.
service pattern are the following (Plate IV, figure 4.)
56 SUR MARINE MINING MA T'ſ RIE. L.
The form is a segment of a sphere, of which the height is two-
thirds of the radius. The bottom is nearly flat, with a central
sand hole plug to empty the casting. Six internal radial ribs
are added to give additional support to the top. The loading
hole, 3 inches in diameter, is at the pole; and is closed by the
compound plug. Before acceptance, an hydraulic pressure of
120 pounds per square inch must be borne without developing
leakage. -
The compound plug consists of a 3-inch wrought iron screw
plug, provided with two double stuffing boxes, for the passage
of the core of the electric cable. Tinned into the inner end is a
short iron rod, which closely fits into a similar pipe. The two
are united by a screw bolt, the object being to prevent twisting
the cores in loading. The free end of the pipe is tinned
into the top of a cylindrical brass fuze can, large enough to con-
tain the fuze and about a pound of dynamite. This priming is
inserted through a hole in the lower end; which is then closed,
water tight, by a brass cap, lead washer and a smearing of red
lead on the screw threads. Through the top of the can are two
stuffing boxes for the passage of the cores to the 3-inch plug.
The whole plug is screwed into the torpedo with a powerful
wrench, any leakage being prevented by a lead washer and a
smearing of red lead upon the threads. This compound plug
fits both ground and buoyant torpedoes, being used in the latter
when the circuit regulator is carried by a separate buoy.
To protect the exposed part of the core outside the torpedo,
to clamp the turk's head of the electic cable, and to receive
the wire mooring rope of the circuit regulator buoy, a cap sim-
ilar to that of the buoyant torpedo, but held by six bolts and
fitted with two rings instead of bales, is provided. The second
ring serves as an attachment for the lowering rope.
The internal capacity is regulated by the rule that one cubic
foot shall be allowed for every fifty pounds of dynamite—with
one additional foot for the space occupied by the compound
plug, for the internal bosses and ribs, and for the rounding of
the sharp angle at the junction of the flat and spherical portions,
needful to prevent weakness in the casting.
The thickness of the iron is regulated by the requisite strength,
and by the weight needful to render the torpedo a safe anchor
for the buoy.
Only one size of ground mine has been introduced into our
MA 7'ſ R T F. J., O If T H E L O A D IN G. Jº O O M. 57
service, because the use of very large explosive charges is not
favored. This pattern is designed to contain from 200 to 300
pounds of dynamite; to rest on the bottom in water not ex-
ceeding 40 feet in depth at high tide; and to serve as an anchor
for the 28-inch buoy above described, when acted on by a
current of 5 feet per second and attached by moorings 30 foot
long. The dimensions (fully discussed in Part II of Profes-
sional Papers No. 23, Corps of Engineers) are the following:
Thickness of iron, 0.7 inches; radius of the sphere, 21.9 inches;
diameter of base, 40 inches; extreme height, 25 inches; weight
empty in air, 1355 pounds; when submerged it looses 515 pounds,
reducing its effective weight as an anchor (charge 200 pounds)
to 1040 pounds. The maximum stress of the buoy being 300
pounds, this allows a weight of 740 pounds, plus the holding
power of the bottom, to anchor the mine in position. The
capacity of this torpedo is about 5 cubic feet, and in warm lo-
calities where compacting the charge is admissable, about 300
pounds of dynamite may be inserted by careful loading. This
is about the service charge for explosive gelatine.
If it be desired to use ground mines with larger charges and
in water exceeding thirty or forty feet in depth, a special pat-
tern must be improvised—preferably of wrought iron or steel.
Old steam boilers will probably be available for the few cases
where such mines may be needed.
The Circuit Closer. This instrument, which it is not ex-
pedient to describe in detail, is in general form a cylinder 2.8
inches in diameter and 4 inches in height, weighing 3 pounds.
It consists, essentially, of a brass base, cut with screw threads for
attaching it to the compound plug of the torpedo or buoy; of a
compound cylindrical jacket of ebonite and brass; of a cap of
brass carrying a zinc disc at top; and of a metallic contact piece.
When assembled, it is both air and water tight; and all contact
surfaces are plated with nickel, or consist of polished metal.
It is enclosed in the dry interior of the torpedo or buoy, and
will remain serviceable for an indefinite period—as practical
trials covering a submergence of more than five years in mines
establish. Circuit closers are used with all skirmish and self-
acting mines; they are of two patterns—erect for the former
and inverted for the latter.
The Circuit Regulator. The circuit closer is converted
into the circuit regulator by screwing into its base a small plug
(15)
58 SUB MA RIWJJ MINING MA. Tſºlº TE L.
designed (1) to open a shunt having a resistance of about 4500
olums, more or less, to earth—thus facilitating the testing and the
operating of the mines; and (2) to provide a convenient mode
of firing the mines at the will of the operator on shore. Circuit
regulators are used in all mines arranged in grand groups.
Electrical Fuzes, Three types of this fuze are required
for use in submarine mining—the mine fuze, the cut-off (see
switch box below), and the gun fuze.
The cut-off differs from the mine fuze described below, only
in the absence of the detonating cap, in a wax-reduced chamber
and priming charge (1} grains), and in a stouter plug to close
the chamber. It is desirable that the electrical arrangements
shall be identical in the two types, but a good cut-off can be
prepared in the following manner. Pass a waxed linen thread
well below the bridge in the full sized chamber; fill the latter
with gun-cotton dust from a compressed cake; press in the
plug; and, finally, tie the ends of the thread tightly across the
latter. The gun-cotton will ignite, not eaſplode, when the bridge
is heated by the current; and the gas will force out the plug,
thus mechanically breaking the bridge. All danger of forming
false contacts in the circuit by the violence of the explosion is
thus avoided; and the time required to raise the thread against
the bridge ensures the explosion of the fuze before the breaking
of the cut-off bridge.
The gun fuze has nothing necessarily in common with the
other two types. Its peculiarity consists in a tube, arranged to
fit the vent, containing a charge of gunpowder to ignite the
cartridge. As it may be necessary to fire several at once, these
fuzes should be rather sensitive—about half an ampère being a
good standard. Hereafter, heavy guns will probably be fired
habitually with electrical fuzes; and as any pattern adopted by
the Ordnance Department can be used in connection with our
firing batteries, no special gun fuze will be issued. If neces-
sary in any case to improvise a fuze of this kind for smooth
bore ordnance, a cut-off enclosed in the cartridge, with fine cotton
insulated wires leading out of the muzzle is recommended; such
an arrangement will in no way interfere with the ordinary ser-
vice of the piece. Tests for insulation after loading will, of
course, be needful. For rifled guns, a small cap containing gun-
powder and a cut-off, and fitted with a primed paper tube
extending down the vent, may readily be improvised.
MA. Tſſ I; IEI, O F TIIJW L O A D IN G R O O M. 59
It only remains to describe the details of the mine fuze (Plate
IX, figure 5). -
Every electrical fuze for use with high explosives should have:
1st, two insulated conductors for conveying the current; 2nd,
a plug to receive and firmly hold an end of each near to, but
not touching, the other; 3rd, a small priming suitably arranged
for ignition at this point; and 4th, a metallic cap containing a
detonating charge of fulminating mercury. Each of these
elements will be considered in turn.
Jºrst. The insulated conductors should be flexible, tough,
unequal in length, and of low electrical resistance. Lake Supe-
rior copper wires of good quality, of about No. 20, B. W. G.,
and 5 and 7 inches in length respectively, are used for the
mining service. The insulation must be proof against deteri-
oration from age, a condition which excludes gutta-percha and
india rubber; it is fulfilled by a braid of cotton thread closely
laid on and coated with paraffine. The free ends of the wires
are bared for about 1.5 inches.
Second. The plug must be a non-conductor of electricity, not
liable to deteriorate with time and exposure to damp air, nor to
corrode the copper wires. Peech wood, kiln dried and coated
thickly on the outside with japan wax, fulfills these conditions.
The shape must be such as to render any contact between the
wires impossible, and to clamp them so firmly that no accidental
stress on the free ends can disturb their internal adjustment.
The form adopted is the following (Plate IX, figure 5):
The plug consists of three parts: 1st, a cylinder, 0.25 inches
in diameter and 0.7 inches long, grooved longitudinally on its
opposite sides to receive the wires. Entirely round the middle
is a cut 0.05 inches deep and 0.15 inches wide. The wires with
their cotton insulation are each pressed into one-half of the lon-
gitudinal grooves until they reach the cut; they are then both
bent sharply to the left nearly at right angles, and are led
through this cut until they have passed half round the cylinder,
when they are again bent at right angles, and pressed into the
other half of the longitudinal grooves. Thus each wire leaves
the plug in the opposite groove from which it entered, and at
no point can they come in contact with each other. The inside
ends of the wire are then bared, scraped, cut to the proper
length (about 0.1 of an inch), tinned with resin, soldered to the
fine wire bridge and, lastly, bent slightly towards each other so
60 S U B MA. I. I.N.J. MINING MA. Tſ; R J JJ L.
as to relieve the bridge from stress, 2nd, of a hollow cylindrical
cap with a stout shoulder at one end, leaving a smaller hole for
the passage of the free ends of the insulated wires. This cap
is made to closely fit the solid cylinder; and the latter, smeared
with glue, is forced into it until the end abuts firmly against
the shoulder, leaving a small chamber round the bridge to re-
ceive the priming. Makers, unless watched, are apt to omit
this glue; it is essential (especially in cut-offs) in order to fill
the grooves round the wires and thus make a solid plug. 3rd,
of a paper disc held in position by a drop of collodion, to close
the priming chamber. These several parts are turned by ma-
chinery to fit each other accurately, and the whole plug is solid,
strong, and a perfect protection to the bridge and priming.
Third. Ignition is effected by the passage of a strong elec-
trical current, which heats the fine wire bridge sufficiently to
explode the priming. The kind, dimensions and attachments
of the bridge, and the composition of the priming, are fixed by
the desired sensitiveness of the fuze, and by the condition of
permanency for long periods of time.
Permanency in the bridge wire is secured by adopting plat-
inum as the material, and by insisting that resin only shall be
used as a flux in soldering it to the copper wires. To ensure
uniformity, a large supply of standard wire is kept in store.
The diameter is 0.0025 inches; the weight is 0.75 grains per
yard; and as the electrical resistance is about three ohms to the
inch, it is probable that the wire may contain a certain per-
centage of iridium—which is advantageous rather than other-
wise. -
Permanency, uniformity, and a low point of ignition are the
essential conditions for the priming. Mercuric fulminate pos-
sesses these merits in a high degree. It flashes at 392° Fahr.
(Champion), but being a better conductor of heat is not quite
so sensitive as gun-cotton, which flashes at 428° Fahr. (Cham-
pion). The greater permanency of mercuric fulminate gives it
decidedly the preference ; and after many trials with various
compounds it has been adopted as superior to any other, about
four grains being used.
The proper degree of sensitiveness of the fuze is determined
by the following considerations. As the heat developed by a
current of electricity is proportional to the square of its strength,
it is desirable, in order to keep the number of cells in the firing
MAT I I I EE OF THE LOAD ING R O O M. 61
battery as small as possible, that the maximum sensitiveness
consistent with safety shall be secured. For ordinary testing,
and for operating the system automatically, it is needful that a
current varying from 0.10 to 0.15 ampères shall traverse the
bridge with absolute safety. About treble the latter, or 0.47
ampères (giving ten times the heating effect), has therefore
been adopted as the proper current for ignition. Many trials
have shown that the service pattern of fuze varies from this
standard (say half an ampère) only within very narrow limits.
The length of the bridge has been established upon the fol.
lowing principles. All unnecessary resistance is, of course, a
disadvantage, whether caused by the length of the bridge or by
the raising of its temperature by the passage of the current.
On the other hand, a certain length is needful, not only for
mechanical reasons but also to reach a point where small ac-
cidental variations shall cause a minimum change in the sensi-
tiveness of the fuze. Hence, for any sample of wire the best
length must be found by trial. For our standard wire this
length is #5 inclies; to determine the proper length for any
other wire, consult Professional Papers No. 23 of the Corps of
Engineers, page 227, where the subject is fully discussed; also
Abbot's Wotes on Electricity, Chapter W.
Fourth. The detonating cap is made by punching a disc of
stout sheet copper into a cylindrical form, fitting the plug close-
ly. The bottom is solid, and contains 20 grains of mercuric
fulminate, full weight, held in place by a paper disc secured by
a drop of collodion. This charge, which added to the priming
amounts to about 24 grains, is found by experiment to be amply
sufficient to detonate dynamite in the shape of loose powder,
whether soft or frozen. The copper cap is 1.0 inches long and
0.4 inches in diameter, and entirely encases the chamber of the
plug. It is rigidly attached to the latter, by applying at two
opposite points near the top a pressure sufficient to indent them
into the wood.
The fuze thus formed is 1.4 inches long and 0.4 inches in
diameter. As soon as completed, it is dipped into melted japan
wax which supplies a uniform waterproof coating to the whole.
The electrical resistance, including the insulated wires, varies
but little from 0.7 ohms cold, and 0.8 ohms at the instant of ex-
blosion ; and a single fuze detonates with a current of 0.48
ampères. A variation in fuze resistance of 10 per cent. seems
(16)
(52 S U R MA R IN J. MINING MA TF12 IAE L.
to produce but little change in sensitiveness—probably because
the latter is more influenced by slight differences in the compact-
ness of the priming round the bridge (which effect its heat
conducting power) than by trifling differences in the length of
the platinum.
A much stronger current is requisite to detonate several fuzes
coupled in series (as is usual in submarine mining) than is
sufficient for a single one. The explanation is obvious. A
minimum current requires a sensible time to produce explosion,
and thus allows the most sensitive fuze to save its neighbors by
breaking the circuit. When a current sufficiently strong to act
instantly is employed, all the fuzes coupled in series detonate
together. This current for the service pattern is 1.5 ampères,
although with 1.3 ampères only about 3 per cent of failures
occur. In practically applying these principles it will, of course,
be remembered that each additional fuze increases the resistance
in circuit, and consequently entails a proportional increase of
electromotive force to maintain the same strength of current.
The Switch Box, When a single mine of a group or of a
skirmish line is exploded, the broken end of its cable remaining
in the water makes earth, and might thus render it impossible
to operate the rest automatically, unless some device were pro-
vided to switch the broken end out of the battery circuit. This
result is accomplished by the cut-off and its box.
As already explained, the cut-off is an electrical fuze, nearly
identical with those for the mines. It is placed in the circuit at
the triple junction-box, and the strength of the firing battery
current is regulated to ensure its explosion simultaneously with
the fuzes when the mine is fired. But if the cut-off be contained
in an insulated air chamber, the exposed end of the core in the
water will be separated from the shore circuit, and the remaining
mines of the group can be operated as before. This insulated
air chamber is the switch box (Plate V, figure 4).
The arrangement consists of a solid steel parallelopipidon, 4}
by 5 by 2 inches. One hole, § inches in diameter and 4 inches
deep, extends downward from the middle of the top. Three
holes of the same diameter and length enter the block horizon-
tally from alternate sides and cut the first. So as to leave small
connecting openings. All four holes are slightly enlarged at
the outer ends, and are provided with false seats and the or-
dinary stuffing box arrangement for the water tight introduction
MA T'ſ, R J JJ L OF THE L () A D TW (; R O O M. 63
of insulated leading wire—a rubber packing, a washer and a
hollow plug or gland. The total weight of the box is about
nine pounds.
Each horizontal hole receives a cut-off encased in rubber
tubing. One of its wires is jointed to a leading wire which
passes out through the stuffing box in its hole; the other cut-off
wire passing into the vertical hole through the small opening, is
jointed to a common leading wire which is passed out through
the stuffing box in that hole. By this plan each of the three
cut-offs is secured in a separate hole where its explosion cannot
injure its neighbors, while sufficient air space is provided to
contain the gases without undue stresses on the metal.
In service the switch box is laid flat on the bottom of its
triple junction box; the cable from the grand junction box is
united to the common leading wire; those going to the three
mines are each jointed to its own cut-off.
When used with the mines of a skirmish line, one of the
three holes is closed with a water tight plug; another contains
the cut-off for the mine; and the third contains an insulated
wire forming the prolongation of the cable.
This device not only serves to introduce the cut-offs into the
circuit, but also facilitates the branching of a single cable into
two or three others—which would involve a difficult joint if
made in the usual manner.
Utensils for the Loading Room. The small tools are
contained in what is known as box B, 24 × 14 × 9 inches in size,
and weighing about 50 pounds. They are the following:
TOOL BOX T3—LOADING ROOM.
2 button brushes. 1 marline spike.
1 cold chisel. 1 monkey wrench.
2 cutting pliers. 2 pair scissors.
1 file, 14-inch bastard. 3 S wrenches.
2 files, 6 inch flat. 1 straight wrench.
2 die sinkers files. 1 oiler.
1 hammer, smith's. 1 pincers.
1 hammer, ball pene. 1 round nose pliers.
1 hand vise. 1 screw driver.
1 hatchet. 1 soldering copper.
12 jack knives, maval. Solder, 2 lbs.
Twine; rubber packing; cut-off tubing; brass jointers;
zinc; cotton cloth; rubber strips.
WRENCIES. Four special patterns are required, known as the
64 S U B MA R IN E MINING MA TF RIE. L.
socket, the S, the straight and the safety break wrench respect-
ively. They are required in the loading room, and occasionally
in the planting of the mines.
The socket wrench is designed for opening and closing tor-
pedoes. The old pattern, of which several are in store, consists
of a stout wrought iron lever, 18 inches long, upon one end of
which is a socket and ratchet to clasp the hexagonal heads of
the compound plugs of the buoyant torpedo, the ground torpedo
and the buoy. Upon the other end, is a spanner with two pro-
jecting steel pins, for screwing and unscrewing the annular plug
of the buoyant torpedo.
The new pattern consists of a wrought iron cylinder with four
lateral sockets, ninety degrees apart, fitted to receive the ends of
four iron levers 30 inches long. If desired, four men can thus
apply their strength at once; but usually 2 levers are sufficient.
The top of the cylinder contains a socket fitting the heads of all
three compound plugs; and the bottom, four projecting steel
pins fitting the holes in the annular plug of the buoyant torpedo.
The S wrench consists of a curved strip of steel, 11 inches
long and 3 inches thick, with a hexagonal socket in the middle
# inches between parallel sides; with an open spanner of the
same size at one end; and with a larger spanner, of the same
shape but 24', inches across, at the other end. This tool is of
general application, as appears from the following table which
shows the different parts fitting it.
TIIIC S WIRENCII.


Used with Glands. Can plug. Cap nuts.
Buoyant torpedo. . . . . . . . . . . . . . . . . 3 1 4
Ground torpedo . . . . . . . . . . . . . . . . 6 1 6
Buoy . . . . . . . . . . . . . . . . . . . . . . . . . . 2 * - 4
Cut-off box . . . . . . . . . . . . . . . . . . . . . 4
Grand junction box. . . . . . . . . . . . . . tº w º, a 4
Single junction box, small . . . . . . e - • * 4
The small wrench consists of a straight strip of steel, 11
inches long and # inches thick, provided with open spanners
at each end to fit hexagonal nuts. The jaws are respectively
+} inches and 24', inches across. The following table shows
the different parts for which this wrench is designed :
MA. T ſº I, II; L OF TH E L O A DING I? O O M. 65
TPIE STRAIG IIT WIRENCH.

Used with cºmp Cap nuts.
Buoyant torpedo. . . . . . . . . ... w e º 'º e º 'º is e º ſº ſº e º & 4 4
Ground torpedo . . . . . . . . . . . . . . . . . . . . . . . . 4. 6
Buoy . . . . . . . . . . . . . . . . . . • * * * * * * * * * * * * * * * * 2 4
Grand junction box . . . . . . . . . . . . . . . . . . . . . . 14 4
Triple junction box. . . . . . . . . . . . . . . . . . . . . . 8 • *
Single junction box, Small . . . . . . . . . . . . . . tº e 4
Cable stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
The safety break wrench is of brass, provided with two small
spanners and a hexagonal socket. It is used only with safety
breaks for self-acting mines.
These wrenches supply all demands except for two multiple
cable clamp nuts in the grand junction box, four cap nuts on
the triple junction box, and four cap nuts on the large single
junction box for multiple cable—for which a monkey wrench
is used; and for two bolts in the self-acting mine cap—for
which the small monkey wrench of tool box A is used.
RIGGER's WISE. This tool is used to insert the thimbles in the
ends of the wire rope moorings of the torpedoes. It consists of
an iron bed plate attached to a solid plank by two screw bolts,
and by two saw teeth strips slightly projecting below the bottom
of the plate and thus engaging in the wood. There are three
jaws moving in horizontal slots. Two are carried on the same
shaft by right and left hand screw threads, which cause them to
approach or recede from each other according to the direction
of revolution; the third moves to meet the point of contact, on
a second screw shaft at right angles to the first. The faces of
the jaws are grooved to fit the wire rope; and, by proper man-
ipulation, it is easy to compress a large bend until it closely fits
the thimble, and to hold it in this position while the wire stops
are applied. The vise should be attached to an end of 2-inch
plank; it occupies, including the levers, a working space of 15
inches by 15 inches by 18 inches, and weighs 39 pounds.
THE TIIIMBLE CLAMP. This is designed to hold the thimble
while the wire wrapping begun in the rigger's vise is completed.
It consists of an iron bed plate 9 inches long, 24 inches wide and
# inches thick, bolted to a rigid 2-inch plank, a similar top plate
and a screw bolt uniting them. One end of the bottom plate is
(17)
66 S U IB M A R / W E M I WIN G MA TAR IAE I, .
fitted to receive the thimble while the top plate clamps it in
position. This end should project over the edge of the plank,
to the position most convenient for working.
LoADING FUNNELs. To introduce dynamite into torpedoes
and fuze cans, two stout tin funnels are provided. They differ
from the usual pattern only in having large nozzles extending
well through the holes, to prevent any of the powder from
lodging in the screw threads.
Insulated Wire. Large quantities of insulated leading
wire are required for various uses in the loading room and min-
ing casemate, and for connecting the latter with the flanking
guns and with the station on the ramparts to be occupied by the
Commanding Engineer.
It may happen that insulated single conductor cable too much
deteriorated for use under water is available for long connecting
wires; if so, it is to be preferred; if not, ordinary No. 8 gal.
vanized iron telegraph wire supported by glass insulators can
be used—the resistance is about # of an ohm per 100 yards.
For short wires used for connections in the casemate, No. 14
copper wire protected by kerite is usually to be recommended.
When the wire is to be laid for temporary use upon the ground,
taped india rubber core, consisting of 3 strands of copper wire,
No. 20 B. W. G., twisted together, insulated with india rubber,
and protected by a double wrapping of tarred tape, is recom-
mended. Its total diameter is 0.4 inches. Kerite insulated
wire, similarly taped, is good but much more costly.
To connect the circuit regulator inside the torpedo or buoy
with the fuzes, a small copper wire, No. 19 B. W. G., insulated
to a diameter of about tº inches with cotton braid, is employed.
To connect the fuzes in the torpedo with the end of the shore
cable in the cap, and for the battery wires of self-acting mines,
No. 14 B. W. G. copper wire, insulated with gutta-percha to a
diameter which will just press through a 0.2 inch hole, is used.
It must always be kept under water when in store.
Rubber insulated wire gauged to pass through a inch hole,
is used with safety breaks for self-acting mines.
Insulated Joint Supplies. The making of insulated joints,
a duty which pertains both to the loading room and to the boat
service, requires a special box (D). Its dimensions are 24 × 11
× 9 inches, and its weight about 35 pounds. Its contents are
the following:
MA T'ſ. R TEL OF THE LOAD IN (; J20 O M. 6'ſ
TO() I., IBOX I).--—JOINTING BOX.
2 cutting pliers. Brass jointers.
2 files, 6 inch flat. Rubber strips.
1 hammer, ball pene, Rubber tubing.
1 monkey wrench. Rubber cement.
2 straight wrenches. Twine.
2 pincers. Marline. tº
2 Scissors. Turk’s head collars.
Insulated wire, assorted for work in hand.
BRAss Joint ERs. These are used in cable joints, for uniting
the ends of the metallic conductors in such a manner that no
soldering is necessary, and that no sharp end of a strand can
subsequently work through the insulating wrapping.
The jointers consist of small brass tubes # inches long and of
elliptical cross section, 1% inches by fºr inches; 500 of them
weigh one pound. Inside, a fine screw thread is cut to give a
better hold. The bared wires to be jointed are inserted side by
side from the opposite ends, and the tube is crushed firmly upon
them with blunt pincers and a hammer.
RUBBER STRIPs. This article is used for insulating the exposed
metallic conductor in cable joints which are to be submerged or
exposed to damp air.
The strips are purchased from the Silvertown works in Eng-
land, because the rubber works of this country have not as yet
succeeded in supplying a good quality. They are technically
known as “India rubber strips for joints, No. 61”; and are usu-
ally furnished in half pound rolls, 6 inches in diameter and #
inches wide. Together with the rubber strip is wound one of
paper of equal size, which being thus interposed between the
different coils of the gum effectually prevents adhesion. The
material is prepared by covering a cloth with a thin coating of
rubber, carefully purified, and then removing and cutting it
into strips. The details of the process are not made known.
As furnished, the strips are thin and very elastic. When fresh
they will stretch six times their length without breaking, and
they usually retain their virtue for considerable periods if kept
excluded from the light. Samples have been kept over two
years at Willets Point without deterioration.
When wrapped under strong tension round the exposed con-
ductor, the different turns adhere to each other and soon form
a solid dielectric, which under water endures for years.
RUBBER Tubing. This is ordinary vulcanized rubber tubing,
68 SUB MA R IN E MINING MA. Tſ; R TEL.
designed to be slipped over the insulated joints described above
to protect them from mechanical injuries; and to enclose cut-
offs in their boxes, to prevent the explosion from making contact
between the wires and the iron case.
Two sizes are needed for these uses—known as joint tubing
and cut-off tubing.
The former is 0.5 inches in outer diameter; the hole is 0.4
inches in diameter; the length is regulated to suit the joint—
usually being about 4 inches.
The cut-off tubing is 0.4 inches in exterior, and 0.3 inches in
interior diameter; and is cut in uniform lengths of 14 inclies.
RUBBER PACKING. This is used to prevent leakage round
leading wires where they enter and leave the torpedoes, cut-off
boxes, etc. It consists of vulcanized rubber rings, of which
only one size is employed, viz., outer diameter, 0.8 inches; di-
ameter of hole, 0.2 inches; length, 0.6 inches.
This packing is purchased in the form of tubing, and is cut
accurately on a lathe to the requisite length by a set cutting
knife.
BRAss WASIICRs. To prevent any twisting of the packing
when the gland is screwed home, a brass washer 0.7 inches in
diameter, pierced centrally by a hole 0.2 inches in diameter, is
interposed between them.
Special Supplies. Certain waterproof coatings, fusible sol-
der, etc., used in the loading room and mining casemate, not
being for sale in the market, must be fabricated or made to or-
der. Directions for the preparation are accordingly given here.
MARINE GLUE. The following formula for making marine
glue was communicated by the Silvertown Works, England.
The material is excellent in battery and other constructions,
being unaffected by acids, adherent, and easily applied ; but it
softens if exposed to high atmospheric temperatures.
Composition of Marine Glue.
40 parts of manilla gum resin.
24 parts of common gum resin.
12 parts hard palm pitch.
21 parts green oil (from gas tar).
3 parts African rubber.
First dissolve the manilla resin by heat (the fumes are very
inflammable); when very thin and pasty, add the common
resin which should be previously dissolved by heat so as not
MA. T. ſº I, II, I, O I' T III, L () A D / W G R O O. M. 69
to chill the mixture—while adding keep stirring briskly; when
thoroughly mixed, add the palm pitch previously dissolved by
heat and kept hot and stirred; now heat the green oil to 200°
Fahr., and add the rubber keeping up the temperature and
stirring till dissolved; finally, add this mixture slowly to the
other ingredients and keep stirring until thoroughly mixed.
When first added this will cause much gas, with danger of
catching fire; all lights should therefore be kept away from
the fumes.
RESIN AND BEEswax CEMENT. This preparation is used for
coating circuit closers and regulators where the ebonite and
brass parts come together, sealing self-acting mine batteries, etc.
It is made by melting resin and beeswax together. A small
quantity of vermilion may be added. The best proportions
are two parts of resin and one part of beeswax by weight. This
forms a hard adherent coating, somewhat brittle if exposed to
bending stresses; reducing the percentage of resin increases the
toughness—indeed a mixture of one part of resin and two parts
of beeswax differs but slightly in its properties from pure
beeswax.
RESIN OIL WASH. The fluid ingredient may be bought
under the name of “resin.” or “kidney’’ oil. Iły melting to-
gether about equal parts by weight of this oil and resin, an
insulating adhesive wash excellent to render screw joints water
tight, and for other similar work is prepared. It does not
harden, but becoming more fluid as the temperature rises should
always be applied hot. It resists water and many acids, and
adheres strongly.
FusiblE Solor:riNG ALLOY. The following alloy was largely
used by Lieutenant Derby for closing cans loaded with rack-
arock and dynamite at the Flood Rock explosion of 1885. Its
melting point is about 160°Fahr. (much below the temperature
of boiling water) and no accident occurred from its use. Heat
was applied by steam exhausted through the soldering iron ; oil
or grease was removed from the surfaces by plaster of paris;
ordinary flux was used (muriatic acid neutralized by zinc). The
following are the proportions of the ingredients:
Lead . . . . . . 25 parts (melting point, 626° Fahr.).
Tin . . . . . . . 12 parts ( do. 446° Fahr.).
Bismuth. . .50 parts ( do, 509° Falir.).
Cadmium. , 13 parts ( do. 608° Fahr.).
100 parts ( do. 160 Fahr.).
(18)
'7() SUB MA R IN E MINING MA TIſ It I E.L.
This alloy is useful for soldering small connections in the
operating casemate, because the soldering iron in tool box A
can be heated sufficiently over an alcohol lamp.
Indeed it is generally applicable where high temperatures for
any reason are to be avoided.
MATERIEL OF THE BOAT SERVICE.
Under this heading will be described (1) the steam vessels
etc. used for planting mines; (2) the matériel used to hold the
torpedoes in position; and (3) that used for connecting them
electrically with the shore station.
The vessels include suitable tugs or steam barges, large row
boats, and, unless ample wharf room is available, a number of
ordinary barges for lighterage.
As to anchorage, ground torpedoes of course rest on the bot-
tom by their own weight. Iłuoyant torpedoes are held in place
by mushroom anchors of peculiar pattern. Wire rope is used
to attach circuit closer buoys to ground torpedoes, and buoyant
torpedoes to their mushroom anchors. Shackles form the con-
necting links. The lowering is done by ordinary hemp rope.
Cable stops are an expedient for making the insulated cable
serve as a temporary mooring, when the mines are planted in
haste for immediate use.
The matériel for shore connections consists of armored in-
sulated cable; turks head collars for throwing all stresses at
joints upon the armor; and of junction boxes of various kinds
to receive and clamp the turks heads. .
Each of these articles will now be described in turn.
Wessels and Boats. In actual war, mines will usually be
planted from steam vessels; although rafts, made from two pon-
tons or large boats, may be employed in slack water when
nothing better is available. What particular kind of craft
should be provided, will depend upon the means at hand and
upon the character of the channel.
At the Engineer School of Application a steam launch was
especially equipped in August, 1872, for drill purposes and to
serve as an experiment in appliances. Her size, which permits
her to be easily removed from the water in the winter, is too
small for actual service. Her length is 32 feet. To secure the
requisite stability, she has been hipped to 11 feet 5 inches beam—
this addition furnishing gangways, fore and aft, past the engine
MA. T ſº I I E L OF T H E J O A T S E I: VI C F. 71
room. She is provided with a drum tank aft (which allows the
easy manipulation of one statute mile of cable); with a torpedo
davit on the starboard bow; and with a cat-head for the torpedo
anchor on the port bow. The windlass for working the latter
is placed forward, over the keel, and has sufficient power to
allow two men to raise a 500-pound anchor from the mud. The
wheel is placed at the after end of the engine room, so as to be
out of the way. Her speed, light, is eight knots; and she can
in smooth water carry a dozen men, besides her torpedo and
equipments.
When the authorized strength of the Battalion of Engineers
was increased in 1884, the steam barge David Bushnell was
constructed to determine experimentally the best outfit for
planting mines rapidly on a large scale.
The special objects sought were great facility in manoeuvre;
ample deck space; powerful and well placed mechanical ap-
pliances, to reduce the number of men and hasten the work;
enough storage room for a complete grand group of 21 mines;
and a light draft to lessen the chances of injuring mines already
in position. The boat was also designed to meet local require-
ments at Willets Point—among which was that she should not
be too large to be hauled out of water on ways in the winter
SCASOI).
The David Bushnell is propelled and steered by a Mallory
patent apparatus, which permits the propeller to work at any
desired horizontal angle with the keel through a full circle from
the usual position. She is steered and controlled by two levers
in the pilot house, where steam and vacuum gauges give the
needed information as to the engine. The steering lever is
moved by hand or steam power, as desired.
The speed of the David Bushnell over the measured mile was
officially determined to be 9.8 miles advancing and 8.7 miles
backing; and she caused her stern post to describe a circumfer-
ence whose centre was at her bow.
The following are her principle dimensions: Length on water
line 75 feet, and on deck 84 feet; beam over planking, 20.2
feet; depth of hold, 8.7 feet; mean draft with 9 tons of coal and
8 tons of water on board, and in working condition as to boilers
and grates (displacement 122 tons), 5.4 feet: mean draft with
one grand group complete and twenty men added (displace-
ment 145 tons), 6.1 feet. t
72 S U B MA R IN J. MINING MA T'ſ R II) L.
Her motive power is supplied by a pair of inclined conden-
sing engines of 120 II. P., with cylinders 14 inches in diameter
and 15 inches stroke, geared to the Mallory steering apparatus.
Her propeller is 5.5 feet in diameter and 10 feet in pitch. The
boiler is of the Scotch type with two furnaces, 36 square feet of
grate and 850 Square feet of heating surface. IIer shaft is of
forged steel. Her hull is composite and very substantial.
The Duvid Bushnell is fitted with a revolving derrick, carry-
ing a lifting and falling boom of ample power to handle 6000
pounds with a Burton purchase. The wrought iron mast is
hollow, to pass the falls to the barrel of the hoisting engine
below. This engine is also geared to two winches on deck, so
that all three may be operated from the deck in unison, or either
one separately.
To have had frequent and intelligent practice at Willets
Point in planting mines with these two steam vessels, will go
far to qualify an officer to select, in an emergency, from the
available craft such models as are best suited to the work.
The faults specially to be guarded against are: contracted
deck space, lack of convenient machinery for handling the
mines, and excessive draft. High speed is not needed. Side
wheels are less liable to injure mines already planted than are
propellers.
The best pattern of small boats for placing grand and triple
junction boxes, is determined by the strength of current to be
encountered. They should be roomy and not too sharp, lest
the boats be drawn under when anchored with a nearly vertical
cable in a strong current.
As to barges for lighterage, any ordinary pattern with a good
deck and equipped with a derrick to handle three tons, will
SCI*VG. -
After the mines are planted, guard boats for patrolling the
approaches will be necessary. They may be ordinary steam
launches, but a regular naval force of torpedo boats is greatly
to be preferred. r
The Mine. In case of necessity, blocks of stone or other
improvised anchors may be employed for holding buoyant tor-
pedoes or buoys in position. When practicable, however, the
regular pattern of iron anchor, described below, should be used.
In any case, two stout iron-rings are essential; one for receiving
the shackle of the wire rope, and the other for the hemp rope
MA 7'ſ RIE L OF THE BOA. T SER VIC E. 73
used to lower the anchor into position. These two rings are
necessary, because with a single one the lowering rope is liable
to jam the shackle, and thus cause, as the torpedo swings in the
current, a constant bending of the wire rope just above it.
This greatly lessens the endurance of the mooring. The central
ring should receive the wire rope.
The buoyant effort of the water upon the anchor should not
be forgotten. The serviceable weight is reduced from this cause
about 64 pounds per cubic foot of the volume submerged. A
cubic foot of cast iron weighs, in air, about 450 pounds; and of
ordinary stone, 165 pounds. Hence, in round numbers, an iron
anchor loses +; and a stone anchor, # of its weight in air, when
submerged.
The service pattern of anchor (Plate V, figure 1) is in shape
a right cylinder about 10 inches in height, and 26 inches in di-
ameter, slightly dished on the bottom to increase the holding
power in mud. It is pierced with four vertical holes, 13 inches
in diameter, for attaching a false bottom of plank in case the
mud be so soft as to threaten undue settling. For a rock bot-
tom, six projecting toes increase the holding power; corresponding
depressions on the top permit piling when in store. The cylin-
drical form is adopted to facilitate handling, since in that'shape
the anchor may readily be rolled on its edge. The two rings
are countersunk below the top surface to secure them against
injury in transportation.
The holding power of such an anchor varies greatly with the
nature of the bottom. If this be hard, the dead weight alone
must be depended upon; if soft, at least double power may be
anticipated. ſ
The absolute stress of the torpedo and its moorings upon a
mushroom anchor of this kind can be easily computed, being
the square root of the sum of the squares of the buoyant effort
and of the horizontal pressure exerted by the current. The
latter, in pounds per square foot of exposed cross-section, may be
estimated at one-half the square of the velocity of the current in
feet per second. A co-efficient of safety should cover the jerk-
ing effect of waves, the shocks of friendly vessels, etc.; it will,
of course, vary with the locality and with the absolute weight
of the anchor, but, in general, a value from 3 to 5 is considered
sufficient.
The Wire Mooring Rope. The ordinary 3-inch galvanized
(19)
74 S U B MA IA IN E M IN ING MA T'Jº I: I J. L.
wire rope consisting of six compound strands, each made up of .
seven iron wires of No. 13, B. W. G., the whole laid round a
tarred hemp core, is usually employed. Its proof strength when
new is about 7 tons. Its weight per running foot, submerged,
is about 0.8 pounds.
Experience has shown that this is the least enduring part of
the mine. The slight bending which occurs near the lower and
upper shackles, appears to remove the protecting coating and
expose the iron, which then rusts gradually off. Trials at
Willets Point indicate about two years as the extreme limit of
endurance at these two places, although the rest of the rope may
still remain serviceable. An additional wrapping of wire ex-
tending about five feet from each shackle, is sometimes a
judicious precaution. . As already stated, care should be taken
to ensure a free movement of the shackles in their rings, or a
life not exceeding twelve months must be expected even in a
gentle current. -
To connect the wire rope to the anchor and torpedo, a thim-
ble is inserted in each end. The eye usually employed has a
clear opening of 1.3 inches, designed to receive the bolt of the
shackle. The wire rope is bent round the groove which forms
the outside of the thimble; and the end is secured by a wrap-
ping of annealed galvanized wire, applied by a process which
will be described in Chapter IV. A stress of about 7 tons may
safely be applied to such a mooring rope. Splicing the end into
the rope below the thimble is another method of securing it, but
it is not recommended.
As just stated, the iron mooring rope gives way from rust
before the rest of the mine. To meet this difficulty, phosphor-
bronze was tried at Willets Point in 1883—both wire rope and
thimbles (of normal size) being made from that metal. At the
end of a year the mooring was found to be perfect; but voltaic
action had taken place at the expense of the iron shackle and
bales of the torpedo, which had rusted very badly; indeed the
whole torpedo showed unusual rusting. When some insulating
coupling between the mooring rope and torpedo has been de-
vised, this difficulty will be avoided; and moorings of phosphor-
bronze should then replace those of iron.
The Shackle, The wire mooring rope is attached to the
anchor and torpedo by shackles (Plate V, figure 3) of which
there are two sizes.
f
MA. T. Iſ R I E L OF T II E B O A T S E I: VI C F. 75
The anchor shackle consists of a wrought iron strap with two
eyes, bent into the usual curved form, and offering a thickness
of 1.5 inches at the bottom where the wear and sand cutting is
greatest; and of a wrought iron 14-inch bolt fitted flush with
the outsides of the strap. The bolt is held in position by a
split key which, after insertion through a small hole in the bolt
and one of the eyes, is opened by a cold chisel and hammer So
that it can never work loose.
The torpedo shackle is lighter, being 1 inch thick at bottom
with a 1-inch bolt; otherwise it is identical in pattern.
The weight of a shackle complete is about 5 pounds.
The Cable Stop. In quiet currents, and especially when
torpedoes are planted in haste for a temporary purpose, the
electrical cable may be made to serve as the mooring rope. Its
strength is ample for short use in this manner, but it lacks en-
durance for continued wear. Much time and labor are, of
course, saved by avoiding the necessity of fitting wire rope
moorings.
The wear of the electric cable when thus used, chiefly results
from the bending and twisting caused by movements of the tor-
pedo. To prevent this occurring near the turks head, the cable
is to be firmly lashed to the mooring ring of the torpedo; while
at the anchor, use is made of a device called a cable stop
(Plate V, figure 2).
The latter consists of two plates of 0.4-inch wrought iron,
clamped together by four screw bolts. A circular groove six
inches long is stamped in them, to receive the cable and give it
a full turn of 90 degrees. Symmetrical ears on the lower part
of each of the plates, are pierced with a common hole to receive
the bolt of the shackle, and to deliver the stress straight upon
the part of the cable leading to the torpedo. When the cable
is firmly clamped in this device, friction opposes so great a re.
sistance that the iron armor will part rather than allow a shifting
of position. A stress of about a ton may safely be applied, the
breaking strength of the cable being 4000 pounds, and that of
turks head, 3500 pounds. The weight of the cable stop is 4.5
pounds.
To resist twisting stresses upon the cable, open laid wrappings
of galvanized wire No. 12, B. W. G., must be tightly applied
for about a dozen feet just above the anchor and just below the
torpedo—indeed, if time permits, it is recommended to Čontinue
76 SUB MARINE MINING MA T'ſ RIE. L.
this wrapping over the whole cable between the anchor and the
torpedo. The wire should be extended through the cable stop,
and care should be taken to prevent any possibility of the ends
piercing the insulation.
