SB 
 
 ,jor4 w. PIS 
 
LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Class 
 
; - 
 
THE 
 Wireless Operators' Pocketbook 
 
 OF 
 
 INFORMATION AND DIAGRAMS 
 
 BY 
 
 LEON W. BISHOP 
 
 \ 9 
 
 1911 
 BUBIER PUBLISHING COMPANY 
 
 LYNN, MASS., U. S. A. 
 
 AND 
 
 H. ALABASTER GATEHOUSE CO. 
 LONDON, ENG. 
 
COPYRIGHTED 1911 
 
 BY 
 
 BUSIER PUBLISHING COMPANY 
 LYNN, MASS. 
 
 ENTERED AT STATIONERS' HALL 
 LONDON, ENGLAND 
 
 BY 
 
 H. ALABASTER GATEHOUSE Co. 
 1911 
 
 THE PLIMPTON PRESS NORWOOD MASS, U.S.A. 
 
PREFACE 
 
 THE purpose of this little manual is to satisfy the 
 desires of the wireless operator and of those experi- 
 menters who have already some knowledge of wire- 
 less phenomena, and who wish for a practical book 
 more suited to their needs than the many elementary 
 ones which deal mostly with the construction of simple 
 apparatus, or the elaborate technical and mathematical 
 treatises which presuppose a technical education to 
 understand them. Although some acquaintance with 
 wireless apparatus is expected, it has been the author's 
 intention to give enough of the theory of the circuits 
 and of each piece of apparatus so that anyone inter- 
 ested may understand it and its working. 
 
 So far as is possible it has been intended to take up 
 the various subjects in their logical order, except 
 perhaps where a purely logical order would not at the 
 same time aid in the general clearness of explanation. 
 The treatment of the transmitting and receiving instru- 
 ments, the ground and the aerial connections, naturally 
 comes before the more general chapters. The chapters 
 descriptive of instruments are also noticeably more 
 simple than those towards the end of the book, where 
 a further familiarity with the author's expression is 
 
 222658 
 
vi PREFACE 
 
 expected. Moreover, it is to be noticed that although 
 most of the popular forms of instruments are mentioned 
 and described, some have been omitted. This has 
 usually been intentional, in order to comprise within 
 the smallest possible space the description of late 
 types of apparatus, and that of the most approved 
 and efficient design. 
 
 The author's knowledge of wireless is based largely 
 on his experience in the Stone Company, and under 
 the direction of Mr. John Stone Stone. He is also 
 largely indebted to Mr. G. W. Pickard for information 
 during the writing of this book. Both Mr. Stone 
 and Mr. Pickard have freely allowed the reproduction 
 of their circuits and theories. On telephony, he is 
 also indebted to Mr. Lee DeForest and others. 
 Thanks are by this means extended to those whose 
 names are mentioned and to many others for help re- 
 ceived, either personally or from their printed works. 
 
CONTENTS 
 
 PAGE 
 
 I THE TRANSMITTING CIRCUIT i 
 
 II TRANSMITTING STATIONS: EXPERIMENTAL OR LOW- 
 POWER APPARATUS 10 
 
 III TRANSMITTING APPARATUS: PROFESSIONAL OR 
 
 HIGH-POWER STATIONS 17 
 
 IV THE RECEIVING CIRCUIT 32 
 
 V RECEIVING APPARATUS 40 
 
 VI AERIALS AND GROUNDS: TYPES AND CONSTRUCTION 68 
 
 VII PROTECTION AND INSTALLATION or A STATION . 80 
 
 VIII OPERATION OF A STATION go 
 
 IX BREAKING-IN SYSTEMS: METHODS OF SIMULTA- 
 NEOUS RECEIVING AND TRANSMITTING . . . 107 
 
 X CODES 121 
 
 XI THE ETIQUETTE OF WIRELESS AND THE SUBJECT 
 
 OF INTERFERENCE 129 
 
 XII WIRELESS TELEPHONY 133 
 
 APPENDIX 149 
 
 SUPPLEMENT. LATEST CALL LETTERS . 
 
 vii 
 
WIRELESS OPERATORS' 
 POCKETBOOK 
 
 CHAPTER I 
 
 THE TRANSMITTING CIRCUIT 
 
 WIRELESS communication is accomplished by means 
 of vibrations set up in the ether by a set of special 
 instruments used for creating and transmitting them. 
 These vibrations, which travel in all directions away 
 from the sending station in the form of waves, are 
 created of a certain length and frequency by the 
 action of a number of different instruments, each of 
 which affects the wave-creating current in a definite 
 manner. If, for instance, we take the following sche- 
 matic diagram of the transmitting apparatus, we may 
 understand the part played by each instrument toward 
 the desired result of producing intelligible effect upon 
 telephone receivers at any station. 
 
 An electric current, set up by the batteries of the 
 primary circuit, passes through the primary winding 
 of the spark coil. This would form a closed circuit, 
 except for the fact that a telegraph key, connected 
 between batteries and primary, allows the operator 
 to make and break the flow of current at his own will. 
 When the key is held down for an instant only, the 
 
 1 
 
WIRELESS OPERATORS' POCKETBOOK 
 
 current flowing through the circuit makes a ' elegraphic 
 "dot." If held down for a longer period, we have a 
 telegraphic "dash." It is thus the will of the operator 
 which controls the flow of current through this primary 
 circuit, transferring his thoughts, by means of an 
 established code, to the receiving station. 
 
 UJ 
 
 F I G.I. 
 
 The current of our primary circuit is direct. There 
 must, however, be alternating current for the secondary. 
 Therefore some form of interrupter must be placed 
 in the primary circuit in order to break the current 
 and to give it the necessary pulsations. A mechanical 
 vibrator connected to the primary of the spark coil is 
 most frequently used, although an electrical inter- 
 rupter on a separate battery circuit may be employed 
 instead. 
 
THE TRANSMITTING CIRCUIT 3 
 
 This Vibrator interrupts the steady current in the 
 primary of the spark coil, varying the magnetism of 
 the core, by constantly changing its polarity. The 
 secondary of the coil picks up the magnetism; and 
 because the number of turns of wire on a secondary 
 are proportionately greater than on a primary, the 
 
 F I D, 
 
 secondary transforms this magnetism into a current 
 of higher voltage. Whereas we had in the primary 
 circuit a direct current of low voltage, we have now in 
 the secondary an alternating current of high voltage. 
 
 The current rushes into the aerial, filling or charging 
 it, and this charge creates an electro-static field around 
 it. Now, if the current ceases to flow, the lines of 
 force of this field will fall flat. We then place a spark 
 
WIRELESS OPERATORS' POCKETBOOK 
 
 FI &. 
 