With buoyant torpedoes, the electric cable is held well clear
of the anchor by this device. With ground mines it is impor-
tant to relieve the turks head at the torpedo from any bending
stress, by allowing sufficient slack between it and the cable stop.
Insulated Cable. Three kinds of armored cable * are re-
quired—single conductor cable with best best iron armor, for
use where it lies quietly on the bottom ; single conductor cable
with steel armor, for use between buoyant torpedoes and triple
junction boxes, and between ground mines and their buoys
where it is exposed to twisting and mechanical injuries; and
seven conductor or “multiple” cable, for use between grand
junction boxes and the operating casemate. If the mines are
only to remain in position for a few weeks or months, the steel
armored cable may usually be replaced by that armored with
iron, but there is then always much more risk of trouble from
faults. In deep water, each grand group and each skirmish line
of buoyant mines requires nearly a mile of steel armored cable,
and an equal amount of iron armored cable—both in addition to
its shore connections. -
India rubber has been adopted as the best dialectric for the
U. S. Service, where long storage is needful; and most of the
cables in store are insulated with it. Gutta-percha, excellent
for immediate use, requires wet storage and must not be exposed
to heat. Kerite is brittle and is not easy to joint in a satisfac-
tory manner. In an emergency it may be necessary to use
cable insulated with any of these or even worse dielectrics—
purchasing the cores from American manufacturers and having
the armor applied at wire rope factories.
A large supply of rubber cable was purchased in England in
1873–75, made upon the following specifications.
SINGLE CONDUCTOR CABLE.
Conductor. To be of seven strand tinned copper of best quality, weighing
together eighty-seven pounds per statute mile, and the conductivity to be not
less than ninety-two per cent. of that of pure copper at a temperature of
* For full information on this subject see Part II of Professional Papers
No. 23, Corps of Engineers.
\
MA. T ſº I I I I, O F 7" IIAE I: O A T S Jº Jº VI C Jø. 77
seventy-five degrees Fah., and the resistance not to exceed thirteen ohms per
statute mile at-said temperature. *
Insulation. To be insulated with three coats of Gray's patent Caoutchouc
to a diameter of twenty-four-hundredths of an inch; the insulation resistance
to be not less than seven thousand megohms per statute mile when tested at
a temperature of seventy-five degrees Fah., after one minute's electrification.
I?ubbered Tape. The core made as aforesaid to be taped with longitudinal
cotton tape, double coated with india rubber, and after that with spiral tape
of the same material, the whole then to be vulcanized together in a compact
body.
Serving. The completed core, made as aforesaid, to be then Served with
tarred jute.
Sheathing Wires. Each wire to be passed through hot compound, and
lapped with cotton tape previously saturated with compound.
Sheathing. The completed core, served with tarred jute as aforesaid, to be
sheathed with ten number thirteen best best galvanized iron wires prepared
as aforesaid, and afterward:
1st. Passed through hot compound.
2nd. ('overed with tarred Russian hemp laid on with a short twist.
3rd. Passed through hot compound.
4th. Covered with tarred Russian hemp laid on as before, but in a re
versed direction.
5th. Passed through hot compound.
SEVEN CONDUCTOR CABLE.
Core. To be composed of seven completed cores, made as aforesaid,
stranded together and wormed with tarred jute, and taped with tarred cotton
tape.
Sheathing. The core to be sheathed with sixteen number nine best best gal-
vanized iron wire prepared as aforesaid, and then to be served with Russian
hemp and compound, as aforesaid.
The cores of the aforesaid cables shall be carefully tested for conductivity
and insulation in the usual manner, and the insulation tests and figures shall
be furnished to the party of the second part, but after being served with jute
and hemp, no insulation tests which require the wetting of those materials
shall be applied, the object being to carefully preserve them from moisture.
The single conductor cable shall be furnished to the party of the second
part in lengths of two statute miles, and the seven conductor cable in lengths
of one-half a statute mile, in each case wound on drums of proper diameter
and sufficient strength for handling and rolling. And after the cables have
been wound on said drums their exposed surfaces shall be covered with some
tarred material securely applied and fastened, the object being to exclude
dampness and damp air from the hemp and iron. And outside of said cover-
ing the usual wooden strips for the protection of the cable shall be applied.
The drums of multiple and single conductor cable, thus
furnished, are cylinders 4 feet in diameter and about 4.5 feet in
length; they weigh, respectively, 2.1 and 2.3 short tons. A
small hole traverses the axis of the cylinder to receive an iron
(20)
78 S Uſ? MA RINE MINING MA T'ſ RIEL.
axle, which should always be inserted to take the weight when-
ever the drum is slung. The use of slings so placed as to throw
weight upon the cable, is not to be tolerated.
In ordering new cable the dimensions of the drums, etc., must
enter the specifications, as makers follow no regular rule.
The pattern of steel armored cable which endures the tests
at Willets Point best, is that supplied by Siemens Bros., of
London. It consists of a seven strand copper wire weighing
about 87 pounds per statute mile, insulated with gutta-percha,
served with tarred jute, and sheathed with steel wire in nine
separate strands; the whole tarred and wrapped with two layers
of tarred Russian hemp. Each strand consists of 14 No. 21. I?.
W. G. steel wires, laid up in long turns and wrapped in tarred
tape. This cable off Willets Point endures a year's service be-
tween buoyant torpedoes and their junction boxes, with but
slight indications of wear.
Turks Head Collars. These are small iron rings just large
enough to slip on the end of the torpedo cable without injury
to the hemp coating. The armor wires are bent back evenly
over the collar, and secured below with a spun yarn or wire
lashing. The collar serves to give a uniform size to the turks
heads, and to equalize stresses upon the different armor wires.
Two sizes are needed, one for multiple and the other for sin-
gle conductor cable. In both the form is similar—flat bottom,
hemispherical top and rounded edges.
TU RKS IIICAI) (JOLI, AIRS.

For Outer Diameter of Thickness
diameter. hole. A l Yºº. A 1 \_ºf = }# 2 &
inches. 7 ſuché8. Žnches.
Multiple cable. . . . . . . . . . . . . . . . . . . 2.5 1.6 1.1
Single cable. . . . . . . . . . . . . . . . . . . . . 2 1 0.75
Single Junction Box. The object of this arrangement is
to splice the cable where an increase of length is required.
Two patterns are issued, one for the single and the other for the
multiple cable; they differ only in size.
The single junction box (Plate VI, figure 3) consists of two
rectangular plates of cast iron—respectively 8 or 10.5 inches
long, 5 or 7 inches wide, and 0.5 or 0.75 inches thick—made
precisely alike, and united by four 0.5 or 0.75 inch bolts at the
MA. T J R J E L OF TII R, JR O A T. S.J. R V 10 E. 79
corners. These bolts have square shanks and hexagonal nuts to
facilitate clamping. The plates are hollowed in the middle to
form a chamber to contain the joint; and the ends are curved
to clasp the turks heads firmly, thus preventing any twisting
stress from reaching the core. The total weight is 14 pounds
for the single cable pattern, and 39 pounds for the multiple
cable pattern. -
Triple Junction Box. This box is used on main lines,
where a single conductor cable branches to the three mines con-
stituting a group; and in the skirmish system, where a branch
cable leads from the single cable to a mine.
The triple junction box (Plate VI, figure 2) consists of two
square plates of cast iron, 14 inches on the edge and 0.75 inches
thick, united at the corners by four 0.75-inch bolts similar to
those described above. The plates are hollowed in the middle
to form a chamber to receive the switch box, described upon
page 62. The four sides of the plates are curved to admit four
cables; but the turks heads upon them are clamped to the lower
plate by separate straps and screw bolts, inside the cavity of the
upper plate. Each cable is thus made fast separately before the
box is closed. The top plate is provided with a lowering ring.
The total weight of the arrangement is 102 pounds.
Where the triple junction box is used with the skirmish sys-
tem of mines, the surplus cable hole is closed by a plug, or an
old turks head, in order to exclude marine animals.
Grand Junction Box. This box is used where a multiple
cable branches to the seven triple junction boxes (Plate VI,
figure 1). It consists of two circular plates of cast iron, 18;
inches in diameter and # inches thick, united by four 1-inch
bolts similar to those of the single junction boxes. These bolts
are placed in rounded projections forming the angles of a
square. Both plates are hollowed to make a lenticular chamber
for the cores. The cables are separately clamped, as in the
triple junction boxes, the top plate overlapping the clamp
straps. The multiple cable enters on one side; three single
conductor cables enter on the opposite side, and two at each of
the intermediate sides. The top plate is provided with a low-
ering ring. The whole arrangement weighs 161 pounds.
Junction Box Buoy. This buoy is designed to mark the
position of all grand and triple junction boxes during the plant-
ing of the mines; and of grand junction boxes subsequently,
8() S UJ3 MA 1: T.W E M I WING MA T'ſ RIE. L.
until the arrival of the enemy. By placing extra buoys in false
positions, spies will be given an extravagant idea of the extent
of the submarine defenses.
The buoy (Plate IV, figure 2) is of galvanized iron, No. 16,
B. W. G. (0.065 inches thick). It consists of two equal right
cones, steam riveted and soldered together at their bases, and
supplied with mooring rings at each vertex. The extreme
length of the buoy including rings, is 31 inches, and its max-
imum diameter is 22 inches. Its weight is 64 pounds.
Planting Buoy. This buoy (Plate IV, figure 3) is de-
signed to verify the submergence of torpedoes when planting.
It is a sphere of sheet brass, No. 20, B. W. G. (0.035 inches
thick) and 10 inches in diameter, with two small rings for
handling. Its weight is 3 pounds. Permanently attached to
one ring is a line graduated in two-foot lengths by colored cords,
the zero being at the buoy end. The marks when the line
(doubled) is read, denote distances from the torpedo in feet.
The length of the line (doubled) varies from 10 to 30 feet,
according to the range of the tide and the strength of the
Cllrrent.
Drum Frames. These frames (Plate VII, figure 1) are
used for reeling off the torpedo cable. A square wrought iron
rod, 24 inches by 2% inches by 66 inches long, with rounded ex-
tensions of 6 inches at the ends for trunnions, is inserted through
the axis of the drum and Secured in place at each end by a disc
and set screw. The frame simply supplies rigid trunnion beds.
The bed plates consist of two pine sills, 8 inches by 8 inches
by 93 inches long, firmly united near the ends by two transoms
of the same material and cross-section. The outside width is
56 inches. IIalved into the middle of the inner sides of these
transoms, and held rigidly to them by two #-inch iron bolts, are
two uprights, 5 inches thick and 10 inches wide. To increase
the stiffness, diagonal braces of the same thickness are spiked to
the edges of these uprights and to the bottom of the frame. To
prevent the uprights from splitting, a 4-inch iron through bolt
11 inches long, is inserted a few inches below the top. The
trunnion beds consist of masses of lead dove-tailed into the tops
of the uprights, so that the axle revolves 20 inches above the
bed plates.
These frames, including the axle, weigh about 500 pounds,
and may be used on land or in a boat.
T II Jº, J., X PJ, () SI V E. 81
The inner end of the cable is always passed through a hole
in one of the heads of the drum, so that a few inches of the
core can be reached for electrical testing. It is sometimes
desirable to revolve the drum during the tests; and to prevent
twisting the leading wires, the following device (Plate VII,
fig. 2) has been found useful.
A longitudinal hole is tapped in one end of the iron axle, and
led out of its side, close to the drum head. A small insulated
wire is jointed to the core and passed outward through this
hole, until it appears at the end of the axle. Here it is united
to a metallic swivel, contained in an ebonite insulating plug
which is screwed temporarily into the axle. All twisting of
leading wires, or escape of electricity over wet surfaces, is thus
prevented.
Boat Earth Plates. These plates (see page 33) are de-
signed for the simple tests made in the boats. They consist of
copper plates, 3 inches by 3 inches, with a 10-foot length of
taped insulated wire soldered to one angle. To prevent any
bending or stress from coming upon the copper strand, a strip
is cut at one of the adjacent angles of the plate and riveted
round the taped portion of the insulated wire. The electrical
resistance of such an earth plate in salt water is about 10 ohms.
Special Tools. The tools required for use in boats are
issued in boxes designated as C. Their dimensions are 24 ×
11 × 9 inches, and their weight about 50 pounds. They con-
fain the following articles:
TOOI, BOX (X. —BO AT SERVICE.
2 cold chisels. 1 hammer, ball pene.
2 cutting pliers. 2 pincers.
1 file, 6-inch flat. 2 marline spikes.
1 monkey wrench. 1 100-foot measuring tape.
2 straight wrenches. Turks head collars.
1 S wrench. Thimbles for wire rope.
2 hand vises. Rubber gland packing.
1 hammer, smiths'. Marline.
Beside these articles, rigger's vises, jointing boxes D, detectors,
and other small appliances used in the loading room and already
described, are indispensable.
THE EXPLOSIVE.
The destructive range of a sub-aqueous explosive is very re-
stricted, especially since the introduction of modern improve-
ments in the hulls of ships of war. The bulk and weight of the
(21)
82 S UIR MA R TW ſ, MINING MA 7'ſ RIE. L.
charge regulate the size of the torpedo, the weight of the anchor,
the diameter of the mooring rope, the wear and tear of the sys-
tem, and in a word, determine the chief practical difficulties in
submarine mining. Iſence, that explosive which represents the
maximum energy in the smallest bulk, and is otherwise suitable,
should be chosen.
Suitable Explosives and their Relative Effects. The
following list includes the best explosives now known for use in
submarine mining, with their relative intensity of action when
fired under water. Local circumstances will often decide which
should be selected in actual service.
Explosive Gelatine: Relative Intensity, 142; Value of E, 375.
Forcite Gelatine: ( & ( & 133; ( & ‘‘ 333.
Dynamite No. 1: { { ſ & 100; “ ‘‘ 186.
Atlas A: £ 4 4 & 100; “ ‘‘ 186.
Gun-Cotton: ( & { % 87; 4 & ‘‘ 135.
The formula on page 16 (Equation 1) resulting from General
Abbot’s investigations at Willets Point between 1869 and 1881,
affords the means of computing the extreme rupturing range in
feet (A) of a submarine mine acting against the hull of a first
class ship of war of that date. In this formula the strength of
the hull to resist a destructive shock is represented by the de-
nominator; should this strength be increased hereafter, the
figure 8 must be increased in the same ratio.
The following table derived from this formula, exhibits the
extreme rupturing ranges of the best high explosives acting
under favorable conditions. The distances are actual, not as
measured on the water surface.
RUIPTURIN (; IRAN (; ES OF SU BMARINE MINIES.

Explosive -- - ---- I'Oroito I) yna Inito No. 1 s fºr tº
.. º, º 'ºis A. Gun-cotton.
Charge. 33 – 3: 33 a; 3 & d; g d; — d.
## | # ##| || 3: ## ##| | ##| | #
$3 | #3 | S3 £3 S 3 £ § 3 | #3
33 q9.2 5% qj.2 5% GD . 3% %
T - E #" > *d E" }- £e !--
feet feet feet. feel. - feel. - feet. - ſeal. -- feel.
100 pounds . . . . 20.9 22.7 | 20.0 21.9 16.3 18.6 14.7 17.3
200 pounds . . . . 29.0 || 31.6 27.8 30.4 22.6 25.9 20.5 24, 1
500 pounds . . . . 44.9 || 48.9 42.9 47.1 35.0 40.0 31.7 || 37.3
Neither explosive gelatine nor gun-cotton is manufactured
82 $5
upon a large Scale in this country, and forcite gelatine is com-
paratively a new product. Dynamite No. 1 is therefore still
T II Jº Jº X. Pſ, O S T V ſº. 83
to be considered the explosive adopted in the United States
submarine mining service, although it may very probably yield
its place ultimately to explosive gelatine.
These explosives, and many others, are discussed in Profes-
sional Papers No. 23 of the Corps of Engineers and its two
addenda, especially in the last. IIere, therefore, attention will
be restricted to practical matters demanding attention when
using them upon a large Scale.
Since nitro-glycerine constitutes the basis of all of these
explosives except gun-cotton, and since there is always a pos-
sibility, in case of deterioration or careless treatment, of its
exuding in a free form, that explosive will be considered first;
although it is quite unfit in its fluid state for any service in
W3]".
Properties of Nitro-Glycerine. Nitro-glycerine, discov-
ered by Ascaghe Sobrero in 1847, and introduced as a practical
explosive by Alfred Nobel in 1864, is, at ordinary temperatures,
an oily liquid having a specific gravity of 1.6. When first
formed its color is a creamy white; but if made from clear gly-
cerine, and allowed to stand for a period varying with the
temperature, it becomes nearly colorless—often, however, show-
ing a faint straw tint. It has a sweet pungent taste, and a
hardly perceptible odor. It is poisonous, and contact with the
skin before the system has become accustomed to its effects in-
duces violent headache and other disorders which continue for
several hours. It is very insoluble in water, but readily dissolves
in ether and alcohol. The evaporation of the ether, or the ad-
dition of water to the alcoholic solution, causes precipitation of
the nitro-glycerine. Decomposition is liable to occur if the ex-
plosive be exposed to acids or alkaline solutions. Strong light
produces no effect.
If thoroughly freed from the acids, nitro-glycerine exhibits no
tendency to spontaneous decomposition, but if impure it de-
mands the most careful attention.
The changes in the properties of this explosive induced by
changes of temperature, cannot be too thoroughly studied. -
Exposed to cold in the fresh milky state, nitro-glycerine con-
geals at from —3° to —5° Fah. (Hill); but in the usual clear
condition, the change occurs at about 40 degrees Fah. This
statement, in general true, is subject to modification in special
cases, varying possibly with the amount of water retained in
84 S U B MA R TWE, MINING MA T'ſ RIET, .
in the liquid. Frozen, it is a white crystalline mass which can
be exploded only with the greatest difficulty. This fact is now
universally recognized, and practical advantage is taken of it in
this country to reduce the danger of transportation; but formerly
it was claimed that, when congealed, nitro-glycerine is specially
liable to detonation. Various reasons may be suggested to ac-
count for so material an error in the results arrived at by the
early experimenters. Thus nitro-glycerine being a very poor
conductor of heat, and hence freezing slowly, may perhaps have
retained its liquid state in the interior of the mass, and thus
vitiated the observation. Possibly incipient decomposition, due
to the presence of acids, may have exercised an exceptional in-
fluence. Finally, different chemical compounds may have been
subjected to experiment—for there are three nitro-glycerines,
mono, di and tri, which possess different properties. Their
formulae are:
Mono-nitro-glycerine C a Ha (NO2) Oa.
Di-nitro-glycerine Ca II, 2 (NO, ) Oa.
Tri-nitro-glycerine Ca II: 3 (NO2) Oa.
The latter is the only one which should be used, and to it alone
reference is here made. -
At ordinary temperatures, as already stated, nitro-glycerine is
an oily liquid of stable composition; it becomes more fluid as
the temperature rises. At about the boiling point of water, it
develops a tendency to decomposition, and becomes slightly
volatile.
Champion reports the following as the results obtained by a
Series of experiments upon effects produced by the instantaneous
application of heat.
At 365° Fah. ebulition, volatilization with liberation of yellow vapors.
‘‘ 381 ° ‘‘ slow volatilization.
“ 392” “ rapid volatilization.
“ 423” “ violent deflagration.
“ 442° “ smart deflagration.
‘‘ 466° “ difficult detonation,
“ 495° “ very sharp and violent detonation
‘‘ 513° ‘‘ feeble detonation.
“ 549° “ feeble detonation with flame.
“ Dull red assumes spheroidal state and volatilizes
If ignited by a flame when unconfined and in the liquid state,
nitro-glycerine burns with difficulty; but if confined, or if
struck a heavy blow, it explodes with violence. If a platinum
T H E E X P L () S I V Jø. 85
wire immersed in the liquid be greatly heated by a current of
electricity, or if a succession of condensed sparks be caused to
pass between terminals, one within and the other without the
liquid, decomposition, indicated by reddish fumes and shortly
followed by explosion, results. The explosion of 20 grains of
fulminating mercury enclosed in a metallic cap, either within
or near the liquid, induces detonation so excessively violent that
tamping is of comparatively little importance—even the pres-
sure of the air being sufficient to develop immense force.
The chemical nature of the reaction varies with the means
employed to effect the change of state. When detonated, the
products are innocuous to health; but if the explosion be of a
lower order, they are injurious.
If it should become necessary to keep nitro-glycerine on hand,
it is to be stored in a cool place, in open tin vessels and under
pure water which must often be changed. When practicable,
the frozen condition is always to be preferred. Any leakage
must be carefully avoided; and emptied cans should be destroy-
ed by exploding a fuze in them, as the film left behind is
dangerous. Hill recommends for removing traces of nitro-gly-
cerine, a solution prepared by dissolving flowers of sulphur in a
solution of sodium carbonate; it causes a harmless decomposition.
The only safe way to thaw frozen nitro-glycerine is by sub-
jecting it to a very moderate heat—the best plan being to
introduce the can into a vessel containing blood warm water.
Experience has established that nitro-glycerine in the liquid
form, is unfit for transportation, long storage, or in general for
any use in the military service.
Properties of Explosive Gelatine. Explosive gelatine
in its strongest form consists of 92 parts of nitro-glycerine, gela-
tinized by 8 parts of nitro-cellulose—the latter"prepared with
special care. By adding from 3 to 5 per cent. of camphor the
explosive is rendered proof against severe shocks—even against
the impact of a rifle bullet. While this sluggishness is of the
greatest advantage in field operations, it has little value in sub-
marine mining. The addition of camphor slightly reduces the
intensity of action and largely increases the difficulty of ignition.
The trade article without camphor is therefore to be preferred.
Explosive gelatine is delivered by Nobels' Explosives Com-
pany, Glasgow, packed in 50-pound boxes. It is in the form of
small cartridges, each wrapped in paper stamped with the name
(22)
86 SUB MA R IN J. MINING MA. T.I., R.I.E.L.
of the company. In appearance the explosive is fine in texture,
being a transparent straw-colored jelly quite elastic to the touch.
It is free from nitro-glycerine in the fluid form, even when
strongly compressed, and no headache results from the handling.
The specific gravity (paper removed) is about 1.53.
Struck by a musket ball the uncamphorated compound burns
and may partially explode. Ignited by a match it blazes with an
intense white flame. When submerged under water in a rubber
bag, it is exploded by sympathy at a distance of about 5 feet
from a priming charge of one pound of dynamite No. 1–the
corresponding range for the latter explosive being twenty feet.
It is fully detonated by the service fuze containing 24 grains of
mercuric fulminate in a copper cap.
Like nitro-glycerine, explosive gelatine may vary greatly in
its freezing point—sometimes only becoming a hard opaque
solid when the temperature falls below zero of the Fahrenheit
scale. In this condition it is much more easily detonated than
frozen dynamite.
Explosive gelatine is unaffected by water; but is dissolved in
ether readily, and in alcohol with difficulty. Unlike the dyna-
mite class no separation of nitro-glycerine from the base is
caused by dissolving in ether. When the latter is evaporated
the explosive gelatine reappears, but with a white opaque color
which only changes to the usual straw color after a considerable
lapse of time.
The stability of the product furnished by Nobel’s Explosives
Company has been tested by long storage under unfavorable
conditions in India and other hot countries with satisfactory
results; but the difficulties of liquification and exudation, sup-
posed at one time to be traced to the nitro-cotton and corrected,
are not yet certainly overcome. Some samples at Willets Point
after continuing in perfect condition for nearly three years
have exuded nitro-glycerine—others of the same lot remaining
unchanged.
Properties of Forcite Gelatine. Forcite gelatine is essen-
tially the same explosive as the above, but slightly inferior in
intensity of action. Its composition is stated to be 95 per cent.
of nitro-glycerine and 5 per cent. of unnitrated cellulose. It
is manufactured in this country while the other is not so
at present; no long continued tests of its stability have been
reported.
T'II E EXPI, OSI V E. 87.
The specific gravity of forcite gelatine is about 1.51; in color
it is slightly darker, and in structure less delicate, than explosive
gelatine; a tendency to exude nitro-glycerine appears at a tem-
perature of 100° Fahr., long continued; when struck by a
musket ball forcite gelatine explodes violently; it explodes by
sympathy when submerged under water at a distance of 5 or 6
feet from a detonated priming charge consisting of one pound
of dynamite No. 1–the corresponding range of the latter being
20 feet. For further details consult Addendum II to Profes-
sional Papers No. 23 of the Corps of Engineers.
Properties of Atlas Powder. This explosive differs from
dynamite No. 1 only in its base, which consists of 2 parts of
sodium nitrate, 21 parts of wood fibre, and 2 parts of mag-
nesium carbonate. The percentage of nitro-glycerine, the in-
tensity of action, and the general characteristics of the two
explosives are the same.
Properties of Gun-Cotton. The general characteristics of
gun-cotton are so well known, and the probabilities of its use in
our submarine operations are so small, that no detailed notice is
required here. The Lenk long staple variety is quite superseded
by that made by the Abel process. The latter is used in com-
pressed discs or slabs varying in weight from half a pound to
25 pounds; also in a granulated form ; also in fine powder. In
the compressed forin, fresh water may be absorbed to the extent
of one quarter of the final weight without materially reducing
the intensity of action when detonated; but a very powerful
initial explosive is then needful to cause perfect detonation.
The resulting safety in handling and storage often causes wet
gun-cotton to be selected for military purposes; but its compar-
atively low intensity, and the uncertainty of always producing
an explosion of the first order, are objections to its use in
submarine mining when good nitro-glycerine compounds are
available. Wet gun-cotton should never be exposed to tem-
peratures below 32° Fahr., because liable to disintegration in
freezing.
Properties of Dynamite. There are several kinds and
grades of dynamite; that to which reference is here made is
known as No. 1. It consists of 75 per cent. of nitro-glycerine
and 25 per cent. of kieselguhr, a silicious earth found in Han-
over and imported into this country because of its excellence as
an absorbent of nitro-glycerine. It chiefly consists of infusorial
88 S U B MA I, IN E MINING MA T ſº I. I.F. L.
envelopes, constituting a countless number of microscopic cells
of great strength and retaining capacity.
Although American bases are now largely used in this country
kieselguhr is always to be preferred for the submarine mining
service. It will absorb and hold 75 per cent. of the explosive;
7. e., the base is then truly saturated. A full charge is impor-
tant—for experiments in France have shown that the rupturing
force developed by an explosion, depends not only upon the
absolute weight of the nitro-glycerine, but also upon the ratio
of the actual to the saturated charge of the absorbent. It may
happen that a less efficient absorbent fully saturated, will pro-
duce more effect than a better absorbent undercharged, even if
the latter actually contains more nitro-glycerine than the former.
Undercharging the absorbent also exerts an extraordinary
influence upon the sensitiveness of the mixture to detonation.
Thus, with randanite (a French silicious earth) as the base, the
following charges of fulminating mercury, contained in a metal-
lic capsule, were required to produce certain detonation.
With 75 per cent. of nitro-glycerine, 0.1 gramme.
4 & 70 { & { { £ 4 £ 4 0.2 { {
§ { 65 g & i & * { £ 6. (). 5 & £
( & 60 § { { { § { { { 0.7 f :
• 55 { { tº £ § { « g (). 8 s &
{ { 50 { { £ 4 4 { { { ().9 { {
* { 45 & & { { { { { { 1 () & 4
Ičeducing the percentage of nitro-glycerine also lessens the
susceptibility to explosion from a violent shock, like that of a
bullet.
Dynamite No. 1 has the appearance and consistency of heavy
brown sugar; the gravimetric density, in pounds per cubic foot,
varies from about 60 in the state of loose powder to about 90
when closely compacted.
Dynamite usually freezes at about 40° Fah., becoming lighter
in color. If it be in the compact form, it is then very difficult
to explode; but in a loose powder it is readily detonated by the
Service fuze, containing 24 grains of mercuric fulminate in a
copper cap—requiring, however, a certain degree of confinement
to develop its normal power. Being a very bad conductor of
heat, the operations both of freezing and of thawing require
considerable time. A certain amount of expansion accompanies
the freezing of dynamite, while liquid nitro-glycerine contracts
in freezing.
T II E JE X PI, O S I V E . 89
IIigh temperatures tend to induce exudation of the nitro-
glycerine from the kieselguhr, and should, therefore, be carefully
avoided; increased fluidity is probably the cause.
Like nitro-glycerine, dynamite burns quietly, without explo-
sion, when ignited in small quantities by a flame or a hot coal.
In large quantities, the heat generated by the burning mass may
raise the temperature of the rest to a dangerous degree, and
thus cause an explosion, probably of the second order. Charges
from five to fifty pounds enclosed in light wooden boxes, have
often been burned with safety; but when, on one occasion, the
amount was increased to 12 boxes each containing 56 pounds, a
violent explosion occurred about six minutes after the first
ignition.
Wetting has little or no effect upon the explosive force of
dynamite, but a stronger igniting agent is required to ensure
detonation. IIence the plan, adopted in submarine mining, of
placing of the fuze in a water-tight can containing a priming
charge of about one pound of dry dynamite, loosely packed
around it; this priming charge never fails to detonate the entire
IY) &SS.
Although water does not lessen the explosive power of dy-
namite, it does cause a separation of the nitro-glycerine from
the absorbent, provided compacted cartridges be used. This
may be seen by packing a little dynamite in the bottom of a
test tube, and adding water. Very soon free nitro-glycerine
appears resting upon the mass; and ultimately the whole or
nearly the whole is thus removed from the kieselguhr. If the
dynamite be in the form of loose powder, no such entire separa-
tion of the ingredients occur. No free nitro-glycerine appears
in the tube; but if the contents be poured out upon a sheet of
tin, many small globules of free nitro-glycerine will be seen
mingled with the kieselguhr. Wetting is, therefore, to be
avoided in every case; but it is not so serious an inconvenience
for the loose powder as for compacted cartridges.
Although many of the characteristics of dynamite are those
of the parent nitro-glycerine, it possesses some great advantages
for the submarine mining service. These are:
First. Exemption from danger of detonation from moderate
shocks—which is due to the difficulty of transmitting the blow
directly to the explosive when protected by its absorbent. For
example, common wooden packing cases containing 50 pounds
(23)
90 S U R MAIR IN E MINING MA TIſ, IRIE L.
have been dropped 130 feet upon solid rock, without exploding
the dynamite; and a like result has followed when a wooden
box loaded with stone to a weight of 2 cwt. fell 60 feet upon a
packing case containing a similar charge. In both instances
the case was completely crushed.
It should, however, be noted that the nature of the material
in contact with the explosive exerts a great influence. Thus a
smart shock of iron upon iron, always detonates a thin layer of
unfrozen dynamite contained between the surfaces; iron upon
stone often fails; iron upon wood never succeeds. At a tem-
perature of 120° Fah. a less shock will suffice than at 60° Fah.
A very violent concussion, like that of a musket ball fired at
short range, produces certain explosion whether the dynamite
(unfrozen) be enclosed in paper, cloth, tin or wood. The shock
of a neighboring explosion transmitted through water to dyna-
mite enclosed in paper or other yielding envelopes, may cause
explosion at long distances. Even a service mine may thus ex-
plode its neighbor, if the shock develops sufficient energy
to crush the metallic case. This subject is fully discussed in
Professional Papers, No. 23 of the Corps of Engineers, page 122.
Second. Reduced danger in case of spontaneous decomposi-
tion from impurities. This advantage is probably due to the
fine granulation, which affects the transmission of the heat of
decomposition through the mass.
Third. Security against leakage or spilling of the nitro-
glycerine, if proper precautions against exudation be taken.
Fourth. Susceptibility to detonation, even in a frozen state,
when care is observed to prevent the mass from becoming
Solidly compacted.
Proof Tests. As sold by the American companies, dyna-
mite is delivered in wooden boxes each containing 50 pounds.
These boxes are of half-inch pine, with covers held by screws,
and they are lined with stout oiled paper. The outside dimen-
sions are 12 x 12 × 18 inches. For the submarine mining
service, it is needful to specify in giving the order, that the
powder shall be supplied loose, and shall be made from kiesel-
gu/ºr imported from //anover; otherwise it will be sent in the
form of compressed cartridges, which are usually preferred for
blasting purposes. If these boxes are to be stored in magazines,
it is well to give them a coat of paint to exclude moisture.
T'Iſ E EXPI, OSI VJJ. 91
I3efore accepting a large lot of dynamite from the contractors,
it should pass the following tests.
To verify the purity of the nitro-glycerine, wash a sample of
the dynamite in distilled water, and boil a portion of this water
taken from the top of the vessel—suspending in the vapor a
strip of blue litmus paper; the latter will redden if free nitric
acid be present. Or, test a portion of this water with paper
prepared with starch and a little iodide of calcium; a blue
color will indicate free acid. If decomposition be more advanced,
it may be shown by suspending a strip of the paper moistened
in distilled water over the surface of the dynamite. Very
active decomposition is made evident by reddish nitrous fumes
easily recognized by the smell. In such a contingency great
care must be observed in handling, and the material must be
promptly burned in small quantities.
That the proper percentage of nitro-glycerine has been in-
corporated with the absorbent, is ascertained by accurately
weighing a small sample, burning out the nitro-glycerine, and
weighing the residue; the loss should be seventy-five per cent.
Another method is to dissolve the nitro-glycerine from a weighed
sample by several washings in ether, and then evaporate the
solution. The weight of the base carefully dried, added to that
of the free nitro-glycerine recovered from the etheric solution,
affords a check upon the accuracy of the test.
The Austrian War Office has prescribed the following test of
strength before acceptance for the military service. A car-
tridge weighing 3.70 ounces, 0.95 inches in diameter and 6.22
inches long, is laid on the middle of a plate of wrought iron,
0.51 inches thick and 6.22 inches wide, resting 19 inches above
the ground upon solid supports 23 inches apart. When the dy-
namite is detonated with a service fuze, the plate must be bent
to an acute, or at least to a right angle. >
The precision of this test must depend upon the quality and
uniformity of the iron; and it cannot be considered a safe abso-
lute standard. For instance, trials at Willets Point with a supe-
rior quality of metal gave the following results, the prescribed
conditions of the Austrian test being exactly fulfilled. With
a charge of 3.7 ounces the included angle was 131°; with 4.3
ounces it was 126°, the back of the plate showing incipient
cracks; with 5.0 ounces the angle became 60°, the back of the
plate being broken. The blow in this test is so sudden, that the
92 SUR MA R IN E MINING MA T'ſ, R.I.E.L.
bending seems to be governed by the number of over strained
fibres. -
For the U. S. Service, the standard test for intensity consists in
detonating a few charges, selected at random from the boxes and
each weighing 3 pounds, in similar water-tight tin cans lashed
centrally in a four-foot ring suspended vertically 35 feet below the
surface, in water about 70 feet deep. The work performed by
each shot is measured upon six dynamometers rigidly attached
to the ring; and a comparison of the mean of the results with
the standard indication, shows accurately the quality of the
shipment. The standard indications for these tests (3 pounds
in four-foot ring) are:
Dynamite No. 1 and Atlas Powder. . . . . . . . . . 15,714 pounds.
Explosive Gelatine . . . . . . . . . . . . . . . . . . . . . . . 22,250 “
Forcite Gelatine. . . . . . . . . . . . . . . . . . . . . . . . . . . 20,880 “
Gun-Cotton. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13,713 “
For a detailed description of this mode of testing, consult
Professional Papers No. 23 of the Corps of Engineers, page 14.
The following are the official English tests (1887) for lique-
faction and exudation, applicable to explosive gelatine, gelatine
dynamite, forcite and analogous preparations.
“For LIQUEFACTION. A cylinder of blasting gelatine is to be
cut from the cartridge to be tested, the length of the cylinder
to be about equal to its diameter, and the ends being cut flat;
the cylinder is to be placed on end on a flat surface without any
wrapper, and secured by a pin passing vertically through its
centre. In this condition the cylinder is to be exposed for one-
hundred and forty-four consecutive hours, to a temperature
ranging from 85° to 90° Fah. (inclusive) and during such ex-
posure the cylinder shall not diminish in height by more than
one-fourth of its original height, and the upper cut surface shall
retain its flatness and the sharpness of its edge. If the blasting
gelatine and the gelatine dynamite to be tested be not made up
in a cylindrical form the above test is to be applied with the
necessary modifications.”
“For LIABILITY To ExupR. There shall be no separation from
the general mass of the blasting gelatine or gelatine dynamite
of a substance of less consistency than the bulk of the remaining
portion of the material under any conditions of storage, trans-
port, or use, or when the material is subjected three times in
T II E EXPI, O S I V E. 93
succession to alternate freezing and thawing, or when subjected
to the liquefaction test herein-before described.”
Needful Precautions, Modern high explosives are justly
claimed to be safer to handle than gunpowder, but there are
certain rules which cannot be violated with impunity. The tre-
mendous power developed by the explosion even of a few
ounces, renders the occurrence of small accidents highly im-
probable; and those whose duty it is to work with them, should
remember that no margin is left for ignorance, carelessness or
stupidity.
The precautions to be observed in manufacture, do not come
within the scope of this Manual; those pertaining to transpor-
tation, storage, and use will be considered in turn.
IN TRANSPORTATION. Provided they be of good quality, all
the explosives under consideration properly packed in light
wooden boxes, are quite safe against any shock to be expected
in ordinary or even rough handling, whether shipped on rail-
ways or steamers. If decomposition or exudation of free
nitro-glycerine has occurred, this is no longer true. Where the
tests before starting have shown that the nitro-glycerine is in
good condition, neither of these dangers is to be apprehended,
wnless the temperature be allowed to rise to an eaccessive degree.
This matter, therefore, should always receive attention. On
steamers, a well ventilated place remote from the engines should
be selected; and on railways, if the weather be hot, good ven-
tilation and ice in the car, so placed that no water can reach the
explosive, are useful precautions.
On the other hand, it is desirable to prevent freezing to avoid
the inconveniences of thawing. In winter, therefore, care
should be taken to protect the boxes against exposure to low
temperatures; packing in straw or sawdust may be useful.
Under no circumstances should cases of fuzes be placed in the
same car, or anywhere in the vicinity of the explosive.
Water should always be kept away from dynamite and Atlas
powder, to prevent a possible exudation of nitro-glycerine; with
cartridges this precaution is highly important.
In the case of a conflagration, there is usually no danger of ex-
plosion with small quantities of high explosives; but this is far
from true with large quantities. In the official trial in England,
already mentioned, a mass of 672 pounds of dynamite No. 1
exploded after burning fiercely for a few moments.
(24)
94 S U B MA. If I WJJ MINING MA. T ſº I, II, L.
IN STORAGE. High explosives should always be stored in
cool magazines in which the temperature does not fall below
45° Fahr., and where there is no dripping of water. Damp
air, except with Atlas powder, is not injurious. The boxes
should be placed on skids; and if kept long on hand, they
should be occasionally inspected and tested in the manner
already described. The usual precautions against fire should
be taken ; and if any of the powder be spilled on the floor, it
should be removed at once. No fuze must ever be allowed
in the magazine.
IN ITANDLING. Nitro-glycerine is an active poison, but is
only dangerous when introduced in considerable quantities into
the circulation. An instance is on record, where ten drops were
swallowed by a man without endangering his life. Smaller
animals have been killed, after a lapse of a few hours, by small
injections under the skin.
Unfortunately, the skin readily absorbs nitroglycerine; and
until the system has become accustomed to its effects, the results,
varying with the individual and exposure, are headache, vertigo,
nausea, intoxication and general lassitude, which often continue
for several hours. Similar effects, caused probably by inhalation
of vapor or of floating particles charged with nitro-glycerine,
occasionally follow from working with dynamite in a close
room. Good ventilation, and avoiding any absolute contact
with the powder, are, therefore, precautions which usually com-
mend themselves after a little experience. The hands should
always be washed thoroughly before eating; and it is well to
use weak potash lye or strong soap, followed by a second bath
in pure water. Habitual workers with nitro-glycerine become
proof against the injurious effects—a continuous experience of
a couple of weeks being in general sufficient.
No satisfactory antidote for nitro-glycerine poisoning has yet
been found; cold water applied to the head, and strong coffee
taken internally, are sometimes recommended. *The Austrian
engineer prescription consists of acetate of morphia mixed with
white sugar, always to be administered by a physician. A dozen
doses are prepared by mixing one or two grains of the acetate
with two drachms of sugar.
IN LOADING. Torpedoes should always be loaded in light.
wooden buildings, well ventilated; the floor should be frequently
swept, and the sweepings including paper wrappings should be
* || 0 | < |S on who V} Onowad. ſºvº & H. *~~~~
'ſuwet Awww.ºvº, 0. oCº A- tu LJ- sºsºr cº-ot, Raº. Ovvv, c.
Č-wav, , wºvew Moveev 44 vºv cº-co, ºva… ºvae....…a. WK,
T H E Jº X P I, O S I V AE). 95
burned in the open air. Extremes of heat and cold are unfav-
orable conditions. No acids or alkalies should be allowed near
the explosives, and above all no fuzes. The latter are as dan-
gerous as matches in a powder magazine.
No unnecessary fire must be permitted in the vicinity. It is
true that small quantities of these high explosives ignited by a
spark or flame, burn away harmlessly; but, as already remarked,
the result is different if the quantity be large enough to give
time for the heat of the burning portion to raise the rest of the
mass to the temperature of explosion. Disastrous accidents
have been traced to this peculiarity as a probable cause; and it
is, therefore, well to have no larger supply in the loading room
than is necessary for immediate use.
The thawing of frozen explosives near a stove is strictly pro-
hibited. The best method is to leave the boxes open for several
hours in a warm room; but if time be lacking the contents, in
open water-tight cans, may be placed in warm water no hotter
than can easily be borne by the hand.
Dynamite must never be exposed to shocks or violent com-
pression between two metals. This rule is specially to be
remembered in loading torpedoes, where care must always be
taken that none of the material remains in the screw threads.
The funnels are made long enough to project entirely through
the loading holes; but examination in every case should be
made to see that both the male and female screw are free from
particles of dynamite, before attempting to close the can or
torpedo. That none of the powder should be scattered about
the floor or among the tools, is self evident.
Any exudation of free nitro-glycerine must be carefully
avoided. It is not likely to occur at ordinary temperatures;
but, as with other oils, warmth promotes fluidity. For this
reason a loaded torpedo must never be left exposed to a hot sun;
the heat of the confined air rises to an extraordinary degree
under such circumstances in a few minutes. Accordingly, the
torpedo must be placed in the shade; or, if this be impossible,
it must be covered with blankets kept wet by frequent additions
of water. Nitro-glycerine which has exuded from its absorbent,
recovers all its dangerous properties; and this rule is, therefore,
imperative.
If there be any chance that the temperature of the sea water
may fall below 45° Fahr., care must be taken in loading the
96 S UI; M.A. R.I.N.J.; MINING MA TF RIE. L.
torpedo, and especially in priming the fuze can, that the dyna-
mite is left loose without any packing. In this state it is certain
to detonate when the fuze explodes; while if packed solid, as
in cartridges, a failure might occur.
Special care is requisite that the fuzes are deeply embedded in
the priming charge of the fuze can. On one occasion, at Wil-
lets Point, a buoyant torpedo which had remained for several
months in the channel failed to explode when the fuze was fired.
Examination showed that the latter had been left at the top of
the can, and that the constant rocking in the waves and currents
had caused the frozen charge to settle fully an inch away from
it; hence the explosion of the fuze, although violent enough to
drive a hole through the tin can where the copper cap had
chanced to touch it, failed to ignite the dynamite from want
of actual contact. A second fuze, properly placed, produced a
violent detonation, the dynamite still remaining frozen.
SHIPPING DIMENSIONS AND WEIGHTS.
The following data will be found convenient in storing,
packing and shipping submarine mining matériel. Whether
additional outer packing boxes should be provided will depend
upon the distance and mode of shipment.
Materiel of the Casemate. This generally consists of
light articles which require special care in packing and handling.
Operating Boales. Each is packed in a separate case; ex-
ternal dimensions of case 25 × 10 × 9 inches; weight about 36
pounds.
Fring Battery. Two 10-cell boxes are packed in one outer
case; external dimensions 30 × 24 × 14 inches; weight about
300 pounds.
Signal Battery. Packed according to pattein.
Wheatstone Dial Telegraph. Each packed in a separate very
light case; external dimensions of case, 17 × 12 × 9 inches;
weight about 27 pounds.
Tool Boſe A. Dimensions 19 × 10 x 8 inches; weight about
25 pounds.
The Smaller /nstruments. All may be packed in one case,
22 × 20 × 14 inches; weight about 100 pounds.
Materiel of the Loading Room. This consists of arti-
cles many of which do not require boxing. In storage, torpe-
does, etc., can be so packed together as to occupy much less
D IME W.S TO WS A WID WEIG II TS. 97
space than would appear from the extreme lengths here given,
which include the bales of the caps, etc.
Buoyant Torpedoes, model of 1875. All sizes of this pat-
tern are 334 inches in diameter at the flange; the lengths and
weights vary as follows:
No. 32; from lowering to anchoring ring, 4.3 feet; weight, 300 pounds.
No. 40; & 4 6.0 “ ‘‘ 615
No. 43; £ 4 & 4 4 & & 4 6.8 4 & & & 760 “.
No. 46; ( & & 4 & & 4 & 7.8 C & & g 925 & 4
No. 48; ( & £ 6. & & g & 8.5 & C £ 6. 1050 g &
Charge Bags. In ordinary packing boxes—size according to
number shipped. -
Self-acting Mine Caps. Diameter at flange, 13 inches, and
at top, 9 inches; extreme length, 13 inches; weight, 50 pounds.
Ground Mine Buoys, model of 1875. Diameter at flange,
29% inches; length from lowering to anchoring ring, 4 feet;
weight, 230 pounds.
Ground Torpedo, model of 1876. Diameter at base, 40
inches; extreme height, 25 inches; weight, 1350 pounds.
Switch Boa. Each box is 5 × 5 × 2 inches in the clear, and
weighs 9 pounds. They are packed in cases of convenient size.
Circuit Closers and Regulators. Circuit closers are packed
by the dozen in cases, 14 × 11 × 6 inches in outside dimensions;
weight, 54 pounds.
Circuit Idegulator Plugs. A case containing 200 of them
occupies 20 × 16 × 11 inches, and weighs 70 pounds.
Jºgger's Vise. Each occupies a space 16 × 14 × 4 inches,
and weighs 39 pounds.
Tool Boa; B occupies a space 24 × 14 × 9 inches and weighs
about 50 pounds.
Tool Boa; D occupies a space 24 × 11 × 9 inches and weighs
about 35 pounds.
The other small utensils and supplies needed in the loading
room, are packed according to convenience.
Materiel of the Boat Service. This also includes many
articles which do not require boxing.
Mine Anchors. Anchors differ in size and weight according
to locality. The standard 1000-pound pattern is 26 inches in
diameter and 10 inches thick. Four of them may be placed in
a pile 36 inches high.
Insulated Cable. Multiple cable is stored in half-mile lengths;
and single conductor cable, in two-mile lengths. Both are
(25)
98 S U B MA R IN E MINING MA TF RIE. L.
coiled on cylindrical drums 4 feet in diameter and 4.5 feet in
length. A drum of multiple cable weighs 2.1 short tons; and
of single conductor cable, 2.3 short tons.
Wire Mooring Jēope. A coil containing 1000 feet weighs
about 925 pounds.
Drum, Frames. These frames, without drums are 7.8 x 4.7
× 2.5 feet in outside dimensions and weigh about 500 pounds.
Junction Boazes. Small single junction boxes occupy 8 × 5
× 44 inclies space and weigh 14 pounds; large single junction
boxes occupy 10.5 × 7 × 6 inches space and weigh 39 pounds;
triple junction boxes occupy 14 × 14 × 13 inches space and
weigh 102 pounds; grand junction boxes occupy 19 × 19 × 12
inches space and weigh 161 pounds.
Junction Boaº Buoys in form are double cones united at the
base—extreme length, 31 inches; maximum diameter, 22 inches;
weight, 64 pounds. They are of thin metal, and must be
stowed away carefully.
Planting Buoys. These also require care in handling. They
are spheres 10 inches in diameter, with two rings each pro-
jecting about 24 inches. Their weight is 3 pounds.
Tool Boa C. occupies a space of 24 × 11 × 9 inches and
weighs about 50 pounds.
(JIIAPTER IV.
FIREE2A ERATORY SHOERE DUTIES.
DUTIES OF THE COMMANDING ENGINEER: locus of the circuit regulators; use
of deteriorated cable; requisitions; local administration.—DUTIES OF
THE ELECTRICIAN: the leading wires; adjusting the testing apparatus;
setting up the batteries; adjusting the disconnector; adjusting the
judgment firing key; adjusting the operating boxes; adjusting the
plates for sea cell tests; testing the fuzes; adjusting circuit closers
and circuit regulators; testing the loaded mines; testing the insulated
cable; adjusting dial telegraphs.--DUTIES IN THE LOADING ROOM:
buoyant mines, to prepare the compound plug, to charge the torpedo;
ground mines, to prepare the compound plugs, to charge the torpedo;
self-acting mines, to make safety rings, to prepare a safety break, to
encase the battery, to charge the torpedo; to charge a main line switch
box; to charge a skirmish line switch box; to charge a switch box for
judgment firing.—LOADING ROOM DRILLS FOR BOAT SERVICE.-Insu-
lated cable, jointing the core, making a turks head, completing the
joint; the moorings, to insert thimbles in wire rope, to attach a cable
stop.–TIME REQUIRED FOR LOADING ROOM. DUTIES AND DIRILLS.
Upon the approach of hostilities, officers of Engineers will be
selected to direct the planting and operating of the submarine
defences at the channels to be obstructed.
They will be provided with specific orders and plans showing
the number and location of the mines; and will make requi-
sition upon the Battalion of Engineers and the Engineer depot,
for instructed enlisted men and the needful matériel.
The present chapter is devoted to this early period of the
work, before operations upon the water begin ; it includes mem-
oranda for the Commanding Engineer and Electrician, and a
complete drill for use in the loading room.
DUTIES OF THE COMMANDING ENGINEER.
His requisitions will first demand the attention of the Com-
manding Engineer; but before they can be drawn up correctly,
he must settle one matter which has been left undecided in the
approved local projects of the Board of Engineers.
Locus of the Circuit Regulators. The normal and sim-
plest arrangement with buoyant mines, is to place this mechanism
inside the torpedo; and with ground mines, directly over it in a
separate buoy. This disposition is liable to the objection that
100 S UIR MA R IN E MINING MA 7'ſ RIE L.
if an effective outrigger torpedo catcher can be devised, the
mine may perhaps be exploded so far in front of the ship as to
do her no vital injury. Three points in this connection are to
be borne in mind.
Fºrst. The explosion of a single torpedo in contact with the
outrigger cannot fail to destroy it, leaving the naked hull to
receive the shock of the next mine; and the groups are so
arranged that no vessel can pass the obstructed zone without
striking several mines.
Second. The operator by judiciously manipulating the firing
battery switch of the key-board box, can delay the explosion
until the ship has over-ridden the mine—unless the catcher be
so planned as to grapple and carry off the torpedo or buoy,
which with our smooth spherical pattern would be hard to cer-
tainly accomplish.
Third. By the device of placing the circuit regulator in a
separate buoy moored from 70 to 100 feet in rear of the charge,
the ship will be over the latter when the catcher touches the
former; and hence the shock of the explosion will be delivered
precisely where desired, in spite of any such plan of protection.
This well known fact must render the efficacy of outriggers so
doubtful that ships in motion will rarely be encumbered with
apparatus liable at any moment to render them unmanageable.
It will be for the officer, after considering the conditions of
his special problem, to decide what proportion, if any, of his
mines shall be planted with detached regulators—for which pro-
vision has been made in planning the details of the system. The
objections are increased time and labor of planting, difficulty in
discriminating between leakage in the torpedo and in the buoy
by the electrical tests, and additional cost.
When the method of detached regulators is to be used with
ground mºnes, one anchor and a few extra feet of single con-
ductor cable and lowering rope, will be required for each of
them. With buoyant mºnes, the following extra articles are re-
quired: 1 anchor, 2 shackles, 2 thimbles, 1 wire mooring rope,
a little extra single conductor cable and lowering rope, 1 ground
mine buoy, and 1 ground mine compound plug to take the place
of the usual pattern issued with the buoyant torpedo. The fact
that a sufficiency of torpedoes provided with two clamps on the
Gaps are in store must also be ascertained.
D UT'ſ E S () R' (; O M M A N D J W G Jº W G IN E E R . 101
Use of Deteriorated Cable. In one contingency, not un-
likely to occur, a radical modification may be necessary in the
projects of the Board of Engineers, and hence in the requisitions
for matériel, viz: when from deterioration in store the supply of
insulated cable is insufficient for the demand. In such a case
judgment firing may have to replace automatic firing. If
possible this change should be restricted to ground mines;
which will then be planted without buoys, and with the con-
ductor attached beyond the fuze, to the fuze-can wire. This
arrangement is serviceable because the mines can be exploded
at will through defective cables.
As this is a very important matter it will be submitted to
mathematical analysis.
, Let C denote the whole current given off by the battery, of
which the electromotive force is E and the internal resistance
R, ; 6', that traversing the torpedo; 6", that escaping through
the fault, which for simplicity will be assumed to be local; r,
the resistance between the battery and the fault; t, the resistance
between the fault and earth at the torpedo; f, the resistance of
the fault; r", the resistance between the battery and earth at
home. Then :
-(15) . . . . . C = 6'. -- 6".
- * , t
(16) . . . . c" = 6' -.
f
(17) . . . . C = E , - -
R, + r + r + -ºſ-
. t -- f'
Combining these equations and reducing:
(18) . . fi o' t (R, + r.' + r.) ©
E – c' (R, + r + r + t)
By the aid of Eq. (18) it is easy to find the minimum resis-
tance of a fault situated at the distance (r) from a given firing
battery, which will not prevent the firing of a torpedo charged
with a fuze that requires, for detonation, a known current (e').
For example, with a service firing battery of 100 Leclanché
cells, and a range of one mile, let the resistance of the worst ad-
missible fault be determined—supposing it to be situated, first,
at no sensible distance from the battery; and second, at no sen-
sible distance from the mine, assumed for simplicity to be a
single torpedo. The resistance of the earth-plates may each be
(26)
Af
102 SUB MA IA IN E MINING MA. T.I., R.I.E.L.
taken at 2 ohms, that of the disconnector at 2 ohms, and that of
the fuze at 1 ohm. The value of c' for the service fuze (there
being no cut-off with purely judgment mines) is 0.5 ampères;
but, for safety, it will be called 0.6 ampères. Hence:
" – 0.6 × 15 (30 + 4)
J = Higº 0.6 (30 + 4 + 15)
f = 0.6 × 3 (30 + 4 + 12)
T 145–0.6 (30+4+12+3)
This computation proves that, in the case above supposed,
many feet of the submerged copper strand might be bared in
any part of the cable, without endangering the explosion of the
torpedo when acted upon by the firing battery. Hence, if ig-
nition were the only matter to be considered, high insulation in
the cables used in submarine mining, would be of little
importance.
So defective a cable, however, could not be used for automatic
firing, for the signal battery would constantly throw on the
firing battery from the leakage through the cable, whether the
circuit regulator remained open or closed.
If the passage of a current through a defective cable had no
tendency to increase its faults, it would be easy to fix precisely
the limit at which automatic firing becomes inadmissible. Thus,
with a signal battery of normal strength the insulation resistance
may fall to 500 ohms without causing the automatic apparatus,
as usually arranged, to act; and, with special devices which will
hereafter be explained, this resistance may safely be allowed to
diminish to about 250 ohms. Such cables, however, would
rapidly deteriorate under the action of a battery; and they
could only be used for automatic firing with very great chances
of failure.
In general, if the insulation resistance per mile has fallen
much below a tenth of a megohm, the cable should be consid-
ered unfit for automatic firing, and the mines must be set for
judgment firing.
Requisitions. The heavier articles, such as torpedoes, an-
chors, etc., are usually stored at the harbors to be defended :
other articles are at the Engineer depot at Willets Point; others
are to be bought. Information on these points will be had at the
depot. The detail of engineer soldiers will also be made there
by the Commandant, guided by the records on file showing the
= 2.6 ohms (leak near battery).
= 0.7 ohms (leak near torpedo).
D UTIES OF COMMANDING ENGINEER. 103
classification and special aptness of every soldier for this duty.
The following lists of articles indicate what will be needed.
They are based on the minimum personnel, only able to work on
one grand group at the same time, and to supply a Sergeant and
12 men for duty in the loading room. If a larger force can be
had, the requisition should be increased for articles marked with
a Star.
For convenience in packing and unpacking, separate lists are
prepared for the mining casemate and the loading room. When
this plan causes the name of an article to appear more than once,
the total number required is added in brackets. Pulky sup-
plies for the casemate, other than chemicals, will usually be
stored in the loading room.
LIST FOR MINING CASEMATE.
1 keyboard box.
1 multiple cable box for each grand
group.
1 set of mine numbers—consecutive
from unity to the total number of
magnets in the operating boxes.
1 set of printed slips for the opera-
ting boxes, (11 for each multiple
cable box and 14 for each key-
board box). .
1 set of casemate cable tags for each
multiple cable box, and 6 for each
keyboard box.
1 disconnector.
1 hundred-cell firing battery (un-
filled).
1 signal battery (unfilled)—to suit
the circuits.
1 judgment firing key.
1 firing battery resistance coils.
1 Siemens universal galvanometer.
1 four-coil Bradley galvanometer.
2 switches—one for each galvanom-
eter.
2 double button switches.
1 double plug switch (usually issued
in Siemens galvanometer case).
2 reading microscopes.
1 bridge rheostat.
1 reversing key.
1 six-cell testing battery (unfilled).
2 large binding posts for testing
table.
*
25 screw cups.
1 set of earth plates for sea cell
tests (zinc, copper, and galvanized
iron).
*4 dial telegraph instruments.
* 6 speaking telephones and alarums.
* 1 service detector with battery un-
filled (6 in all).
*2 Submarine Mining Manuals (6 in
all).
4 Abbot's Notes on Electricity.
4 copies of the pamphlet on the
switch-board automatic apparatus,
printed on the Battalion press in
1878, should it become necessary
to issue this old pattern. They
are in depot at Willets Point.
6 Daily test books—form printed at
Willets Point.
* 6 note books (12 in all).
1 small balance and weights.
1 tool box A.
1 set of bar magnets—strong.
1 amalgamating dish.
2 wire amalgamating brushes.
1 iron mercury spoon.
2 battery syringes.
2 acid mixing pots.
2 acid ladles.
1 melting dish for paraffine—porce-
lain lined.
6 glass funnels, assorted.
6 pipettes, assorted.
104
SUR MA R IN E MINING MA 7'ſ IRIE L.
12 evaporators, assorted.
2 graduated glass measures (8 oz.).
500 feet of leading wire for case-
Illilt,0. -
200 feet of braided cotton wire for cir-
cuit regulators (No. 19 B. W. G.)
100 feet of rul)ber insulated wire
gauged to fit hole of an inch in
diameter—for self-acting mines.
10 pounds of large staples, assorted
for cable shaft and cable drums.
1 pound of small staples for leading
wires in casemate.
2 yards of standard platinum fuze
wire for operating boxes.
2 sheets of emery paper—finest
made.
1 chamois skin.
2 pounds of pure mercury for oper-
ating boxes.
100 pounds of commercial mercury.
50 pounds of paraffine.
10 pounds of resin.
10 pounds of beeswax.
5 pounds of marine glue.
5 gallons of wood spirits.
1 gallon of asphaltum varnish.
1 quart of Prench varnish.
4 ounces of vermilion.
1 gallon of sulphuric acid.
1 gallon of hydrochloric (muriatic)
- acid.
100 pounds sulphate of copper.
100 pounds Sal ammoniac.
5 pounds of sulphate of zinc.
1 pound of alum.
2 pounds of special solder (lead 25,
tin 12, bismuth 50, cadmium 13).
5 pounds of common solder.
5 pounds of white sugar for self-
acting mines.
1 pound of gum arabic for self-acting
mines.
1 pint of resin or kidney oil for self-
acting mines.
LIST FOR LOADIN (; ROOM.
* 3 tool boxes B (4 in all).
1 tool box C (4 in all).
* 3 tool boxes I) (8 in all ).
* 5 socket wrenches (6 in all ).
*10 levers for socket wrenches (12
in all).
* 3 Service detectors with batteries
unfilled (6 in all ).
*4 Submarine Mining Manuals (6 in
all).
4 copies of pamphlet of Aug. 1874,
if old model (1873) torpedoes are
to be used.
*4 photographs of loading connec-
tions.
* 6 note books (12 in all).
* 3 sets of 6-inch blocks and falls
for slinging torpedoes.
* 2 riggers' vises (6 in all).
* 2 thimble clamps (6 in all).
1 large bench vise.
* 3 crowbar3.
* 1 heavy mallet.
12 stiff brushes for applying red lead
to 8Crew threads.
* 3 funnels for loading torpedoes.
* 3 large scoops for ditto.
* 3 funnels for loading fuze cans.
* 3 small scoops for ditto.
Compound plugs—1 for each tor-
pedo.
Charge bags—1 for each torpedo.
Split keys extra–1 for each torpedo.
Circuit regulators—21 for each grand
group.
Circuit regulator plugs—21 for each
grand group.
Circuit closers—1 for each skirmish
mine.
Special torpedo caps—1 for each self-
acting mine.
2-cell firing batteries—1 for each
Belf-acting mine.
Safety breaks—1 for each self-acting
mine.
Circuit closers, inverted—1 for each
self-acting mine.
Mine switches—7 for each grand
group and 1 for each skirmish
mine.
J) UT'I E S () F (7 O M M A WI) ING JEW (; I WJ} E R .
Service platinum fuzes—3 to each
mine (1 extra).
Service cut-offs—2 to each mine (1
extra).
Gutta percha loading wire (No. 14
B. W. G. insulated to fit #1-inch
hole)—10 feet for each mine.
Rubber packings—200 to each grand
group.
Brass gland washers—200 to each
grand group.
Rubber jointing strips—10 half-
pound rolls for each grand group.
Rubber tubing for joints—100 feet
for each grand group.
Rubber tubing for cut-offs—100 feet.
Rubber tubing for self-acting mines
(# an inch in internal diameter)
—25 feet.
Rubber bands for self-acting mines
(half-inch by 2 inches)—1 groS8.
LIST FOR BOAT SERVICE
* 1 large tug fitted for handling
mines.
* 5 large row-boats—1 grand junc-
tion, 3 triple junction, and 1 for
Commanding Engineer.
* 1 large lighter?
* 3 tool boxes C (4 in all).
* 5 tool boxes D (8 in all ).
* 1 tool box B (4 in all ).
* 1 socket wrench (6 in all).
2 levers for ditto (12 in all ).
*4 riggers' vises (6 in all ).
*4 thimble clamps (6 in all ).
* 5 earth plates for boat use.
2 grappling irons.
* 3 binocular field glasses.
1 large telescope.
2 railroad transits.
1 100-foot chain.
* 2 cable drum frames, with empty
drums and axles complete.
* 6 signal flags.
* 2 service detectors with batteries
unfilled (6 in all).
6 Chesternan's metallic tapes—100
feet.
*2 sounding lines—graduated in feet.
105
Rubber cement—6 boxes.
Brass jointers—1 pound (500) to
each grand group.
Sheet lead, of an inch thick—two
square feet for each buoyant, and
one for each ground mine.
Sheet zinc–10 pounds.
Fine cotton cloth–1 yard to each 21
ground mines.
25 pounds of white lead ground in
oil.
10 pounds of red lead, dry.
6 hanks of twine for each grand
group.
1 ball of linen thread—for self-act-
ing mines.
1 pot of tallow.
100 pounds of cotton waste.
12 sheets of emery paper, coarse as-
sorted.
1 gallon of lubricating oil.
AND MISCELLANEOUS.
Buoyant torpedoes—according to
project.
Ground torpedoes—according to pro-
ject.
Ground torpedo buoys—according to
project.
Junction box buoys—8 to each grand
group.
* 6 planting buoys. .
Mine anchors—according to project.
* Extra anchors—4 500-pound mush-
rooms for junction box boats.
Grand junction boxes—1 to each
grand group.
Triple junction boxes—7 to each
grand group and 1 to each skir-
mish mine.
Single junction boxes, large—2 to
each grand group.
Single junction boxes, small—5 to
each grand group.
Insulated cable, multiple—according
to project.
Insulated cable, single conductor,
iron armor—1 mile for each grand
group, and 2 miles for each skir-
mish line. -
(27)
106 S U R MA R IN E MINING MA T K R II, L.
Insulated cable, single conductor,
steel armor—1 mile for each grand
group and 1 mile for each skirmish
line.
Insulated cable, single conductor,
defective—for telegraph and gun
wires, according to locality.
Turks head collars, large—6 to each
grand group.
Turks head collars, small—5 to each
mine.
Cable clamps—according to circum-
Stances.
Shackles—2 large and 2 small for
each mine.
Extra split keys for ditto—2 for
each mine.
Thimbles—3 to each mine.
Annealed galvanized iron wire, No.
12 B. W. G.-75 feet for each
mine.
Wire mooring rope, #-inch—accord-
ing to numbers and depth.
Local Administration.
* Lowering and buoy rope—3-inch
tarred hemp, length according
to circumstances. {
Braided cotton line, 13-inch, for
planting buoys—500 feet.
Lashings, 2-inch rope—1 coil.
Marline (in 25 lb. coils)—1 pound
(about 200 feet) for each torpedo.
* Cod line—1500 feet.
Clasp knives, naval—2 to each En-
gineer soldier.
The explosive—100 pounds to each
buoyant mine, and 250 pounds to
each ground mine.
Apparatus for electric light, com-
plete—according to circumstances.
Hundred-cell Bunsen or Grove bat-
tery—according to circumstances.
Two carboys of nitric acid—accord-
ing to circumstances.
One carboy of sulphuric acid—ac-
cording to circumstances
Having reported with his party
to the Commanding Officer of the fort from which the mines
are to be operated, the Commanding Engineer will first make
arrangements for a mining casemate and a suitable loading room;
and will satisfy himself that sufficient wharf accommodations
are available to plant the mines in the manner proposed; he
will then organize his laborers and procure his flotilla. -
The Engineer detachment is detailed solely for performing
the skilled labor required in loading and planting the mines.
The number of ordinary laborers needed to transport the tor-
pedoes, etc., to the loading room, and thence when charged, to
the wharf; to supply the explosives in boxes, in small quantities
as needed; to do the manual part of laying the telegraph and
gun wires; to load the material on the vessels for planting; and
in general, to perform all the unskilled labor on shore, will de-
pend very much upon the locality. To handle the flotilla will
require sailors, and especially good oarsmen, but the actual
number can only be determined on the spot. The average force
needful for rapid work is estimated at from thirty to fifty men.
The organization of the flotilla will be a matter of no slight
importance. When Congress has provided funds for putting
our chief harbors in a proper state of preparation for defense,
JD UT'ſ Jº S () };" O'O M M A WJD IN G, E W G IN E EIR. 107
one or more special vessels for planting mines will be kept in
each of them housed on ways, ready to launch at once. Such
vessels should be about 85 feet long and 20 feet beam, with a
draft of about 5 feet. Their weight empty should be about 90
tons. The essential requirements are great facility for man-
ouvre, and especially for backing, ample deck room, convenient
steam crane and steam windlass machinery, space below for
storage of torpedoes and anchors, a speed (at least 9 miles)
sufficient for ready handling in our strongest tidal currents, and
entire sea-worthiness in the roughest water where mines can be
planted. With such a vessel, the work can be done much more
rapidly than with any which could be chartered in an emer-
gency; but, if it be necessary to charter, the above conditions
should be fulfilled as nearly as practicable.
For each grand group to be planted independently, one
steam vessel, one grand junction box boat and three triple junc-
tion box boats should be provided—also a steam launch or yawl
to transport the officer in charge of the work. The size of these
boats will depend on the depth of water and strength of cur-
rent to be encountered. In ordinary harbors they should be
large and strong enough to carry a 500-pound mushroom anchor
slung at the stern, and should have sufficient buoyancy to ride
nearly vertically over it in the strongest tides. Such boats can
be chartered with good crews of about four men each, in any of
our principal harbols. In deep water and rapid currents, barges
large enough to carry a 1000-pound mushroom anchor with a
crew of six or eight men, will be necessary.
Usually wharf facilities will be deficient at our forts; more-
over, much time will be saved in planting by having the mines
near at hand. Hence, barges with deck room for the matériel
of one or more grand groups should be provided, to be anchored
in the vicinity of the work.
Each grand group is a unit, but with a skilful and well
trained electrician, two may be planted simultaneously. A good
party in favorable weather and at a favorable locality, should
plant a grand group in from one to two working days. Upon
this basis, and the urgency of the case, the size of the flotilla
should be determined.
Having made arrangements for chartering his flotilla, the
Commanding Engineer should select his base lines for locating
the grand junction box boats, for controlling his movable fish
108 S U B MA R IN E MINING MA 7'ſ RIE L.
torpedoes, and if necessary, for operating the mines by judg-
ment. The length of these base lines may usually be determined
with sufficient accuracy from the map received from the Engineer
Department to indicate the positions of the mines. As soon as
time permits, a special map should be prepared to show the zone
covered by the mines, the borders being subdivided and graduated
to correspond with the graduation of his two theodolites, upon
the system prescribed for the mapping drill in Chapter VI.
His own station in action will be the same as that occupied
by the Post Commander and Chief of Artillery. This station
and the mining casemate should be connected electrically. For
such land lines, single conductor torpedo cable too much dete-
riorated for use under water, will serve every purpose. -
The selection of the guns to be used for automatically flanking
the different grand groups, the arrangements for sweeping the
channel with the electric light, and any needed preparations for
operating fish torpedoes controlled from the shore, will not be
overlooked.
The best position for a friendly steamer passage through the
mined zone must be considered, and how it shall be prepared—
whether mined as usual, or left unmined, or defended by judg-
ment mines, or closed with ground mines which do not expose
vessels to any possible danger of cutting through the cases into
the dynamite by blows from their propellors. The nature of the
channel and the amount of passing must decide this matter.
Dummies are an essential feature of a complete system of
submarine mines. The extent to which they can be used and
their character, must be determined by the Commanding En-
gineer on the spot.
A series of heavy anchors or blocks of stone connected by
short taut ropes well tarred and planted in front of and between
the grand groups, will delay countermining and afford much
protection against the operation of steam launches by night.
Insulated cable, especially multiple cable, soon beds itself in the
muddy bottom of most of our harbors, while hemp rope will
not do so. When time permits, this expedient should never be
neglected.
Efforts should be made to deceive the enemy’s spies as to the
location of the mines, and to give them an exaggerated idea of
the extent of the system, by planting false buoys and by opera-
ting in waters beyond the actual zone to be defended.
JD Uſ T / ES OF T H E E L E G T R J (JIA W. 109
The moral effect of the concealed dangers should be increased
by every practicable device—even the extreme expedient of
blowing up one or two worthless vessels of our own, in a manner
to cause the belief that they were destroyed accidently in pass-
ing a mined area, may be worthy of consideration in emergencies,
such as an unexpected arrival of the enemy before the channels
can be fully closed against him. All these matters are left to
the discretion of the Commanding Engineer.
DUTIES OF THE EIECTRICIAN.
The first duties of the Electrician will be to start any car-
penter work needed to equip the casemate; and then to unpack
his apparatus and inspect it for injuries which may have oc-
curred in transit. Two intelligent enlisted men should be
detailed as his assistants. -
All being right, the testing apparatus should be set up first;
but as soon as possible thereafter, the operating and other ap-
paratus must be prepared. The calls from the loading room
for tested articles will soon begin; and, for a time, there should
be great activity in the casemate.
The Leading Wires. The diagram of casemate connec-
tions (Plate VIII) will sufficiently recall the general arange-
ment of the leading wires; noting that the earth wire—a piece
of uninsulated copper or galvanized iron wire stapled round the
edge of all the tables, and in good metallic connection through-
out—will serve its purpose at first, without any earth attachment.
As soon as a submerged armored cable is led into the shaft,
however, the ends of all its iron wires should be scraped, united
by a copper wrapping twisted round each separately, and placed
in permanent connection with this earth wire. The electrical
resistance of such an earth should not exceed two or three ohms;
but the joint in the shaft must be soldered to ensure its retaining
this low figure—a matter of the very first importance in sub-
marine mining.
Adjusting the Testing Apparatus. Very little time is
required to prepare this apparatus for use.
The Bradley galvanometer needle should be released by low-
ering the stop, and the zero line should be carefully placed in
the magnetic meridian. By shifting the pin, any one of the four
coils can be thrown into the circuit as desired. One of the
(28)
110 SUB MARINE MINING MA TFIRIE L.
reading microscopes is habitually kept on the table by this
galvanometer.
The Siemens universal galvanometer is adjusted in a similar
manner. Short flexible wires should always be used in imme-
diate contact with its binding posts, and the bridge wire must
be carefully wiped and never touched with the fingers. The
needle is released by the screw at the base of the glass cylinder,
near the letter B. The top screw must only be touched in ac-
curate adjustments; and never without, at the same time, watch-
ing the needle through the reading microscope. The levelling
screws are to be set so that the needle is seen to hang clear of
its surroundings; and the top is revolved until the needle points
to zero. The travelling box of this galvanometer should be
kept inverted over the instrument when not in use, to preserve
it from dust.
Setting up the Batteries. The subject of batteries is
so fully treated in Chapter II of Abbot's Wotes on Electricity,
that little need be added here.
The six-cell testing battery, if of the Leclanché pattern, is
prepared by opening the cover, inserting about a fluid ounce of
pure water into each cell, and replacing the corks. The battery
should then be ready for immediate" service. Its internal re-
sistance should be from 10 to 5 ohms per cell; any sluggishness
will probably be due to excessive internal resistance, which can
be corrected by cleaning the zincs.
If the testing battery be of the chloride of silver pattern, the
cells should be about two-thirds filled with an aqueous solution
of zinc sulphate—12 ounces to the quart.
The service detectors issued for the party are all to be pre-
pared by the electrician. The slide in the back part of the box
is opened; the two cells are carefully withdrawn; a fluid ounce
of pure water is inserted in each, half in each hole; the cells are
re-corked, sealed with resin and beeswax cement, replaced and
wedged in position; and, finally, the internal leading wires are
connected. The resistance of these cells should be about 6 ohms
each ; that of the galvanometer coils is about 120 ohms. The
instrument is ready for immediate use so soon as these adjust.
ments are made; but it must never be tipped, and the circuit
between its exterior binding posts must be left closed no longer
*, ł z 1 tº g tº -
than necessary. Sluggish action is corrected as above.
DUTIES of TIII, II, ECTR 101A N. 111
To set up the firing battery, the sawdust packing is removed;
the cells are taken out, and their connections filed bright;
two cork stoppers are removed and eight fluid ounces of pure
water are poured into the filling holes through a glass funnel.
This should be done slowly and carefully to avoid overflow, and
most of the water should be put into the hole leading to the
zinc compartment. After carefully replacing the corks and
wiping away any water remaining on the tops of the cells, they
are put back into the boxes and connected in series by the straps
provided for that purpose. The action of sal-ammoniac upon
copper is rapid and destructive; much care, therefore, should
be taken to keep the connections dry.
Experience has shown that the sal-ammoniac packed round
the zinc plates gradually absorbs dampness, and coats them with
hard and nearly insoluble crystals, probably oxy-chlorides. By
thus covering the surface of the metal, they may increase the
internal resistance of the cell from its proper value (about 0.3
of an ohm) to an ohm or more, and thus destroy the efficiency
of the firing battery. Should this be found to have occurred,
each cell must be opened and the zinc be cleaned and re-amalga-
mated. Great care is needful in removing the sealing material
to avoid breaking the top of the ebonite jar. The crystals ad-
here strongly to the zinc ; and the latter should be treated with
a mixture of equal parts of hydrochloric and sulphuric acids,
diluted with about 8 parts of water, and be well scraped. These
crystals attack all charged forms of the Leclanché battery
whether wet or dry; and for long storage, no charged pattern
should be purchased.
After the battery has been set up it will require no attention
except the adding of fluid, and perhaps the removal of these
crystals, at intervals of several months. Any difficulty will
usually be traced to an increase of internal resistance, and not
to a loss of electromotive force.
The mode of setting up the signal battery, and its treatment,
will be governed by the pattern supplied—its carbon pole will
be at once connected to earth through the disconnector as indi-
cated on the diagram (Plate VIII).
Adjusting the Disconnector, Wind it up and see that
it is in perfect order. Provision is made for varying the posi-
tion of the projection on the wheel, so that the breaking of
the signal circuit may occur more or less promptly as desired.
112 S U B MA R IN E MINING MA TF RIE L.
This adjustment should be made very fine, only allowing about
4, of a second for the interval. As soon as time allows, the
correctness of this adjustment should be verified as follows.
Connect one end of a leading wire to a torpedo post of the
key board box, and the other end to the top plate of a circuit
closer; connect the metallic base of this circuit closer by a
leading wire to one wire of a fuze, the other wire making
earth; call this circuit A. Arrange a second circuit B from
another torpedo post of the key board box to earth in precisely
the same manner. The object proposed is to make the explosion
of the fuze in A instantly close the circuit closer in B. This
may be accomplished by supporting the latter on a stout wire
thrust through the wrench hole, with the circuit closer axis
inclined as much as possible without closing the electrical cir-
cuit. It is supported at this inclination by a piece of thread
attached near the top plate. The middle of this thread is tied
round the outer end of the fuze in circuit A, so that the ex-
plosion will cut the thread and thus allow the circuit closer in
B to tip over and close its circuit. •
Now switch on the firing battery, and with the hand close
circuit closer A–thus exploding the fuze in A, and very quickly
thereafter closing the circuit closer in B. Unless the break in
the disconnector has opened before the latter is accomplished
the second fuze will also explode. If it has opened, this fuze
will not explode until the bell stops ringing—thus verifying
the delicacy of the adjustment of the break.
This is made evident by considering what occurs when a
circuit closer is closed by the shock of a mine explosion in the
vicinity. When the primary explosion occurs: (1) the fuze ex-
plodes; (2) the charge explodes and communicates a shock to
the surrounding water; (3) this shock is transmitted through
the water to the neighboring mine; (4) the motion thus caused
in its circuit closer (in any inclined position of stability) may
possibly close its circuit; (5) should this be the case, it allows
the signal battery to flow, thus moving the armature in the
operating box, closing the circuit of the firing battery, and ex-
ploding the second mine. In the above test all these operations
succeed each other in the same order, except that (2) and (3)
are omitted, and that the position of the circuit closer is much
more favorable for quick action. Hence, if the projection on the
wheel be set fine enough to save the second fuze in the above
J) UT'ſ JWS () ſº TPI ſº ſº I, ECſ 7" ſº I (J J A W. 113
test, ample time will be given for the safety of its neighbors
when a torpedo explodes. No practical difficulty will be found
in this adjustment. &
Adjusting the Judgment Firing Key. See that the
springs work properly; place sufficient mercury in the contact
cups to ensure good circuits through the bridge wires, in both
positions; lastly, verify the low resistance of these circuits by
actual measurement.
Adjusting the Operating Boxes. The internal adjust-
ments of the key-board and multiple cable boxes are identical.
They consist in attaching the mine numbers and, if not already
done, the printed labels; in inserting a platinum wire in the test
clips; in introducing mercury into the cups, and regulating their
relative levels; and in attaching the leading wires other than
those of the mines.
The distance between the clips (ºr of an inch ) should be
verified by measurement, and if necessary be corrected. To do
this, remove the six large brass screws and lift out the false bot-
tom by the diagonal binding screws; this will expose the
adjusting nuts. -
The cups are next examined ; and, if found to be too dirty on
the inside to ensure a good mercury contact, they are cleaned
with a die-sinker's file from tool box A ; or, if necessary, are re-
moved from the box and thoroughly polished. They may be
detached by loosening the armature pivots, and removing the
four screws holding the standard to the false bottom—after
which they can readily be unscrewed and taken from the box.
As they are nickle plated, this will rarely be necessary.
The box is now moved to its permanent place on the table ;
the zinc pole of the signal battery is connected through the dis-
connector; and its switch is turned to the automatic post.
The single cups are next filled about half full of pure mer-
cury, and by unscrewing are adjusted to such a height as to give
a good contact with the single pin when the number drop is
set. The cups should not be raised too high, lest the screw
contact be made defective. A small pipette, or a folded paper,
or a wooden spoon prepared with the knife, is convenient in
inserting the mercury.
The double cups are now charged in like manner, great care
being taken to regulate the level so that the bridge cannot touch
the mercury in them until the single pin has fully emerged, and
* (20)
114 SUB MA RIN E MINING MA T'ſ RIE. L.
that it plunges in deeply when an earth wire is applied to the
torpedo post. *
One of the leading wires from the bridge rheostat is now
temporarily attached to the firing battery post, and the other
leading wire in succession to all the gun posts. No sensible re-
sistance should be shown when the corresponding bridges are
inserted in the mercury. The temporary wires are aſ once re-
moved when this test is completed.
The zinc pole of the firing battery is now attached through
the judgment firing key to its post in the key board box, and
the firing battery resistance coils are connected as shown in
Plate VIII. The carbon pole of the firing battery is united to
earth through the judgment firing key and the disconnecter.
Finally, the platinum wire is to be inserted in the test clips.
Wind a few inches on a bit of paper; holding this in the left
hand, engage the loose end in the nearest clip and clamp it with
the right hand; draw the wire tightly down into the other clip,
and clamp it; deposit the bit of paper near by, where it can
cause no false contact.
A set of printed labels should be issued with each box. If
not already in position, they are to be pasted on the top edge
(each opposite the corresponding binding post), and on the
levers of the battery switches. A good paste for this purpose
is made as follows. Dissolve one-fourth of a gill of alum in
enough cold water to make a syrup; mix very thoroughly with
1 pound of flour; cook over a slow fire, frequently stirring the
mixture until it becomes very thick; when cold, it remains un-
changed for a long time. For use, add enough cold water to
bring it to the requisite consistency, and apply with the finger.
When the labels have partially dried, protect them with a coat
of shellac or French varnish.
The box being now ready for use, should be tested in the
manner prescribed in the next chapter under the heading “daily
tests.” Should any of the magnets prove sluggish, remove the
false bottom and adjust the distance between the soft iron cores
and armature more perfectly.
The permanent leading wires connecting the testing apparatus
with the key board box being attached, and the different boxes
being united as shown in Plate VIII, the automatic apparatus
is ready for service.
I) U 7'ſ ſº S () ſº 'ſ' Iſ // JE I, Jº (; 7" R / O J A W. 115
Adjusting Plates for Sea Cell Tests. It will be needful
for certain tests to have available in the casemate good copper,
zinc and galvanized-iron home earth plates. These plates should
be submerged in Sea water, easy of access, and secure against
mechanical injuries—-conditions not always easy to fulfil.
Usually a wet hole will be found or can be made in the cable
gallery, where they may be placed connected by leading wires
with the casemate. Care must be taken that they do not touch
each other and they must frequently be cleaned.
If no suitable place can be found for such plates in the sea,
the following expedient may be adopted—but it is not favored
unless absolutely necessary.
Fill a glass jar in the casemate with clean sea water; insert in
it a small coil of the galvanized armor of the multiple cable,
connected by a leading wire with the home earth. This water
may be assumed electrically to form part of the sea, and the
auxiliary plates needed for the test may be inserted in it as de-
sired. Such plates should be removed and wiped dry at once
when the test is finished, and the water should often be renewed.
Before regular work can begin in the loading room, a supply
of tested fuzes, cut-offs, circuit closers and circuit regulators
must be received from the electrician, who should give his per-
sonal attention to providing them.
Testing the Fuzes. The first test of a fuze is to see that
no circuit exists between the wires and the copper cap. This is
ascertained with the service detector, which should exhibit no
deflection of the needle.