THE TRANSMITTING CIRCUIT 
 
 gap between aerial and ground. Now, when the aerial 
 charge is great enough to overcome the resistance of 
 air between the points of the spark gap, a spark 
 will jump between them, thus discharging the aerial 
 abruptly and jerking the lines of force sharply to the 
 ground. The repeated charge of the aerial and its 
 
 LU 
 
 FI&. 
 
 repeated discharge through the spark gap will snap 
 off portions of the field, detach them from the aerial, 
 and thus form electric waves. Series or trains of 
 these detached waves follow one another with great 
 velocity, travelling at the same speed as light (186,400 
 miles per second). 
 Instruments connected according to Figs. 3 and 4 
 
WIRELESS OPERATORS 1 POCKETBOOK 
 
 will transmit messages into space, but our wave 
 frequency will be very high, and therefore the wave 
 length will be very short. Now short waves are espe- 
 cially liable to all influences tending to shorten their 
 lives to absorption by the neighboring hills and trees, 
 to reflection and refraction, which tend to change their 
 direction, and to polarization or complete annihilation. 
 
 
 
 LU 
 
 
 FI&. 
 
 Therefore short waves are inefficient for transmission 
 to any distance. In order to lengthen the waves, we 
 must decrease their frequency. If a coil is placed in 
 the aerial (between spark gap and aerial) it will pro- 
 duce this effect, and the waves will be lengthened. 
 A condenser across the spark gap will produce a 
 similar effect in lengthening the waves. By combin- 
 ing the two, using both coil and condenser, we will 
 add together the two effects. Not only can we obtain 
 
THE TRANSMITTING CIRCUIT 7 
 
 the desired long waves in the manner shown in Fig. 7, 
 but coil and condenser may be placed in series (see 
 Fig. i), with the same results; or they may be con- 
 nected as shown uf Fig. 8. Usually it is considered 
 best to have both devices together. Thus is formed 
 a resonance or oscillatory circuit, in which the amount 
 
 FIG. 7 
 
 of inductance and capacity (i.e. of coil and condenser) 
 offers a path for a spark discharge of a certain perio- 
 dicity; that is, of a definite wave length and frequency. 
 It is to be noted that under normal conditions the 
 aerial acts as a condenser, aerial being one plate and 
 ground the other. 
 
 Thus are formed the simplest forms of transmit- 
 ting circuits. An oscillation transformer will give us 
 
. 
 
 8j WIRELESS OPERATORS' POCKET BOOK 
 
 an additional circuit, which with coil and condenser 
 balanced with the first circuit will again be in reso- 
 nance. By substituting an oscillation transformer for 
 a helix, we do not really change the circuit formerly 
 used, we merely separate the primary entirely from 
 the secondary, while both of them existed on the helix. 
 
 By separating them completely we gain an additional 
 variation, that of the distance between the two coils, 
 the coupling. If these coils are drawn far apart, the 
 tuning is made very sharp, the signals can only be 
 received when the oscillation transformer used in the 
 receiving station has a carefully ascertained amount 
 of primary, secondary, and coupling. Such an arrange- 
 ment of the oscillation transformer at the sending 
 station would be ideal, if it were not for the fact that 
 
THE TRANSMITTING CIRCUIT Q 
 
 more energy is lost when the coils are at a great distance 
 apart, and consequently the transmitting distance of 
 the station is lessened. However, if' the coils are too 
 near together, there will be another set of waves formed, 
 following the first, but with crests between. This sec- 
 ond tuning point will detract from the strength of 
 signals at the first point, and as a consequence the 
 receiving station will get its signals less clearly. 
 
CHAPTER II 
 
 TRANSMITTING STATIONS: EXPERIMENTAL OR LOW- 
 POWER APPARATUS 
 
 THE experimenter's station will usually consist of 
 the following pieces of apparatus for transmitting: 
 
 Batteries Spark Gap 
 
 Telegraph Key Condenser 
 
 Spark Coil Helix 
 
 'Lhe Primary Circuit. Batteries are the most avail- 
 able source of power unless the electric light current 
 is already installed in the house. For low-power 
 apparatus, the dry battery is most commonly used, 
 is fairly cheap, and requires little or no care. The 
 Storage or Edison-Lalande cells are more efficient, 
 and cheaper in the long run, even if somewhat more 
 trouble to handle and keep in order. The advantage 
 of any one of these over the ordinary wet batteries is 
 that the amperage is higher, and high amperage is 
 necessary to operate a spark coil. 
 
 In selecting dry batteries, the best one for wireless 
 work will have only a moderate amount of amperage, 
 however; say, 18 to 22; and not a high amperage of 
 
 10 
 
TRANSMITTING STATIONS 11 
 
 from 30 to 35, as the latter deteriorates much more 
 rapidly. In order to get the best and most lasting 
 results, the cells should be connected in series multiple. 
 Thus the amperage of the number in multiple is larger 
 and the voltage is less than when connected in series. 
 Only a storage cell of a known make should be used, 
 as a poor one will prove very expensive to maintain. 
 The storage battery has the decided advantage over 
 the dry battery that its output is always even. 
 
 Telegraph Keys in regular use by commercial com- 
 panies are adapted for wireless work. Either the leg 
 or the legless type is well suited to all requirements. 
 Platinum contact points are essential and are usually 
 found on commercial types of keys. For the rest, 
 easy action and capability of fine adjustment are all 
 that need be looked for in buying one. 
 
 The Spark Coil increases (or technically speaking, 
 "steps up") the voltage in order to charge the aerial, 
 and thus to create around it an electro-static field 
 which is to be broken down by the spark gap. A 
 good coil is more cheaply bought than made, except 
 in the larger sizes. Such a coil, to be thoroughly 
 reliable, must be carefully constructed; and it is diffi- 
 cult for the experimenter to use all the precautions 
 necessary to avoid loss of energy. A coil of good 
 efficiency is built with a primary of two layers of nos. 
 14 to 1 8 single covered copper wire, wound on a core 
 of soft drawn iron wires. The secondary is wound 
 with a very fine wire, nos. 34 to 38, and carefully 
 
12 WIRELESS OPERATORS' POCKETBOOK 
 
 insulated. Enamelled wire in coils, as on most pieces 
 of wireless apparatus, is not satisfactory; the weather 
 is apt to affect the enamel, crack it, and thus spoil its 
 insulating qualities. 
 