The resistance of the platinum must then be accurately de-
termined ; it should be about 0.7 ohms—including the copper
resistance of the fuze wires, but excluding that of the leading
wires, carefully measured for the purpose. Any variation ex-
ceeding 0.1 of an ohm in either direction, * any fluctuation in
resistance, or other unusual electrical indication, and any visible
defect or flaw, should cause the fuze to be rejected.
The resistance of fuzes may easily be measured within less
than one-hundreth of an ohm, either by the bridge rheostat—
*It should be understood that this rule rigidly applies only to fuzes and
cut-offs in (tetual service, inhere absolute certainty as to the normal condition is
essential. Variations of 0.1 or even 0.2 of an olam may be caused by slight
errors in the length of the bridge which produce no sensible effect upon the
current required for ignition. Any fluctuation of resistance under test implies
defective soldering and is a fatal defect.
116 SUR MAI. IN J. MINING MA TÉ RIEL.
using the Siemens universal galvanometer connected as a sine
for balancing; or, directly, by the bridge of the latter. In either
case, one cell of the festing battery supplies the proper current.
These fuzes are highly dangerous if exploded accidentally, and
care must always be observed in testing them. It is well to
place them in the cable shaft—in a stout box to prevent the
flying copper fragments from injuring the cables.
If the bridge rheostat be used, 10 ohms should be unplugged
on the right, and 1,000 ohms on the left side; the amount un-
plugged in balancing, divided by 100, will then give in ohms
the total resistance of the fuze and leading wires.
With the Siemens bridge, the shunt plug should be carefully
inserted in the 10 hole, the 100 and 1,000 holes being plugged.
When the needle is balanced, the resistance of the fuze and lead-
ing wires in Siemens assumed ohms (see Abbot's Wotes on
Electricity, page 90), may be taken from the table without
multiplication.
The cut-offs must be tested with similar care, and in precisely
the same manner as platinum fuzes. The electrical resistance
should be 0.7 ohms, and no variation exceeding 0.1 ohm must
be allowed (see foot note on page 115).
Adjusting Circuit Closers and Regulators. These in-
struments will often be issued wholly, or in part, adjusted for
service. If incomplete, it will be the duty of the electrician to
assemble the several parts; and, under any circumstances, he
must make the final tests prescribed below.
A little red lead mixed with boiled linseed oil and made wer/
thºok, or, better still, white lead ground in oil and thickened
with red lead, is prepared.
The face of the base is polished with chamois skin, and if
not already so secured is red-leaded into the cylinder—marks
being first inade so that the set sorew hole may fall in the riſ///
place. The red-leading should be thorough, not forgetting to
put a little in this hole. The set screw is then inserted, care
being taken that it does not touch the brass jacket. If any red
lead appears round the inside edge of the base, it is to be very
carefully wiped off with chamois skin.
The face of the cap is next polished with chamois, and the
Small screw tested to see that it is firmly in position. Any in-
dication of rust on the steel springs must be very carefully
removed by scraping with a knife and touching with kerosene.
I) Uſ T'ſ ES OF T II E ſº I, E! O'T' ſº I (? TA N. 117
Next apply a coat of thick red lead round the screw, leaving
fully a quarter of an inch newt the face clean, start the cap in
the threads of the cylinder, and, with the regulator on its side,
revolve the former until the contact piece is clamped; turn the
screw backward about three-quarters of a revolution ; finally,
try if a sudden jerk will cause the contact piece to stick at any
point of the circumference. If so, turn the cap back a little
more, and repeat until no sticking is possible.
Now place one detector wire on the zinc disc, and the other
on the base; and, tipping and revolving the mechanism, note if
the circuit closes properly in every position. If so, put a little
thick red lead in the hole and turn the set screw firmly into
position, being careful that it does not touch the brass jacket of
the cylinder. This set screw burrs the theads against which it
abuts, and accordingly it must never be set home until it is to be
permanently ºn position.
Next test on an operating box, by uniting wires from a tor-
pedo post and earth to the zine disc and the base. The signal
battery being on the automatic circuit, and the firing battery off,
the instrument should work perfectly as in a torpedo.
Finally, insert a braided cotton wire, No. 19, B. W. G., 11
inches long, through the hole in the cylinder, and attach one
end closely to the zinc disc by one of its screws. The other end,
after passing through the small hole in the base, is to be tested
with the detector for no contact with the base when the in-
strument is in a vertical position. The sumall hole in the base
(if a circuit closer) is then well plugged with melted paraffine,
and the slack of the wire is neatly coiled away in the base
chamber.
The junctions of the cylinder with the base and the cap, the
ends of the brass jacket, and the set screw holes are now to be
well coated with resin and beeswax cement; and the brass
jacket is to be painted with asphaltum varnish. When the lat-
ter has been dried before a gentle fire, the instrument is ready
for use as a circuit closer, i. e., on a skirmish line, or in any
mine which is designed solely for automatic action.
For the general case, where either automatic or judgment
firing may be desired, it remains to examine and insert the plug
which transforms the circuit closer into a circuit regulator.
The resistance of the circuit between the small screw and
case is first measured ; it should be about 4500 olims, more or
(30)
118 S U B MA R IN J. MINING MA T K R II. L.
less. The small screw is then removed and the ebonite cap is
unscrewed. The movable part is examined to see that it is en-
tirely free from rust, that it moves freely, and that it is strongly
magnetic—if not, it should be taken out and remagnetized by
rubbing the two halves alternately with the opposite poles of a
very strong magnet, beginning the strokes at the middle and
moving outward ; great care must be taken to give the proper
polarity, i. e., the curved (firing) end should be rubbed by
that pole of the magnet which attracts the north seeking end
of a galvanometer needle. When strongly magnetic it is re-
placed and delicately adjusted by the friction pin (this has a
screw head and is often mistaken for a screw). This adjust-
ment requires patience and a delicate touch. If the spring
presses too hard, a failure to fire will result; if too lightly, the
little magnet may make permanent contact, and compel the rais-
ing of the mine. There is no trouble in finding the mean between
these extremes if the officer be accustomed to the handling of
instruments.
The plug is next tested by uniting the case through about
100 ohms in the resistance coils to earth, and clamping the
small screw upon a fine wire leading from a torpedo post—the
corresponding gun plug being in, the counterpoise off, and the
firing battery switch moved for the instant of the test to its
automatic post. Holding the plug upside down (in its normal
inverted position) it should now work perfectly when the lever
of the judgment firing apparatus is reversed. It is absolutely
essential to unplug about 100 ohms in the circuit, and to let go
the lever promptly (thus breaking the low resistance circuit), to
preserve the plug from serious injury in this test. It is also well
to reduce the firing battery to about 50 cells, to ensure delicacy
in the adjustment.
Having passed this test, the ebonite cap and small screw are
replaced ; the ebonite cap must be screwed down gently; if set
hard home it is liable to disarrange the adjustment just inade,
and thus cause a failure in firing. The screw at the solid end
is tightened, if necessary; and its cavity is filled with resin and
beeswax cement. The junction of the brass case and ebonite
cap is then coated with the latter.
The threads of the base screw are next coated with thick red
lead, and the plug is firmly screwed into the base of the circuit
closer; after which the bight of cotton wrapped wire is bared
I) UT'ſ ES OF THI H, J, L E O TR I (? IA W. 119
for a short distance, twisted round the small screw of the plug,
and the latter is set gently home. A little slack must be left,
lest the wire be injured in uniting the regulator to the com-
pound plug. Next verify the operating box test, as above.
Finally the space around the plug is filled with melted paraffine,
first closing the wire hole to prevent the fluid from escaping.
The regulator is now placed in a vertical position, and a
measurement is made to see that the resistance of the circuit
between the free end of the fine wire and the base remains the
same as before; and that when on its side, this resistance is sen-
sibly zero. If so, the regulator is ready for the loading room.
Testing the Loaded Mines. When the mines are to be
used in actual service, it will be advisable to mark and submit
them to a more delicate test than is possible with a detector. A
double insulated wire extending from the casemate to the load-
ing room is needful.
In this test the gun plugs should be withdrawn, the signal
battery should be reduced if of low internal resistance, and the
firing battery should be detached entirely from the operating
box. The electrician must give this matter his personal atten-
tion; with ordinary care there is no possible danger, and the
test is an important one.
In the loading room the sergeant tags the mines, and attaches
one of the leading wires to an A wire (or to a D wire, the E
and F wires being united temporarily by a short leading wire)
and insulates the joints in air. The other leading wire he at-
taches to the buoyant torpedo or buoy by jamming the end
between a split key and slot of the cap, filed bright for the
purpose.
In the casemate, one leading wire is put to earth; and the
other, to a torpedo post of an operating box set to report the
striking of the mine without exploding it. No circuit should
be shown when the torpedo receives as much motion as it will
be likely to experience in the waves and currents; while a
violent tip should work the apparatus.
The leading wires in the casemate are finally shifted to the
delicate testing apparatus; and the vertical resistance, less that
of these wires, is carefully recorded, with the designation of
the torpedo. This resistance, which should be about 4500 ohms,
will be a useful element in the future testing, if the electrician
be kept informed as to the marks of every mine as planted.
120 S UB MA R IN E MINING MA T'ſ. R TEL.
Testing the Insulated Cable. As soon as practicable
after its arrival from the Engineer depot, unless its serviceable
condition has been recently verified, the insulated cable should
be tested for conductivity and insulation.
The conductivity should be tested first. This is done by re-
moving the wooden strips and tarred canvas, and measuring the
resistance of the copper strand—using the 6-cell testing battery,
and the Siemens universal galvanometer and bridge rheostat.
The resistance should be about 11 ohms per mile. Should no
circuit be shown, about half the cable should be wound on the
spare drum, and cut; and each piece should be again tested. By
continuing this operation the break must soon be found.
If time allows, the insulation resistance should be approxi-
mately measured in the manner prescribed in Chapter IV of
Abbot’s Notes on Electricity, article “Insulation by deflec-
tions”—using the whole firing battery, and Siemens universal
galvanometer connected as a sine. The following rough test
must under any circumstances be applied.
The copper wire at the inner end should be very carefully
insulated with rubber wrappings, in the manner prescribed for
making a joint—this includes not only the bared end, but also
any part of the exposed core which looks as if it had received
an injury. Unwrapping a sufficient portion of the free end, the
drum should now be submerged in salt water. A leading wire,
connected to the zinc pole of the signal battery, should next be
attached to the free end of the copper strand, the junction
being wrapped with rubber to avoid any possible contact with
the iron armor. The coke pole of the battery is then connected,
through the 150-ohm coil of the Bradley galvanometer, with an
earth plate submerged in the salt water. If no circuit be shown
after the drum has been allowed to soak for a few moments, the
cable may be considered to be sufficiently good for service.
In applying this test to a multiple cable, each copper strand
at the inner end should be separately insulated; and the whole
seven at the free end should be united and attached to the bat-
tery wire.
If a deflection of the needle be observed in the test, it may
be due to some local injury, or to a general deterioration at-
tributable to the time during which the cable has lain in store.
A comparison of the results obtained with several drums may
throw light upon the matter.
1, U TIES IN LOA DIN (A R 00 M. 121
If a sensible defect be indicated, and especially if a violent
deflection of the needle points to the existence of some bad
fault, the drum should be removed at once from the water, and
preparations should be made to ascertain exactly the locus and
character of the difficulty.
This subject is so fully treated in Chapter IV of Abbot’s
Motes on Electricity, article “To determine the locus of a
fault,” that little need be added here.
Time will usually be saved by applying the Varley and
Murray tests at once. Should the locus prove to be near the
middle of the cable, general deterioration may well be feared.
To decide the matter, the free end should be wound on the
spare drum; the cut should be made; and each part should be
again tested in the same manner. If faults near the middle be
again indicated, it may usually be assumed that the drum is
bad throughout; and the actual insulation resistance should be
measured with the bridge, to determine the disposition proper
to be made of the cable. t
If, after the cutting, one piece prove good and the other
show a fault near the new end, a local injury is indicated ;
which may usually be found by passing the cable through salt
water in the manner laid down in Chapter IV of Abbot's Wotes
on Electricity—article “Rude practical tests.” In this opera-
tion, too much care cannot be taken to prevent the end of the
copper strand from coming in accidental contact with the water
or iron armor; or the revolving contact at the drum from be-
coming wet or even damp. Great loss of time, and useless
cutting of the cable, may result from a neglect of these
precautions.
All of the insulated wire which is to be exposed to salt water
in the cable gallery, or elsewhere, must be tested in the manner
just described—and, in every case, the whole of a coil must be
tested for conductivity before any cutting.
Adjusting Dial Telegraphs. The electrician should see
that all the dial telegraphs are in good order before issue—for
this, full directions are given in Abbot's Wotes on Electricity,
Chapter VI. -
DUTIES IN THE L()ADING ROOM.
Under this heading will be included the mechanical operations
required for preparing the mines in the loading room. Such
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122 SUB MARIN / MINING MA 7'ſ R Iſ L.
operations are: the preparation of compound plugs for tor-
pedoes, both buoyant and ground; charging torpedoes, both
buoyant and ground; preparing self-acting mines; and charging
mine switches (three modes).
The loading room should be placed in charge of a sergeant
of Engineers, selected for his knowledge of the subject and his
skill in the command of men. IIis duties are to keep his de-
tachment busy in such parts of the work as each is best fitted to
perform, detailing and transferring men between the squads for
this purpose as he deems best; to see that no accident occurs
from carelessness or neglect ; to make the electrical tests and
the prescribed examinations in person ; to keep himself in-
formed as to the general progress of the work, so that no part
may fall behind and thus create delay; and finally, to allow no.
unauthorized persons in the building. It is needless to say that
his duties are onerous and responsible, and that he should be
encouraged to communicate freely with the Commanding En-
gineer as to every detail.
In all these drills the men are supposed to be regularly num-
bered in squads of four, and to be equipped with the full
loading room outfit prescribed above. At the outset, every man
should be individually questioned, to test his familiarity with
the precautions prescribed in Chapter III for handling the
explosives. -
The following instructions and drills are applicable to the
approved models of the spherical torpedo (1875) and of the
ground torpedo (1876). When the models of 1873 are used,
reference should be made to the pamplet printed on the Bat-
talion Press in August, 1874, entitled Torp Edo DRILL For
LOADING TOOM AND BOAT SERVICE. Copies are in depot at
Willets Point, and should be issued if old model torpedoes are
stored at the localities where mines are to be planted by the
party.
Buoyant Mines--to Prepare the Compound Plug. In
actual Service, all the screws and washers of the compound plug
are to be put together with white lead ground in oil and thick-
ened with red lead, and the set screws are inserted; in drills
this may be omitted. The following are the duties of each
member of the squad.
Mumber 1 prepares the connecting wires, in sets, accurately to
the following lengths (Plate IX, figure 6). Wire A, insulated
J) UT'ſ ſº S I W J, O A /) / W (, Iº () () M. |23
with rubber or gutta percha, and carefully gauged to fit the
gland (which is 0.2 of an inch in diameter), is 18 inches long.
At one end, the copper conductor is bared for # of an inch ; the
strand is firmly twisted with the pliers, and the surface bright-
ened with a file. The adjoining insulation is next cut into a
tapering conical form, so as to expose a surface at least half an
inch long, which must be left untouched with the fingers, in
order to preserve it free from grease.
Wire C is of No. 19, B. W. G., and is insulated with closely
woven cotton braid. It is 11 inches in length, and is perma-
nently attached to the circuit regulator by the electrician. The
free end is bared for an inch and brightened by Wumber 1.
The following are the rules for putting together the com-
pound plug (Plate IX, figure 2), for use in either automatic or
Judgment firing.
Mumber 2, after brightening the terminals, connects the two
fuzes by a telegraph joint, closely inade, and attaches wire A
as follows: Wire A is held horizontally, bared end to the right;
one bared end of the fuze wire is placed parallel to and along-
side of the latter, and both are firmly held together with the
pliers, which should grasp the outer end of wire A for of an
inch and the fuze wire near the insulation; the latter wire is
then tightly wrapped round and round the former; the of an
inch at the end of wire A is next bent back and hanmered
down, so as to expose no sharp ends; wire C and the free end
of the fuze wire are connected by a telegraph joint.
The work is then carefully examined by the non-commissioned
officer and submitted to an electrical test—which should show
a good circuit between the end of wire A and the zinc plate,
and a poor one between wire A and the base of the regulator
when the latter is vertical.
All exposed copper joints are next covered with rubber wrap-
pings, beginning well back on the insulation. The strips are
applied under strong tension, each turn overlapping the pre-
ceeding by about one-third of the width. This winding is
continued forward and backward, sometimes in a straight and
sometimes in a diagonal direction, until a substantial insulation
is secured.
Mumbers 3 and 4 disconnect the parts of the compound plug.
They next pass the unbared end of wire A down through the
top of the fuze can ; introduce the fuzes into the can ; smear
124 SUB MARINE MINING MA. T.I., R.I.E.L.
the screw of the circuit regulator with red lead ; and force it
firmly home, being careful not to tangle the fuzes in the ground
wire of the can. -
They next fill the fuze can loosely with dynamite, allowing
none to adhere to the screw, and seeing that the fuzes are well
covered; smear the screw threads with red lead ; force the cap
as firmly as possible down upon its lead washer with the S
wrench, and set the set screw home—this is imperative, for plugs
have come apart in torpedoes from its neglect; slip up on wire
A, in the order named, a false seat (if one be necessary to
reduce the hole to a diameter of 4% of an inch), a rubber pack-
ing, a brass washer and a gland; smear the packing with tallow
and force it into the stuffing box; draw wire A up until the
joint is near, but below, the rubber packing; move up the
washer and gland, and force the latter firmly home, using the
S wrench. They must be careful to leave no fault in the in-
sulation, especially outside the gland. If the packing be hard,
Žt may be softened by pounding. These rules are general for
all gland packings. t
Mumbers 3 and 4 next finish closing the compound plug as
follows:—Wire A is pushed up through the lower tube and
plug proper; the former, red-leaded, is screwed hard into the
fuze can, and the set screw is set home; finally, the false seat
(if necessary as above), the rubber packing, washer, and gland
are inserted in the manner already prescribed.
The compound plug is now ready for its final electrical test
by the non-commissioned officer, who will see that afterward it
is handled carefully. When the plug is held vertically in its
normal position the test should show a good circuit between
the end of wire A and zinc plate, and a bad one between the
former and the fuze can. If it be laid horizontally, however,
the last named connections should show a good circuit. If the
circuit described as bad proves to be good, the difficulty will
usually be remedied by tapping the side of the regulator
smartly when vertical.
For purely automatºo fring, (as on skirmish lines) the com-
pound plug is charged identically in the manner just described;
but, as the circuit regulator plug is omitted, the tests will differ
by showing no circuit in place of the bad circuit.
If judgment fring only is intended, the free fuze wire is
attached to the ground wire of the can ; and no circuit regulator
J) UT'ſ ſº S / W L O A D MAW (; Jº () () M. 125
is needed. Its hole remains filled with the wooden plug, which
should be well red-leaded in position and coated with melted
paraffine. The tests should show a good circuit between wire
A and the compound plug, in any position.
Buoyant Mines--to Charge the Torpedo. Two strips
of 5-inch scantling, about 3 feet long, are spiked to the floor
parallel to each other and 3 inches apart. The middle of the
support thus formed is hollowed to roughly fit the curvature of
the torpedoes. -
The latter, numbered to correspond with the plugs withdrawn
to be loaded, are lying in the vicinity with the caps loosely
attached.
Mumbers 1, 2, 3 and 4 roll a torpedo to the loading blocks;
insert the crowbar through the lowering ring; tip it into posi-
tion; and chock it with two bevelled strips of 2-inch plank
laid across the blocks. They next remove the cap, using a
blunt cold chisel to start the keys, and replace the washers, nuts
and keys on their bolts.
Mumbers 1 and 2 now steady the torpedo, while Mumbers 3
and 4 apply the large wrench and remove the annular plug.
They invert it upon a table, and carefully remove the grease
from the shank by rubbing with cotton waste, while Mumbers
1 and 2 make ready the charge bag.
Mumber 1 aided by Mumber 2 next slips on the lead washer,
and lashes the bag firmly upon the shank, using marline in
regular wrappings applied under strong tension. They then
smear the screw thickly with red lead; insert it; and steady the
torpedo, while Mumbers 3 and 4 force it home with all their
power—if needful, a few blows with a mallet may be given to
the lever of the wrench. *
Mumbers 1 and 2 next introduce the dynamite, being careful
to get none in the screw threads. Numbers 3 and 4 slip the
lead washer on the compound plug; smear its screw with red
lead; and, finally, introduce it into the torpedo. The squad
then force it home as prescribed for the annular plug; replace
the cap, leaving the end of wire A outside; and, lastly, sling
the torpedo for testing.
This is done by the non-commissioned officer. For automatic
firing, the torpedo when horizontal should show a good circuit
between wire A and the metal of the case; but when vertical a
very bad one, or none at all, according as the torpedo is charged
(32)
126 S UB MA R IN E M IN IN G M A T ſ R II) L.
for a main or skirmish line. For purely judgment firing, this
circuit should be good in any position of the torpedo.
The tests being satisfactory, wire A is pushed into the cap,
and the mine is ready for planting. It should be stored in a
cool place, and covered with a wet blanket whenever eaſposed to
a hot sun. This rule is general for all loaded torpedoes.
Ground Mines--to Prepare the Compound Plugs. For
automatic firing, ground torpedoes and buoys form parts of a
single mine; and, as they may be prepared conveniently at the
same time by a squad of four men, they will be treated together.
For purely judgment firing no buoy is required.
Whenever in a ground mine (or in a buoyant torpedo loaded
for a detached regulator) two wires are left in sight after load-
Žng, the one which should lead directly to the operating
casemate is to be cut on a bevel.
Two plugs are required for a ground mine (Plate IX, fig. 3),
one for the torpedo, and one for the circuit regulator buoy. In
actual service, the screws and washers are to be put together
with red lead and the set screws inserted; in drills this may be
omitted.
The following are the duties of each number:-
Mumber 1 prepares the connecting wires, accurately, to the
following lengths. Wire D, insulated with rubber or gutta
percha, and carefully gauged to fit the gland, is 18 inches long.
At the fuze can end, the copper conductor is bared for # of an
inch; the strand is firmly twisted with the pliers, and the sur-
face brightened with a file. The adjoining insulation is next cut
into a tapering conical form, so as to expose a surface at least
half an inch long, which must be left untouched with the fingers
in order to preserve it free from grease. The unbared end is
then to be plainly marked by cutting it off on a bevel.
Wires E and F are precisely like wire D, except the bevel.
Wire C is of No. 19, B. W. G., and is insulated with closely
woven cotton braid. It is 11 inches in length, and is attached
to the circuit regulator by the electrician. Number 1 bares and
brightens the free end for 1 inch.
The following are the rules for putting together the compound
plugs for use in grand groups.
Mumber 1 after thoroughly scraping the wires, connects the
fuzes by a telegraph joint, closely made, and attaches wires I)
&A
I) U T'I /'S / W I, O A D / W. G. Jº O O M. 127
and E to the free ends as follows: Wire I) or E is held hori-
zontally, bared end to right; one bared end of the fuze wire is
placed parallel to and alongside it, and both are held firmly
together with the pliers, which should grasp the end of wire
D or E for 4 of an incland the fuze wire near the insula-
tion; the latter wire is then tightly wrapped round and round
the former; the of an inch at the end of wire D or E is next
bent back and hammered down, so as to expose no sharp ends.
The work is then examined by the non-commissioned officer,
and submitted to an electrical test; which should show a good
circuit between the extreme ends of wires D and E.
Mumber 2 covers all exposed copper joints, except that of
wire D, with rubber wrapping, beginning well back on the
insulation. The strips are applied under strong tension, each
turn overlapping the preceding by about one-third of the width.
This winding is continued forward and backward, sometimes
in a straight and sometimes in a diagonal direction, until a sub-
stantial insulation is secured. The joint between wire D and
the fuze, is next closely wrapped with a strip of sheet zinc,
which is pounded into firm contact with the copper. It is then
protected by several wrappings of fine cotton cloth, tied securely
by twine beyond the ends of the metal.
Mumber 2 next attaches the circuit regulator to the com-
pound plug of the buoy, the screw threads being red-leaded
and forced home hard. He then draws wire C out through
the hole; firmly unites it to wire F in the manner just de-
scribed for D and E; insulates the joint with rubber strips in
the manner above prescribed ; and then lashes wire F to the
tube in such a manner as to prevent it from being in the way
in introducing the plug into the buoy.
Wumbers 3 and 4 separate the two parts of the compound
plug of the ground torpedo; remove the glands of the two plugs
and fuze can ; and open the filling hole of the latter. They
next pass the unbared ends of wires D and E down through the
fuze can and its stuffing boxes; introduce the fuzes into the
can ; slip down on each wire in the order named, a rubber
packing, a brass washer and a gland; smear the packings with
tallow and press them into the stuffing boxes; draw up the
wires until the joints are near, but below, the rubber packing;
move down the washers and glands, and force the latter firmly
home with the S wrench; this must always cease if the wires
128 SUB MA R IN E MINING MA T'ſ RIE. L.
should begin to turn. They must be careful to leave no fault
in the insulation outside the gland. - 4
They next fill the fuze can loosely with dynamite, allowing
none to adhere to the screw ; Smear the latter with red lead ; and
force its cap solidly down upon its lead washer.
The fuze can thus loaded, is to be tested electrically by the
non-commissioned officer, to see that the ends of the two wires
give a circuit, while none can be obtained between one of them
and the fuze can. -
AWumbers 3 and 4 next smear with tallow the four rubber
packings; slip down upon the wires in the order named, a gland,
a brass washer and a rubber packing; pass the wires through
the plug proper; unite the latter to the fuze can and set its
screw; slip down on each wire, a rubber packing, a brass
washer and a gland; and, finally, force the four glands home
in the manner prescribed for the fuze can, beginning with the
two last put on.
The compound plug is now to be tested by the non-com-
missioned officer. A good circuit should be shown between the
ends of the wires, but none between one of them and the can.
Mumbers 3 and 4 next take in hand the plug of the circuit
closer buoy, passing wire F through the hole and packing it in
the manner prescribed for wires D and E.
The non-commissioned officer now tests this plug; seeing that
a good circuit is shown between the end of wire F and the zinc
plate, but a very bad one between the former and the plug
proper when held vertically in its normal position; if laid hori-
zontally, however, the last named connections must give a strong
deflection of the needle.
For skirm/s/, //nes (purely automatic firing) the charging of
the plugs is precisely like that just described ; but the absence
of the circuit regulator plug will cause no circuit to be shown
between wire F and the plug when vertical.
For purely judgment firing, no circuit regulator buoy is
required. Wire E may be used as a plug to close the fuze can
and torpedo; if so, its outer end should be cut to a conical form
and well insulated with rubber to prevent infiltration; a better
plan is to close these holes with solid discs of rubber packing.
The free end of the fuze wires is attached to the fuze can ground
wire; and the tests should show a good circuit between wire I)
and the compound plug in any position.
J) U 7' I ſº S I W L () A /) I W G R O () M. 129
Ground Mines--to Charge the Torpedo. Wumbers 1 and
2 remove the cap, replacing the washers, nuts and keys on the
bolts; insert the funnel; introduce the dynamite into the tor-
pedo with the scoop and a suitable stick, being careful not to
spill it or get it into the screw threads; and prepare a cavity
below the filling hole to receive the can easily. They then slip
the lead washer on the compound plug; smear the screw thickly
with red lead; wipe the threads of the female screw; pass the
can through the hole, and start the plug in as far as can be done
by hand.
Meantime Mumbers 3 and 4 have inserted a crow-bar through
the lowering ring, and inverted the buoy on a seat prepared by
spiking to the floor two 6-inch scantlings, 3 feet long and hol-
lowed to fit the curvature of the buoy. They are placed parallel
to each other and 3 inches apart. The men then remove the
cap, replacing the washers, nuts and keys on the bolts; slip the
lead washer on the compound plug; smear the threads thickly
with red lead; and introduce the plug as far as can be done by
hand.
Mumbers 1 and 2 now steady in succession the torpedo and
the buoy, while Mumbers 3 and 4 force the compound plugs
home with a large wrench—a few blows, if necessary, may be
given with a mallet. The squad now replace the caps leaving
the ends of the wires projecting outside through the holes; and
sling the buoy by the lowering ring.
The non-commissioned officer now makes his final tests; to
See, when automatic firing has been ordered, that a good circuit
is shown between wires D and E, and none between one of them
and the torpedo; for purely judgment firing, a good circuit.
must be shown between wire D and the metal of the torpedo.
He then sees that a good circuit appears between wire F and
the metal of the buoy when horizontal; but when vertical, a
very bad one or none at all, according as the buoy is designed
for a main or skirmish line.
These tests being satisfactory, the wires are thrust inside the
caps, and the mine is ready for planting. Loaded torpedoes
should be stored in a cool place, and covered with wet blankets
whenever eaſposed to a hot sun.
Self-acting Mines--to make Safety Rings. If a supply
of these rings cannot be issued from the depot, one capable
man equipped with the following articles (most of which are in
(33)
130 S UB MA R IN J. MINING MA 7'ſ RIEL.
tool box A) is required to make them: four rings per hour is
fair average work.
1 small balance and set of weights.
1 Wedgewood mortar and pestle.
1 small vessel for water—to counterpoise mortar before gum
arabic is added.
2 mixing dishes (evaporators).
1 Safety ring mould.
1 small screw-driver.
1 oiler.
2 camels' hair brushes, for oiling mould.
1 mallet and wooden drift to fit mould. -
Cupric sulphate ; loaf sugar; gum arabic.
Weigh out 4 drachms (240 grains) of loaf sugar and 8
drachms (480 grains) of cupric sulphate; pulverize them sep-
arately in the mortar to extreme fineness; mix thoroughly in
an evaporator. This material will make two rings. Put about
half of it in the mortar; and, balancing with water as above,
add 1 scruple (20 grains) of a solution of gum arabic in water,
made as thick as honey; incorporate to a pasty mass free from
powder with the pestle; press a little of this mass into the
mould, previously oiled to prevent sticking, and compact firmly
with the wooden drift and mallet; continue this operation until
no more can be inserted; cut off the surplus. at top smoothly
with a knife blade, being careful to make no depression ; un-
screw the mould ; insert the knife blade, held vertically, between
the outer edge of the ring and the mould until the halves sep-
arate; press out the centre piece, without distorting the ring;
place the ring back in the mould (omitting the centre piece),
and press the halves together to accurately gauge the outer
diameter; remove the ring and dry for two or three days, when
it will be found to be hardened thoroughly. Finally, apply one
or two coats of the gum arabic solution to the surface to pre-
vent crumbling; after they have dried the ring is ready for use.
Self-acting Mines--to Prepare a Safety Break. One
capable man is required, equipped with the following materials,
most of which will be found in tool box A ; he should prepare
four of these breaks per hour.
1 spirit lamp.
1 blow-pipe.
1 Stevens’ vise.
1 safety-break wrench.
1 cutting plier8.
J) Uſ T' I E S ſ N J, O A D M W G R O O M. 131.
1 small round-nose pliers.
1 loading stick, # of an inch in diameter and 8 inches long.
1 detector. - -
Safety breaks complete, including the soluble rings; rub-
ber tubing # of an inch in internal diameter, and cut
in lengths of 14 inches; waxed linen thread; common
solder (2 parts of lead, 1 part of tin); rubber insu-
lated wires gauged to fit hole of an inch in diameter
and cut in lengths of 12 inches; resin; resin oil wash;
wood spirits for lamp.
He first unscrews the ebonite cylinder from the brass ebonite
plug; applies a little hot resin oil wash to the threads, and then
screws the ebonite cylinder home.
He next bares an end of one of the insulated wires for one-
fifth of an inch; scrapes it bright and doubles it back upon
itself; holds the platinized tip in the pliers, hole (brightened)
upward, and places a little resin and solder on top; directs the
flame of the blow pipe upon it until the liquid solder fills the
hole; inserts the prepared end of the wire in the solder, and
holds it straight until solidified in place.
He next passes the other end of the wire successively through
the brass ebonite plug, a rubber packing, the washer and the
gland; clamps horizontally in the vise; draws the platinized tip
well home, and holds it there by pressure applied with the
platinized terminal; and, finally, closes the stuffing box in the
usual way. Care is needful to prevent the compression of the
rubber packing from pushing the tip down out of place ; if this
occurs, insufficient play is allowed when the plug is assembled,
and the electrical test will show no break in the circuit. A
rubber packing fitting too closely may cause this difficulty.
He next inserts the platinized terminal in a rubber tubing and
lashes it firmly, being careful that no rubber projects above the
grooves; slips the rubber tubing over the brass ebonite plug,
with the platinized terminal in the hole, until a play of about
0.15 of an inch is allowed; and lashes the tubing firmly to the
brass ebonite plug. To test, attach one wire of the detector to
the insulated wire, and touch the other to the platinized
terminal; no circuit should at first appear, but by pressing the
terminal home the needle should be deflected.
To assemble the safety break, insert the brass spring, the
sliding cylinder and a safety ring; compress the spring with the
loading stick, and screw the closing ring firmly home.
132 S UB MA RIN E MINING MA TIſ, R TEL.
Finally, screw the brass ebonite plug into place. The platin-
ized terminal should nearly or quite touch the head of the
sliding cylinder. Test by uniting one leading wire of the de-
tector to the wire of the safety break, and touching the platinized
terminal with the other; no circuit should be shown. Next,
with the latter wire in contact with the case, press the platin-
ized terminal home (about 4 of an inch) by a metallic pin
inserted through the hole in the head of the sliding cylinder and
Žn metallie contact with it; a good circuit should appear.
These tests should be verified by the electrician.
Self-acting Mines--to Encase the Battery. One capa-
ble man is required, equipped as follows: With cells already
prepared, he should easily encase two batteries per hour.
1 spirit lamp.
1 cutting pliers.
1 detector.
1 standard platinum bridge.
Brass battery boxes; chloride of silver cells; resin and beeswax
cement; twine ; rubber bands (half inch by two inches);
paraffine; wood spirits for lamp ; sets of gutta percha
loading wires, gauged to fit a 0.2-inch hole—one wire is 18
inches and the other 12 inches long, and both have unbared
&nds. -
In general terms, the cells are to be connected in series and
placed in a brass battery case, which is then to be filled with
melted paraffine, and closed at the top with a brass cover,
Securely sealed against leakage. The details of the operation
are as follows:
The cells as drawn from the depot will usually be complete
except the fluid. In this case they are opened carefully; the
roll is slightly moistened in a saturated aqueous solution of zinc
sulphate; the ebonite case is filled about one-third full of the
same solution; the roll is inserted very carefully, to avoid false
contacts between the wires and plates; the screw threads are
smeared with hot resin oil wash (a half and half mixture of
resin and resin oil incorporated over a spirit lamp), and the cover
is screwed hard home.
If the cells are received in parts, they are assembled as pre-
scribed in Abbot's Notes on Flectricity, page 58. Special care
must be taken to avoid false contacts between the wires and
plates inside the cell. If the positive terminal is a wire sol-
dered to the silver plate, too much care cannot be taken to cover
D U T’ſ ſº S I W I, () A I) / W (), ſº O O M. 133
the solder with a water-proof insulation; but this terminal should
should always form part of the plate itself. The resin oil wash
must be applied hot, and thick enough to perfectly seal the cover
against leakage.
The cells should be prepared and allowed to stand at least a
week before loading, in order to detect obscure defects should
such exist. The standard test is a distinct reddening of the
bridge of a cut-off, held in testing clips or otherwise; the
manipulation should be rapid and the test should be repeated no
oftener than is unavoidable, because the supply of chloride of
silver is necessarily limited to keep the internal resistance within
proper limits, and the battery is therefore easily exhausted by
overwork. .
To encase the battery, brighten the four terminal wires and
place the two cells side by side with their top strips in line—one
copper and one silver terminal being on each side of the line of
strips; spring a rubber band around the tops of the cells (a twine
lashing will do) to hold their axes parallel; clamp the bottoms
very gently in a vise, to keep the cells in place.
Prepare two leading wires by uncovering about 0.4 of an inch
of the copper core and bending it 90 degrees to the right, then
bending an equal length of the adjacent insulated part 90 de-
grees to the left, and finally lashing the two wires together in
the form of a fork, with all parts in the same plane; straighten
the wires and (removing the cells from the vise for the purpose)
pass the free ends (left unbared) downward between the cells
until the lashed end rests on their tops; wrap a battery wire
closely around each leading wire, secure the ends, trim off,
straighten and press the uninsulated parts well into the angle
at the base of the strips. Bend the other two silver and copper
wires down flat, and connect them by a twisted joint, being
careful not to strain them; cut off any excess of length and
gently press the whole into the angle at the base of the strip;
examine carefully to see that all joints are too short to permit a
short circuit even if shifted in position; finally, remove the cells
from the vise and lash their bottoms together with twine.
Cover the top of the cells with resin and beeswax cement
flush with but not above the top of the strips, being careful to
insulate all metal in sight; and, finally, place a single thickness
of stout brown paper over the top, and trim it to fit the ellip-
tical form of the battery (the hot cement will hold it in place).
(34)
134 S UB MA R IN E M IN ING MA 7'ſ R I ſº I, .
Slip the battery thus prepared upside down into the brass
case; bend the insulated wires into position to pass through the
holes in the cover; and pour melted paraffine around the cells.
The temperature must be kept as low as possible. To this end,
begin pouring before the whole quantity in the vessel is melted,
and make two or three successive additions, quickly cooling the
brass case after each by standing the lower part in cold water.
Stop adding paraffine when the surface rises to the top of the
ebonite; and before it can cool, pass the wires through the holes
in the cover, and press the latter home gently; when cold, Seal
with melted resin and beeswax cement around the edges and
wire holes; and, lastly, invert the case. It must always be kept
Žn this inverted position.
After all is complete, the battery should be tested (1) with a
detector to see that there is no circuit between either wire and
the case, and (2) to see that it reddens the standard platinum
bridge. After lying a week, the tests should be repeated. If
no trouble has developed, the battery may be trusted to retain
its power for many months.
Self-acting Mines--to Remove the Battery. This is
done by removing the resin and beeswax cement with a knife,
taking off the cover, and then holding the different parts of the
brass case successively over a spirit lamp. So Soon as the para-
fine begins to melt the fluid portion is decanted; and very soon
the cells can be withdrawn still well coated. Care should be
taken to apply as little heat as possible. The remaining paraffine
is removed with a knife.
Self-acting Mines--to Charge the Torpedo. The case is
charged precisely like that of any buoyant mine, except that
only one fuze is inserted; that an inverted circuit closer is used,
and that the electrical tests are made in an inverted position.
The subsequent work will occupy a capable man about half an
hour. *
The non-commissioned officer first examines the work already
done, and makes the following electrical tests of the special
parts to be added.
The safety break is tested with a detector very carefully (1)
to see that no circuit is shown between its leading wire and the
outer case or the platinized terminal (which may be reached
through the hole in the head of the sliding cylinder); and (2)
to see that a good circuit is shown between these points when
. J.) UT'ſ B, S J W /, O A D M W G Jº () () M. 135
the platinized terminal is pressed home (about 4 of an inch)
with a metallic pin in contact with the sliding cylinder. Upon
the care with which these tests are made will depend the lives
of the men handling the torpedo, and its efficiency when planted.
He next verifies the condition of the battery by reddening
for an instant the standard platinum bridge; and makes sure
that the torpedo may be safely capped by seeing that the detector
shows no circuit between either battery wire and the metal of
the cap. -
To assemble the cap, screw the safety break into its place,
first coating the screw with red lead ; slip the brass case con-
taining the battery into its receptacle, and wedge it in place with
cotton; pass the leading wires out through the stuffing boxes
and bolt the cover down hard upon the rubber packing under it
(the monkey wrench from tool box A is convenient for this
purpose); in actual service, upset the end threads of the screw
bolts, to prevent them from working loose; insert the rubber
packings, the brass washers and the glands in the usual manner;
finally, repeat the three electrical tests ordered in the last
paragraph.
Connect the wires in the cap as follows: Joint the wire of
the safety break to the short battery wire by slipping on a rub-
ber joint tubing, winding the small wire several times round the
large one, bending back the end of the latter with the pliers
until no sharp point is exposed, wrapping the exposed copper
with a rubber strip, and, finally, drawing up and lashing the ends
of the rubber tube in the usual manner. Then, and not until
then, unite the other battery wire in a similar manner to the
wire coming from the charge; and, lastly, attach the cap to the
torpedo, being careful that neither wire is injured in so doing
—carelessness in this matter may involve danger to the party
loading.
The torpedo is now ready for planting. In order to hold the
battery in its proper position the cap must always be kept up.
To Charge a Main Line Switch Box. As explained on
page 63, the mine switch fulfils the double duty of insulating
the ends of cable exposed by the explosion of the mines, and
of protecting the difficult joint necessary where a single con-
ductor radiates into two or three branches.
As its gland packings are liable to be exposed to much more
water pressure than those in any other part of the system,
136 PIE // PA /* A 7'0 ſº Y S II () ſº ſ! /) U 7' / // S.
extreme care is needful; and only skilled and trustworthy men
should be detailed for the work.
It must be noted that the usual rule in planting mines, to
connect any bevelled wire to the wire coming from the case-
mate, does not apply to 80%teſ, bowes. With them, it is never
followed, the IT wire being always so joined.
The following drill is for the new square form of switch box,
but is also applicable with slight modifications to the old tri-
angular pattern.
The non-commissioned officer personally inserts the cut-offs,
makes or examines the joints, does the testing, and closes the
glands. Two assistants do the rest of the work, under his
direction.
Mumber 1 prepares the wires (Plate IX, fig. 6). Wire H,
insulated with rubber or gutta percha and carefully gauged to
fit the 0.2-inch gland, is 6 inches long; one end is cut square;
at the other, the copper is bared and scraped for three-quarters
of an incl.
Three other wires, named K, are prepared exactly like II.
AWumber 2 prepares three cut-offs, as follows. The jaws of
the hand vise are opened to such a distance that the wires will
fall easily between them, with the plug resting firmly upon
them; the rubber tube, previously cut to a length of 3 inches,
is then forced on by steady pressure, until the whole plug is
covered; finally, the shortest wire is bent over 180 degrees, so
as to closely hug the cap. -
He next joints each of the wires K to a short cut-off wire
in the following manner, care being taken to scrape all the
surfaces bright, and to have one and a half inches of the cotton
insulation removed. Wire K is held horizontally, the bared
end to the right; the short cut-off wire, the bared end to the
left, is placed parallel to and alongside of the latter, and both
are firmly held together with the pliers, which should grasp
the end of the copper of wire K for an eighth of an incl, and
the cut-off wire near the end of the insulation ; the latter is
then wrapped tightly round and round the former; the eighth
of an inch at the end of wire K is next bent back and ham-
mered down, so as to expose no sharp ends; finally, a thick
wrapping of pure rubber is wound tightly over all the exposed
copper—beginning well back on the insulation. If needful, the
end is made fast by a little rubber cement.
I) Uſ T'ſ Jº S IN L, () A D IN (# R O O M. - 137
The switch box (Plate V, fig. 4) is opened, all the glands
being removed; and any oil on the outside is carefully wiped
off with cotton waste. Looking in the H chamber, any rough
edges round the holes connecting with the three K chambers,
are carefully removed with a conical or acorn shaped die-sinker's
file from tool box B.
The non-commissioned officer next inserts the three cut-offs in
the box, solid ends down and priming ends outward, thrusting
the long wires through the K chambers, and connecting holes,
into and through the H chamber; extreme care is required to
avoid chafing the insulation, and success should be verified with
the detector, by placing one wire on the box and the other suc-
cessively on a wire of each cut-off. A small blunt stick of pine
is useful to press the three cut-offs gently to the bottom of their
respective chambers.
The three ends of wire which project from the H chamber,
are next brought together and held firmly with the thumb and
finger, while with a pair of pliers they are twisted into a strand
three-quarters of an inch long, and are brightened with a file.
Another test with the detector should now be made, as before,
to ensure no contact with the box.
Wire H brightened with a file, and the triple strand just made,
are inserted in the opposite ends of a brass jointer and pushed
well home; the pincers are then to be carefully applied so as to
press upon the middle of the jointer, parallel to the wires; rest-
ing the lower jaw upon some firm support, several hard blows of
the hammer are next to be given to the top jaw so as to firmly
jam the brass down around the wires; finally, having tested the
closeness of the contact by a strong steady pull, during which
the strand must be held by the thumb and finger to prevent
injury to the insulation within the box, any sharp ends are to be
carefully rounded off with the cutting pliers or file. A strip of
pure rubber, about two inches long, is then cut from the coil;
and, beginning well back on the insulation, is wrapped under
strong tension round and round the exposed metal—each turn
overlapping the preceding by about one-third of the width.
This winding is continued forward and backward over the
whole joint, the turns sometimes crossing in a straight and some-
times in a diagonal direction, until the strip is used up. The
end is secured by firm pressure, continued for several seconds.
By gentle twisting, and the use of the pine stick, the joint is
. (35)
138 PIR EP A R A TO R Y SHO Jº Jº D UT'ſ Jº S.
next pressed into the H chamber, until it rests just below the
shoulder.
The false seat is now slipped over the end of wire II, and
pressed down until it rests on the shoulder provided for that
purpose. A rubber packing coated with tallow is then worked
squarely down upon the false seat. A brass washer follows.
Finally, the gland is inserted and screwed down until it begins
to go hard. Reversing the box, the cut-offs are again gently
pressed home; and the test for no contact with the box is
repeated.
The three short wires are now, in like manner, twisted gently
and pressed into their chambers until the joints rest just below
the shoulders; finally, the false seats, the rubber packing, the
brass washers, and the glands are inserted as already described.
The test for no contact is again repeated.
The box is now held firmly in the bench vise, and with a
monkey wrench the four glands are screwed home; this usually
should cease if the wires begin to turn. A final test for no
contact between wire H and the box, and for good contact
between the former and each of wires K, is then made.
To Charge a Skirmish Line Switch Box. The drill,
so far as the practical manipulations are concerned, is identical
with the last; but the object being different, the arrangements
in the box are unlike.
The object is to unite a short cable leading to the mine,
through a cut-off, to a continuous insulated cable. When prac-
ticable, both ends of the latter will be connected with operating
boxes; which may be placed either at one or two stations as
most convenient. An open circuit is always used.
To fulfil these conditions one of the K holes of the box is
to be closed effectually against leakage. This may be done by
inserting a short piece of insulated wire by the usual method of
gland packing, or better by inserting a solid disc of sheet rubber
packing. To prevent infiltration with the first method, the
exposed end must be tapered for a short distance and be well
covered with a rubber strip. /
Another of the K holes contains a cut-off, inserted identically
as prescribed for a main line box.
The third K hole contains a small continuous insulated wire
instead of a cut-off. It is connected and inserted precisely like
J) Jº II, I, S F() I., B () A T S Jø IAE VI C Jº. 139
a cut-off; but to distinguish it, the outer end of its wºre K is
ºut on a bevel.
These differences being noted, the box is to be charged in the
manner already laid down for a main line box.
To Charge a Switch Box for Judgment Firing. This
differs from the charging of a main line box only in the in-
ternal arrangements. The object is to protect the difficult joint
where a single conductor radiates into three branches. This is
accomplished by substituting short continuous insulated wires
for the three cut-offs. To distinguish a box so charged, the
outer ends of the three wºres A are out on bevels.
Should there be a deficient supply of boxes, a triple joint
may be made by ordinary rubber wrapping; but, as there will
always be danger of leakage, the plan is not to be recommended.
LOADING ROOM. DRILLS FOR BOAT SERVICE.
The mines, when ready for planting, will be transported by
ordinary laborers from the loading room, or place of storage,
to the wharf; where a crane or derrick should be provided for
transferring them to the boats.
In case of necessity, the manoeuvering of the boats and the
handling of the mines on the water, will be done by sailors
—who can always be hired in our large seaports—but the
supervision of the work, and certain mechanical manipulations
connected with it, must be entrusted to instructed Engineer
soldiers. Such of these manipulations as require preliminary
training on shore will now receive attention. They comprise:
jointing the insulated cable, including core joints; the making
of turks heads and the union of the parts in a junction box;
inserting thimbles in wire rope; and attaching cable stops.
Insulated Cable--Jointing the Core. Too great care
annot be taken in this matter; as a single bad joint will cer.
tainly entail much loss of time and labor, and may even compel
the raising of a whole triple group of mines. With torpedoes
planted in the usual manner, there will necessarily be for each
multiple cable that leaves the casemate, either 63 or 105 joints
in the core, according as buoyant or ground mines are em-
ployed. The importance of doing the work well is, therefore,
apparent. A good joint should have an insulation resistance of
many thousands of megohms.
140 P Hº B, P A R A T' O If Y S II () Jº Jº D U T' I Jº S.
Jointing a cable consists of two distinct operations:—
Fºrst. Uniting the conductor, and insulating any metal ex-
posed in so doing. This is called jointing the core.
Second. Causing the iron armor to bear any strain that may
be thrown upon the joint. This involves the making of turks
heads, and firmly clasping them in junction boxes, or in the
torpedo caps.
One private with a jointing box D can joint the core. In
actual service; men of especial intelligence should be selected;
and scrupulous care should be taken to keep the hands clean,
and the cores and materials dry and entirely free from grease.
No cut surface of the insulation should be touched with the
fingers.
Convenient access being secured to the two ends to be united,
a rubber tube 4 inches long should be slipped over one of them
—preferably the smaller—and moved up well out of the way.
Each core should then be prepared as follows (Plate IX, figure 1).
The end of the copper strand should be bared for a distance of
three-quarters of an inch, by cutting the insulation and pulling
it off with the fingers. The strand should then be twisted
firmly with the pliers and its surface brightened with a file.
The adjoining insulation should next be cut into a conical form
at least a quarter of an inch long.
The two bared strands are now to be inserted in the opposite
ends of a brass jointer and pushed well home; the pincers are
then to be carefully applied so as to press upon the middle of
the jointer, parallel to the wires; resting the lower jaw upon
some firm support, several hard blows of the hammer are next
to be given to the top jaw, so as to jam the brass down around
the wires; finally, having tested the closeness of the contact by
a strong steady pull—not jerk—any sharp ends are to be care-
fully rounded off with the cutting pliers or file.
A strip of pure rubber, about 4 inches long, is then cut from
the coil; and, beginning well back on the insulation, is wrapped
under strong tension round and round the joint—each turn over-
lapping the preceding by about one-third of the width. This
winding is continued, forward and backward, over the whole
joint, the turns sometimes crossing in a straight and sometimes
in a diagonal direction, until the strip is used up. The end is
secured by firm pressure, continued for several seconds. If by
reason of cold weather the end will not adhere, a little rubber
D R / J, J, S Jº'O Jº J3 O A 7' S /; IP V ſ(; ſº. 141
cement may be used; but this should never be done unless
absolutely necessary, because the cement has a bad effect upon
the rubber. Another strip of rubber, similar to the first, is next
cut and applied in the same manner, and the end is secured by
pressure, or if necessary, by a little cement. The joint should
now be of uniform size throughout, and solidly compacted.
The rubber tube is now drawn down so as to entirely cover
the joint, and is tied on securely—especial attention being given
to the ends.
Jare should be taken to protect the joint, thus completed,
from any strain or bending.
Insulated Cable--making a turks head. In submarine
telegraph cables, the armor is jointed by a long running splice
with the iron wires, similar to the splicing of a rope to run
through a block. In case of necessity, the same device may be
employed in the torpedo service, but the method of turks heads
is greatly to be preferred when junction boxes are at hand—and
it must be exclusively used in connecting the cables to the
mines.
To make a turks head (Plate IX, figure 4) two privates
equipped with a jointing box D are required. They are de-
signated No. 1 and No. 2. The former is responsible for the
work; the latter aids by holding the cable, passing the tools, etc.
If the object be to splice a single cable, or to unite a multiple
or single cable to several single cables, with or without inter-
vening cut-offs, the turks head will be made first; but if it be
desired to attach the cable to a torpedo or buoy, the free end
will first be passed through the clamping hole of the cap. In
either case, the turks head will be made in the following
I (1811) () (? I’.
Trim the end square; slip on a collar, flat side first, and place
it nine inches from the end; unwrap the jute covering, and bend
it back regularly over the collar; do the same with the iron
wires and the interior hemp serving; cut off the iron wires with
the pliers, removing about four inches from one, and six inches
from the next, alternately; trim off about four inches from the
jute and hemp wrapping; bend the iron wires separately to
closely fit the collar (making two right angles with the pliers)
and arrange the ends smoothly along the cable; engage the end
of a strand of marline under one of the wires near the collar,
and wrap it regularly and closely around the cable, until a point
(36)
142 P. R. E. PA R A T' O J Y S EI () Jº Jº O U TI // S.
about one inch beyond the end of the jute and hemp is reached;
lastly, secure the free end of marline with two half hitches.
About 12 feet of it are required. - •
In case no collars are at hand, a wrapping of marline of
similar form may be substituted.
Insulated Cable--completing the joint. If the object
be to splice one cable to another, the cores are jointed in the
manner already described; the turks heads are placed in their
positions in a single junction box; and the latter is bolted
together, great care being observed not to injure the exposed
parts of the cores coiled inside, and to see that the wrappings of
the turks heads are so firmly clamped that no motion is possible.
If the cable is to branch into two or three cables, a switch
box and triple junction box will be used. The turks heads are
first secured in the latter, and then the cores are united as al-
ready described. Lastly, the triple junction box is closed.
If a multiple cable is to branch into single conductor cables,
a grand junction box will be used. The turks heads will first
be secured; then the cores will be united ; lastly, the box will
be bolted together.
If the cable is to be joined to a torpedo or buoy, the turks
head is first drawn up until the swell is in contact with the cap,
and the clamps are then bolted fast. It is essential that the
clamps shall take a firm hold; and if the iron jaws touch, it is
sufficient proof that there is not enough of marline wrapping.
Afterward the cores are jointed, and the cap is immediately
screwed to its seat. Care is needed to avoid any unnecessary
bending of the cores, especially at the point where the wire
leaves the plug; and no pulling whatever must be allowed.
The Moorings--to Insert Thimbles in Wire Rope. The
floating part of the mine is subjected to the torsional action of
varying tidal currents, and to continual wave oscillation. Ex-
perience has revealed a tendency to twists and kinks in the
connecting cable, which is overcome by the use of galvanized
wire rope as a mooring; but if the ends of the latter be rigidly
held fast, the constant bending soon occasions the destruction of
the wires. To obviate this difficulty, so far as possible, thimbles
are inserted in the rope; and shackles are used to connect it with
other parts of the mine.
To insert thimbles in wire rope is not an easy operation; and
as it should be done rapidly, drilling is very needful to render
J) /? / /, L S. Ji'() ſº ſ? () A T' S /ſ/ R V ſſ/ſ/. 143
the men proficient. Much of the work should be done on shore,
the rope being cut in suitable lengths according to the depth.
By this plan, one thimble may always be inserted in each moor-
ing, before embarking; and where the bottom is fairly smooth,
the preparation of complete moorings in assorted lengths will
certainly save time.
Two privates of Engineers are required, although the work
can be well done by one of them when time is not important.
They should be equipped with :
1 rigger's vise bolted to a rigid support.
thimble clamp.
tool box C.
coil of wire mooring rope.
coil of annealed galvanized iron wire, No. 12 B. W. G.
.
The three jaws of the vise are opened wide; the end of the
wire rope is bent by hand, and inserted in such a manner as to
bring the single jaw in contact with a point about one foot from
the end. It is usual with riggers to allow at least eighteen in-
ches for this distance, but in torpedo moorings the lesser length
is sufficient. The slack should be held at the proper height, by
stopping it to a vertieal handspike.
The double jaws, and if needful the single jaw, are screwed
together until the bend is reduced to the proper size to receive
the thimble—the double jaws pressing the rope opposite its
point. By working the vise, tapping the rope with a hammer,
and driving the thimble home with a stick used as a drift, it is
now easy to bring the two parts of the rope closely round the
thimble and in contact with each other.
The first stop is now put on, inside the double jaws, by taking
two turns with a bit of wire, and drawing it tight by twisting
the ends with the nippers. The hold is then shifted so as to
bring this stop outside the vise.
The short end is next untwisted into strands, using first the
nippers and then the fingers; the strands are spread evenly
round the rope; and the hemp core is cut off as far up as
possible.
Each strand is next untwisted in the same manner, and the
wires are singly straightened by taking a firm hold of the end
with the nippers and giving a violent twitch in a direction par-
allel to the rope.
144 PR EP A R A 7"O R Y S HO R E D UTI ES.
The wires are now laid uniformly round the rope, and the
second stop is applied like the first; its place is about an inch
from the ends of the untwisted wires.
The next step is to attach the wrapping ball of annealed wire;
which has been prepared by cutting about 25 feet off the coil,
and winding it loosely, first round the hand and then round the
turns thus formed. A couple of inches of the outer end of this
ball is inserted under the first stop, and is then bent out of the
way into the opening of the thimble. The annealed wire is
then unrolled among the unstranded wires, parallel to them.
The third stop is next applied, around the middle of the mass
of unstranded wires, care being taken to see that the latter are
uniformly disposed.
The three stops are now well tightened by using the nippers
as a lever, the fulcrum being supplied by a wooden wedge
placed under the jaw; the ends are twisted as fast as slack is
thus obtained. The hammer may also be useful, to aid in get-
ting the loose wires into a compact mass.
The rope is now shifted from the vise to the thimble clamp,
and is rigidly secured therein. All being in readiness for the
wrapping, the annealed wire is bent sharply over, at right angles
to itself, at a point just above the second stop; this bend is
made with the pliers. Holding the angle in place with the left
hand, the ball is passed twice over the rope and drawn as tight
as possible with the right, thus binding the turn. A small loop
is now made by passing the ball twice under the rope. The
marline spike, or if preferred a cylindrical iron rod, is thrust
through this loop; by revolving it round and round the rope,
and regulating the tension by passing the ball over it, a close
even wrapping is applied over the unstranded wires; and the
end below the thimble is thus perfectly secured. The third
and first stops are removed successively as they are reached by
the wrapping. After extending the latter well up to the point
of the thimble, any part of the ball remaining is cut off; and
the two ends of the annealed wire are secured by twisting them
together, and hammering them down out of the way.
It only remains, after removing the second stop, to trim off
and secure the short ends of the unstranded wires, by bending
them up over the wrapping and hammering them down so
closely as to leave no sharp point to chafe the insulated cable.
J) I? I I, I, S JPO R B (). A 7' S E R VIC E. 145
The wrapping thus made should be at least six inches long;
if it be a foot long, the rope will part before the thimble will
yield. If needful the wrapped portion will be straightened by
tapping with a hammer.
The Moorings--to attach a cable stop. The use of or-
dinary mooring requires considerable time; for each rope must
be prepared to exactly suit the depth of water at the spot
selected for the planting. Where celerity is of primary impor-
tance, this objection to the method has so much weight that the
cable stop, which permits the use of the insulated cable for the
mooring, has been devised as a temporary expedient. As the
cable is deficient in endurance for this purpose, it is necessary
to relieve it at the earliest practicable moment, by raising the
mines and adding the usual wire mooring ropes; hence, the
plan is only recommended for emergencies, and, indeed, is in-
applicable where strong currents prevail. At Willets Point,
mines thus anchored have often remained in position from one
to two weeks without injuring the cables.
To attach a cable stop two privates are required, equipped
with :
1 tool box C.
1 coil of annealed galvanized iron wire, No. 12 B. W. G.
Cable stops.
Torpedo cable, attached for service.
It is necessary that an open wrapping of wire should be ap-
plied tightly round the cable at the upper end, and also just
above the stop. In deep water, at least a dozen feet at each
place should be protected in this manner.
Having fixed by accurate measurement and marked the posi-
tion of the stop, the men first apply these wrappings—each
working independently. Care is needful to secure the ends so
that they can neither slip nor endanger the core, and to use all
possible tension. One end may be clamped with the turks head
by loosening the cable clamp of the torpedo or buoy, inserting
the end, and reclamping it; another may be secured by mar-
line and left to be held in place permanently by the cable stop;
the others must be drawn back under a few of the previous
turns. About twice and a half the desired length of the pro-
tection should be allowed in cutting the wire; this will give
turns about 14 inches apart.
(37)
146 P R /; P A R A T'O IR Y S II () ſº ſº JD UT'ſ ſº S.
AWumber 1 now opens the cable stop (Plate V, fig. 2) by re.
moving the top half. Wumber 2 bends the cable to the proper
curvature and, aided by Mumber 1, inserts it in the groove; the
latter now fits on the top half, and clamps the two parts
together. It only remains to shackle the stop to the anchor.
The temporary use of the stop is often convenient with ground
mines, where the buoy is not planted over the torpedo. It is
sometimes, but very rarely, advisable to use it even when the
buoys are over the torpedoes. In such cases, the insulated
cable uniting the two parts of the mine, must be cut consider-
ably too long; and the slack should be thrown in a single spiral
turn round the anchoring ring.
TIME REQUIRED FOR LOADING ROOM IDUTIES
AND DRILLS.
Very much of course depends upon the skill and practice of
the men. The following estimates are based upon records of
the time actually occupied by the prescribed details of average
first class Engineer soldiers, working steadily but without undue
haste.
To prepare the compound plug for a buoyant mine—20
minutes. 4. g #
To charge a buoyant mine, including opening, inserting the
dynamite, and closing—45 minutes.
To prepare the compound plugs for a ground mine and its
buoy—30 minutes.
To charge a ground mine and its buoy ; including opening,
inserting the dynamite and closing—55 minutes.
To make a safety ring for a self-acting mine—15 minutes.
To prepare a safety break for a self-acting mine—15 minutes.
To encase the battery (issued complete except fluid)—30
minutes.
To charge the special cap of a self-acting mine—30 minutes.
To charge a main line switch box—20 minutes. •
To joint the cores of two insulated cables—8 minutes.
To make a turks head on a single conductor cable
minutes.
To make a turks head on a multiple cable—20 minutes.
To insert a thimble in a wire mooring rope—30 minutes.
To attach a cable stop, including wire wrapping the cable, 30
minutes.
1()
(; H A PTE R W.
PLAINTING THE MINIES.
DUTIES OF THE COMMANDING ENGINEER.—Time required for planting
mines.—Local Administration.—DUTIE8 of THE EI, ECTRICIAN.—
DUTIES OF BoAT PARTIES: to place a grand junction box; to place
triple junction boxes; to plant a buoyant mine; to plant a ground
mine; to raise single mines; to plant mines in grand groups; to raise
or repair mines in grand groups; to plant skirmish mines; to raise
skirmish mines; to plant self-acting mines: to raise self-acting
mines. –THE AUTOMATIC II,ANKING GUN 8.
The four general dispositions for mines—grand groups, skir-
mish lines, detached groups and self-acting mines—have already
(page 11) been explained. Here, therefore, it only remains to
consider the duties of officers and enlisted men during the oper-
ations of planting, and, so far as practicable, to systematize the
work in the form of drills.
I) UTIES OF THE ()() MMANI) IN (; ENGINEER.
Time will usually be of the utmost importance when a chan-
nel is to be obstructed; and success will very largely depend upon
the skill of the Commanding Engineer in so arranging the work
as to keep every one constantly and octively employed. To
accomplish this it is needful to know the time required for per-
forming the different mechanical operations.
Time Required for Planting Mines. The following
records, kept with this object specially in view at the planting
of twelve mines of a grand group in 1881, furnish valuable
data. The mines were laid off Willets Point with the small
steam launch, by the usual detail of Engineer soldiers, under
Lieutenant Abbot; who directed the work on the water and
kept the notes, while Lieutenant Fiebeger acted as electrician.
The mines, wire mooring ropes equipped with thimbles, anchors,
etc., were towed out on a ponton raft and anchored in the
vicinity of the grand group. Four row-boats were used; the
water varied from 30 feet to 110 feet in depth; the weather
was favorable; the current never exceeded about two feet per
second, varying in strength and direction with the changes of
the tide.
148 P L. A. W. T.' I W G T H E MIN E S.
To place the grand junction box anchor in position at a dis-
tance of half a mile from the starting point, required about
half an hour; and to plant the twelve mines required 7.5 work-
ing hours. Thirteen hours would therefore have been spent in
planting with this poor outfit a complete grand group. With
war facilities, a well drilled party should certainly be able to
accomplish that task in one long day’s work. Each grand
group being independent of all others, an ample force with a
good outfit should be able, in a week or ten days after work
begins, to have enough mines planted in the approaches of any
of our great ports, except perhaps San Francisco, to defy a sud-
den assault.

TIME RECORDS OF MINES PLANTED AT WILLETS POINT IN 1881.
--- |
# 3 re: To prepare mine. . * #:
§: ãa 3 º: g
d; 3 & 53 o, red if: 3 º 5
# £5 | # = : à 3 || 3a | 3 || 3 || 5
•y .4 tº- $2.3 £ # . O rcſ •4-> £: º
E as 3 : * Q, Q ſº dº 80%: Q º
&H "F.E, º 5 3 ºf Q 3 £, E3 3. 2 (AE)
O # 2 º' --> . *: £ A3 2. § C. 3.
º y- 23: q) "c g * -º dº *4
º 3 º 'º 3 : | 3: = | 3 §3 5 | E
C --> {0 O -
7mºn, mim. mim. mim mim. mim. mim. mim. mim. mim.
1 | 9 || 10 || 2 | 15 3 3 5 || 2 | 40
2 3 6 8 2 || 13 4 4 || 3 || 3 || 31
: ſ 3 6 2 7 || 3 4 || 6 || 3 || 41
* | 2 || 7 | ... 10 || 4 4 || 3 || 3 || 29
5 3 5 6 2 7 || 8 8 || 4 || 2 || 38
* | 6 7 6 6 6 2 35
3 4 ... 6 || 4 || 5 || 3 || 2 || 26
8 . 4 3 8 11 || 6 || 3 || 5 || 2 || 35
| | 6 7 | 7 || 5 || 4 || 3 || 3 | 40
tº 12 . . . . . . 14 ... 22 ... . . . . 44
11 4 . . . 8 | . . . 11 to . . . 50
is | ... 7 | . . 7 | 6 2 3 || 3 || 38
Man. 4 || 6 || 7 || 2 | 10 || 5 || 0 || 4 || 3 | *
i . | |
Notes. These records give the actual times consumed in the Several oper-
ations including accidents. For example, in planting mine No. 10 the anchor
got foul in deep water and had to be raised. The time of stopping the
electric cable to the wire mooring rope varied with the depth—75 to 100-
foot moorings requiring from 5 to 10 minutes.
D UTIES OF COMMA N DIN (# E N G IN E E R. 149
Local Administration. Obviously, the first operation in
planting a system of mines, will consist in locating one or more
of the grand junction boxes. The Commanding Engineer will
be provided by the Chief of Engineers with a map showing the
topography in the vicinity, and the position of every proposed
mine. He will identify, upon the map and ground, stations for
his theodolites suitable for covering the mine field with well
conditioned triangles; different stations may, of course, be oc-
cupied in succession.
This done, he will measure carefully upon the map, the an-
gles included between a straight line connecting two stations,
and straight lines drawn from each to the first grand junction
box. These angles set off with the theodolites upon the ground,
will fix the location of the grand junction box; knowing this,
its seven groups of mines may be placed in position by a process
almost mechanical, as will appear below.
During the planting, the place of the Commanding Engineer
will be where the work appears most likely to be interrupted,
whether on the water or on shore. Certain matters which must
never be overlooked are:
First In deciding the order of planting the grand groups
and skirmish lines, avoid as much as possible the necessity of
moving over mines already in position; because, at low water,
they may be injured by blows from the propellers or paddles of
the steam vessels at work. As a rule, therefore, the advanced
groups should first be placed in position—subject of course, to
the necessity of obstructing the channel as rapidly and effec-
tively as possible if the enemy be in the vicinity. Too much
care cannot be taken to see that the cables of the mines already
planted do not lie dangerously near to mines subsequently
placed. No cable should ever cross a grand group, or pass
within less than 100 feet of a mine. Planting buoys may be
left temporaily attached to the outer mines of grand groups, or
special buoys may be set to indicate the locus of the cables
where there is likely to be crowding—the Commandant on the
water should be ordered to have this matter constantly in
mind.
Second. Where any grand junction box is to be placed, the
Commanding Engineer should satisfy himself that the non-com-
missioned officers at the theodolites have properly adjusted their
instruments, and correctly set off the angles taken from the map;
(38)
15() PLANTING THE MINES.
or, if range flags are to be used, that they are rightly planted.
Any error here might involve ruinous confusion and loss of
time. If this box be correctly placed, the whole grand group
can hardly fail to be right, so far as location is concerned.
Thºrd. If the wharf facilities be contracted, or if the steam
vessel be small, or if the mines are to be planted at a distance,
time will be saved by placing the loaded torpedoes upon barges
anchored near the work. Local conditions should be studied in
this connection.
Fourth. The operation of inserting thimbles in wire rope is
slow and tedious, and if done entirely on the water will be cer-
tain to cause delay. Hence, as stated in the last chapter, the
moorings should always be cut in suitable lengths, and the
thimble at one end be inserted on shore before the planting
begins. If the depth be nearly uniform, it will be well to put
both thimbles in some of the lengths—making an assortment of
completed moorings slightly differing in length, from which a
selection can be made.
Fifth. Too much care cannot be given to a systematic num-
bering of the mines as planted. The electrician must be fully
instructed in this matter; and the parties attaching the cables
to the triple and grand junction boxes, must be cautioned to
observe the prescribed arrangement exactly in every case.
Waff. The preparation of self-acting mines requires time,
which if use is to be made of them must not be forgotten.
Sevent/. The chief should satisfy himself that every respon-
sible assistant understands his duty and performs it. Much time
may be lost by blundering of the electrician, or by needless
elaboration of his casemate tests; a loaded torpedo left un-
covered in a hot sun may occasion an accidental explosion ;
negligence in watching the insulated cable in the water near the
steam vessel, may result in fouling the propeller and entailing
vexatious delay; and last, but not least, a defective joint made
in any of the boats may cost hours. The presence of the Com-
manding Engineer should be felt everywhere, no detail being
too trifling for his supervision.
A%ghtſ. As the work advances, attention should be given
to auxiliary expedients. Every practicable device to deceive
spies should be adopted. Junction box buoys should be moored
where there are no mines, to give an exaggerated idea of the
area covered. Newspapers should be encouraged to magnify
J) Uſ T' ſ B. S. O ſº T' Eſ Jº Jº I, ſº () 7" ſº I ( / A. W. 151
the extent of the work. In case the enemy should make his ap-
pearance off the harbor before it has been possible to close all
the channels of approach, a vessel may be blown up well to the
front, under circumstances calculated to make him believe that
she was accidentally destroyed by a mine in position. In a
word, every effort should be made to derive benefit from the
dread engendered by dangers unseen, and therefore magnified
by the imagination. This is a vital element in submarine
mining; it renders futile any attempt to determine the value of
such a defense by experimental attacks upon harmless mines in
time of peace.
I) UTIES () F THE EI,ECTRICI A N.
The testing of one set of mines when loading, and of another
set as planted, will be in progress simultaneously; and, with a
large party on the water, work in the casemate must be care-
fully systematized to avoid loss of time.
The avoiding of accidents is the first consideration. The
firing battery wires must be detached at the battery terminals;
loose leading wires are always dangerous in the casemate. The
signal battery should never be sent through a fuze unless one of
the operating box magnets (80 ohms), or an equivalent resist-
ance, is in circuit; this is specially true when several grand
groups are to be operated, calling for a signal battery of low in-
ternal resistance. Hence, always begin by removing all gun
plugs in the operating boates (see page 30). Even the testing
battery should be tried, and only enough cells be used in series
to give proper motion to the galvanometer needle in the desired
test. The exploding current of service fuzes being about 0.48
ampères, it is perfectly safe to pass 0.15 ampères through them—
the safety coefficient being then nine; and a simple computation
on this basis will indicate what is safe in any doubtful case.
The electrician, by night work if necessary, must always have
on hand an ample supply of tested articles for use in the load-
ing room; so as not to be interrupted by calls for them during
the work on the water. He may, however, be called upon to
test simultaneously two sets of mines, one just loaded and the
other planting.
The best arrangement for testing the former in such cases, is
to connect one or two cells of the testing battery, and the lead-
ing wires from the loading room, to the Siemens galvanometer
152 PI, A N TING THE MIN E S.
adjusted as a bridge. A resistance measurement will then only
require a moment, and no changes in leading wires will be de-
manded. The operating box test prescribed on page 119 may be
omitted when time presses. .
To test with accuracy and promptness each mine as planted,
demands previous preparation. Just before the work begins the
electrician disconnects the key board box from the multiple
cable boxes; puts the signal battery on the testing circuit, and
passes a leading wire from one of the mine posts through the
resistance coils of the bridge rheostat to the home earth wire.
Now unplugging successively first 4500 ohms, and then 1500
ohms, he closes the Bradley galvanometer circuit, and tabulates
the observed deflections for each of the four coils of that in-
strument. The deflections of a single mine in good order, when
tested in like manner through the same post of the key board
box, should not differ much from the first set of values; and
those of a triple group, from the last set of values. The actual
mine resistance in ohms may be computed by multiplying the
tangent of rheostat deflection, by 4500 or 1500 as the
tangent of mine deflection
case may be. Another method when time allows, is to first ob-
tain a mine deflection, and then replace the mine by the bridge
rheostat connected to the home earth, and unplug until the
same deflection is noted. The amount unplugged will be the
desired resistance. These methods are approximate only, their
accuracy depending on the constancy of the battery and of the
earth plate polarization; but, in general, they are amply suffi-
cient to determine whether all is right enough with the mines
to allow the planting to proceed. With proper preparations,
and skill in manipulation, these tests may be executed very
quickly. Hence, the electrician can have no good excuse for
delaying the boat parties.
The electrician must also make arrangements to be informed
regularly and at short intervals as to the state of the tide, which
it will be his duty to report by telegraph to the grand junction
box boat at each change of 1 foot.
Work on the water beginning, the two Engineer privates,
equipped with a jointing box D, are sent into the cable gallery
as soon as a cable end is received. They drag it to the place in
the shaft selected for the junction with the insulated wires
already laid from the casemate, and make the joints. Even if
fraction,
J) Uſ T' I E S O }' T H E E L E O T'R I (JIA W. 153
no water is expected to touch these joints, they must be made
regularly and with care; for otherwise dampness will occasion
trouble. They must also be protected against the possibility of
receiving even slight strains. To avoid the latter danger, the
armored cable and the insulated wires, must both be stapled to a
stout wooden frame in the shaft.
While these joints are making for the first cable, and the tug
is proceeding to pay it out, the electrician will prepare his earth
plate. This is done by wrapping a single piece of flexible cop-
per wire around each of the several wires of the armor to the
cable—thus bringing the whole into good metallic contact. The
junctions must ultimately be soldered, but it is not necesssary at
first. The earth wire from the casemate is then united to this
earth plate, of which the electrical resistance per statute mile of
submerged multiple cable should not exceed a couple of ohms.
Having thus made his preliminary arrangements, the elec-
trician prepares for correctly numbering and testing the cables
leading to the several mines. The first step is to open tele-
graphic communication with the sergeant at the grand junction
box. -
To do this, the electrician dips into a bottle of mercury the
casemate ends of the leading wires just jointed to the several
cores of the cable. Another wire connects this mercury with
one pole of his dial telegraph instrument (or telephone if that
be preferred), the other pole making earth. So soon as the
continuous signals come from the boat, he ascertains which wire
conveys them by successively removing the ends from the mer-
cury. This wire is then attached directly to the dial telegraph
instrument or telephone; the signals are interrupted; the in-
struments are put in unison ; and regular communication is thus
established.
The general system to be adopted for numbering the mines,
and the numbers to be assigned to the grand group now plant-
ing, will be understood from the directions given in the drill
“to plant mines in grand groups” below. The electrician has,
therefore, only to place the proper cable tags on the six cores
not in use; to attach them to the six mine posts marked with the
smaller of the seven numbers; to see that this multiple cable
box is connected to the key board box; to switch the signal
battery to the automatic post; and to telegraph to the sergeant
the mine numbers successively dropped in the operating box as
(39) *
154 P L. A. W. T.I.W. G T H E M IN E S.
the earth wire is successively applied to the different cores in the
boat. The wire used for telegraphing will always receive the
largest of the seven numbers pertaining to its multiple cable.
After the boat ends have all been carefully labelled, the work
must be verified by repeating the dropping of the numbers.
It only remains to make the above insulation test, as mine
after mine and group after group are successively planted.
The cable, the fuzes, the cut-offs, and the circuit regulators have
all been separately tested on shore by the electrician; the cor-
rectness of the connections and the freedom from injury of all
the parts, have been verified again and again at every step of
the work by the non-commissioned officer in charge; each tor-
pedo or buoy has been marked and its resistance recorded.
This final operation tests the several joints made in planting the
mines, as they are reported ready by the Sergeant.
The cores leading to the grand junction box when it is sub-
merged after the grand group is planted, should show deflections
not differing from the above; being no longer in telegraphic
communication, the electrician must arrange with one of his
assistants to communicate the result of these final joint tests by
flag signals to the boat.
For the tests made during the planting of skirmish mines,
the flag method of communication must also be employed. An
observation will be taken as each mine is placed in position.
With perfect cables and joints, no circuit should be indicated;
but a small deflection, gradually increasing as the work proceeds,
will usually be noted. Any sudden increase denotes a defective
junction.
The tests made when planting detached groups for judgment
firing, especially when the cable is bad, are chiefly useful to
verify the continuity of the circuit. The total resistance with
good cables should equal that of the cable itself, increased by
two or three ohms for fuzes and earth plates. A defective
cable will reduce this amount; hence, any large increase should
suggest a break in the circuit.
So soon as time allows (whether by night or day) each cable
must be carried to the delicate testing apparatus; the resistance
shown between it and the home earth be accurately measured;
and the records be duly entered in a “daily test book,” for
future comparison. The method of measurement recommended
is that by instantaneous reversals, although Mance's method may
J) U 7" IAE S OF 7' H E B () A T P A R TIE/AS. 155
sometimes be the only safe and practicable one. The dexterity
of the electrician will appear in these more than in any other of
the tests he is required to make. They should be followed by
sea-cell tests with the three home earths, which will be explained
in the next chapter.
DUTIES OF THE BOAT PARTIES.
These duties consist in placing grand and triple junction
boxes, and in planting and raising mines of various kinds.
This work can, of course, be done best in calm weather and
still water; but currents of 4 feet per second, and strong winds
unaccompanied by waves, do not materially interrupt the work.
Rough water is a more serious matter; and where the height
from valley to crest exceeds 3 or 4 feet, the planting becomes
very difficult, and with small craft impracticable.
The manner in which the work must be done in actual service,
will vary with the peculiarities of the locality, and with the
means at hand. Nevertheless, a routine form of drill is as nec-
essary as for pontoniering, to train Engineer soldiers in their
duties; and the following forms, adapted to a steam vessel ar-
ranged like the launch used at Willets Point, are accordingly
prescribed. A different character of vessel will modify the
details of manipulation; and in such work it must be remem-
bered that practice is better than drill books.
However the mines may be planted, one rule is general.
AWever wet the end of a core of the insulated cable until it is
protected by a good rubber wrapping. This is exceedingly
important.
To Place and Serve a Grand Junction Box. The fol-
lowing matériel is required:
2 railroad transits, or theodolites.
4 signal flags, red and white combined.
1 tug, or large rowboat.
1 heavy mushroom anchor.
2 cables for ditto.
1 grand junction box.
1 junction box buoy.
2 shackles for ditto.
1 cable for ditto,
1 tool box C.
1 jointing box D.
1 binocular field-glass.
1 dial telegraph instrument or telephone
156 PI, A WT'I W G THE MIN ES.
2 earth plates for boat use.
1 set of lead tags.
1 set of lashings and marline.
1 set of movable ballast equal in weight to the anchor.
The party in the tug should consist of one non-commissioned
officer, one private, one engine-driver, and one steersman. If
a large row-boat be employed, which in any but a strong current
is preferable to a tug, the engine-driver will be replaced by the
necessary number of oarsmen. The boat will carry all the pre-
scribed matériel, except the transits and flags.
The party on shore will consist of two non-commissioned
officers of Engineers, and two privates to act as signal men.
The non-commissioned officers will set up their transits at the
stations previously selected, and carefully adjust and level them.
Each, after clamping his top plate at zero, will then direct his
telescope upon the plumb line of the other instrument, and
clamp the lower plate. Unclamping the top plate, he will then
turn off the angle previously determined from the map, and
again clamp the plate.
The axis of the two telescopes, prolonged, will now intersect
at the exact position for planting the grand junction box.
Three cases may occur:—
First. At each of the stations, the ground in rear of the in-
strument may be clear and level for a sufficient space (depending
on the distance to the location for the grand junction box) to
admit of placing good range flags. If so, the telescope will be
revolved in the Ys, and each flag-man will place two flags cor-
rectly on the line marked by the cross hairs. Sometimes the
depth may permit the planting of one, or even both of the
range flags in front in the water; and the use of range buoys
may not always be inadmissable.
Second. No good range flags can be placed. In this case,
the signal men will post themselves near the instrument, and
prepare to signal as directed by the non-commissioned officers.
Third. At one station, only, can range flags be placed. In
this case the flags there will be established as above described;
and at the other station, the flag-man will act as in the second
(28,862.
When notified that all is in readiness, the boat will proceed to
the desired locality. The mushroom anchor, of sufficient weight
to hold her in position without any slack, is slung at the stern
I) U T' IJES O /?' T'J/ / /3 O A T' PA Iº T' IES. 157
by a stout lashing—with the two cables connected together (to
avoid risk of losing the anchor in deep holes) and coiled to
pay out from the top; the end is secured strongly to the boat,
which, before starting, is trimmed by shifting the ballast.
In the first case, the non-commissioned officer— binocular
glass in hand—so directs the boat as to place her on one of the
ranges, and then keeping carefully on it moves toward the other.
On arriving at the junction, he orders the private, who is in
readiness with a knife, to cut away the lashing. The boat is
then trimmed by shifting ballast; the cable is moved to the
bow, hauled taut and belayed; and the position is verified by the
two theodolites.
In the second case, the boat is conducted to the desired spot
by the following code of signals. Each flag-man, directed by
the observer at the transit, holds his staff horizontal, with the
flag pointing toward the side to which the boat should move.
As the line is nearly reached, he raises and lowers the flag
rapidly through an angle not exceeding forty-five degrees.
When the boat is on the line, he holds the flag vertically over
his head. Any divergence from the line after it is once reached,
is corrected in a similar manner. By placing himself on one
range, and moving steadily upon it toward the other, the non-
commissioned officer will thus be able to find his position, and
anchor as before.
In the third case, the two methods above described are com-
bined in a manner too simple to require description.
So much of this exercise as has been already described should
be frequently practiced—the precision of the work being
checked by hauling the anchor rope taut, and fixing the exact
position of the bow by triangulation from the shore. The
following part of the drill will only be used when a grand
group is to be actually planted.
The tug carrying a drum of perfectly tested multiple cable,
drops anchor as near the entrance of the cable gallery con-
ducting to the mining casemate, as her draft will permit.
She is accompanied by two or more skiffs, according to the
needs of the locality. A warp line is stretched from the tug to
the shore; several coils of the multiple cable, the ends of all
the cores being carefully insulated with rubber, are laid in one
of the skiffs, and she is hauled by hand along the warp line;
the slack is buoyed from the bottom by the other skiffs, which
(40)
158 P L. A. W. T.' I W G T II Jº M I W E S.
successively receive it as required, allow it to run across their
gunwales until enough has passed, and then holding fast to the
cable, follow along the warp after the leading skiff toward the
shore. When the end has passed the line of surf, it is carried
into the gallery by a detail of men, the skiffs holding fast to the
warp line and allowing the cable to pass ashore without dragging
on the bottom more than is necessary. -
The tug then proceeds to the grand junction box boat, paying
out her cable as she goes; cuts it to the exact length, and passes
the end on board; where it is lashed to cleats or the thwarts,
and a turks head is made and secured in the grand junction box.