 Coils are classified by the manufacturer according 
 to the distance the spark will jump. This jump spark 
 is long and thin, and is unsuited for wireless work. 
 For this purpose, a short thick spark, demanding 
 a relatively high amperage is necessary, the same 
 names are applied, however contrary they may seem 
 to the facts of the case. Thus, a one-inch coil, suitable 
 for wireless, should give a one-half inch spark, suffi- 
 ciently thick and hot to ignite a piece of paper placed 
 between the sparking points. This short thick spark 
 is called the " caterpillar spark." In buying a coil, 
 a good test is to draw out the spark to the breaking 
 point. If good, the discharges should then sound very 
 sharply. This loudness of discharge, together with the 
 hot caterpillar spark, shows the coil adapted for wire- 
 less work. 
 
 The Vibrator interrupts a current in the primary 
 of the spark coil, thus producing magnetism on the 
 core, which is picked up by the secondary. To give 
 satisfactory results, a coil must have a good vibrator. 
 Such a vibrator should have either platinum or iridium 
 contacts, and the larger the better. The vibrator 
 giving a high-pitched spark is much better than a 
 vibrator giving one of low pitch. Not only does it 
 give more current to the primary, but it causes 
 
TRANSMITTING STATIONS 13 
 
 a spark which is more penetrating, is more easily read, 
 and at a greater distance. Such a vibrator is by all 
 means the one to choose, even although it consumes 
 the battery current somewhat more rapidly than one 
 of lower pitch. 
 
 All commercial spark coils are fitted with a condenser 
 across the vibrator to stop the sparking at the vibra- 
 tor contacts. By this means the current is abruptly 
 broken, and thus the interruptions are sharper. Such 
 a condenser is very essential, and must be carefully 
 
 F I G.7 
 
 fitted in capacity to the vibrator by an expert. It is 
 not well to tamper with it or to change its value. 
 
 The Spark Gap discharges the charged aerial, and thus 
 creates a series or train of electro-magnetic waves. 
 The electrodes of a good spark gap are of the utmost 
 importance, both as to their form and as to the material 
 of which they are made. The best form for the 
 electrodes is that of a flat-faced circular rod. A sharply 
 pointed or spherical electrode wastes energy and is 
 less desirable. As to materials, silver is best of all, 
 because while it is an excellent conductor when new, 
 the oxide forming when it becomes black is almost as 
 good a conductor as the pure silver. Moreover, silver 
 
14 WIRELESS OPERATORS' POCKETBOOK 
 
 is less apt to allow an arc to form across the gap. 
 Pure tin also forms a good electrode. For general 
 use, a commercial compound known as nickel-steel 
 may be recommended. There is no difference between 
 the horizontal and the vertical types in efficiency, 
 although one should always choose the Gap with the 
 finest adjustments. 
 
 The Condenser is a unit of balance in the transmitting 
 set. The aerial, helix, and condenser must all be 
 brought into resonance in order to transmit the waves 
 to greater distances. This rinding a point of resonance 
 is the important thing. Almost always the condenser 
 is of a fixed value, although it is possible to have it 
 variable instead of the helix, as is usual. Transmitting 
 condensers consist generally of glass plates and tin- 
 foil. The glass margin around the tinfoil should be 
 wide enough to prevent sparking over the edges. The 
 capacity of the condenser should be sufficiently large 
 to balance with the rest of the circuit. Leyden jars 
 are also used as transmitting condensers, although 
 some energy may be lost in this type by a brush dis- 
 charge around the upper edges of the jar. 
 
 The Helix is another unit of balance in the set. As 
 already stated, it is oftenest the helix which is varied 
 when bringing the helix, condenser, and aerial into 
 resonance. A helix of soft-drawn strip copper on hard 
 rubber posts is the best one; but if built of copper 
 tubing or heavy wire (the soft-drawn is always best), 
 and on insulated wooden posts, it will be satisfactory 
 
TRANSMITTING STATIONS 15 
 
 for low-power stations. Helices for this work should 
 have one stationary and two variable contacts. 
 
 Having completed the general description of the 
 qualities of the instruments in a transmitting set, it 
 will be advisable to show a selection of instruments 
 which will work harmoniously together. The first 
 transmitting set usually depends upon a one-inch 
 spark coil, and so that will be our starting point. 
 
 Transmitting Set No. i. With a one-inch spark coil, 
 provided with a good high-pitched vibrator, there will 
 be necessary from six to twelve dry cells. Six cells 
 will run the coil, but of course the energy will be 
 greater with more. A greater number than twelve, 
 however, should not be used, as it may break down 
 the secondary winding and burn out the primary. An 
 ordinary telegraph key, such as can be purchased for 
 about a dollar, will give good satisfaction. A spark 
 gap with silver points may be mounted on the coil or 
 on a separate base. The transmitting condenser should 
 consist of from ten to fifteen 5 by 7 glass plates and a 
 suitable amount of tinfoil or leadfoil, with good margins. 
 A simple home-made helix, made either of strip copper 
 or copper wire, wound in a spiral or on a drum, will be 
 all that is necessary. With an aerial of fair size and 
 a good ground connection, this set of apparatus will 
 transmit signals to a distance of from four to seven 
 miles over land, or a somewhat greater distance over 
 water. 
 
 Transmitting Set No. 2. A two-inch spark coil, 
 
16 WIRELESS OPERATORS' POCKETBOOK 
 
 with a good vibrator, should give a hot caterpillar 
 spark which will ignite a piece of paper when the 
 sparking points are from one inch to an inch and a 
 quarter apart. Such a coil requires from ten to twenty- 
 four dry cells, or a storage battery of ten to fifteen 
 volts, sixty ampere hours. The same key used for the 
 one-inch coil will be adequate for this set also. An 
 adjustable spark gap, mounted on a separate base, 
 would be best. The transmitting condenser and the 
 helix may be the same as those described for Set No. i. 
 Greater pains must be taken with the insulation 
 when a higher voltage is used. Such a set as this 
 will send from ten to eighteen miles over land, or three 
 times this distance over water. 
 
 After outgrowing these outfits, the experimenter 
 will naturally wish to have a more powerful set, and 
 for this purpose he will probably want a small trans- 
 former. Sets of that type are described in the follow- 
 ing section. 
 
CHAPTER III 
 
 TRANSMITTING APPARATUS! PROFESSIONAL OR HIGH- 
 POWER STATIONS 
 
 IN large stations where high power is used, the 
 apparatus differs from that used in smaller ones less 
 in character than in size and capability of standing 
 increased current. A station containing a transformer 
 of from one-quarter to five kilowatt capacity will use 
 the following apparatus: 
 
 Alternating Current (or Pulsating Direct) 
 
 Telegraph Key 
 
 Transformer 
 
 Spark Gap 
 
 Condenser 
 
 Helix, or better, an Oscillation Transformer 
 
 The Power is usually an electric light current of 
 either no or 220 volts, and preferably alternating. 
 The alternating current is necessary for running a 
 transformer to its best advantage. If only direct 
 current, however, can be obtained, a somewhat simi- 
 lar effect may be produced by using a chemical or 
 mechanical interrupter with the direct current, 
 
 17 
 
18 WIRELESS OPERATORS' POCKETBOOK 
 
 The Electrolytic and the Mechanical Interrupter 
 produce the same effect upon the direct current and 
 give an effect approximating the alternations of the 
 alternating current, which is what we need. An 
 
 P I G . 10 
 A LTE1R N AT I N & 
 
 C URRE.N f 
 
 alternating current (see Fig. 10) makes complete 
 cycles, passing from negative to positive, back again 
 to negative, and then beginning a second revolution. 
 The changes of polarity of this alternating current 
 may be represented by the curve shown in Fig. 10, a 
 
 F I D . U 
 
 PULSATING c 
 
 E.NT 
 
 complete cycle being included between (A) and (B). 
 A pulsating direct current, produced by means of an 
 interrupter vibrates between the zero point and either 
 negative or positive pole, but it does not change its 
 
TRANSMITTING APPARATUS 
 
 19 
 
 direction or polarity. Such a current may be repre- 
 sented by the curve shown in Fig. n. There are thus 
 no cycles, but the vibrations or pulsations have much 
 the same effect upon a transformer as the alternations 
 of the alternating current. An Electrolytic or Chemi- 
 cal Interrupter produces pulsations of the direct current 
 in this manner: The positive lead goes to the anode 
 in a glass jar containing a mixture of approximately 
 
 PI G.J2 
 
 nine parts water to one of sulphuric acid. When a 
 current passes through this, bubbles are formed at 
 the anode, and these discharging, the current from the 
 large kathode or negative plate rushes to fill up the 
 space and thus completes the circuit. This is done 
 at very rapid intervals. A battery current of fifty 
 volts is necessary to start the operation. 
 
 Mechanical Interrupters are of many types, but of 
 nearly the same effectiveness. It is much better to 
 buy a good instrument than to attempt to make one. 
 
20 WIRELESS OPERATORS' POCKETBOOK 
 
 It should be of high pitch, and as simple in construc- 
 tion as possible. An excellent interrupter is shown in 
 the diagram, Fig. 13. Its principle is that of the 
 electric buzzer. It consists of a vibrating steel spring 
 suspended tightly between two points. On one side 
 of the spring is a magnet, and just above is a heavy 
 platinum contact. The current, passing through the 
 magnet, pulls down the spring and thus breaks the 
 
 F I Gr. 13 
 AXLCHANICAL INTERRUPTER 
 
 circuit. At once the spring jumps back again to 
 the contact and starts the current again. These 
 interruptions are .at a very rapid rate and at a high 
 pitch, which may be varied by adjusting the spring. 
 The pitch will also give a pure tone, such as is easily 
 read at the receiving end. 
 
 The Key may be any one of the more substantial 
 makes of commercial telegraph keys, provided there 
 are heavy platinum contacts. Special wireless keys 
 
TRANSMITTING APPARATUS 
 
 21 
 
 suitable for use with transformers of from J to 2 kilo- 
 watts are manufactured, and there are larger ones for 
 heavier currents. The contacts may be of platinum, 
 iridium, or silver, a compound of platinum and iridium 
 making the best ones. A key for use with a J to 2 
 kw. transformer should have contacts of about no. 10 
 wire. All keys used in high-power stations should 
 have a one microfarad condenser strapped (or shunted) 
 
 i 
 
 1 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 FIG .17- 
 OPEN CORE THANSFO 
 
 across the contact points to prevent an arc from form- 
 ing or the key from sticking. 
 
 The Transformer, like the spark coil, steps up the 
 voltage of the current in order to charge the aerial. 
 Indeed the spark coil is one form of a transformer, 
 the so-called "open-core" type. In transmitting, 
 both the open and closed core types may be used, but 
 it is impossible to use the latter with pulsating 
 direct current. The open-core type is preferable up to 
 5 kw. The closed-core type is less efficient, although 
 
22 WIRELESS OPERATORS' POCKETBOOK 
 
 many prefer it even in the smaller sizes. It has the 
 advantage that its size and output may be more closely 
 computed. The difference between the two types 
 
 CLOSED COttE. TBANSFORfAEK 
 Fl G-. 
 
 may be understood from the accompanying diagrams. 
 Manufacturers have divided the closed-core types into 
 the O type and the E type according to the shape of 
 the core. The E type is perhaps slightly the more 
 
 F I 
 
 CLOSED COKE TRANSFORMER 
 TYPE. E. 
 
 efficient, but both are good; and they are less expen- 
 sive than the open or induction coil type. 
 
 The transformer for wireless work should have a 
 secondary potential of from 15,000 to 30,000 volts. 
 
TRANSMITTING APPARATUS 
 
 23 
 
 The core of the closed-core transformer should be built 
 of soft iron (laminations), matched together closely. 
 Insulation should consist either of empire cloth or 
 paper (the difference is slight) which is treated with 
 a preparation containing linseed oil. Transformers 
 are wound both for no and 220 volts, 60 or 120 cycles 
 
 -o 
 
 F I &.17 
 REACTANCE RE&ULATOR 
 
 per second. Some commercial forms are so built that 
 no impedence coil or rheostat, such as is usual, is 
 necessary. 
 
 An impedence coil and a rheostat answer the same 
 purpose in cutting down the primary current of the 
 transformer, but in different ways. An impedence 
 coil (usually called a Reactance Regulator) may be 
 used only to cut down an alternating current. Fig. 
 17 will show this. A core of soft iron wire has wound 
 on it several layers of single covered copper wire. An 
 alternating current, passing through the coil, mag- 
 
24 WIRELESS OPERATORS' POCKETBOOK 
 
 netizes the core. When the current is flowing in one 
 direction, the poles of the core become north and south, 
 respectively. The change of direction of the current 
 then reverses this polarity and tends to retard the 
 flow by bucking it. This lagging or bucking offers a 
 resistance or impedence to the current. If, then, this 
 coil is tapped at intervals, and the leads are connected 
 
 F D . 18 
 KHELOSTAT 
 
 to a many-pointed switch, we may regulate the amount 
 of reactance effect upon the current. 
 
 The principle of the rheostat is simpler. A wire of 
 lower conductivity is placed in the circuit with points 
 of adjustment, which determine the amount of resist- 
 ance to be added to the circuit. This resistance wire 
 is often German silver or iron. 
 