The non-commissioned officer now opens telegraphic com-
munication with the fort, to learn the numbers designating the
different cores of the cable.
To do this, he drops one earth plate overboard and binds its
connecting wire to one pole of his instrument, the other being
attached to any one of the cores. He then revolves the handle
continuously if a dial telegraph be used, or alternately calls and
listens if a telephone be supplied.
The electrician in the fort, who by means of a small vessel of
mercury has previously united all the cores to one terminal of
his dial telegraph or telephone, the other making earth, de-
taches them successively until he ascertains which is the one
carrying the current. He then interrupts the operator in the
boat, and both instruments are arranged for communication.
If telephones be supplied, they must be kept continuously at the
ears of the operators when not in use—otherwise loss of time
and great annoyance will result.
The other six cores are then attached to the permanent posts
of the operating box in the casemate; and their numbers are re-
ported to the non-commissioned officer in the boat, as he
successively closes their circuits by touching his ends with the
connecting wire of the second earth plate previously dropped
into the water. Once established, these numbers are carefully
preserved by attaching cable tags to the ends in the casemate,
and lead tags to the ends in the boat.
In order to preserve communication with the boat as long as
possible, the electrician should assign the highest of the seven
numbers to the core temporarily used for telegraphing.
As fast as the ends of the cables leading to the triple junction
box boats are received, they are secured by temporary lashings;
J) Uſ TIES () /?' 7" // ſº J3 () A 7" P A R 7'ſ E! S. 159
turks heads are made and clamped in the proper places (Plate
VI, figure 1) in the grand junction box, and the cores are per-
manently jointed accordingly. The sergeant then holds himself
in readiness to coöperate with the electrician in the tests.
If changes of tidal level are great, frequent regulation of the
length of mine moorings must not be forgotton.
When the work is done, and the grand junction box is low-
ered, it should be buoyed with its own buoy. It is well to
attach the rope to shackles in the rings, at both ends, to prevent
wear—allowing plenty of slack for tidal changes.
To Place and Serve Triple Junction Boxes. There are
seven of these boxes to each grand junction box. Three skiffs
are required in placing them; and if time be important, seven
may be employed. Each should contain a sufficient number of
oarsmen to control its motion in the current, and in addition
thereto two Engineer privates. Each skiff is equipped with :
1 jointing-box D.
1 heavy mushroom anchor.
2 cables for mushroom anchor.
1 junction box buoy.
2 shackles for junction box buoy.
1 set of ballast equal in weight to anchor.
1 stout cod line, at least 325 feet long.
1 triple junction box.
1 mine switch, charged.
Stout lashings and marline.
The anchor, which must be heavy enough to hold the skiff in
position without slack, is slung over the stern ready to be let go
by the run. The two cables (united to avoid risk of loss should
a deep hole be encountered) are secured, one end to the middle
ring of the anchor and the other to the boat. The ballast is
shifted to trim the latter. The cod line, which must have been
previously wet and stretched to free it from any tendency to
kink, is knotted at each 100 feet, allowing about twelve feet at
each end for use in lashing.
The following is the method of operating when only three
skiffs are available.
The skiff to be nearest to the grand junction box boat, is
placed first. It is brought alongside; and the cod line is made
fast at the first mark, to the anchor cable of the boat. The
line of mines is always so planted as to be flanked by some par-
ticular part of the fort, which has been pointed out to the
160 PJ, A N T I W G T H E MINAE'S.
non-commissioned officer in the grand junction box boat. He
directs the skiff to row off on a course perpendicular to the
straight line drawn from himself to the designated point, paying
out the cod line as it moves. If it deviates from the true
course, he corrects the direction by verbal orders. On reaching
the first 100-foot mark, the private in charge of the skiff causes
his assistant to cut the anchor lashing. The boat is then
trimmed, and the cable is hauled taut and belayed without
slack. The end of the cod line is then thrown off by the non-
commissioned officer, and is drawn on board the skiff.
The other two skiffs now come alongside the one already an-
chored, and make their cod lines fast to its anchor cable at their
first marks. The one farthest from the fort then rows away
from it, keeping the anchored skiff and designated point in
line. On reaching the 300-foot mark, the anchor lashing is cut,
the cable is hauled taut and belayed, and the cod line is drawn
on board.
The third skiff is anchored in a similar manner on the side
toward the designated point, the private in charge of the first
skiff keeping the third on the line by verbal directions; the
oarsmen will be assisted by the position of the two boats already
anchored.
If there be other skiffs, they are placed in position in a simi-
lar manner, attaching their cod lines successively to the one last
established, and dropping anchor at 300 feet distance.
The first group of mines is planted, in the manner soon to be
described, at the skiff first in position—which, when only three
are used, then proceeds to prolong the line by the means indi-
:ated above. The work of planting is then continued on the
same principles until completed—operating always from the
middle group outward.
This drill, in combination with that already given for estab-
lishing the position of the grand junction box, is to be frequently
practiced; the precision attained being determined by triangu-
lation from the shore.
The duties in the skiff during the planting of the mines, are
the following. When the cable leading to the grand junction
box boat is received, its end is temporarily lashed and a turks
head is made and secured in the triple junction box, being care-
ful to keep the core dry. As each mine cable is received, it is
lashed and secured in like manner ºn the proper clamps (Plate
D U T'II'S OF THI E' B O A T P A R TIES. 161
VI, figure 2); a temporary joint, dry and carefully insulated
Žn air, is made between its core and that leading to the grand
junction box boat; and the Sergeant is notified that mine No.—
is ready for the electrician's test. When signalled back that the
tested mine is right, lay the mine switch flat in the bottom of
the triple junction box, and permanently joint the mine core to
a K wire. When the three mines have been thus attached,
make a temporary joint between the grand junction box core
and the H wire, and signal for a test of the whole group. If
correct, make this joint permanent; carefully stow the mine
switch so that none of the cores shall be sharply bent at the
glands; attach the cover; reeve a line through the ring; lower
the box overboard and signal for a new test. If correct, lower
away and buoy the box, or not, as ordered. Usually, only the
two outer triple junction boxes are thus buoyed; and this is only
done when other mines are to be planted near them.
To Plant a Buoyant Mine. The men will first be exer-
cised in the mechanical operations of planting and raising the
the mine, without being required to place it at a particular spot.
Subsequently, when the requisite skill has been acquired, the
exact position will be indicated in advance. This is, in effect,
the preliminary drill for planting all systems of mines.
The detachment consists of one commissioned Öfficer, one
sergeant, one corporal (who usually steers), at least six privates
designated No. 1, No. 2, No. 3, No. 4, No. 5, No. 6, etc., and
an engine driver. Mines prepared for automatic firing will be
used. The following matériel should be provided:—
1 buoyant torpedo, loaded with 100 pounds of dry smooth gravel;
sand is objectionable, being liable to become damp and
thus interfere with the electrical tests.
1 planting buoy, with its graduated line.
1 torpedo anchor and lowering rope.
1 75-pound ponton anchor and cable.
1 drum of insulated cable, with its sling.
1 boat hook.
1 sounding line, carefully graduated.
1 cod line, 400 feet long.
1 jointing box D.
1 tool box ().
1 rigger's vise.
1 thimble clamp.
1 service detector.
1 earth plate for boat use.
1 coil of wire mooring rope, with thimbles at ends.
Shackles, marline, lashing rope, annealed wire and thimbles.
(40)
162 P L A N T' I W G T II E M I W Jº S.
The steersman, engine driver and No. 2 bring the launch
alongside the wharf, under the falls of the crane, where the
rest of the detachment with the torpedo matériel is collected.
She is made fast with long bow and stern lines, so as to admit
of an easy shifting of position forward and back.
The commissioned officer superintends the loading.
The sergeant superintends the attaching of the block to the
different articles, and gives the necessary orders for lowering.
The corporal, assisted by No. 2, receives them on board.
The rest of the detachment man the falls.
The drum, if not already in position, is first lowered into its
trunnion beds, so as to feed from the top—and the free end of
the cable, carefully kept dry, is passed by the corporal and No.
2 forward on the starboard (torpedo davit) side, and thence to
the torpedo on the wharf. No 1 aided by No. 3 has removed
the cap, and they now pass the free end of the cable through
the hole, so that the bight shall lie in the plane of the anchoring
'ring; make a turks head; clamp it in the cap; joint the core
to the taped wire of the torpedo; replace the cap, and stop the
cable firmly with marline to the junction of the bales.
Meantime No. 4 knots one end of the lowering rope to the
side ring of the anchor; passes the free end to the corporal, and
hooks the block in the centre ring; the sergeant causes the an-
chor to be lowered away. The corporal passes his end through
the sheave of the cat-head; draws the anchor into position as
high as possible; takes three turns over the top and round the
head of the windlass; passes the rope round the cleat and belays.
He then unhooks the block.
The block is next hooked to the anchoring ring of the tor-
pedo; a short lashing rope is attached to the lowering ring, and
the free end is passed to the corporal. The torpedo is now
lowered nearly to the deck, and is guided by No. 2 round the
stem to the davit; the block on the davit is hooked in one of
the bales by the corporal, and made fast to the cleat so as to
leave the cap about 3 feet above the deck. The block is un-
hooked by No. 2. No. 1 goes on board, and, aided by No. 2,
firmly lashes the torpedo in a convenient position by the short
lashing rope in the lowering ring, and, if needful, by another
made fast to one of the bales. They then cover it from the
Sun, and take in the slack of the cable on the drum.
D Uſ T' I B, S O Hº' 'T' II E B O A T' PA I? TI E S. 163
Meantime the men on the wharf pass down the small articles,
and go on board. The sergeant and No. 3 and No. 4 take po-
sition forward, with No. 1 and No. 2; the remaining numbers
take position aft. -
The bow and stern lines are now cast off, and drawn on board
carefully by No. 3 and No. 6, so as not to foul the propeller.
The commissioned officer now directs the launch to the point
selected for planting the mine; and, after checking the headway,
causes No. 3 to drop the ponton anchor, and to make fast its
cable when the needful slack is paid out.
Meanwhile the sergeant and No. 4 have shackled one end of
the wire mooring rope to the centre ring of the anchor; and, if
the depth at which the mine is to be planted is accurately
known, have cut the rope to the proper length; inserted a
thimble; shackled it to the anchoring ring of the torpedo; and
stopped the insulated cable at intervals of 6 feet to the wire
mooring rope—the last stopping being not less than 6 feet from
the anchor. If the exact depth is not known, the mooring rope
must be cut after the launch is in position, and a sounding has
been made by No. 3. About 5 feet should be allowed for the
torpedo, shackles and anchor; and, as a general rule, the top
should be placed 3 feet below low water mark, when, as at
Willets Point, the tide has a range of eight feet.
All being in readiness, the cover and lashings are removed
from the torpedo, under the direction of the sergeant, by No. 1
and No. 2; and the block is slacked off by No. 4 until the tor-
pedo rests on its side upon the water. The sergeant then
tests it electrically, for a good circuit between the end of the
cable on the drum and the earth plate in the water, the service
detector being intermediate between the two.
The block is now removed from the torpedo, and the anchor
is lowered under the direction of the sergeant, No. 3 slacking
off. The drum is served at the same time by No. 4 and No. 5,
while No. 6 guides the cable, taking care that is does not come
near the propeller. So soon as the torpedo floats vertically,
work is suspended to allow the sergeant to repeat the electrical
test. If a good circuit be shown, which cannot be broken by
rolling the torpedo with the boat hook, the joint is bad or the
circuit regulator is at fault, and the mine must be raised to cor-
rect the difficulty.
164 PI, A N T IN G, TII E M IN E S.
All being perfect, the planting buoy (page 80) is attached
by passing the free end of its graduated line through the top
ring of the torpedo, and then securing one of its graduations
to the planting buoy, so as to leave ample slack in the bight;
the mine is then lowered to the bottom, stopping occasionally
to permit No. 1 to lash the lowering rope to the insulated cable
with marline. The end, especially, is carefully made fast.
In strong currents and water not too deep the operation of
lowering may be varied, if the size of the launch permits, by
slinging the anchor alongside, and when the torpedo has drifted
well away cutting the slings and thus allowing the anchor to go
by the run. Care must be taken to dispose the electric cable
and lowering rope in such a manner as to render freely without
endangering the men. In this method, of course, only the end
of the lowering rope can be stopped to the cable.
When the mine is down, the planting buoy is brought along-
side and the depth of submergence of the torpedo is verified;
after which the buoy is detached.
Everything being in readiness for paying out the insulated
cable, the commissioned officer directs Nos. 1, 2 and 3 to raise
the ponton anchor as rapidly as possible. Taking advantage of
the wind and tide, and being especially careful not to foul the
cable round the propeller, he heads the launch as nearly on her
own ground as possible, and slowly proceeds to the point for
delivering the end. No. 4 and No. 5 stand in the tank and
serve the drum, and No. 6 sees that the cable feeds freely through
the after-chock and does not foul the propeller.
When not otherwise employed during the drill, No. 6 will
watch, boat-hook in hand, to prevent any loose rope from
fouling the propeller. This accident will often occur with
poorly drilled men.
Should there be supernumeraries present, the officer in com-
mand will cause them to give such aid as he may see fit.
To Plant a Ground Mine, The following matériel should
be provided :
1 ground torpedo, unloaded (model of 1873 should be ballasted
with 100 pounds of gravel), with the fuzes in the can.
1 lowering rope for ditto.
1 ground torpedo.
1 planting buoy with its graduated line.
1 75-pound ponton anchor and its cable.
1 drum of insulated cable, with its sling.
D U TI ES OF T H E B O A T P A R TI E'S. 16.)
1 loose coil of ditto, of a length not less than the depth of water.
1 boat hook.
1 sounding line, graduated in feet.
1 jointing box D.
1 tool box C.
1 riggers vise.
1 thimble clamp.
1 service detector.
1 earth plate for boat use.
1 coil of wire mooring rope, with thimbles at ends.
Shackles, marline, lashing rope, annealed wire and thimbles.
The steersman, engine driver and No. 2 bring the launch
alongside the wharf, under the falls of the crane, where the
rest of the detachment with the torpedo matériel is collected.
She is made fast with long bow and stern lines, so as to admit
of an easy shifting of position forward and back.
The commissioned officer superintends the loading.
The sergeant, assisted by No. 1, attaches the block to the
different articles, and gives the necessary orders for lowering.
The corporal, assisted by No. 2, receives them on board.
The rest of the detachment man the falls.
The drum, if not already in position, is first lowered into its
trunnion beds, so as to feed from the top—and the free end of
the cable, carefully kept dry, is passed by the corporal and No.
2 forward on the port (cat-head) side, and thence to the torpedo
on the wharf.
Having in the meantime removed the torpedo cap, No. 1 in-
serts this end through one clamping hole, and an end of the
short coil of insulated cable through the other clamping hole.
The sergeant then orders No. 3, No. 4, No. 5 and No. 6 to make
turks heads on these ends; and, when done, sees that they are
drawn close to the cap and firmly clamped. He and No. 1
having in the meantime prepared the insulated wires of the
torpedo; joint the cores to them—uniting the long cable to
beveled wire D. While this is done, No. 3 holds the cap in a
convenient position; and then he and No. 1 place it on the tor-
pedo—using care to avoid jamming the exposed cores. They
then firmly screw down the bolts, and insert and open the split
keys.
Meanwhile No. 4 has inserted a shackle in one ring of the
cap, and attached the end of the lowering rope to the other by
two half hitches. IIe then hands this rope to No. 2, who passes
the end through the cat-head.
(42)
166 PI, A WTING THI E' MIN E S.
The sergeant then hooks the block to the anchoring ring, and
lowers the torpedo into position; No. 2 draws the rope taut,
takes three turns over the top and round the head of the wind-
lass, and, passing it round the cleat, belays. He then neatly
coils the short insulated cable forward, while No. 1 goes on
board, and aided by No. 2 takes in the slack of the long cable
on the drum.
The block is next hooked to the anchoring ring of the buoy;
a short lashing rope is attached to the lowering ring, and the
free end is passed to the corporal. The buoy is now lowered
nearly to the deck, and is guided by No. 2 round the stem to
the davit; the block on the davit is hooked in one of the bales
by the corporal, and made fast to the cleat so as to leave the
cap about 3 feet above the deck. The block is unhooked by
No. 2. No. 1 aided by No. 2 firmly lashes the buoy in a con-
venient position with the short lashing rope in the lowering
ring, and if needful, by another made fast to one of the bales.
No. 1 and No. 2 now proceed to shackle one end of the wire
mooring rope to the anchoring ring of the torpedo.
The small articles having been passed down, the detachment
go on board the launch. The sergeant and No. 3 and No. 4
take position forward, with No. 1 and No. 2; the rest take
position aft.
If the depth at the proposed anchorage be known, the ser-
geant now sees that Nos. 1 and 2 lower the buoy until it rests
on the deck and remove its cap; cut the short insulated cable
so that, measured between turks heads, it will be about 2 feet
longer than the wire mooring rope; pass the end through the
clamping hole, so that the bight shall lie in the plane of the
anchoring ring ; make a turks head and clamp it; joint the
core to the taped wire; replace the cap, and stop the cable to
one of the bales. Meanwhile, under his direction, No. 4 and
No. 5 cut the wire mooring rope to the proper length ; insert a
thimble; shackle the end to the anchoring ring of the buoy;
and stop the insulated cable to the mooring rope with marline
at intervals of about six feet.
If the depth be not known, this is done after the launch is
anchored and soundings have been taken. -
In deciding upon the proper length of the wire mooring
rope, about five feet should be allowed for the buoy, shackles
I) U TIES OF THI E' B O A T P A R TIES. 167
and torpedo; and the top of the buoy must be brought at least
3 feet below low water mark.
The commissioned officer directs the launch to the point se-
lected for planting the mine; and, after checking the headway,
causes No. 3 to drop the ponton anchor, make fast its cable as
soon as enough slack is paid out, and take a sounding.
All being in readiness, the cover and lashings are removed
from the torpedo by No. 1 and No. 2; and the block of the
davit is slacked off by No. 4 until the buoy rests upon the
water, when the block is removed. The sergeant then tests the
mine electrically, seeing that a circuit is shown between the end
of the cable on the drum and the earth plate in the water—the
service detector being intermediate between the two—when the
buoy rests on its side; and that (according to circuit) none or
a bad one is shown when it floats vertically.
The planting buoy is now attached by passing the free end
of its graduated line through the top ring of the buoy, and then
attaching one of its graduations to the planting buoy—leaving
ample slack in the bight.
The torpedo is now lowered to the bottom, under direction
of the sergeant, No. 3 slacking off. The drum is revolved at
the same time by No. 4 and No. 5, while No. 6 guides the cable
away from the propeller. The work is stopped occasionally to
permit No. 1 to lash the lowering rope to the insulated cable
with marline. The end, especially, is carefully made fast.
After verifying the depth, the planting buoy is detached.
The method of “letting go by the run" prescribed in the
drill for planting a buoyant mine, may also be used with a
ground mine unless the bottom be rocky. -
Everything being in readiness for paying out the insulated
cable, the commissioned officer directs Nos. 1, 2 and 3 to raise
the ponton anchor as rapidly as possible. Taking advantage of
the wind and tide, and being especially careful not to foul the
cable round the propeller, he heads the launch as nearly on her
own ground as possible, and proceeds to the point for delivering
the end. , No. 4 and No. 5 stand in the tank and serve the drum,
and No. 6 sees that the cable feeds freely through the after-
chock, and does not foul the propeller.
When not otherwise employed during the drill, No. 6 will
watch, boat hook in hand, to prevent any loose rope from
fouling the propeller.
168 P L A N T IN G T H E M I W E S.
Should there be supernumeraries present, the officer in com-
mand will cause them to give such aid as he may see fit.
To Raise Single Mines. There are no differences which
need be specified in the drills for raising a buoyant and a ground
mine.
The launch with the detachment and outfit on board, pro-
ceeds to the point where it is to receive the end of the cable.
It is rove through the hole in the drum for at least a foot, by
Nos. 4 and 5, and secured by staples so as not to interfere with
the revolution—which is always to be made in such a direction
as to receive the cable on top.
The detachment now take post as follows:—No. 3 by the
anchor rope forward; Nos. 4 and 5 in the tank by the sides of
the drum to revolve it; No. 6 just aft to feed the cable; Nos. 1
and 2 between him and the stern, to haul in through the after-
chock; the sergeant supervises the work, and sees that the cable
is coiled away evenly and regularly. If there are extra men,
they will relieve the others from time to time.
All being in readiness, the commissioned officer causes No. 3
to cast off the moorings of the launch. The party at the cable
now begin to take it in. If the tide or wind is strongly opposed
to the motion of the launch, it may become necessary to back
the engine; but this endangers the fouling of the propeller, and
usually should not be done. When the vicinity of the mine is
reached, the ponton anchor is cast by No. 3, unless the current
be slack. - &.
When the end of the lowering rope comes on board, the
lashings are cut by No. 6, and it is carried forward on the port
(cat-head) side by No. 3, aided by Nos. 1 and 2, and passed
through the sheave of the cat-head, three times over the top
and round the head of the windlass, and round the cleat. No.
3 then takes position to haul in the slack.
Nos. 1 and 2 now man the windlass, and raise the anchor or
ground torpedo until it reaches the cat-head—when the rope is
belayed by No. 3. The sergeant will cut the stops near the
Water.
The buoyant torpedo, or buoy, is then guided by Nos. 1 and
2 under the davit, using the boat hook and wire mooring rope.
Then they attach a lashing rope to the lowering ring, and hook
the block to one of the bales of the buoyant torpedo or buoy.
Nos. 1, 2, 4 and 5 then raise it out of the water, by heaving on
D U TIES OF THE BOA. T P A R TIES. 169
the fall; while No. 3 passes the free end round the cleat, and
takes up the slack. When sufficient height has been gained, he
belays; and then draws the wire mooring rope on board over
the stem. Meanwhile, Nos. 1 and 2 lash the buoyant torpedo
or buoy securely, and Nos. 4 and 5 take up the slack of the
cable on the drum.
The commissioned officer then directs the launch to the wharf,
so as to bring her port side under the falls of the crane—where
she is made fast with long bow and stern lines, thrown by Nos.
3 and 6.
Meanwhile, under the direction of the sergeant, Nos. 1, 2,
and 3 unshackle both ends of the wire mooring rope; and cut
off the cable close to the cap. The end is then wound up on
the drum and secured by Nos. 4 and 5. With a ground torpedo,
the short piece of cable also is cut at the cap. Should he deem
it expedient, the commissioned officer may dispense with this
operation and leave the two parts of the mine coupled together
and united to the drum.
Arrived at the wharf, the corporal and No. 2 remain on board,
to hook on the block and cast loose the ropes. The remainder
of the detachment, carrying up the small articles, proceed to
the wharf to receive the rest. The sergeant and No. 1 handle
the block, while No. 3, 4, 5 and 6, man the falls. The articles
are landed in an order inverse to the loading.
After delivering the matériel, the corporal, No. 2, and the
engine driver take the launch back to her moorings; and the
rest of the party remove the articles to the store-house.
In this drill, No. 6, when not otherwise employed, watches to
prevent the propeller from fouling loose ropes; supernumeraries
assist as directed by the officer in command.
To Plant Mines in Grand Groups. The seven triple
groups in each grand group are numbered consecutively from
right to left, as seen from the grand junction box; and their
cables are clamped in the latter in the same order, beginning
at the multiple cable and following in a reverse direction the
hands of a watch. The position of each cable in the box is
thus independent of the order of planting. The numbering of
mines and clamping of cables at the triple junction boxes follow
the same rules—which are imperative in all cases, to facilitate
the tracing of any individual mine.
(43)
170 - P L A NTING T H E MTN ES.
To avoid confusion in the casemate, grand groups will ul-
timately be ignored and triple groups will be designated con-
secutively—thus No. 1 of the second grand group will be known
as No. 8; and of the third grand group, as No. 15. This system
will be followed in attaching mine numbers to the operating
boxes, and mine tags to the cables; but during the planting
the casemate records will be kept upon the system used in the
grand junction box boat—the grand groups being distinguished
by their natural sequence as planted.
The order of planting will usually be: (1) triple group No.
4; (2) the adjacent group farthest from the flanking guns; (3)
the adjacent group next the flanking guns, and so on alternately.
This renders alignment easy, and by separating the boats facil-
itates manoeuvres of the tug. -
After the grand and three triple junction box boats are an-
chored in position, the tug first lays the single conductor cables
connecting them, beginning in each case at the grand junction
box boat and carefully avoiding slack. The ends of these
cables are at once prepared and clamped in their respective
boxes. At the grand junction box the core is permanently
jointed to the proper core of the multiple cable; the core in
the other boat is carefully kept dry in air.
It only remains to prescribe the method of planting one of
the triple groups of mines. +
The tug should have on board a non-commissioned officer of
Engineers in charge, and at least four well instructed privates,
with half a dozen laborers. She should be provided with a
derrick powerful enough to raise a torpedo or anchor, and sling
it overboard; and with a cat-head, to which the anchors (or
ground torpedoes) may be slung. There must also be on board:
1 planting buoy, with its graduated line.
1 drum of insulated cable, and its frame.
1 tool box (). sº
1 jointing box D.
1 service detector.
2 earth plates for boat use.
1 rigger's vise.
1 thimble clamp.
1 boat hook.
1 sounding line, carefully graduated in feet.
1 coil of wire mooring rope—where the depth is tolerably uni-
form, it is well to have several assorted lengths of this rope
with one or both thimbles already inserted.
1 coil of lowering rope.
D UTIES OF THI E' B O A T P A R TIES. 171
1 cod line, with a length of 100 feet marked on it, and slack at
both ends.
Shackles, extra spit keys for ditto, lashing rope, marline, an-
nealed wire and thimbles.
As already stated, the three mines are to be planted at 100
feet from the triple junction box—two on the line of these
boxes, and the third perpendicularly in front.
Ascertaining the depth by sounding, and the state of the tide
from the sergeant in the grand junction box boat, the length of
the mooring rope is determined (allowing 5 feet for torpedo,
shackles, etc.); the first torpedo is coupled to its anchor or buoy
ready for planting; a mine buoy is attached by its graduated
line passed through the lowering ring with both ends (at marks)
secured to the buoy; the torpedo or buoy is lowered overboard;
the tests prescribed in the drill for planting an isolated mine
are made; the torpedo or buoy is hauled alongside; lastly, the
anchor or ground torpedo, at a suitable depth above the bottom,
is made fast by a stout lashing on its lowering rope—with wire
mooring rope and insulated cable carefully prepared ready to be
let go by the run. With ground mines on a rocky bottom, the
torpedo must not be allowed to strike hard.
In still weather and slack water the mine may be placed in
the desired position as follows. The tug slowly approaches the
skiff from such a direction that, allowing for wind and tide, she
will be able to back into position. One end of the cod line is
thrown to the skiff, where the 100-ft. mark is held to the anchor
rope. The tug now backs off slowly in the right direction; and
the instant the other 100-foot mark is reached, the lashing is cut
and the mine sinks into its place. The lowering rope is then
stopped to the insulated cable, and (allowing for the state of
the tide) any surplus is cut off. The tug now goes alongside
the skiff; cuts the insulated cable; passes the end on board;
backs off and secures the planting buoy; hauls the torpedo to a
vertical position and verifies its submergence by the graduation.
If correct, the graduated line is freed from the torpedo, the
planting buoy is taken on board, and the tug prepares to plant
the second mine. " . -
The following method of planting is to be preferred to the
above in water not too deep (say in 50 feet or less), if the cur-
rent or wind be too strong for easy manoeuvring, or if time be
of importance.
172 P I, A W T I W G T LI Jº M I W E S.
About 150 feet of cable have been regularly jointed to each
mine on shore. An auxiliary steam launch or row boat, guided
by the cod line, holds itself successively in the three positions
designed for the mines. The tug steams alongside, drops the
torpedo coupled as above, and passes the end of the cable to the
triple junction box boat—either itself or by the auxiliary boat.
as most convenient. The men on board haul in the slack, cut
it off, make a turks head, and secure it in the proper clamp of
the triple junction box. In drilling the slack should not be cut
off, and the second turks head may be made on shore.
Each mine when planted is tested electrically as follows. The
core of its cable is temporarily united to that of the cable lead-
ing to the grand junction box boat; and the sergeant on board,
on receiving a signal that all is ready, telegraphs the number of
the torpedo and group to the electrician—who makes the pre-
scribed tests. If all be right, the cores in the triple junction
box boat are separated, and the mine cable is jointed to a K wire
of the switch box, which has already been laid flat in the bottom
of the junction boº. With turks heads properly made there is
no difficulty in inserting the switch box in this manner, but in
case of necessity it may be set on its bottom, great care being
taken to avoid injuring the H wire in closing the junction box.
The other two mines are treated successively in like manner.
All being right, the connecting cable is jointed to the H wire,
and the triple junction box is closed and lowered overboard for
testing. If all be right, the box is let go and the boat proceeds
to the next station. By this method the electrician himself
tests and is responsible for the electrical condition of each mine,
and the use of detectors in the boats is avoided.
When the mines are planted from a small handy vessel like a
steam launch, it is easy to avoid striking mines already in posi-
tion; but for a larger craft the space becomes contracted and
more care is needful. This is specially the case in planting the
No. 3 mines of triple groups where the adjacent left hand
group is down; and the No. 1 mine of triple groups where the
adjacent right hand group is down—in these positions a long
tug must back and manoeuvre obliquely, or it will be certain to
strike with its propeller the torpedo already in position.
When the last triple group of the grand group is planting,
the non-commissioned officer in the boat, after warning the elec-
trician, will detach his instrument and temporarily connect the
D UT' IAE S OF T H E B O A T' PA I? TIE S. 173
core to the core of the insulated cable of the group. After
waiting a sufficient time for the tests to be made, he will again
open communication and learn the result. When each of the
three mines and the entire group together, has thus been satis-
factorily tested he will permanently joint the two cores together;
attach the cover to the grand junction box; lower it into the
water, to enable the electrician to test all the joints he himself
has made; and make some preconcerted signal to a man on the
look-out, that this has been done.
When the electrician is satisfied that all is right, he will cause
this fact to be signalled to the boat; and the grand junction box
will be lowered to the bottom, and buoyed. When it is to
remain long in position, it is well to make the lowering rope
fast to shackles in the rings of the grand junction box and
buoy, to avoid chafing. Finally, the boat anchor will be raised,
or the tug will be signalled for assistance, according to the facil-
ities on board.
To Raise or Repair Mines in Grand Groups. If the
object be to raise the whole group—as, for instance, at the end
of the war—the work will begin at the fort. The end of the
multiple cable will first be drawn on board by a hawser, and the
cable will then be coiled up on its drum until the grand junc-
tion box is reached; each of the seven branches will there be
cut, and followed to its triple junction box; and, finally, each
torpedo of each group will be raised by its lowering rope, if
the end has been recovered while taking up its insulated cable.
If the mines have been in position a few months the lowering
ropes will be rotten, and the torpedoes must be grappled—their
insulated cables indicating their exact positions. These cables
themselves should never be used to raise anchors or ground
mines. A sling round the torpedo or buoy, as prescribed below,
is the proper method. Usually there will be ample time for
these operations—which, of course, involve no danger from
accidental explosions—and the method of operating can best be
decided in each individual case by the officer in charge.
If an injury to the system should occur during the war, it
would be discovered and its nature defined by the electrical
tests; and repairs might become advisable. Such a contingency
has been guarded against as carefully as possible; but the pos-
sibility of its occurring, even repeatedly, must be admitted; and
some of the minor arrangements have been made accordingly.
(44)
174 P L A N 7"I W G 1' HE MIN ES.
e
Thus the junction boxes are kept buoyed as long as possible;
because, when they are accessible, no grappling or under-running
of cables is necessary. By raising the triple junction box of
the defective group and cutting one, two or three of the joints
in it, nothing can be easier than to ascertain which mine is in-
jured, and to proceed at once to repair it without disturbing the
others; or, if the fault is in the mine switch, or in the cable
between this box and the fort, to ascertain that fact without
disturbing the mines at all.
If the buoys have been removed because an attack is immi-
nent, the position of the grand junction box can always be found
by triangulation, the angles being on record. Grappling in its
vicinity from a boat provided with a windlass will soon recover
it by one of its cables. From the grand junction box, the
defective triple group may be found by under-running its cable;
or a new triple group of mines may be planted on a single
conductor cable, to fill the gap caused by the injury.
If repairs become necessary, great assistance will result from
there being no crossing of cables—an advantage which it will
be noticed has been secured by the manner of arranging the
mines.
Experience has suggested various mechanical methods for
recovering mines when the usual holds upon the anchor or
ground torpedo are lost.
I. When only the lowering rope is lost (a common occurrence
from rotting), under-run the insulated cable from the triple
junction box until the boat is directly over the mine; make a
running bowline on a three-inch hemp rope, and press the noose
down over the torpedo with a boat hook until it takes hold
below the bales; pass the free end through the cat-head sheave;
raise as high as possible and make fast; take a new hold with
another hemp rope around the wire rope, and raise as before;
continue this operation until the anchor or ground torpedo is
reached. The only difficulty is to get a good lifting hold upon
the wire rope—this may be done by a rolling hitch, or by stop-
ping a marline head tightly round the wire rope and attaching
the hemp rope below it.
II. When the insulated cable as well as the lowering rope is
parted, the mine must be found by sweeping with a 3-inch hemp
rope about 50 feet long, held between two skiffs and carrying
a weight of thirty or forty pounds at the bight. When the
D UTIES OF THE B O A T P A R TIES. 175
torpedo is fouled, take two good turns round it by crossing the
boats and (if the mine is too deeply submerged for the plan
suggested above) raise by the doubled rope and the windlass on
the tug. The approximate position of the mine may be inferred
from that of the triple junction box.
III. If the torpedo is leaky and has sunk, and the lowering
rope is parted, grapple for the wire mooring rope with a strong
hook and cable and raise by the windlass. More power than
usual will be required, because flotation is lacking.
IV. When the wire mooring rope and buoy of a ground
mine are missing, the great weight of the torpedo and the
suction of the mud render the operation a difficult one; it has
been accomplished at Willets Point in depths exceeding 20 feet,
and where the bottom was very soft, in the following manner.
A large hook of 1.5-inch iron attached to a 4-inch hemp rope
was lashed to the end of a 30-foot pole, and was engaged by
hand in one of the ears. The weight being too great for the
windlass, the rope was made fast at the middle of a two-ponton
raft, and the torpedo was started from the mud by a tidal lift;
afterward it was easily recovered.
Under no circumstances should an attempt be made to raise
the mine or anchor by the electric cable until all other means,
including the use of a diver, have failed. The chance of success
is small.
To Plant Skirmish Mines. The officer in charge avails
himself of every skiff suitable for the purpose; and, accom-
panying them himself, causes them to anchor successively, with
short cables, as nearly on the line laid down on the map as he
finds practicable to designate. The distances apart he judges
by the eye. If the line be situated near or between main lines,
the floating junction box buoys will enable him to secure con-
siderable accuracy, and to avoid placing any of his mines too
near the others.
Having thus marked out and verified the positions, he causes
the tug to lay a properly tested single conductor cable in the
usual manner—but passing it over each skiff in succession. The
end should be led back to the casemate, or introduced into a
coöperating fort; if not, its copper strand must be carefully
insulated.
Each skiff carries two Engineer privates, equipped with :—
176 - P I, A W T TNT G T H E M IN E S.
1 jointing box D.
1 heavy mushroom anchor.
1 signal flag.
Triple junction boxes, mine switch boxes charged for skirmish
mines, old turks heads. -
The insulated cable is cut as soon as it is received on board;
turks heads are made on the ends; they are secured in a triple
junction box; their cores are jointed, one to the bevelled wire
R of a mine switch placed flat in the junction box, and the other
to wire H.; and, lastly, the extra hole of the junction box is
closed by an old turks head.
Having laid the cable, the tug returns with the mines. She
is equipped precisely as prescribed for planting mines in groups;
and plants one mine (loaded for purely automatic firing) about
one hundred feet in front of each skiff, by one of the methods
there laid down. If the bottom be stony, ground mines should
not be cut loose too near the surface, lest they be injured by the
shock. .
The men make a turks head on the cable; clamp it in the
triple junction box; joint the core to the remaining (unbevelled)
wire K of the switch box; close the junction box; make a pre-
concerted signal to a man on the look-out on shore; and lower
the box into the water. If the electrician be satisfied with his
tests, thereupon made, he signals to that effect, and the box is
cut loose and allowed to sink to the bottom. The skiff then
raises her anchor, and proceeds to execute the further instruc-
tions of the officer in command. -
To Raise Skirmish Mines. The cable is coiled up on the
drum in the usual manner, by a tug accompanied by several
skiffs. As each triple junction box is reached, the branch cable
is cut, and the end passed on board a skiff—which proceeds to
recover the end of the lowering rope of the mine, in the usual
way. The tug subsequently comes back, and raises the mines
with her windlass.
To Plant Self-acting Mines. A large and powerful tug
should be used, fitted with several cat-heads and strong cleats.
She is equipped with :—
Loaded torpedoes prepared for use as self-acting mines.
Anchors for ditto, suited to the channel.
Rigger's vises.
Thimble clamps.
Wire mooring rope.
Annealed wire and thimbles.
D U 7"I E'S OF TEI E B O A T P A R 'I' IJſ, S. 177
Tool boxes C.
A sounding line graduated in feet.
Shackles with spare split keys; lowering ropes; marline; lashing
rope.
The tug receives her mines at the wharf, where a crane or
derrick will be available.
The torpedoes must all be slung to cat-heads by short ropes.
One end will be permanently attached to the cat-head; the
bight will be rove through the ring of the cap, and the other
end will be belayed in such a manner as to permit gradual
slacking off. It should be borne in mind that this class of tor-
pedo must always be kept inverted.
The mooring is arranged as follows: Two shackles are hooked
together; one is bolted to the bottom ring of the torpedo as
slung (the usual lowering ring); and the other, to a thimble in-
serted in one end of a coil of wire mooring rope of suitable
length. The latter is placed on deck near the mine.
The lowering rope for the anchor is attached to the side ring,
and a shackle is inserted in the mooring ring. The anchor is
then slung by the lowering rope, through a hawse-hole near the
torpedo; and is secured by making the rope fast in such a
manner as to permit of readily slacking off.
Having slung her mines in this manner, the tug proceeds,
with the officer in charge, to the most distant part of the chan-
nel to be defended. She is accompanied by several small boats,
each provided with a heavy anchor and a sounding line. The
officer will cause these skiffs to anchor at such positions as he
may select for the mines—the object being to cover the ground
thoroughly as the work proceeds, so that a return to the same .
vicinity may be unnecessary. The precision of location observed
with electrical mines is not to be attempted; but a good project
for a moderately narrow channel is a square, with one diagonal
coincident with the middle of the passage. The torpedoes
should never be placed nearer to each other than about 250
feet. Where the range of the tide is considerable, arrangements
for signalling the stage above low water must not be forgotten.
Having established the boats to his satisfaction, the officer
proceeds to the most distant one, and learns the exact depth
there from the man with the sounding line. He then causes
the mooring rope to be cut to the proper length; the thinnble
to be inserted, and shackled to the anchor; and the latter to be
(45)
178 P I, A N T IN G T H E MIN E S.
lowered nearly to the bottom. He then steams close alongside
the boat, being careful not to foul its anchor line, and lowers the
torpedo anchor until it begins to draw upon the torpedo—then
both are slacked off together, the lowering rope of the torpedo
being disengaged from it entirely so soon as it is supported by
the water in its inverted position. In case the sea is too rough
for this operation, the torpedo may be released on reaching the
boat, and the anchor be allowed to go by the run immediately
afterward. Lastly, the lowering rope of the anchor is detached
as low down as possible.
The small boat is then established in its second position, while
the wire rope of the torpedo to be planted at the next boat is
preparing.
This manner of planting is safe, since there is no danger of an
accidental explosion until the time has elapsed for which the
safety break is regulated (about an hour).
A careful record of the number and positions of all self-acting
mines must be kept, to facilitate their removal when no longer
needed.
To Raise Self-acting Mines. The operation of clearing a
channel from self-acting mines of the approved pattern is trouble-
some, even although their number and exact location be known.
If it be necessary to preserve the matériel (which is not to
be recommended), proceed to the vicinity in a flat bottom boat
provided with a strong windlass; send down a diver to find the
anchor and attach a strong new line to it (the old rope soon
rots and becomes unsafe); raise the anchor very carefully until
the torpedo comes in sight; sling it by the cap ring and get it
on board without allowing it to turn over—which it has a
strong tendency to do; and, lastly, remove the cap and at once
detach the battery wire from the wire entering the torpedo.
When the end of the battery wire is insulated the torpedo
becomes perfectly safe to handle; but such work can only be
done in calm weather, and it is considered to be too dangerous
to be usually attempted. t
Even if it be decided to clear the channel by sacrificing the
torpedoes, the operation is not entirely simple. The method by
countermines acting as globes of compression, is uncertain and
very expensive. Grappling to locate the mines is dangerous,
since explosion follows decided tipping even without a shock;
and in a strong current it is not always possible to be sure of
T H E A Uſ T'O M A TIC FL. A. W. KING G UN S. 179
operating at a safe distance from every mine which may be
fouled by the sweeping line. The safest and proper plan is to
send down a diver to attach a small charge to the mooring rope,
and to explode this by electricity at a safe distance. The tor-
pedo, when thus released, will shoot upward with great velocity;
and as it may reach the surface before turning over and
exploding, dangerous fragments are liable to be thrown horiz-
ontally to long distances. If sufficient buoyancy be given to a
ten-pound charge to make it float upward along the mooring
rope to the torpedo, the latter will probably be exploded by the
concussion, and the danger from fragments will be lessened.
THE AUTOMATIC FLANKING GUNS.
The flanking of every grand group with a heavy fire of
canister, grape and shrapnel from large smooth bore or rifled
cannon, supplemented by machine and rapid firing guns of large
calibre, constitutes an important part of the defence. The can-
non, without in any way interfering with their ordinary service,
can be arranged to be fired automatically by the enemy when
tampering with the mines by night or in a fog.