 A bank of lamps placed in the circuit has the same 
 
TRANSMITTING APPARATUS 25 
 
 effect, and because much cheaper, is often used for 
 the purpose. (See below, Fig. 53.) 
 
 The Spark Gap in high-power stations is different 
 from that used in the smaller stations only in having 
 larger sparking contacts, in its capability of standing 
 increased current, and in its fineness of adjustment. 
 Nickel-steel is generally used for the points, although 
 silver is much better. When using over \ kw., radi- 
 ators on the handles of the sparking points will be 
 found advantageous, and in fact almost necessary in 
 order to keep the hot contacts cool, and thus to prevent 
 the formation of an arc between them. A highly 
 insulated base and handles are necessary to prevent 
 damage to the operator from leakage of the current. 
 With very high-power sets, several sparking points 
 should be placed on the gap. This is the Multiple 
 Spark Gap. In connection with it, a blow-pipe or 
 fan is necessary to dissipate the gases formed and to 
 cool the contact points, since if hot, these will allow 
 the formation of an arc between the gaps. In sets of 
 2 kw. or more, the spark gaps should be encased in a 
 box to prevent damage to the operator's eyes from the 
 ultra-violet rays, and to his ears from the deafening 
 noise. A glass front on the box may be used, since 
 glass is impervious to the ultra-violet rays. 
 
 The Condenser, in high-power sets, should embody 
 the same principles as that previously described. A 
 glass-plate condenser is advisable by all means. Good 
 flawless glass should be used. Plates should be of the 
 
26 WIRELESS OPERATORS' POCKETBOOK 
 
 left and right design, since this ensures an even capacity 
 per plate; for there are two sheets of tinfoil between 
 each one. The plates should be arranged in units so 
 that faulty ones may be removed without destroying 
 the whole condenser. It is well to have the plates 
 cast in some insulating material such as beeswax or 
 rosin; or to immerse them in castor oil, which is one 
 
 n 
 
 FIG- 19 
 
 R I OH T 
 CONIDEN 5 ELPl 
 
 LE.FT 
 PL ATE. S 
 
 of the best dielectrics known. With care in these 
 respects, the condenser will be satisfactory. 
 
 The Helix for this set of instruments should be made 
 of heavy strip copper or large copper tubing and should 
 be mounted on hard rubber. There should be two 
 stationary and two or three variable contacts. 
 
 Oscillation Transformer. Better than a helix, how- 
 ever, and answering the same purpose, is an Oscillation 
 Transformer, which gives not only more radiation, 
 but more sharply tuned radiation. This instrument 
 is an additional transformer, giving greater sharp- 
 
TRANSMITTING APPARATUS 
 
 27 
 
 ness jof tuning to the station than is possible with a 
 helix. Instead of the helix, we have now the pri- 
 mary of the oscillation transformer, which inductively 
 passes on the oscillations received from the transmit- 
 ting transformer to the secondary of the. oscillation 
 transformer. Through this process of induction, if 
 the value of coupling, i.e., the distance between the 
 
 HELIX 
 
 two coils, of the oscillation transformer is right, 
 pure trains of waves are given off the aerial. The 
 advantage of giving off sharply tuned or pure trains 
 of waves from the transmitting station is that they 
 may be picked up with less interference at the receiv- 
 ing end. These pure trains of waves (see Fig. 20) 
 are formed by attracting to the same apex the 
 apices of the weaker trains of waves, which would 
 
28 WIRELESS OPERATORS' POCKETBOOK 
 
 otherwise form so-called humps in the wave (see Fig. 
 21). When there are humps there may be several 
 tuning points, at the crests of each subordinate wave. 
 An oscillation transformer may be built to advan- 
 tage by the operator. Both primary and secondary 
 
 FID . 20 
 
 should be of soft drawn copper ribbon or tubing wound 
 on hard rubber or some other material of as high 
 insulating or dielectric strength. There should be one 
 stationary and one variable contact on both primary 
 and secondary. 
 
 With apparatus like that here described, and with 
 
 F i & . ai 
 
 suitable aerial and ground connections, stations may 
 be fitted up from \ to 15 kw. capacity. We shall 
 add detailed lists of the instruments necessary for a 
 few sizes of transformers. 
 
 Transmitting Set No. j. \ Kilowatt. The no- volt 
 alternating current is all that should be used, although 
 
TRANSMITTING APPARATUS 
 
 29 
 
 the 2 20- volt current may be used with specially built 
 apparatus. If direct current only can be obtained, an 
 interrupter must be added. 
 
 The Key should be of a special wireless type with 
 heavy contacts, and with a i-mf. condenser con- 
 nected across them. 
 
 The Transformer may be of either the open or closed 
 core type. With direct current, the open-core type 
 
 COMPLETE SET 
 
 must be used with interrupter, the closed-core type 
 giving little or no efficiency under the circumstances. 
 
 The Spark Gap should have contact surfaces of silver, 
 of the design shown in Fig. 9. 
 
 The Condenser should have twelve or eighteen glass 
 plates 8 x 10 inches. 
 
 The Helix may be of the general type described above, 
 or, if desired, an Oscillation Transformer may be used. 
 
 Transmitting Set No. 4. | Kilowatt. The same power 
 
30 WIRELESS OPERATORS' POCKETBOOK 
 
 requirements as in Transmitting Set No. 3. The Key 
 should be similar to that in Set No. 3. There should 
 be a transformer of J-kw. capacity, of either the open 
 or closed core type. The Spark Gap, with silver con- 
 tacts f inch in diameter, should have radiators on 
 both arms. The Condenser should be of J-inch glass 
 and should consist of from twelve to eighteen sheets 
 of 10 x 10 glass, the insulating margins around the 
 tinfoil being about i| inches. The Helix should have 
 two or three variable contacts, of the same type as 
 in Set No. 3. An Oscillation Transformer would be 
 advisable. 
 
 Transmitting Set No. 5. i Kilowatt. The same power 
 requirements as in Set No. 3. The Key should have 
 very heavy silver contacts, of special i-kw. design. 
 The Transformer of i-kw. capacity, of either open 
 or closed core type. The Spark-Gap contacts should 
 be one inch in diameter, and with radiating surfaces. 
 The Gap should be of the enclosed type, in order to 
 muffle the noise and to keep the injurious ultra- 
 violet rays out of the eyes. The Condenser as in Set 
 No. 4. A Helix may be used, but a i-kw. Oscilla- 
 tion Transformer is strongly advised. 
 
 Transmitting Set No. 6. 2 Kilowatt. Power re- 
 quirements as in Set No. 3. A Key with heavy 
 J-inch silver contacts. A 2-kw. Transformer of 
 either open or closed core type. An enclosed Spark 
 Gap with silver sparking surfaces ij or if inches in 
 diameter. A Condenser constructed in units so that 
 
TRANSMITTING APPARATUS 31 
 
 it may be connected in series multiple to relieve the 
 dielectric (or insulating) strain. There should be 
 thirty to forty sheets of J-inch glass, 10" x 10" in 
 size, and immersed in castor oil. A Helix may be 
 used, but is not recommended. The 2-kw. Oscillation 
 Transformer is necessary to stand the current. 
 
 Transmitting Set No. 7. 5 Kilowatt. Power re- 
 quirements as in Set No. 3. A special Key with 
 f-inch silver contacts and a 2-mf. condenser. A 
 5~kw. Transformer, preferably of the open-core type. 
 An enclosed multiple Spark Gap, with blow-pipe or 
 fan, is necessary. Five or six sparking surfaces, f 
 inch in diameter will be sufficient. The Condenser 
 must be in units, with twenty to forty plates of J-inch 
 glass, 14" x 14", and with 2-inch margins, and im- 
 mersed in castor oil. An Oscillation Transformer of 
 special design is necessary. 
 
CHAPTER IV 
 
 THE RECEIVING CIRCUIT 
 
 THE transmitting apparatus is always engaged in 
 radiating waves from its aerial. These waves, starting 
 from that aerial as a common centre, pass on in ever- 
 widening circles, as do the ripples in water when a 
 stone is dropped. All original activity is confined to 
 this process of sending waves from the transmitter, 
 and the journey of the waves in their circles is as far 
 as the electrical current behind the transmitting appa- 
 ratus is able to send them. But another process is 
 necessary before wireless communication is established. 
 Not only must waves be sent out, but there must be 
 a way of determining what signals they bear. This 
 is done by stationing another set of instruments 
 somewhere in the circular course of the waves, and 
 this second set of instruments must be able to reveal 
 to the operator the meaning of the signals. This 
 second set is called the receiving station. It must be 
 placed within the radius of the waves sent out from 
 the transmitter, but the nearer it is to the sending 
 instruments, the louder and clearer will the signals 
 be received. 
 
 32 
 
THE RECEIVING CIRCUIT 33 
 
 Again an aerial is used, but instead of acting as an 
 outlet for waves generated by the instruments below, 
 the receiving aerial or antenna (just as the antenna 
 or feeler of the crab informs him what is passing) 
 conveys to the operator through the receiving instru- 
 ments news of what is passing. Wireless messages 
 cannot at present carry any secrets of importance, for 
 every aerial within the sending range of the transmitter 
 will carry the message to the operator below. The 
 electrical current necessary to radiate wireless mes- 
 sages from the transmitting aerial is very great, because 
 the waves must radiate in every direction, and cannot 
 be confined to one path as the wire of a wire telegraph 
 confines its current. At the same time, the power 
 received at the receiving station will be infinitesimal, 
 for the very same reason of this scattering of energy. 
 Thus it is necessary to have the most sensitive of 
 receiving instruments in order to detect the waves 
 and make their signals known to us. 
 
 The two absolutely necessary parts of the receiving 
 circuit are an aerial and a ground connection. The 
 aerial receives or picks up the wave signals by vibrating 
 with the frequency of the waves. Thus a surging 
 effect is set up in the aerial between air and ground. 
 But however true this may be, we must add other 
 instruments before we shall be able to discover them. 
 First of these is the detector, which, as its name implies, 
 is used to detect the presence of electric vibrations 
 in the aerial circuit. These vibrations or oscillations 
 
34 WIRELESS OPERATORS' POCKET BOOK 
 
 may be detected in various ways, and the several 
 different detectors work on quite different principles. 
 As the mineral forms are most common, and are 
 probably the most efficient, it will be enough in this 
 
 "RECEIVER 
 
 FID. 
 
 place to take one of these, the silicon detector. When, 
 in a detector attached to an aerial circuit through which 
 oscillations are surging, a point of brass rests against 
 a flat surface of silicon, it will allow the current to 
 pass more readily in one direction than in the other. 
 
THE RECEIVING CIRCUIT 
 
 35 
 
 Thus instead of the alternating current set up by the 
 electric waves, we have a rectified direct current 
 passing through the telephone receivers connected 
 
 FID. 2.3 
 
 across the detector. By this means we hear the inter- 
 mittent splashes of the sending key, and by means of a 
 recognized code we are able to form words from them. 
 
36 WIRELESS OPERATORS' POCKETBOOK 
 
 Thus is formed the simplest receiving circuit (see 
 Fig. 22) which will be capable of receiving signals of 
 a wave length comparable with our aerial. But if 
 
 Fl 
 
 waves of greater length are passing, they cannot be 
 picked up by our simple aerial. We therefore add to 
 its (the aerial's) inductance that is, to its time of 
 
THE RECEIVING CIRCUIT 
 
 37 
 
 vibration by placing a coil of wire in the aerial cir- 
 cuit. A variable contact on this " tuning" coil allows 
 
 us to lengthen our oscillatory circuit in accordance 
 with varying wave lengths. 
 
 The first purpose of the receiving instruments is to 
 make it possible for the aerial to vibrate in harmony 
 with the waves it picks up. The tuning coil is a dis- 
 
38 WIRELESS OPERATORS' POCKET BOOK 
 
 tinct addition in increasing this capability of tuning, 
 but another instrument, the condenser, adds the 
 second improvement in this respect. The effect of 
 the condenser is similar to that of the coil it adds 
 capacity to the circuit and makes it possible to balance 
 
 the circuit with the frequency of an incoming wave. 
 Fig. 24 shows the addition of a condenser of fixed 
 capacity to the circuit, and Fig. 25 shows the further 
 addition of a variable condenser. This latter secures 
 the very finest adjustment for balancing the circuit. 
 
 The next improvement in the receiving circuit is 
 to remove the detector circuit entirely from the aerial. 
 This is done by using an oscillation transformer instead 
 
THE RECEIVING CIRCUIT 39 
 
 of a tuning coil. We have now two entirely separate 
 circuits, both of which may be equally balanced to 
 any frequency, and which are connected only by 
 induction (inductively coupled, we say). The primary 
 of the oscillation transformer is in the aerial circuit, 
 where a complete oscillatory circuit is made. We can, 
 then, vary the primary in the aerial circuit; vary the 
 secondary in the detector circuit, balancing it with 
 the primary; and we can vary the coupling between 
 the two. Then, when our aerial is tuned with the 
 incoming wave, and the secondary circuit is balanced 
 with the primary, this variation of coupling enables 
 us to cut down interference from stations we do not 
 want to receive, and at the same time to bring in 
 more clearly those stations we want. 
 