The Post Commander will decide what guns shall be so
arranged for each grand group—the more of them the better.
The artillery officers will note during the planting the proper
direction and elevation for each gun—the object being to dis-
tribute the total fire over each group to the best advantage.
The Commanding Engineer will see that the electrical circuits
are properly prepared.
This is done by leading one single conductor cable from the
mining casemate to the group of guns flanking each particular
group of mines—choosing the most sheltered route where it
will be least exposed to the fire of the enemy or to accidental
injuries. Deteriorated cable unfit for use under water is en-
tirely serviceable for this purpose.
The end at the casemate will be secured and tagged with
the number of its grand group; and its core will be extended
by a leading wire to the operating table, by the electrician. He
will also make a good electrical connection between its iron
armor and his home earth.
The other end will be led to the most distant gun, passing
each gun of the group en route. In casemates it should be
stapled overhead entirely out of the way. Near each gun the
180 PI, A WT'I W G T H E MIN E S.
armor should be untwisted, not cut, and the core be drawn out.
This core should be cut and extended by two leading wires
long enough to reach the vent of the gun—being careful to
insulate the joints from the armor. At the last gun, a leading
wire well connected with the iron armor will supply the place
of the second fuze wire.
When the guns are to be set for automatic action, an electrical
gun primer is joined to the two leading wires and inserted in
each gun, after it has been properly loaded and pointed by the
detachment. Simply drawing out these primers prepares the
gun for service in the ordinary manner.
It will be noted that the fuzes are all coupled in series, and
that the explosion of the whole group will be simultaneous
when the firing battery is applied to the single leading wire in
the mining casemate. With 100 cells in perfect order, and half
a mile of gun-connecting cable and leading wires (giving with
return iron armor say 12 ohms), the total number of guns (n)
which can certainly be fired may be thus computed:
4-º-º- 145
T 30+ 12-E0.87,
Hence, n = 68 guns.
This number is largely in excess of what will be required.
The electrician of course should actually measure the circuit
when completed; and, allowing about 0.1 of an ohm for the
increased resistance of each fuze bridge by heating, and sub-
stituting the measured values of the electromotive force and
internal resistance of his battery as set up, should verify the
above computation. He can hardly fail to have a large excess
of power.
When it is desired to set any group of guns for automatic
action, it is only needful to remove the gun plugs in the corres-
ponding operating box; attach to the seven gun posts, seven
leading wires all radiating from the core of the proper armored
cable; and, lastly, switch the signal and firing batteries to their
automatic posts. The guns and not the torpedo will now ex-
plode if the mines are tampered with by the enemy.
(; H M PTER WI.
OI2EER ATING TEHE SYSTEM.
THE ELECTRICAI, TESTs; the firing battery; the signal battery; the automatic
apparatus; the disconnector; the judgment firing key; the mines and
cables; occasional tests; repairing injuries to the system.—DRILL OF
THE DETACIIMINT; automatic system drill; mapping drill; judgment
firing drill.—DEFENSE of THE MINES; modern modes of attack;
attacks by daylight; attacks by night or in fogs; the electric light;
movable torpedoes; injuries from friends; attempted passage by force.
Before the arrival of the enemy, the duties of the officer in
charge of the submarine mines will consist; (1) in daily or more
frequent electrical tests of the condition of the system ; (2) in
any repairs which may be necessary and practicable; and (3)
in drilling his detachment for their duties in action.
After the enemy appears in front of the position, attempts to
destroy the mines, or cross the mined zone, must be thwarted by
unceasing vigilance and every known expedient.
THE EIECTRICAL TESTS.
The object of these tests is to see that the mines are unin-
jured, and that every part of the operating apparatus is in
proper working order.
Daily Tests--The Firing Battery. The minimum
strength of the firing battery at any station is determined by the
resistance of the circuit of the most distant torpedo ; which may
be safely estimated by allowing 12 ohms per mile for the con-
ductor, and 8 ohms for the disconnector, fuzes and two earth
plates. The resistance thus computed, will indicate the maxi-
mum external circuit through which the firing battery must
give a current of 1.5 ampères. But to deflagrate fºr inclies of
the standard platinum wire * in the testing clips, requires a cur-
rent of only 1.0 ampères. Hence, before the clip test can be used
with safety, it is needful to compute what increased resistance
must be inserted to reduce the needful mine current of 1.5 am-
pères to a rheostat current of 1.0 ampères. Denoting by R, ,
the internal resistance of the firing battery; by R, , the maximum
*This wire (of which the fuzes and cut-offs are made) weighs 0.75 grains
per yard; is 0.0025 inches in diameter; and has an electrical resistance of 3
ohms per inch.
(46)
182 O P E R A 7"I W G 1'EIE S YSTEM.
external resistance, computed as above; and by ſo the amount to
be unplugged in the coils, which shall verify, by deflagration,
the requisite strength of the battery, we have:
E E
1.5 : 1.0:: ~~~~ : –-º-.
º, + R, R, + æ
Hence:
(19) . . . . a = 0.5 R, +1.5 R, .
Usually, a battery having an excess of power will be supplied;
but the minimum limit of strength must be computed by this
formula, and daily tests must be made to see that it is never
passed.
To deflagrate ſº inches of our service platinum wire, requires
about double the strength of current which brings it to a very
faint red. Hence, if the battery power be considerably in ex-
cess of the minimum limit, it will be sufficient to find by trial
exactly the number of ohms which, nnplugged in the set of re-
sistance coils, will give a faint red color to the test piece when
the firing current is switched to its testing post. A record being
kept of this resistance, the daily tests of the firing battery will
simply consist in unplugging the amount in the set of resistance
coils, and switching the firing battery through it. If the plati-
num wire shows a faint red color, the battery remains unchanged;
if not, further trials must determine through what resistance
the desired result can be obtained. The advantages of this
modification of the deflagration test are, that the battery is less
polarized, that a more delicate measurement of its power is made,
and that the trouble of replacing the test wire is avoided. It
is not, however, quite so determinate; and near the limit of
power, it should not be trusted. It need hardly be mentioned
that in these tests, care should be taken to make as few and as
short contacts as possible, to avoid polarizing the battery.
To this end it is far better, when determining by trial the
number of ohms through which the bridge inay be reddened or
deflagrated, to begin with less than the computed resistance and
work upward rather than the reverse. The contacts polarize
the battery, and it is easier to meet than to overtake its effects;
moreover, deflagration gives the minimum duration of contact.
By working downward the battery may be much weakened.
Should any considerable loss of power be detected, the diffi-
culty will usually be due to a defective cell. To find the box
Z’ H E E L J' ('T'Jø I. O. A /, 7' E. S. 7"S. 183
at fault, the two wires are detached from the battery terminal
poles, and a new earth wire is provided; the firing battery
switch is put on its testing post, and about a dozen ohms are un-
plugged in the resistance coils; the line wire and new earth
wire are now applied, successively, to the terminal poles of each
battery box, and the resistance unplugged is varied in each case
until a faint red color is shown on the test wire; the worst
boxes are thus readily detected and noted. Proceeding in like
manner with the separate cells in these boxes, the loss of power
is exactly located. When the defective cell is thus discovered,
it may either be repaired or, if time presses, be cut out of cir-
cuit. The normal connections are then restored, and the usual
test is made.
If the battery has been kept long in action, a general deteri-
oration caused by polarization may result. This will disappear
after a few hours of rest. The normal electromotive force per
cell of the service Leclanché firing battery is 1.45 volts, the
internal resistance in perfect condition being about 0.3 ohms.
When the latter quantity is actually measured, the fifth method
given in Abbot's Motes on Electricity should in general be pre-
ferred. It is sufficiently accurate for practical purposes, and is
less injurious than any other available at a mining station.
Daily Tests--The Signal Battery. To test the signal
battery, a wire should be attaehed to the terminal of the set
of resistance coils not connected with the earth wire, and a
resistance of at least 100 ohms should be unplugged. Touch-
ing one of the torpedo posts with the free end of this wire
should then cause the corresponding automatic apparatus to
work. If a defective cell is suspected, it may be discovered by
disconnecting the Bradley galvanometer from its usual con-
nections, and touching the terminals of each cell with two wires,
the other ends of which are attached to the two binding posts
of the galvanometer, its zero coil being plugged. A comparison
of the deflections will show which cell is weakest, and to what
extent. For an actual measurement of the internal resistance,
Mance's method is usually to be preferred.
Daily Tests--The Automatic Apparatus. The only
parts of this apparatus which require especial attention are the
mercury contacts. These must be kept free from dust, and
from the oxidation caused by sparks when the circuit is broken.
The latter occur chiefly in the circuits of the firing battery, but
184 O P E R A TING T H E S Y S T E M
must not be neglected for the signal battery. If the boxes be
kept habitually closed, but little trouble will be experienced
from dust.
The mercury used should be pure, and if treated with dilute
nitric acid should subsequently be thoroughly washed in pure
water. If any acidity remains, it may coat the interior of the
cups with oxide and thus introduce much resistance into the
circuit. Should such a condition be suggested by the tests, the
bad cups should be removed from the box and scraped clean
with a die sinker’s file from tool box A.
The only daily test is the following—which is but an ex-
tension of that already prescribed for the signal battery.
A wire long enough to reach the most distant of the tor-
pedo binding posts, is attached to one terminal of the box of
resistance coils, the other being joined to the earth wire. At
least 100 ohms are unplugged; and, the firing battery being off
its automatic post, each torpedo post is touched in succession
with the free end of the wire. A rapid vibration of the lever
should occur. Should any lever fail to vibrate, the difficulty
may usually be removed by regulating the strength and position
of the spring connecting it with the base-board and magnet.
Close attention should be given to see that the firing bridge
considerably disturbs the mercury in both of its cups. If not, the
mercury level must be so adjusted as to secure this result. Care
in adjusting this level is necessary. If the signal circuit be not
broken before the firing circuit is closed, the gun plug being in,
a furious and continued vibration certain to bend the lever is
the result. This is caused by the current of the firing battery
flowing to home earth through the signal battery. It is cor-
rected by readjusting the mercury level in the three cups, so
that the signal circuit shall be broken before the other is closed.
Daily Tests--The Disconnector. The proper condition of
this instrument has been incidentally verified when testing the
firing battery. If the bell rings correctly at the contacts which
send the current through the resistance coils, the mechanism is
in perfect order. Occasional rewinding of the clock-work is
required, but it is not desirable to retain too strong a tension on
the spring; when the bell begins to work sluggishly is soon
enough to rewind.
Daily Tests--The Judgment Firing Apparatus. No
test is required, other than to ascertain by inspection that the
T EI E E L E O TR TO A. L T E S T S. 185
mercury cups are in good order and properly filled ; that the
leading wires are securely attached to the binding posts; and
that the lever works freely.
Daily Tests--The Mines and Cables. The nature of the
daily tests will depend entirely upon the condition of the cables.
While the mines were planting, a record was kept of the de-
flection of the Bradley galvanometer with the signal battery
switched to the testing circuit, as group after group was suc-
cessively placed in position. Final tests of the same character
measured the aggregate leak of each grand group, and of the
whole system; and if these remain unchanged from day to day,
it is safe to infer that no injury has occurred to mines or
cables. As the condition of the signal battery may vary
slightly, a small change may be noted in the standard deflec-
tions, sometimes an increase and sometimes a decrease; but it
cannot be confounded with the effect of a serious injury to a
cable, or of a leak in a torpedo. With the signal battery on the
automatic circuit, either of those accidents will instantly sound
the alarum, and drop the mine number of the injured group;
with the battery on the testing circuit, a violent deflection of
the needle will certainly be shown.
Should such indications occur, or should an alarming increase
in standard deflection be noted, the fault must be traced to its
origin. To do this (if the leak is not sufficient to drop the
number of the defective group), an assistant should remove the
torpedo cables one after another from their posts, while the
electrician, with the Bradley galvanometer and signal battery
switches on their testing posts, attentively observes the needle,
the coil giving the most sensitive deflection being plugged. A
sudden fall will occur when the defective wire is detached.
The next step is to determine whether the difficulty results
from a loss of insulation in the cable, or from a defect in the
torpedo. The best method is that known as the sea-cell test.
The electrician first measures the resistance of the group by
the method of reversals, taking care to leave the fault depol-
arized; and then, after carefully seeing that the circuits of both
signal and firing batteries are broken at the key-board, re-attaches
the defective wire to its post; removes the counterpoise; in-
serts the gun plug, if not already in ; and closes the galvanometer
switch to earth.
(47)
186 O P E R A TI N G T H E S Y S T E M.
By so doing, he has detached this group from all connection
with its neighbors, or with any battery in the operating room,
and has closed the circuit of the cable through the galva-
nometer to earth. But if the copper strand be exposed, or if a
leak has occurred in the torpedo, a feeble sea-cell has been
formed thereby. The sea water is the exciting fluid. In the
former case, the plates are represented by the home earth and
the tinned copper strand; in the latter, by the home earth and
the zinc plate of the circuit regulator in a buoyant torpedo or
buoy, or the zinc strip in the fuze can of a ground torpedo.
These feeble cells in completing their circuit through the cable,
traverse the galvanometer, and, of course, effect the needle.
The nature of the injury is inferred by noting the amount and
direction of these deflections, and then considering the results in
connection with the resistance already measured.
To have several unpolarized home earth plates of different
metals is needful in such a test; and for this reason a zinc, an
iron and a copper plate, all carefully separated from each other
and plunged in the sea, have been provided; they are connected
with the casemate by insulated wires so labelled as to be readily
distinguished. The terminals are successively connected to the
earth post of the Bradley galvanometer switch, the 150-ohm
coil being plugged; or, if this fail to give determinate readings,
to that of the Siemens galvanometer connected as a sine. The
switches on the testing table are so arranged as to permit this
to be rapidly done without changing leading wires.
To arrive at correct conclusions from such measurements,
may call for individual skill on the part of the officer; for a
complete set of rules can hardly be laid down to serve as arbi-
trary guides. For this reason, the following examples have
been extracted from the records at Willets Point. The re-
sistance of each fault was determined by the method of short
reversals. The casemate leading wires in the sea-cell tests were
connected as shown on Plate VIII; and the direction of the
deflections refers to the south seeking end of the needle.
THI E' E L E (/TRI ('A J, 7' E. S. T.S. 187
J. XAMPLIES OF SEA-(JICI, I, TEST’S.
Resistance Deflection of needle—
Nature of distant Of' distant home earth being :
Carth. Garth Galvanometer. -- - - -- - -- - - - - - - - - - -
in Ohms. Zinc. IrOn. | Copper.
|
No. 1, good torpedo, • a ſilic, ºr 1 º' i
; ; *! 1.8 | Bºº. || 34° E. 2° E. ww.
No. 2, leaky torpedo.. 1.5 £ 4 4° E. , 30° W. 50° W.
No. 3, leaky tºrpedo: 1.5 { { | 20 E. 32° W. 51° W.
Nº Plus in-Q wº & 4 21° E. 5° E. 30 w.
No. 5, cable fault..... 12ſ) & 4 7° E. 3° E. 1° W.
No. 6, cable fault..... 8 $ 4 38° E. 15° E. 19° w.
No. 7, cable fault..... 75 4 * 14° E. 9° E. 15° w.
No. 8, cable fault..... 24000 Siemens, as sine. 7° E. 2° E. 3° w.
No. 1. A torpedo in perfect order, connected to the shore by a perfect cable;
the circuit was completed by closing the regulator.
No. 2. Identical with No. 1; except that the torpedo was full of water.
No. 3. Identical with No. 1, except that the regulator was open, and that
the torpedo was full of water. Closing the regulator mechanically
produced no sensible effect upon the sea-cell indication.
No. 4. A defective torpedo set for an open circuit. It had been ballasted
with Sea Sand in lieu of a charge of dynamite; and the moisture con-
densed from the air had dampened the sand, and thus bridged the
insulating band of the regulator, forming a circuit to earth. The
test (compare No. 1) is characteristic of a total loss of insulation in
Some part of the circuit through the compound plug. No leakage
had occurred in the torpedo.
No. 5. A defective cable, the fault being a clean cut leaving the exposed end
e in the sea.
No. 6. Identical with No. 5, except that 6 inches of the insulation at the cut
was exposed.
No. 7. A fault caused by an anchor strain, in a cable of which the distant
end was insulated.
No. 8. A fault caused by an anchor strain, in a cable of which the distant

end was insulated. It gave 10° deflection upon the Bradley galva-
nometer, 150 ohm coil, when tested by a small 10-cell Leclanché
battery. The sea-cell current was too feeble to produce any effect
on that galvanometer.
The following general principles are applicable in deciding
what inferences should be derived from such observations.
(1) When the home and distant earth plates consist of the same
metal, the sea-cell current will be very feeble as compared with
that obtained with the other home plates. This is illustrated by
Nos. 1 and 4, in which both plates are iron; Nos. 2 and 3, in
which they are zinc ; and No. 5, in which they are copper.
188 O P E R A TING TH E S Y S T E Mſ.
The apparent discrepancies shown by Nos. 6, 7 and 8 are due to
the fact that the copper strands of the cable are tinned, thus
making the distant plate only in part copper. (2) A leak in
the torpedo is always characterized by a very small resistance;
while in a cable fault it is usually much higher, depending upon
the surface exposed. (3) With an iron home earth, the South
seeking end of the needle is normally deflected to the west by a
leak in the torpedo, and to the east by a fault in the cable; but
care must be taken to depolarize the plates if they have been
subjected to the action of the signal battery, or these character-
istic deflections, especially in the case of a cable fault, may be
reduced or even reversed.
In fine, with mines operated upon an open circuit, or one of
high resistance, a skillful electrician should be able to decide
promptly upon the locus and cause of any serious fall of
insulation. With a circuit of low resistance, the matter of de-
termining injuries would be far more difficult; and this, with
other good reasons, decided the choice for our service.
Occasional Tests. The internal resistance and electro-
motive force of the signal battery should be measured as often
as once a month, using any of the available methods. The
firing battery has so small an internal resistance, and is so much
exhausted by the process, that this better not be attempted un-
less serious indications of failing are given. g
The circuits of the several mines may be mechanically tested
by operating on the circuit regulators, in cases where they are
kept in position for so very long periods as to render this de-
sirable. It may be done at low water by striking them with a
small side-wheel tug, moving at slow speed—or by passing a
rope round each wire mooring rope in turn, and holding fast by
it over the mine, while the buoy or buoyant torpedo is suddenly
tipped over by a boat-hook, or by lowering a small mushroom
anchor upon it. A large boat is necessary for this purpose, and
a tip and sudden jerk are both desirable. It need hardly be
mentioned that the connections in the casemate should receive
the most careful attention during this test—the firing battery
wire being entirely detached from the apparatus, the gun plugs
being removed, and the signal battery being switched on the
automatic circuit in order to report the result.
The resistance of the home earth should be frequently meas-
ured. To do so, one auxiliary plate of known resistance, or two
TIſ E E L E (; TIP TO A L T E S T'S. 189
auxiliary plates must be employed. The home earth plates
afford every needed facility for the measurement. The best
result will usually be obtained with the zinc and iron plates, as
the iron armor of the torpedo cable is galvanized.
It is well, occasionally, to verify the condition of every part
of the automatic apparatus in the casemate, by testing it as a
whole at the nearest possible point to the water. This is done
by entering the cable shaft, and, with a needle attached to an
independent earth wire, pricking each core to the copper at
the point where the separate leading wires enter the multiple
cable, which, of course, is never submerged. If the signal bat-
tery be on the automatic circuit, this should drop all the
numbers in succession. By inserting a fuze, a cut-off, and the
standard resistance in the independent earth connection, and
setting the signal and firing batteries for automatic action, the
test may be made to include the automatic firing arrangements.
Of course the channel should be watched in the meantime, to
see that no friendly vessel is near.
Repairing Injuries to the System. While awaiting the
close approach of the enemy, both batteries should be kept off
the cables; but when he presents himself, it may be desirable,
especially by night, to keep the signal battery on its automatic
circuit continuously. With good cables, good joints, etc., this
will cause no trouble—but if it should be necessary to employ
poor materials, the faults may, under the action of the usual
zinc current, become worse. It is, therefore, important to re-
member the effect of reversing the signal battery (putting zinc
to earth). When this is done, the faults have a tendency to
close, from the deposit of chloride of copper and other non-
conducting salts; and, for a short time, this may be a valuable
resource. Still, these salts are formed at the expense of the
copper core, and ultimately must lead to its destruction. The
expedient, therefore, should always be used with caution. With
really bad faults, not much advantage will result—but with
many small faults the temporary relief afforded by this device
may be important.
The trouble occasioned by many small and increasing faults
may become serious. A deflection of about 80° on the 150-ohm
coil of the Bradley galvanometer, corresponding to a current of
about 0.02 ampères, can be permitted in any cable, without
danger of an accidental switching on of the firing battery. If
(48)
19() O P J R A TI W G T H E S Y S T E Mſ.
this limit be approached, the battery must be kept off the cables
as much as possible; and when on, the following expedients
may be used.
Fºrst. The weight of the counterpoise may be increased.
The amount by which this can be done must be determined by
trial—as it depends largely upon the strength of the signal
battery. The operation will consist in replacing the cable by a
wire connected through the box of resistance coils to earth;
and, after unplugging a resistance corresponding to that with
the circuit regulator closed at the mine, weighting the armature
by trial until the maximum safe load which will not prevent it
from working is determined.
Second. Another plan is to shunt this magnet by such a
resistance as will produce the same effect. The shunt is intro-
duced between the automatic signal post and the torpedo post
for the cable in question. Its minimum safe resistance may be
determined by the unethod given above.
Thºrd. The better plan, perhaps, is to reduce the electro-
motive force of the signal battery to a minimum. The apparatus
can usually be safely worked with 6 volts; but the minimum
number of cells can readily be found by trial, as above, with
the resistance coils of the rheostat.
The foregoing expedients are designed to retard deterioration
exhibiting itself in the system too late to permit thorough
repairs. It remains to consider cases where mines have become
unserviceable with such methods of operating, but which never-
theless may not be absolutely worthless in action. Of course,
when time permits, such mines would be replaced; but during
an actual siege this could not usually be done, and it only re-
mains to derive such uncertain assistance from them as extreme
measures suggest.
Mines usually become unserviceable from one of three causes
—leaking of the cases; faults at joints, or from accidental
abrasion of the cable from chafing upon sharp rocks, the
swinging of the torpedo, etc.; and successful severing of the
cables by the enemy. Each will be considered in turn.
Leaking of the cases can be certainly detected by the elec-
trical tests. As wetting dynamite does not materially weaken
its explosive force, and as the fuzes are kept dry in their water-
tight fuze cans, such an injury is only fatal because the water
destroys the buoyancy of the case, and hence sinks the circuit
T II E E L E (/ T R T (/A ſ, T'Jº S T'S . 191
regulator below the draft of the enemy's hull. The mine is,
therefore, still available for purely judgment firing; and, if the
channel be not too deep, and be sufficiently narrow to admit of
precision in triangulation, it may sometimes be thus used. As
mines on main lines, however, are planted in triple groups, and
as such an injury would be unlikely to occur in more than one
of the three, the best course would usually be to remove the
counterpoise, insert the gun plug, and explode the damaged tor-
pedo by switching on the firing battery—this would also explode
the cut-off, and thus leave the two remaining mines serviceable.
The same method is applicable to a leaky skirmish mine.
When a bad defect in a joint has developed itself, or when
the cable has been so chafed as to expose, but not sever, the
copper strand, mines may often be used for automatic firing by
connecting the shore end of the cable to the zinc pole of a pow-
erful and constant battery, its carbon pole being attached to
earth. The closing of the circuit regulator by the enemy will
then open a second route through the fuze, which will usually
divert sufficient current to effect an explosion with our sensitive
fuzes (see page 101). It is needless to say that the Leclanché
firing battery is not suited for such uses, owing to its inconstant
character; but as most important stations will be supplied with
the electric light and a dynamo inachine, or a large battery of
Grove or Bunsen cells, the officer will have all needed facilities.
With ground mines, if the injury has occurred between the tor-
pedo and buoy, applying the current may cause an explosion;
and, not to endanger the other mines, the precaution should be
taken of seeing that the Leclanché firing battery is switched off
its automatic circuit when the experiment is tried.
When the enemy has had access to the cables, the amount of
injury done will vary greatly with the part he has been able to
grapple. On main lines, if he has cut the cable between a mine
and its triple junction box, the other two of the group may
usually be rendered available by attaching a constant battery, as
just described. If he has cut the cable between the triple and
grand junction boxes, he has effectually destroyed that triple
group. If he has cut the multiple cable, the whole grand group
is worthless; this injury, however, is unlikely to occur, owing
to the cable sinking into the mud by its great weight. With
skirmish mines, when two forts occupy opposite sides of the
channel, each cable should enter both mining casemates. A
192 t O PAE R A T'I W G T H E S YAS 7' E.M.
single cut will then do no harm, if the device of attaching a
powerful and constant battery be employed at each station.
Indeed, in this case, the enemy must either sever the cable close
to each fort, or cut off each mine from it in detail, or attach un-
commonly good earth plates to each end of the cut in order to
seriously injure the group. Such operations, under the auto-
matic and close fire of the works, will not be easy; and the
actual amount of damage may be quickly ascertained by the
electrician.
Thus, considering the case when both ends of the cable enter
the same casemate, measure the resistance between the two ends
(a) and subtract the corresponding resistance of the cable before
it was cut (r); the result will be the joint resistance of the two
faults at the cut. Next, measure the joint resistance of each
piece of cable and of the home earth, and subtract the known
resistance of latter—the results, (b) and (e), will be the sum of
the resistance of each fault and of its line to the casemate. If
(a) differs but slightly from the sum b + c, it may be assumed
that the measurements are correct, and that the joint resistance
of both faults, and the joint resistance of each fault and of its
own piece of cable are known. Further than this it is not pos-
sible to measure, but from these figures useful inferences may
be drawn. *
If, for example, (a) sensibly equals (r), the faults are very
low in resistance, and the mines near the out can hardly be
made active even by a very powerful battery; this is not true,
however, for those at a moderate distance from the cut. The
joint resistance of the cut-off, of the 100-foot length of branch
cable, of the two fuzes in the torpedo, and of the torpedo earth,
may be assumed at 3 ohms, through which 1.5 ampéres must
pass to certainly explode the mine when its circuit closer is
closed by the enemy. At 3 ohms distance (one-quarter of a
mile) from the cut, by the law of derived circuits one-half of
the battery current will be diverted through the torpedo, and
explosion will be certain, provided the current flowing through
the cable be three ampères. If the cable resistance from the
casemate to the cut be 12 ohms—corresponding to about a
mile—the number of large Grove cells (n) to maintain this
current is easily computed by Ohm’s formula, thus:
TJJ E JEJ, JE (1 TJ2 ſ ("A L T'Jº S T S. 193
2 n.
3 × 3
0.1 m + 9 + - C :
3 + 3
3 =
Hence,
n = 19 large cells.
This, however, is a very unfavorable and improbable suppo-
sition. If the resistance at the fault be 8 ohms, corresponding
to about six inches of bare copper wire, the resistance of the
cable branch at a point one-quarter of a mile from the cut will
be 11 ohms, while a torpedo branch at that spot has only 3
ohms. Hence, a main cable flow of only 1.9 ampères is required
to give 1.5 ampères through the mine, and the number of cells
becomes:
2 n.
11 × 3
0.1 m + 9 + ITT3
n = 12 large cells.
Evidently, with a battery of 50 large Grove or Bunsen cells
available to apply to the home ends of the injured cable, only
one or two mines in the immediate vicinity of a cut will, in
general, be unfit for automatic action on this system; and the
electrician, if both ends of the cable are in his own casemate,
can by three rapid measurements assure himself what fraction
of that battery is needed. If one end enters the casemate of
the côoperating fort, he has only to telegraph to its electrician
(through another skirmish line cable) to measure his fault and
compare notes. The result, although not quite so determinate,
will furnish a sufficient practical guide when discussed on the
above principles.
It is not necessary to prescribe mechanical methods to repair
injuries discovered in the system; they must be decided by
local considerations. It is well, however, to state that in raising
a junction box or mine, an hour should always be selected when
the tidal current sets away from the line of mines. This pre-
vents the boat from drifting in a direction to foul other buoyant
mines with the cable she is raising—the most troublesome diffi-
culty likely to be encountered in practice.
DRILL OF THE DETACHMENT.
Each man of the party should be frequently practised in per-
forming all the duties which in any contingency may be required
1.9 =
(49)
194 O P E R A T'ING TEI E S YST'ſ) M.
of him. Thus to set up, adjust and operate the dial telegraph
instruments, to make joints, to load torpedoes for new mines,
and to make the electrical preparations for flanking guns, etc.,
may devolve upon any one; and to act as assistant electrician
may happen to any of the non-commissioned officers.
At stations supplied with the electric light, the whole party
should be exercised with the dynamo or in Setting up the bat-
tery, in manipulating the lens by night so as to skillfully
control the illuminated field, and in taking apart and cleaning
every part of the apparatus.
In like manner, if fish torpedoes steered and controlled by
electricity are provided, the party should be exercised in their
U1S62.
Beside becoming familiar with the details of their routine
work, frequent practice should be had in the special drills soon
to be described, which are designed to cover what may occur in
an actual attack.
The importance of great promptness and efficiency in this
part of their duties will be apparent when the short time given
to act is considered. A vessel 300 feet long, passing directly
over a mine, will be within its dangerous range only about thir-
teen seconds if moving at a rate of fifteen miles an hour, and
sixty-five seconds if moving three miles an hour. Between these
limits the available time will probably lie.
In many, and indeed in a majority of cases with automatic
mines, the duties will be exceedingly simple. The hostile fleet
will be seen approaching the position. The Commanding En-
gineer, equipped with a map and field glass, and having his
telegraph operator with dial telegraph and copy of code for
action (telephones cannot be trusted during the noise of a
cannonade) within hearing, will be at his post where a clear
view of the channel can be obtained. He will telegraph to the
casemate to set the apparatus for automatic action. This order,
received by the operator there, will be instantly communicated
to the electrician—who then has nothing to do but to set the
switches correctly; to report the number of any mine as soon
as it is exploded; and to manipulate the apparatus so as to pre-
vent any further explosions from being caused thereby. By
night, and in dense fogs, only this method of operating should
be attempted. t
J) R ſſ, L () J' TII E' DJſ, TA G JIM AE W T. 195
But circumstances may occur which will complicate even the
automatic Service of the mines. Some of our own vessels may
be in the close vicinity; or the enemy may send worthless hulks
ahead, steered by electricity, to draw the fire; or he may at-
tempt to protect his vessels by out-rigger frames or rafts in order
that the explosion may occur too soon to inflict serious injury.
In such cases, the Engineer, without ordering any explosions in
advance, must know at once what mine is struck, so that from
its known locality and the visible position of the vessels, he can
decide on the instant whether or not to fire—and if the latter,
be able to do so precisely when it will be most effective. In
other words, he must know almost as soon as the electrician in
the casemate, when any particular mine is struck; and must
then be able to perfectly and promptly control the action there
taken.
Evidently, instructed telegraph operators and a cool and
prompt electrician are demanded for such work; and previous
drilling based upon the most unfavorable conditions is requisite.
To prepare to meet this need, the following drill has been
devised and practiced at Willets Point; and it should be fre-
quently repeated in actual service, while awaiting the approach
of the enemy. In order to cover the whole ground, simulated
injuries to the mines have been included—although in battle
nothing could be done in such cases but to detach the cable.
Automatic System Drill. The Commanding Engineer
causes a few insulated cables to be extended from the casemate
to the wharf, or other station where a full view of the channel
can be obtained, and where the water is close at hand. He
proceeds there himself with two privates and the following
matériel—leaving the electrician, and a private to serve the tele-
graph, in the casemate.
1 dial telegraph instrument (telephones should not be used ).
1 earth plate and connecting wire.
1 circuit regulator to each cable.
1 lowering cord.
1 piece of torpedo cable, about 25 feet long, with a place near
the middle prepared by grinding off one side of the armor
and slightly exposing the copper strand to simulate such an
injury as would be likely to occur from chafing upon sharp
rocks.
1 box containing fuzes, cut-offs, screw cups, a zinc plate, small
insulated wire and cutting pliers.
1 photograph of loading connections.
196 O P J R A T' I W G T H E S Y S T E Mſ.
# * ***
One of the privates serves the telegraph on the wharf; the
other makes the connections as ordered. To guard against
accidents (11) is always telegraphed before beginning work,
and before making any changes in the matériel. As the fuzes
are dangerous, they are to be so placed and covered that frag-
ments by no chance can strike any of the party.
The ends of the cables have been left insulated in the air on
the wharf. By attaching them through fuzes, cut-offs and cir-
cuit regulators, in the manner shown on the loading photograph,
to a wire connected with the earth plate submerged in the water,
the officer prepares electrically a set of mines; and can, there-
fore, easily ascertain the promptness and skill of his party by
seeing whether his adjustments and telegraphic orders are fol-
lowed instantly by the results intended.
Having satisfied himself that the party thoroughly understand
how to operate the mines in action, he proceeds to exercise them
in detecting defects in the mines and cables. These can be
closely simulated. For instance, by attaching the end of one
of the cables to the zinc plate, and lowering it into the sea, he
can produce the electrical conditions of a leaky torpedo. In
like manner, by attaching a cable to one end of the strand of
his piece of chafed cable, and sinking the injured part below
the water surface (both ends being kept in the air), he can ac-
curately imitate a loss of insulation in the cable of that sup-
posed mine.
In fine, he has every needed facility for exercising his party
in their duties in operating the system—such, for instance, as
automatic firing; firing a designated mine not struck by the
enemy; detecting and reporting, without firing, the touching of
a mine, and promptly executing the orders thereupon received;
operating the flanking guns; detecting and deciding upon the
cause of injuries occurring to the mines, i. e., whether due to
leaking of the torpedo, or to chafing of the cables, etc., etc.
TELEGRAPH OPERATORs. The duties of the operators and the
code for action, have been prescribed in Chapter II, under the
the heading “Wheatstone Dial Telegraph.” The latter is here
reprinted for convenience of reference.
The instruments must have been put carefully in unison;
and, with the switches up, the operators fix their eyes on the
receiving dials. All signals now refer to the inside characters
—the right hand figures denote the mine groups, each being
J) Jº Iſ, I, O F 7'IIſ, J) Jº TA (VIIMF, WT. 197
designated by its number; the left hand figures are used for the
abbreviated code given below. After sending a message, the
stop is always to be made at the +. -
Should either operator desire to send a message not provided
for in the code, he will stop three times at the +, after which
his signals will be read on the alphabet; but every message so
sent must be preceded by a triple stop at the +.
In every case whether in action or at drill, all code messages
must be instantly repeated by the receiver for verification.
The following is the regular code for action. By a further
combination of numbers, it may be extended indefinitely; but,
to avoid complexity, it should be restricted to urgent messages.
TII E COI) E FOR ACTION.
11 See that circuit of firing battery is broken at its switch.
22 Report number of any group struck, and prepare to fire it. '
33 No vessel near—find out difficulty and report.
44 Friend—let pass.
555 Enemy is over the mine—fire.
666 (Adding number in right hand figures). Prepare to fire group
No.—. When I am ready, message (555) or (44) will be sent,
according to circumstances.
777 Automatic adjustment to fire flanking guns if torpedoes or cables
be disturbed.
888 Automatic adjustment to fire the mines—enemy approaching.
121 Trouble here requires your presence.
131 My message was not understood—I now repeat it.
141 Your message is not understood—please repeat.
151 Leak in torpedo.
161 I loss of insulation in cable.
171 The circuit is broken—end of core insulated.
181 The cable has parted—end of core in water.
THE ELECTRICAN. To prepare for the drill, the electrician
detaches the multiple cable boxes, removes the real torpedo
cables from the key-board box, and attaches the wharf wires as
directed by the commanding officer. The leading wires of the
firing battery and of the signal battery remain attached as usual.
While awaiting instructions, the circuits of both the batteries
leading to the key-board box are kept broken at their switches;
and care must be taken not to exhaust the firing battery un-
necessarily during the drill.
Orders to the electrician, so far as practicable, will be sent
by the service code. The following are his duties for messages
requiring manipulations of the apparatus; being the same, of
course, as in action.
(50)
198 () P E R A T'IWG THE SYSTEM.
CODE MESSAGE 22.
Switch signal battery to automatic post; see that firing battery is off; tele-
graph any number dropping; remove its counterpoise, and see that its gun
plug is in; switch signal battery off.
CoIDE MESSAGE 33.
Close earth circuit at Bradley galvanometer, plug being in 150-ohm coil,
and the double button switches right; make sea-cell test as already prescribed;
finally, if necessary, measure the resistance of the circuit. Having discovered
and reported the cause of the difficulty, replace the counterpoise and re-set
the number drop.
CODE MESSAGE 44.
Replace the counterpoise, and re-set the number drop.
CODE MESSAGE 555.
Switch firing battery to automatic post; and if disconnector does not report
an explosion in a few seconds, shift lever of judgment firing apparatus. The
first motion will usually explode the mine struck, and the last will fire the
whole group, which although not desired in automatic firing, is preferable to
allowing the enemy to escape. In judgment firing, the triple explosion is
advantageous, as largely increasing the chances of success. After explosion,
break circuit of firing battery; replace counterpoise; re-set number drop if
only one mine has exploded, and detach cable if group has been fired.
CODE MESSAGE 666.
Switch signal battery off its automatic post, if on; see that firing battery is
off; remove counterpoise of designated group, and see that its gun plug is in.
CODE MESSAGE 777.
Remove gun plugs; attach gun wires; switch signal and firing batteries to
their automatic posts—the latter, last.
CODE MESSAGE 888.
First switch signal battery, and then firing battery to their automatic posts,
seeing that all gun plugs are in and all gun wires off. If after an explosion
any lever vibrates, switch firing battery off before bell stops ringing.
No electrician who cannot obey these code messages correctly
and instantly by their numbers without referring to the text, is
sufficiently instructed to be trusted with the charge of the case-
mate in action.
Mapping Drill. The extremely short horizontal range even
of the largest charges, and the practical difficulty of determining
exactly the relative positions of the mines and the enemy, render
firing mines by judgment advantageous only in very narrow
channels. For these reasons, also, no enormous charges are em-
ployed, it being considered that triple groups of small mines are
more effective for the few cases where the method will be used.
By night, or in fogs, or when shrouded by his own smoke, or by
that of our guns, or when advancing with a front of several
vessels, or when tidal currents strong enough to sway buoyant
J) Jº II, L OF THI E' DJ? TA (J. H. M. E. W. T. 199
mines from their normal positions prevail, the enemy might
confidently expect to pass with impunity through an ordinary
channel defended only by judgment firing.
Nevertheless, it is important that the Engineer charged with
the direction of the torpedo defense, should know as accurately
as possible the position of the hostile vessels; and it is even
more important that the artillery should be constantly supplied
with the range, and hence with the elevation to use in pointing
the guns; moreover, if the cables have become defective, mines
which are useless for automatic work may still be fired by
judgment. For these reasons, a mapping drill applicable both
to judgment firing and artillery practice has been prepared for
low sites where single-station position finders cannot be
employed.
A map of the channel on a large scale, showing the position
of the forts, the mines and their numbers, and the most suitable
base line, is prepared, and is attached to the top of a convenient
table. One end of the base line should be located at the station
to be occupied in action by the Commanding Engineer, where
the map will be used. From it and from the other extremity,
as centres, arcs of circles are drawn on the map, large enough
to include the entire channel within range. The intersection of
every convenient radius with the border of the map, should be
distinctly marked and numbered to correspond with the limb
graduation of the theodolite—the zero being placed on the pro-
longation of the base line.
At each of the two centres on the map, one end of a black
silk thread, well waxed, should be pinned with a small tack—
the other end being free.
If, now, two theodolites placed at the ends of the base line
and so adjusted that their reading shall correspond with the
graduation of the maps, are kept pointed at some designated
part of an approaching vessel, and the free ends of the threads
are drawn tightly over the marks corresponding to the readings
of their verniers, the intersection of the threads will mark at
every instant the position of the vessel—and hence will indicate
what torpedo she is approaching, and what is the true range for
every gun bearing upon her.
The drill based on this system, is the following. Two
non-commissioned officers and four privates of Engineers are
required, with the following matériel.
200 O P E R A TI W G T H E S Y S T E Mſ.
1 map and table, with small tacks and waxed silk thread.
2 theodolites or railroad transits.
2 speaking telephones or dial telegraph instruments.
Insulated wires, and earth connections.
One non-commissioned officer and three privates, with the
map, a theodolite, and a set of telegraphing apparatus, are sta-
tioned with the Engineer in charge—who is also accompanied
in action by a private to serve the dial telegraph instrument
connected with the operating room. The rest of the party and
instruments are at the other end of the base line. The telegraph
line and good earth connections are established. -
The two theodolites are planted over the stakes, and carefully
adjusted by the non-commissioned officers. The top plates are
clamped at zero, and each telescope is directed upon the plumb
line of the other instrument. The lower plates are then clamped
and the top plates unclamped, ready to follow the designated
vessel; the verniers to be read, being those corresponding to
the graduation of the map, are selected.
The telegraphing apparatus is attached to the line wire, and
tested by trial.
The map and table are placed in the most convenient shel-
tered position near the station of the officer, who gives specific
instructions as to what part of the vessel is to be followed by
the cross hairs of the telescope.
The non-commissioned officers now take their positions at the
instruments, each with a private to call out the readings as the
zero of the proper vernier passes the designated divisions of the
limb –the one at the map station directly, and the other through
the telephone which he holds to his mouth. The two remaining
privates stand by the table, each holding the free end of a
silk thread ; one of them has the telephone connected to the
distant station applied to his ear. The other has a pencil to
mark the track of the vessel on the map.
Each non-commissioned officer now keeps the cross hairs of
his telescope directed upon the vessel. The private at the map
station calls out the reading of the middle line of the vernier as
it crosses each convenient line on the limb, and the private
holding the corresponding thread, places it accordingly on his
map graduation. The private at the distant station calls out
the readings through his telephone, and the receiver moves his
thread accordingly.