 If the coil in any of these circuits is inadequate to 
 receive waves from any desired station, another coil 
 may be placed in the aerial circuit to add greater 
 inductance. Such a coil is called a loading coil, and 
 may be used as well with an oscillation transformer as 
 with an ordinary tuning coil. 
 
CHAPTER V 
 
 RECEIVING APPARATUS 
 
 THE receiving station is usually the first one experi- 
 mented upon, and might more properly precede the 
 transmitting station in our description. It has, 
 however, been thought best to keep to the logical 
 order. 
 
 The instruments necessary for a receiving set are 
 as follows: 
 
 Detector Fixed Condenser 
 
 Telephone Receivers Variable Condenser 
 Tuning Coil Oscillation Transformer 
 
 The Detector is the most essential part of the receiving 
 apparatus, and its purpose is most vital for receiving 
 wireless signals. The waves received from transmit- 
 ting stations are picked up by the receiving aerial. As 
 a result, an alternating current of very high frequency 
 is set up and surges in the aerial and the receiving 
 circuit. The detector causes this exceedingly feeble 
 current to become perceptible to our ears, by means 
 of very sensitive telephone receivers. The methods 
 are based on different theories according to the type 
 
 40 
 
RECEIVING APPARATUS 41 
 
 of detector used, the earliest form, the coherer, de- 
 pending upon a quite different principle from that 
 of the recent mineral detectors. Some forms once 
 used have been discarded, while new and more sen- 
 sitive detectors are still being discovered. We shall 
 mention only a few of the most important types, 
 giving them in their historical order, which has proved 
 to be the order of their respective values. 
 
 The Coherer is mentioned only because it was the 
 earliest form used. This is constructed of a small 
 glass tube with two highly conducting electrodes of 
 
 I \28L 
 
 FID.2^ COHERE.* 
 
 silver. Between these the space is partially rilled by 
 a mixture of nickel and silver filings. Large filings, 
 which have a low resistance, are used with relays of 
 low resistance, while finer filings, lying in the tube with 
 a high resistance, are used with relays of high resist- 
 ance. The filings have normally high resistance. When 
 a signal is received from a transmitting station on an 
 aerial or oscillator, an electric wave conducted_to these 
 filings breaks down the resistance caused by the oxide 
 existing on their surface, causes them to cohere and 
 thus lowers the resistance. This lowered resistance 
 and the consequent more perfect path for the current 
 can be easily detected by a relay which is in the circuit 
 
42 WIRELESS OPERATORS' POCKETBOOK 
 
 with a battery. This relay in turn may be coupled 
 to any electrical device, for instance the ringing a bell, 
 lighting a lamp, directing a torpedo boat, etc. The 
 coherer of this principle is no longer 'used, other and 
 more sensitive detectors having taken its place. 
 
 The Carbon Detector was a transient device, used 
 but a short time for wireless work. It would be hard 
 to find one to-day, although they became prominent 
 
 CARBON DLTECTOB 
 
 only a few years ago. It was an improvement over 
 the coherer, being somewhat more sensitive and 
 reliable. It is often called a microphone detector. 
 It consists merely of two blocks of carbon, upon which 
 rests a steel needle. The pressure of the needle upon 
 the carbon is varied by the pull of the permanent 
 magnet underneath. Adjustment depends upon having 
 an imperfect contact between the needle and the 
 carbon. The effect of electric waves upon this detec- 
 
RECEIVING APPARATUS 
 
 43 
 
 tor is to vary the resistance between carbon and needle 
 and to indicate this in a telephone receiver, connected 
 in the circuit together with a battery. 
 
 The Electrolytic Detector works on an entirely differ- 
 ent principle, and was a great improvement over the 
 two earlier forms. It is still largely used. This 
 detector works on a rectifying principle. It may be 
 
 SEALED POINT BARE. 
 
 FID. 29 
 
 POINT 
 
 constructed in two ways, the sealed point and the bare 
 point. The bare point has a fine platinum wire for 
 an anode which rests in a cup of dilute nitric acid. 
 In the sealed point type the fine platinum wire is 
 sealed in a glass tube with its lower end flush with the 
 tube's lower or sealed end. Both forms work on the 
 same theory, which is shortly this: A fine platinum 
 wire just touches the surface of the liquid, and when 
 a slight battery current passes through the circuit, 
 
44 WIRELESS OPERATORS' POCKETBOOK 
 
 bubbles are formed at the wire. If the adjustment is 
 just right, these bubbles will continually form, thus 
 making a gaseous insulation about the wire. Now, 
 if there is an aerial and ground connection, a wave 
 picked up by the former becomes a feeble alternating 
 current which breaks down these bubbles. When the 
 circuit between acid and point is thus made, the current 
 
 SILICON DETECTOR 
 
 passes through and may be detected in the telephone 
 receivers connected in the circuit. At the same time, 
 the acid rushing to the temporary conducting point 
 starts up a direct current which is perceptible in the 
 receivers. This is a rectifying effect. 
 
 An electrolytic detector is more easily made than 
 purchased, and is quite as likely to be satisfactory. 
 For the sealed point no adjustments are necessary, 
 but the bare-point type requires very fine adjustments 
 
RECEIVING APPARATUS 45 
 
 indeed; for unless the wire can be placed exactly, no 
 effect is produced. It is essential that a battery and 
 potentiometer be used in circuit with either form. 
 
 The Solid Rectifiers, sometimes incorrectly called 
 Crystal Detectors, may depend upon any one of sev- 
 eral different minerals which have been proved by ex- 
 periment to have rectifying influence upon alternating 
 currents of high frequency. It is thought by many 
 that this is aided by some thermo-effect. The silicon 
 
 
 
 r^>- 
 
 
 / ^ 
 
 FIG. 30 
 
 detector was the first of this type to be universally 
 considered successful. It is still one of the most 
 important and popular ones. Its principle, as has 
 already been stated, is that of a rectifier. No battery 
 is necessary, although a battery and potentiometer 
 help matters along to some extent. The silicon detec- 
 tor consists of a flat surface of highly polished silicon 
 (the flawless kind is best), upon which rests a brass 
 point. A circular or spherical piece of brass resting 
 on the flat surface of silicon makes the finest contact 
 of all. A good experimental form is to allow a sharp 
 
46 WIRELESS OPERATORS' POCKET BOOK 
 
 fragment of silicon to rest upon a flat surface of highly 
 polished brass. The detector stand should be so 
 arranged that any part of the silicon surface may be 
 
 Sm ^E~ 
 
 
 \. Ai-Tl r 
 
 V \ 
 
 FIB. 31 
 
 used. Its simplicity is one chief advantage in favor 
 of the silicon detector. No special care is necessary, 
 and its adjustment is very easily made. The adjust- 
 ment is, however, easily broken when used with a 
 
 FIG. 3 
 
 transmitting set. Nevertheless the silicon detector is 
 advised for all general purposes. 
 