D R II, J., () };" T'II E D E 7" A CII ME W.T. 201
. A glance at the map will now show the position and course
of the vessel—the latter being marked with a pencil, following
the moving intersection of the threads.
An artillery officer furnished with a scale graduated to yards,
can take off, as often as he deems necessary, the ranges for any
of his guns, and communicate the same by flag signals, or other-
wise, to his cannoniers.
This triangulation will certainly be required in any attempted
passage of the enemy, and the party should be frequently exer-
cised in their several duties. If few vessels are passing, a fast
sail boat should be sent out to be tracked on the map.
Judgment Firing Drill. When the men have become
skillful in the mapping drill, it is to be extended to include
practice in judgment firing, so conducted as to measure the de-
gree of precision attained. The matériel needed is the following:
1 map and table, with small tacks and waxed silk thread.
2 theodolites or railroad transits.
2 speaking telephones or dial telegraph instruments. assºr
1 fast sailing boat or steam launch.
3 planting buoys, with light mushroom anchors and extra long
cables.
Fuzes; small (3-ounce) dynamite cartridges; leading wires;
earth connections.
A specified course is ordered for the boat. Near it on the
map, certain imaginary mines are located and numbered. Cor-
responding small charges of dynamite are laid on shore, where
the explosions can be seen from the boat; the fuzes are con-
nected with earth and with the apparatus in the casemate. If
more convenient, guns loaded in like manner with blank car-
tridges of gun powder may be employed.
When the sail boat passes over one of the imaginary mines,
the corresponding shore charge is fired precisely as the real
mine would be exploded by judgment in active service; i. e.,
the Engineer watches the approach of the intersection of the
threads to his mines; telegraphs (666) and the proper mine
number to the casemate; and, finally, when the boat is probably
within destructive range, telegraphs (555). The explosion of
the fuze should occur within less than five seconds thereafter.
If from a change in the boat's course he finds that he has made
an error in the mine first designated, he has only to telegraph
(44), and then (666) followed by the correct number—adding
(555) at the proper time for firing.
(51)
202 O P E R A 7"I N G T H E S YST'J. M.
Upon seeing the flash, the sail boat instantly drops a small
anchor attached to a line and buoy. A skiff proceeds to haul
the line taut, and its exact position is then fixed by triangulation
and located upon the map. By comparing this with the location
laid down for the imaginary mine the precision of the practice
can be estimated.
DEFENSE OF THE MINES.
The primary defense of the mines rests with the guns of the
forts commanding the channel where they are planted. For
our more important harbors, the aid of the Navy may be ex-
pected—especially by fast torpedo boats and by picket boats to
give warning of boat expeditions of the enemy. Here, however,
this assistance will not be assumed, and only the duties of the
land forces in independently defending their position, will be
considered.
Modern Modes of Attack. The following resumé is quoted
from “Lecture Notes” prepared for the Torpedo Station at
Newport in 1885, by Lieutenant-Commander J. S. Newell,
U. S. Navy.
“In forcing a passage through submarine defenses, the prin-
cipal operations likely to be available are: (1) Sweeping; (2)
dragging; and (3) countermining.
“SweBPING. The object of sweeping is to discover, locate, or
destroy all buoyant material connected with the defensive sys-
tem in the channel by which the advance is to be made.
“It will be a slow, tedious and an uncertain operation, and
unless the greatest possible care be exercised, torpedoes may be
left undiscovered. It can hardly be carried out where the boats
or vessels are much exposed to the enemy's fire.
“The channel to be cleared should be distinctly marked, and
as straight as possible, no wider than necessary, as any width
beyond what is required for the vessels engaged, will be a waste
of time and material, and will be a source of error resulting from
careless work. A passage swept should be distinctly marked,
or else the labor will be thrown away.
“In operating, provision should be made for the protection
of the passage cleared and the boats engaged. An active enemy
may place mechanical mines in a channel supposed to be cleared
unless prevented.
D EFE NS E O JP THE MIN E S. 203
“Each sweep requires two boats at least to work it. These
boats should be handy and of light draught, enabling them to
pass over mines close to the surface.
“Sweeps should be of convenient length, that boats may
readily handle them. It has been determined that sweeps
buoyed from the surface are preferable to ground sweeps. The
sweeps should be weighted and supported by three buoys, Sep-
arated by distance lines at the surface; one buoy at each end,
and one in the middle.
“Sweeps can be used: (1) to discover whether buoyant tor-
pedoes are employed; (2) to locate such torpedoes; and (3) to
destroy those found.
“The discovery and location of mines by sweeps will be ac-
complished by the sweep described. Towing lines of suitable
length should be attached to each end of the sweep, and if the
boats proceed slowly keeping the sweep taut, the bearing of the
sweep-floats will indicate the position of the thing caught, which
can then be located by a suitable buoy. To destroy whatever
has been caught, explosive charges must be dragged into contact
and exploded. For this purpose, explosive sweeps must be used.
A form of sweep experimented with by the English, consists of
20 fathoms of 1-inch hemp, with 7-pound weights attached to
its centre and ends, aud supported at these places by distance
lines from floats connected by a surface line the same length as
the sweep. The distance lines should exceed in length the
deepest draught of the vessels employed. Towing lines 20
fathoms long are attached to the ends of the sweep and outside
buoys. The explosive charges secured to the ends of the sweep
are fitted with horns or hooks, to ensure a favorable contact with
the object to be destroyed. To facilitate the fitting of new
charges, pieces of wire rope are secured to the tow-rope and
sweep on each side of the charge. When the charge is exploded,
this piece is rarely broken, and upon hauling in the tow-lines, a
new charge can easily be fitted. The electric cable from the
charges leads into the nearest boat, where a battery is carried.
If the towing lines are marked to feet, the distance of the
charge can always be known.
“When any object is caught, the sweep is hauled in by the
nearest boat, and when the charge is hooked, it is fired. Twenty
pounds of gun-cotton will, when exploded in contact with
204 6) Pſ) R A T' I W G T H E S Y S T E Mſ.
moorings, buoys or mines 10 feet below the surface, destroy any
description of circuit closer, mine or mooring.
“Sweeping boats should be provided with means for anchoring
So that they can haul in the sweep when required. Any form
of anchor that will not hook on the bottom will do, as it would
be extremely dangerous to attempt to weigh anything caught
by a sweep or hooked by an anchor.
“Sweeping boats should always work with the current. As
it is difficult to maintain the sweep taut, it is not probable that
with sweeps 20 fathoms long, more than 10 fathoms will be
swept by each, and in clearing a passage, there will be on the
sides a space about one-half the length of the sweep that will
not be swept. In a channel marked by buoys 200 yards apart,
the passage swept will be 160 yards, and as one sweep clears but
20 yards, there will be required for this channel 9 sweeps. The
leading sweeps should be on the flanks, followed by the next
one at a safe distance to the rear, of 200 yards say, the outer
boats of the second sweeps being immediately in rear of the
centre float of the sweep ahead, and this same order be pre-
served throughout, the odd sweep taking the course through the
mid-channel.
“To do this when the wind and current are across the channel
will be difficult, and considerable practice will be required to
maintain the proper positions. -
“After the channel has been swept, and when time or length
of channel prevents the slow and tedious operation just de-
scribed, a length of chain dragged slowly along the bottom
between two gun-boats well protected, would be likely to dis-
cover mines left by the boats, and reveal the fact if mines
occupy the space searched.
“DRAGGING. This consists in dragging with grapnels or
hooks over the suspected ground for electric cables.
“The grapnels used by the ocean telegraph companies, have
been found better adapted for this purpose than the ordinary
grapnel. Ordinary grapnels are apt to skip the ground. The
telegraph companies employ grapnels that on picking up a cable,
cut it, or cut it and nip one end so that it can be raised to the
surface. They also employ tripping grapnels that release them-
selves when foul of anything that cannot be weighed, as rocks.
“Electrical mines will generally be found in the vicinity of
batteries that can protect their cables and attachments. A few
J) E, FE WASJ) () };" 'ſ II E MJ W E S. 205
observation electrical mines may be found where channel ap-
proaches are very narrow. It must not be forgotten that masked
batteries may be employed in places where they may least be
expected to defend this type of mines. Whenever necessary to
approach the shore within effective gun range, the possibility of
the presence of electrical mines must be considered, and pre-
parations begun to search for the cables.
“Searching the beach is one of the most effective ways to
find cables. If this cannot be done, then recourse must be had
to dragging.
“When not exposed to hostile fire, or only at long ranges, it
will be better to weigh all obstructions caught. By that
means, information may be obtained regarding the system of
defense operated against. A cable may lead to a multiple
junction box, where a number of mines could at once be ren-
dered inoperative or destroyed.
“When exposed to hostile fire at moderate or short ranges,
the obstructions grappled must be destroyed. This can be ac-
complished by using an explosive grapnel. Two to four pounds
of gun-cotton placed between the shanks of a four-pound grap-
nel will answer the purpose.
“A short length of chain connected to the grapnel, and to
this the drag rope, five to eight times the depth of water
searched, will prevent jumping to a great extent. The result
usually obtained with explosive grapnels is, if an armored cable
is caught and the charge fired, that the conducting wires or
cores are cut, but not all the wires of the armor. If the ex-
plosive grapnel be followed by a picking up grapnel, the cable
can still be raised, and followed or cut as the case demands.
Where a number of boats are used following each other, it will
be desirable to cut the cable to prevent the others wasting time.
The cable when raised can be examined, and if single, by fol-
lowing it a junction box may be found where a number of
mines may be rendered inoperative at once.
“Steamers should be used for this work, as the men can be
more protected from fire. Not under fire any boat will answer.
“Attacking boats should have the screw protected by guards,
to prevent its being fouled by nets and ropes. They should be
fitted with false bows to jump obstructions, and also have
weights secured by spans for sinking ropes and nets.
(52)
206 O P E R A T'I W G T H E S YSTR) M.
“Boats should be painted black, and the crews dressed in dark
clothing, with faces blacked when operating against electric
lights. Officers should be provided with shade glasses.
“In the presence of batteries, before starting the dragging
boats, the ships should open the heaviest fire possible, with a
view of silencing such guns as bear upon the channel to be
operated against, and to divert the enemy’s attention from the
boats. The latter should proceed at full speed to the spot
where operations are to commence, and then proceed more
slowly. Boats should drag along the shore where possible; but
it is very improbable that any cables will be found except where
exposed to a heavy fire, therefore they must be supported by
heavier vessels.
“To prevent loss of time in retracing steps or skipping any
ground, steamers engaged in this work should tow astern a raft
or boat, to which the grapnels are slung in such a manner that
they can easily be dropped to avoid loss of ground. The boat
or raft towed should have a drag towed astern, to keep it in
proper position. Axes, hack saws, cold chisels and hammers
should be provided for cutting anything. #,
“The object of dragging is to disable and render inoperative
electric mines, in order to save the vessels engaged in counter-
mining. As multiple cables must go ashore from the field
defended, and as they will generally be led well in the rear of
the field, it must be considered whether it is practicable to send
the boats engaged in dragging inside the field defended to
operate against these main cables.
“It is desirable that the field should be gone over by two
boats at least; and, if possible, these boats should proceed in
opposite directions. The field should be divided among the
boats, and paths pursued that lead lengthwise the channel, and
particularly across it. Each boat, under these conditions, can
proceed at full speed when not on her own ground. By pur-
suing this plan of running opposite courses, up and down and
across the channel, obstructions and dummy cables are more
likely to be avoided. It is very probable that many will be
missed. The best place to drag for cables will be in rear of the
field, or along the shore in front of the fortifications, for in
them the firing stations are most likely to be found, and the
cables must lead there. The plan of laying lengths of old cables
and chains in the field is a formidable obstruction to success in
D JE FE WAS E O F T H E MIN ES. 207
dragging. The English use what is known as the Admiralty
creeper —a shank with an eye at each end, divided into three
equal parts, and on it three pairs of hooks, each pair at an angle
of 60 degrees with the others.
For small boats, 84 pounds, 22 inches long; hooks, 4 inches long.
w For large boats, 17 pounds, 29 inches long; hooks, 6 inches long.
“CounterMINING. The improbability, and one might say the
impossibility, of a channel being entirely cleared by the opera-
tions of sweeping and dragging when exposed to an enemy's
fire, leads to this operation, that involves the expenditure of large
quantities of material in proportion to the space cleared.
“If the operations of dragging and sweeping could insure a
clear channel, there would be no reason for adopting this one;
but as it is quite probable, considering the uncertainty attending
those operations and the difficulty in thoroughly performing
them when exposed to sweeping fire, that certain mines (prob-
ably observation) will be left; it would not be safe for the fleet
to pass over thern, no matter how well protected it might be;
therefore, recourse must be had to this method. Dragging and
sweeping carried out in the rapid manner they must be if ex-
posed to fire, lessen the chances of disaster to the vessels
engaged in countermining.
“Countermining when applied to the destruction of submarine
defenses, consists in dropping a succession of large charges in a
straight line, or in two or more parallel straight lines, at such
distances from each other that their simultaneous explosion will
destroy all mines within their radii of destruction.
“It has been determined by a large number of experiments,
that 500 pounds of gun-cotton exploded at a depth from 27 to
48 feet, may be expected to destroy all mines within 90 feet,
and contact mines at much greater distances. *
“If two parallel lines are laid so that the circles of destruction
impinge, the mines will be 180 feet apart, and any object equi-
distant from four charges would be not less than 125 feet from
any charge; and it is very probable that with the simultaneous
explosion of four charges, it would be destroyed or rendered
inoperative. •.
* This is true for some foreign systems but not for ours. We have no need
to fear a 500-pound countermine at 80 feet, or a 100-pound countermine at 40
feet. H. L. A.
208 O P ſº I. A 7'ſ N (A T H E S Y S T J M.
“Any plan for carrying out countermining charges must be
arranged for the boats carried by ships, and should fulfill the
following conditions.
“1. The channel or passage to be cleared must be defined.
“2. The charges accurately spaced and in a straight line.
“3. That the operation as far as possible should be automatic,
so as not to be stopped by injury tu, or nervousness of those
employed.
“4. That the destruction of the boat should not prevent the
charges already placed from being fired.
“5. That it should be distinctly known whether every coun-
termine placed was exploded.
“6. That the channel cleared should be accurately marked,
and
“7. That the operation be done with the utmost rapidity.
“The countermines can be accurately spaced by using dis-
tance lines between each, which, upon tautening, drop the next
charge; and so on until all have been dropped. It will only
then be necessary that the first one should be dropped by hand.
“The line of countermines should be arranged to be fired
from either end.
“By placing small buoys over each mine, their disappearance
will be sufficient proof of the explosion of the charge. Large
buoys placed between the mines at stated intervals will not be
disturbed, and will sufficiently mark the channel. Use may be
made at night of Holmes’ lights.
“Boats fitted to carry the countermines, their anchors and
buoys, the channel buoys and the necessary cables, should be
taken in tow by a gun-boat or launch, and proceeding at full
speed on a straight course, the countermines be laid. Where
two or more parallel lines are laid, they should be laid at the
same time.
“One end of the electric cable is kept on board some vessel
moved up for the occasion, and the other on the towing vessel.
The boats carrying the countermines, should carry one or more
men who can, if accidents happen to the tripping or dropping
gear, start it again, and in the beginning drop the first charge.
“Signals must be arranged between the towing vessel and the
vessel controlling one end of the cable.
“The mines and their sinkers should be arranged around the
sides of the boat, the latter hanging over the side, the former
D E, FE WASJ, O Jº T' H E M IN E S. 209
resting on the countermining thwarts. The slings of each mine
and the sinker belonging to it, come to the slip on the thwart,
which is so arranged that they are both let go together auto-
matically as the strain comes on the electric cable, which answers
the purpose of a distance line between the mines, as well as the
conductor for firing them.
“The electric cable is coiled up outside the mines, and to en-
able it to run clear, every three or four turns should be hung by
rope yarns, which carry away in succession as the strain comes
upon them. *
“In addition to the mines, each boat should carry three large
buoys, which are intended to mark the channel cleared, and are
arranged to drop, one at the beginning, one in the middle, and
one at the end of the line. These buoys being on the surface,
and at a distance of 90 feet from the nearest counterinine, are
not destroyed by the explosion.
“To make sure that every mine has fired, place a small buoy
immediately over it, and the fact of these buoys being all de-
stroyed will be evidence that all the countermines have been
exploded. They also serve the purpose of floating the electric
cable up to the surface, and thereby keeping it sufficiently far
from the mines to save it from being blown away. It has been
found by experiment that if the electric cable is allowed to be
in contact or nearly so with one of the mines, it may be blown
away before those beyond have fired.
“Three-quarters of a knot of cable is sufficient for 12 coun-
termines, furnishing 60-foot branches for each charge, and 500
feet stray cable at each end.
“The first buoy is dropped by hand by those in the counter-
mining boat at the spot where the clear channel ends. The
electric cable pays itself out by carrying away the stops in
succession, until it comes to the point where it is attached to the
slip of the first countermine; it slips that with its sinker and
goes on in the same way. When all are down, the key is
pressed at the towing steamer and the line exploded; as soon as
this is known, the key at the other end is pressed.
“Four minutes is a fair time after dropping the first buoy
until the mines are laid and fired.”
A study of published modes of attack proposed abroad has
led to the following conclusions.
(53)
210 O P E R A TTW (W. T.III. S. Y S T E Mſ.
Attacks by Daylight. In designating as “mines” what are
often called torpedoes, the word is used advisedly. Whether
subterranean or submarine, the same general principles as to at-
tack and as to defense are applicable.
The only systematic method of attacking land mines has
been found to be countermining; and it is believed that future
wars will show the same to be true for Sea mines.
One or more small heavily armored vessels or possibly steam
launches controlled by electricity, will move up to the supposed
outer limit of danger; will plant from one to four countermines;
will back off; and by exploding them through the agency of
electricity, will destroy any mines in the immediate vicinity.
They will then steam forward into the vortices and plant one or
more buoys. By repeating this operation, it is evident that a
channel—plainly marked—will ultimately be made through the
system, and the whole fleet will be free to pass rapidly past the
guns.
This operation, however, will neither be expeditious nor safe.
The attacking vessels will necessarily indicate their successsive
positions of rest; and high power guns, and sea coast mortars
provided by their chassis and horizontal azimuth circles with
the means of accurate pointing, will prepare for their advances,
and will severely tax their powers of endurance, both as to sides
and as to deck. Movable torpedoes steered by electricity will
assail them below the armor belt. By night, new mines will be
planted in the buoyed channel—even the self-acting class being
available in emergencies. In fine, the delays and disasters
familiar in mining and countermining on land, will find their
counterparts on the Sea.
But other less elaborate plans of attack may be attempted.
An ironclad may try by outrigger frames or wire rope crino-
line, to explode the mines at a safe distance from her hull.
With electrical mines, this operation will be hazardous in the
extreme; the Engineer will delay the explosion until the mine
has passed under her bottom, or he will have planted his circuit
regulator buoys say 100 feet in rear of his mines, and thus will
ensure her receiving the intended blow; or finally, by shattering
her defenses with one torpedo, he will leave her encumbered by
the wreck, among others equally dangerous.
Should divers be sent forward to destroy the system, so soon
as their work is revealed by the electrical indications, a mine
DJ? If E W S E O Hº' 7" EIJſ, MI W E S. 211
exploded in the vicinity will promptly put an end to their
labors.
If old hulks steered by electricity are sent forward to explode
the mines in the channel—or rafts provided with grapnels are
allowed to drift in with the tide, the electrician will switch off
his batteries; and, although injury may result to the system,
terrible uncertainty as to how many perfect mines may still be
waiting to receive him, will be left to the enemy wishing to
follow in his armored ships of war.
Remembering that these operations must be attempted by
daylight, or no definite knowledge of the result can be had by
the enemy; and that by daylight the guns of the fort will cover
the mines by their deliberate fire, the uncertainty of such means
of attack is apparent. A cleared passage well buoyed is a sine.
qua non for the hostile fleet.
Attacks by Night or in Fogs. By night or in fogs, the
firing of the guns and the operating of the mines cannot be so
intelligently directed by the defense; but, on the other hand,
the enemy can derive but little information as to the details of
the damage inflicted, unless he sends boats forward to work sys-
tematic mischief, and to drop buoys accordingly. How to
defend the mines against boat attacks conducted when shrouded
from view, becomes therefore, an important problem. Here
the best of all assistance can be rendered by regular naval picket
boats; but when they cannot be had, or substitutes improvised
by the land forces, four powerful auxiliaries may be employed—
fouling lines, automatic action of the guns, the electric light and
movable torpedoes under control from the shore. Each will be
considered in turn.
Fouling LINEs. The general subject of mechanical obstruc-
tions such as nets, floating booms, etc., does not come within
the Scope of this Manual ; but an excellent defense of this
nature against grappling the electric cables whether by drifting
rafts, by mortar boats throwing grapnels, or by small boats,
should never be neglected. It consists in anchoring one or more
six-inch hawsers across the channel among the mines. The ob-
ject being to cause these ropes to entangle the grapnels, it will
be advisable to attach them to the heavy anchors or blocks of
stone holding them in position by very short lengths of rope,
thus preventing any part from sinking into the mud. As mul-
tiple cables soon bury themselves by their own weight in the
212 O P E R A T'IN G. T.' II. E. S. YST E Mſ.
Soft bottoms of many of our harbors, and as a harmless hawser
can only be detected after the laborious operation of raising it,
the expedient cannot fail to delay the enemy—unless, indeed,
use be made of explosive grapnels, in which case he will be
deceived as to the damage he is inflicting.
FLANKING GUNs. In the preparation of the plans for the
defence of our important harbors by submarine mines, the prin-
ciple of so arranging the main lines as to admit of their being
effectively covered throughout their whole extent by the fire
of the works, has been accepted as fundamental. It will, there-
fore, be easy for the officers commanding the forts to train their
guns, by daylight, in such manner as to sweep with a heavy
fire of canister, grape or shrapnel, the positions occupied by the
mines and their cables. By marking the true positions of the
chassis, and recording the elevations proper for the guns, this
fire may be maintained, even at night, so soon as the presence
of hostile boats becomes known. If, therefore, the artillery is
made aware that this kind of attack is in progress, it is fully
within its power to open an effective fire. &
To supply this information as soon as any injury has been
inflicted, and before any systematic work can be done, the
device of providing for the instantaneous and automatic dis-
charge of the flanking guns was early incorporated into our
torpedo system. So soon as any circuit regulator is closed—as
it must certainly be during the effort to raise the mine—or so
soon as any cable is cut, the whole volley will be automatically
fired, without involving the discharge of the torpedo with which
the enemy is tampering.
The preparation of these automatic trains, and the requisite
arrangements in the operating casemate, are of a simple char-
acter, and it is believed that they will do much to render boat
attacks by night unsuccessful; for, be it rembered, unless a
practicable and buoyed channel through the mines be prepared,
no large vessel can advance on the morrow with any reasonable
hope of impunity.
ELECTRIC LIGHT. To coöperate with the above system, and
to expose the enemy to artillery fire as soon as discovered, the
electric light is an important auxiliary.
It was found by experiments at Willets Point, 1872–77, that
in clear dark nights a Fresnel lens and hemispherical reflector,
JD EFJ; W S E O Ji' 'I’II E MJ W E S. 213
made to order by Lepaute in Paris, and supplied with an elec-
tric light produced by a magneto-electric Alliance machine, or
by one-hundred Grove or Bunsen cells, would reveal the pres-
ence of any ordinary boat operating within a range of one mile.
By keeping her within the beam of light, the practice of ar-
tillery could be made murderous. It would be easy in many
cases by the use of reflectors, to arrange the apparatus behind a
traverse, or within a turret or embrasure, so as to protect it
against the fire of hostile shipping. It was also found that the
observer, provided with a good night glass, should be stationed
at a considerable distance from the lens, and well out of the
illuminated field. The dazzling effects of the light, and the
rays reflected back by particles of moisture in the air are thus
avoided. The conclusion was also reached that in clear moon-
light nights and in fogs, but little assistance can be derived from
the light.
Experiments conducted recently in Europe with the best
modern appliances, have led to the following conclusions as to
the efficacy of the electric light in coast defense.
I. If the object sought have a dark and poorly reflecting sur-
face, or if the enemy burn smoke balls, the observer must be
near at hand to detect its presence. It is possible to throw a
light sufficiently intense to make type readable where the enemy
is situated, without making the rays reflected back by him
visible at any considerable distance. This fact explains the dis-
cordant results often reached in experiments to determine the
practical limits of efficient illumination by the electric light;
thus one series of trials made in France in 1879 indicated for
this limit:
Distance from light to object, 8800 yards; from observer to object,
55 yards.
Distance from light to object, 8580 yards; from observer to object,
110 yards.
Distance from light to object, 6600 yards; from observer to object,
660 yards.
Distance from light to object, 1650 yards; from observer to object,
4730 yards.
In other experiments, the objects were sufficiently defined to
offer a fair target for artillery at the following ranges:
Distance from light to object, 6600 yards; from observer to object,
4290 yards. -
Distance from light to object, 6600 yards; from observer to object,
4950 yards.
(54)
214 O P E R A TING THE SYSTEM.
Distance from light to object, 4400 yards; from observer to object,
7150 yards.
Distance from light to object, 3740 yards; from observer to object,
7150 yards.
II. The position of the observer should be entirely without
the cone of light and as low down as possible. The light itself
should be out of his sight, and no rays should strike the ground
or any reflecting surface near him. Suitable means of commu-
nication with the man directing the beam must of course be
established.
III. Explorations should be made with a somewhat diffused
band of light; but when found, the object should be scrutinized
and followed by concentrated rays. Good results have been
reached upon this system at 2200 yards, the band having a
width of 640 yards, and the concentrated beam a width of 80
yards.
IV. Practice increases the power of distinguishing objects in
this manner. A trained observer has a longer range of vision
than one without experience.
V. The color of the illuminated object is of material impor-
tance. White and light colors are readily seen; the darker the
shade the more difficult this becomes. A white boat was
readily distinguished at 1000 yards; while a black boat with a
black crew and blackened oars was only detected at half that dis-
tance, and then only by reflections from the splashing of the
oars. If, however, a dark object is projected upon a light back-
ground, it becomes visible.
WI. The electric light thrown strongly upon a vessel may
render it impossible for the pilot to direct its course in a difficult
channel. - -
VII. In some Austrian experiments one light was opposed
to another, the beam being thrown normally; this produced a
veil which intercepted vision.
VIII. An electric light apparatus is but little endangered
by hostile fire; because, dazzling the eyes of the gunner, the
Source appears to be a moving object. Its elevated position de-
ceives him as to distance. Its changes, eclipses and flashes
confuse him. In Russia two batteries practiced at an elevated
light and reflector 1485 yards distant, without any effect;
shells exploding beyond or short, could not be distinguished
from each other—all seemed to take effect near the light.
D E H E N S E O F T H E M I W E S. 215
There are two recognized modes of establishing the light in a
fortress. In one the generating apparatus is fixed in position,
and the current is conveyed to the stations chosen for the re-
flector by permanent leading wires; in the other, the whole
apparatus is movable. The former involves more waste of
electric power; but local conditions must determine which is
preferable at any given station.
As to outfit, Colonel Mangin of the Corps du Genie, in 1877,
applied his aplanetic mirror to military and naval purposes. The
firm, L. Sautter, Lemonnier et Cie. of Paris, have developed
this idea, and now supply a complete electric light apparatus
comprising a three-cylinder Brotherhood engine of 13 horse-
power; a Field steam generator; a Gramme machine DQ,
which, coupled in quantity, supplies from the luminous face of
the positive electrode, a light of 4000 Carcel burners; a Serrin
lamp and a hand-regulated lamp (which for high powers they
consider superior to any automatic pattern); and a Mangin 35-
inch aplanetic mirror, with an auxiliary concavo-convex lens.
The light generating apparatus may be mounted upon one
vehicle, and the lamp and attached reflector upon another—per-
mitting the whole to be moved from place to place and operated
100 yards apart if desired.
The directed rays can be either thrown in a horizontal band
of about 12 degrees, or by mechanical means can be concen-
trated upon any desired point. It is claimed that a light
colored object in a clear dark night can be distinguished by this
apparatus at a distance of 7000 yards.
In operating this light, the channel is first swept with a beam
of diverging rays (about 12 degrees); and, as soon as any sus-
picious object is noticed, it is studied by a concentrated beam.
The observer should be stationed as near the object sought as
possible; but under any circumstances he must be entirely
without the illuminated beam. If the channel exceeds 2000
yards in width, it should be lighted from both sides. About 30
feet above the water is a good elevation for the reflector; the
observer should be lower down. If possible, the reflector should
be sheltered from hostile fire; but, if necessary, this condition
may be ignored, as experience has shown that it is almost im-
possible to direct a close fire upon so intense a light.
MovABLE TORPEDOEs UNDER ControL. No patterns of this
weapon have yet been adopted as part of the regular matériel
216 O PJ. I. A 7"I W G T H E S Y S T E M.
of the submarine mining service, although no little labor has
been devoted to their experimental investigation at Willets
Point. In the absence of an effective fire of artillery, and par-
ticularly if armored vessels should be specially constructed for
countermining, movable torpedoes under control from the shore
will prove a very useful auxiliary in the defence. At present
the Sims' torpedo is regarded as best fitted for such service;
and several of them have been purchased and are now in store
at the Willets Point depot.
They carry 400 pounds of the explosive, and 11000 feet of
cable; are steered and controlled from the shore, turning on a
radius of 250 feet; have a speed of 10 miles per hour; are in-
vulnerable to the fire of shrapnel, and machine or rapid firing
guns; and dive under a spar or other similar floating obstruction
without injury. The motive and steering power is electricity,
generated on shore and conveyed through an insulated cable
which is carried by the torpedo and laid as it advances.
The special function of movable torpedoes under control is
to assail counterminers when operating within the mined Zone,
whether by day or by night; but they may be useful to attack
a fleet at anchor, or to follow up and destroy any vessel which
has succeeded in passing the defences and entering the harbor.
When issued, each pattern will be accompanied by directions
for putting together and operating.
It has been recently claimed that this class of torpedo may
be superseded by pneumatic guns of moderate range, firing
large charges of some high explosive to be detonated by elec-
trical fuzes operated either by impact or by submergence under
water. Evidently the use of such a weapon is barred; because
it would work injury to our own submarine defences, and thus
aid the enemy in a very effective manner. Indeed the inven-
tion appears to be better suited to the attack than to the defence;
but as no safe channel through the whole mined field can be
certainly opened by such means, they may safely be classed with
sweeps, grapnels, and other mercly auxiliary modes of attack.
Injuries from Friends. No vessel must be allowed to
anchor at any point within the portion of the channel covered
by the mines. In time of war, this rule can readily be enforced.
No danger either to the mines or to the ships, need be appre-
hended with sailing vessels. They can pass freely through the
channel at any desired speed.
DJſ, FE WAS Jº O //, / II Jº M I WAE S. 217
With steamers, certain precautions must be observed. To
make torpedoes sufficiently strong to bear the heaviest blows of
paddles or propellers, would require them to be too bulky and
unwieldy for convenient use. All such vessels must, therefore,
be compelled to pass as slowly as is consistent with proper steer-
age way; or, better still, they should be towed over the mines
by light draft side-wheel tugs. When a special steamer-pass
has been left unobstructed, all steamers should be compelled to
follow it.
In a simple defensive action, our fleet, of course, will keep
away from the mines, so as not to prevent the use of the auto-
matic apparatus through fear of injuring friendly vessels. This
will not interfere with any desired offensive returns—since, by
giving due notice, any portion of the channel can be left safe
while all the rest is dangerous.
Attempted Passage by Force. After the enemy imag-
ines that he has a clear channel, he will attempt to pass the
obstructions with his fleet. The Commanding Officer of the
Fort will have designated the position to be occupied by the
Engineer party during such an attempt; and he will naturally
remain in the near vicinity himself.
This station should be selected where smoke from the guns
will not be likely to obscure the view; where the instruments
so far as possible can be kept under cover; and where the noise
of the cannonade will interfere as little as may be with the use
of the mapping telephone. If the latter condition cannot be
fulfilled, the instrument must be replaced by a dial telegraph or
ordinary key.
At sites where single-station position-finders cannot be used,
the Engineer in charge of the mines will have laid two carefully
protected insulated cables from this station—one to the mining
casemate, and one to the other triangulation station; and will
also have seen that a good earth is provided.
His party will consist of a private to work the dial telegraph
connected with the mining casemate, and of the sergeant and
three men prescribed for the plotting station of a mapping drill,
with their instruments. •
The map of the channel, with the locus and condition of the
mines laid down upon it, will be so placed as to be readily con-
sulted by the commanding officer, the engineer officer, and an
218 O P E R A TI W G T H E S Y S T E Mſ.
artillery officer whose duty it will be to regulate by signals the
elevations of the guns. * *
As the fleet approaches, the position of the leading vessel will
be shown on the map by the Engineer triangulations; and every
facility for judicious action both with guns and torpedoes will
thus be afforded.
If the mines are in good order, and no friendly vessels are in
danger from them, it will not be well to attempt to interfere
with the automatic working of the system. As a rule, under
such circumstances, the fewer the orders sent to the mining
casemate the better will be the chances of success.
INI) EX.
Anchor, for buoyant torpedo, 72. Commanding Engineer, preparatory
Attack, modern modes of, 202; by duties, 99; requisitions of, 102;
daylight, 210; by night or in fogs, during planting, 147; during oper-
211; in force, 217. ating, 181; post in action, 217.
Atlas powder, properties of, 87. Countermining, 207, 210.
- Cut-off, description of, 58.
Battery, firing, description of, 32;
tests of, 181; strength for firing David Bushnell, description of, 71.
flanking guns, 180; strength for a Defence of the mines, 202.
cut cable, 192. Detector, description of, 34.
Battery, signal, description of, 32; Dial telegraph, description and use of,
analysis of size of, 18; tests of, 183. 36; adjustment of, 121; code for ac-
Battery, testing, description of, 33. tion, 40, 197.
Battery for self-acting mine, descrip- Disconnector, description of, 31; ad-
tion of, 52; to encase, 132. justment of, 111; test of, 184.
Batteries, setting up, 110. : Dragging for mines, 204.
Boat parties, duties of, 155. Drills, in loading room duties, 121; on
Boat service, matériel for, 105; drills, shore for boat service, 139; in plant-
139, 155. ing mines, 155; in operating auto-
Brass jointers, description of, 67. matic system, 195; in judgment
Brass washers, description of, 68. firing, 201; in mapping tracks of
Bridge rheostat, description of, 35. vessels, 198; of electrician, 197.
Buoy of ground mine, description | Drum frames, description of, 80.
of, 54. Dynamite, properties of, 87; proof
Buoy of junction box, description tests, 90; precautions in handling,
of, 79. etc., 93. -
Buoy, planting, description of, 80;
use of, 167. Earth plates, for boat use, 81; at
Buoyant mines (see mines). i mining casemate, 33, 109, 158; re-
Buoyant torpedo (see torpedo, buoy- sistance of, 33.
ant). Electrician, preparatory duties, 23,
- 109; during planting, 151; during
Cable (see insulated cable). i operating, 181; drill for, 197.
Cable mooring, description of, 73. Electric light, efficacy, 212; outfit,
Cable drums, description of, 77. 215.
Cable drum frames, description of, 80. Explosive gelatine, properties of, 85;
Cable stop, description of, 75; to at. proof tests, 92.
tach, 145. Explosive energy and distance, 15.
Cable tags (casemate), description of, Explosives, rupturing ranges of, 82,
36. 207; precautions in handling, etc.,
Charge bags, description of, 51. 93.
Circuit closer, description of, 57; ad-
justment of, 116. i Faults, interpreting, 185; expedients
Circuit regulator, description of, 57; for reducing, 189.
adjustment of plug of, 117; locus Firing battery (see battery, firing).
of, 99. Firing key, description of, 31; adjust-
Circuits, electrical, discussed, 16. ment of, 113; test of, 184.
Coast defence, elements of, 9. 'Flanking guns, to prepare, 179; use
Code for action, 40, 197. of, 212.
220
I W D E X.
Forcite, properties of, 86.
Fouling lines, 211.
Fuzes, description of, 58; testing
115.
Funnels loading, description of, 66.
Fusible alloy, formula for, 69.
of,
Mines, conditions to be fulfilled by,
10; circuits for operating, 16; buoy-
ant and ground compared, 14; drag-
ging for, 204; four systems of dis-
posing, 11; how numbered, 158, 169;
operating automatically, 194; attack
and defence of, 202; drills for load-
ing, 121; drills for planting singly,
161, 164; drills for planting grand
| groups, 169; drills for planting skir-
mish, 175; drills for planting self-
i acting, 176; drills for raising, 168;
| map of zones of, 199; precautions
in planting—Commanding Engi-
neer, 149; precautions in planting—
Electrician, 151; planting when
practicable, 155; sweeping for, 202;
tests of loaded, 119; tests during
planting, 152, 172; tests, daily, when
planted, 181; tests, occasional, when
planted, 188; to submerge, several
methods, 163, 171; to recover when
lost, 174; time required to plant,
147 (see also torpedo).
Mining casemate, description of, 21;
matériel of, 103.
Moorings, iron, 73; phospher bronze,
74; to insert thimbles in, 142.
Movable torpedoes, 215.
|
}
|
|
|
Nitro-glycerine, properties of, 83.
Operating boxes, description of, 29;
adjustment of, 113; daily test of,
183.
Passage, by force, 217; for friends,
108.
Personnel, when planting, 24; when
operating, 25.
Repairs in a mined zone, 189.
Requisitions for matériel, 102.
Resin and beeswax cement, formula
for, 69.
Resin oil wash, formula for, 69.
Resistance coils, description of, 31.
Reversing key, description of, 35.
Riggers vise, description of, 65.
Rubber packing, description of, 68.
Rubber strips, description of, 67.
Rubber tubing, description of, 67.
Safety break, description of, 52; to
prepare, 130.
Safety rings, composition of, 52; to
fabricate, 129.
Sea-cell plates, adjustment of 115.
Galvanometer, Bradley, description
of, 35.
Galvanometer, Siemens, description
of, 35.
Grand junction box (see junction box,
grand).
Grand groups, arrangement and cost
of, 11; drill for planting, 169.
Ground mines (see mines).
Ground torpedo (see torpedo, ground).
Gun-cotton, properties of, 87.
Gun fuzes, description of, 58.
Guns, flanking, to prepare, 179; bat-
tery power for, 180.
Injuries, from friends, 216; repairing,
189; time to repair, 193.
Insulated cable, three kinds of, 76;
jointing the core, 139; making turks
heads on, 141; completing the joint,
142; tests of, 120, 185; injuries to,
191 ; use of deteriorated, 101 ; to
submerge the shore end, 157; never
to cross grand groups, 149; when
ordering new, 78.
Insulated joint supplies, 66.
Insulated wire, patterns of, 66.
Jointers, brass, description of, 67.
Joints, electrical in cable, 139.
Junction box, grand, description of,
79; to place and serve, 155.
Junction box, triple, description of,
79; to place and serve, 159.
Junction box, single, description of,
J unction boxes, to use, 142.
Judgment firing key (see firing key).
Launch, planting, description of, 70.
Leading wires, patterns of, 66; in
casemate, 109.
Loading funnels, description of, 66.
Loading room, description of, 24;
matériel of, 104; duties of sergeant
in charge, 122; drills in, 121.
Loading room duties, time required
for, 146; drills in, 121.
Map of channel, 149, 199.
Marine glue, formula for, 68.
Matériel, of casemate described, 28;
of loading room described, 41; of
boat service described, 70; requisi-
tions for, 103.
| Sea-cell tests, to make, 185.
| Self-acting mines (see mines).
Self-acting torpedo (see torpedo, self-
acting).
I N D Bº X.
221
| Torpedo buoyant, conditions to be
fulfilled, 41; service 32-inch pat-
tern, 43; larger sizes, 44; dimen-
sions for varying conditions, 50;
computations when ordering, 45; to
prepare compound plug for, 122; to
charge, 125; to test loaded, 119, 185;
to treat leaky, 190.
Torpedo ground, conditions to be ful-
filled, 55; description of, 56; to pre-
pare compound plugs for, 126; to
charge, 129; to test loaded, 119, 185;
to treat leaky, 190.
Torpedo self-acting, description of,
51; to make safety rings for, 129; to
prepare safety break for, 130; to en-
case battery for, 132; to remove
battery, 134; to charge, 134.
i Torpedo fuzes, description of, 58.
Triangulation, for position of enemy,
198.
Turks head collars, description of, 78.
Turks head, drill for making, 141.
i
: Utensils for loading room, 63.
|
Vessels and boats, description of, 70.
Weights of submarine mining maté-
riel, 96.
Shackles, description of, 74.
Shipping dimensions and weights, 96.
Signal battery (see battery, signal).
Skirmish mines (see mines).
Steam barge for planting mines, 71.
Sweeping for mines, 202.
Switch box, description of, 62; to
charge, 135, 138, 139.
Switch keys and switches, description
of, 36.
Telegraph (see dial telegraph).
Tests of loaded torpedoes, 119, 185; of
firing battery, 181; of signal bat-
tery, 183; of automatic apparatus,
183; of mines and cables, 185; sea-
cel 1, 187; occasional, 188; when
planting mines, 152; when oper-
ating mines, 182.
Testing apparatus, adjustment of, 109;
description of, 34.
Testing battery (see battery, testing).
Thimble clamps, description of, 65.
Thimbles, to insert, 142.
Time, for loading room duties, 146;
for planting mines, 147.
Tool box A, contents of, 40.
Tool box B, contents of, 63.
Tool box C, contents of, 81.
Tool box D, contents of, 67.
Tools special, for boat use, e.81; for Wire, insulated, patterns of, 66.
loading room, 63.
Wire mooring rope, 73.
| Wrenches, description of, 63.
PLATE I
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PLATE
VI
V||
VII
Judgment.
Open Circuit.
A EARTH
Judgment.
EARTH
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M. or L.
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EARTH
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FTIC.1. BUOYANT TORPE DO,
FIG.2 JUNCTION-Box BUOY.
F|C. 3 PLANTINC BUOY.
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MINE ANCHOR.
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PLATE VI
FIC. T. C. RAND JUNCTION BOX.
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