 A very good solid rectifier or mineral detector is 
 the Pyron Detector, which also works on a rectifying 
 
RECEIVING APPARATUS 47 
 
 principle. The adjustment is harder to obtain than 
 with silicon, but once found is more stable, remaining 
 for months at a time in a very sensitive condition. It 
 works with a brass point against the oval fractures of 
 the mineral iron pyrites, sometimes called "fool's 
 gold." A pyron detector stand is somewhat different 
 
 PERIKON DETECTOR 
 
 from that for silicon, the cup containing the mineral 
 being held more rigidly by a pivot and screw, so that 
 adjustment, once found, may be retained. 
 
 The Perikon Detector is now generally held one of 
 the best. It gives far more sensitive and quick ad- 
 justment than does silicon, and retains it better. It 
 works on a rectifying principle. The perikon detector 
 
48 WIRELESS OPERATORS' POCKET BOOK 
 
 consists of a vertical cup into which are fused five or 
 more fragments of zincite, or zinc oxide. Another cup 
 containing a fragment of chalcopyrite, or better still 
 of bornite, is fused into a cup held at the end of a 
 rotating rod which may be adjusted, by means of an 
 inside spring, to any desired pressure against the zincite 
 fragments. The zincite best for this work occurs in 
 
 PERIKON-ELEKTRA DETECTOR 
 
 layers, and the cross-section of these layers forms the 
 best surface for adjustment. A pressure of from \ to 
 2 ounces is necessary to secure the best results. 
 
 A very recent form is the new Perikon-Elektra 
 Detector, which also acts on the rectifying principle. 
 This detector uses a micrometer adjustment, and its 
 stability is remarkable, while it is half as sensitive 
 again as is perikon. This is Mr. G. W. Pickard's 
 latest achievement in detectors. 
 
RECEIVING APPARATUS 
 
 49 
 
 There are numerous other forms of detectors, but 
 those already described are the best and most sensitive. 
 We will, however, mention two or three others in pass- 
 
 ^ 
 
 F I Q . 3 3 
 
 ing. The Tripod Detector (Fig. 33) consists of three 
 needles resting on an aluminum plate, and works on 
 the principle of partial contact. The Carborundum 
 Detector is a crystal form, somewhat less sensitive 
 
 =0 
 
 FID. 3* 
 
 than silicon (Fig. 34). It consists of a piece of carbo- 
 rundum resting between two carbon blocks. 
 
 The Magnetic Detector works on the principle of 
 
50 WIRELESS OPERATORS' POCKETBOOK 
 
 diminution of hysteresis; that is, on the principle of 
 the sudden drop in magnetism caused by a shock to 
 a piece of shakily magnetized soft iron, and its con- 
 sequent effect in producing a current in a near-by coil 
 connected to a telephone receiver. 
 A battery is often used with the detector and is 
 
 Fl G.33- 
 
 necessary for the proper results with a coherer, a carbon, 
 a carborundum, and an electrolytic detector. It will 
 also increase the efficiency and aid in the quick adjust- 
 ment of the silicon, pyron, and perikon, 'but should 
 not be used with the magnetic or perikon-elektra forms. 
 The choice of a detector depends largely on the kind 
 of station constructed. For general experimental pur- 
 poses, silicon is most adaptable. The electrolytic is 
 
RECEIVING APPARATUS 
 
 51 
 
 useful and very reliable, but inconvenient to handle. 
 The patent rights on pyron, silicon, and perikon detec- 
 tors make them more expensive, however much they 
 are superior to other forms. 
 The potentiometer is a necessity when using an 
 
 FlCr. 
 
 electrolytic, carborundum, carbon detector, or coherer, 
 and an advantage even with a mineral detector. Its 
 purpose is to vary the voltage, and thus to fix a definite 
 amount of potential necessary for the best advantage 
 
 FIG. 
 
 SLIDE 
 
 of the detector used. The potentiometer may consist 
 either of German silver wire or a stick of high-resist- 
 ance graphite connected across a local battery. A 
 slide is necessary, and if desired, the potentiometer 
 may be tapped in the middle and a lead carried 
 
52 
 
 WIRELESS OPERATORS' POCKETBOOK 
 
 into the circuit. The advantage of this last is that 
 the direction of the battery may be reversed without a 
 pole-changing switch. 
 
 The potentiometer used with the silicon or other 
 rectifying mineral forms may be of less resistance than 
 that used, for instance, with the electrolytic detector. 
 With the electrolytic, about 300 ohms resistance and 
 three old dry cells are needed, requiring about 140 
 
 BATTETW 
 
 FI&.38 
 
 feet of no. 32 German silver wire or 90 feet of no. 
 36. With the silicon and other detectors, only one 
 cell and about 150 ohms should be used. 
 
 A Testing Buzzer is of great advantage with any 
 detector; it generates feeble electro-magnetic waves 
 which affect the detector and thus enables the operator 
 to obtain the most sensitive adjustment. A small 
 buzzer is best, and a wooden push button affords the 
 necessary insulation. Only one cell and a small con- 
 
RECEIVING APPARATUS 53 
 
 denser are needed. The diagram (Fig. 38) shows the 
 connection. The vibrator point (V) or better the point 
 (A) must be connected through the condenser (C) to the 
 ground (G). The condenser should be about six square 
 inches of tinfoil on each side of a sheet of waxed 
 paper, with some variation of size, according to the 
 strength of signals desired. It will be observed, how- 
 
 HEAD SET 
 
 ever, that weak signals are usually best, and for these 
 a small condenser is needed. 
 
 Telephone Receivers are necessary with all of the more 
 recent types of detectors, in order to make perceptible 
 minute fluctuations of current. For wireless work 
 receivers of high resistance are advisable, and up to 
 a certain point, the higher this resistance the more 
 sensitive the receivers are to feeble currents. Not 
 that a great resistance makes the receivers sensitive, 
 
54 WIRELESS OPERATORS' POCKET BOOK 
 
 but that a very large number of turns of fine wire 
 around the magnet influences the magnetism of the 
 core on receiving a much feebler current from the 
 detector. Therefore very fine copper wire, a large 
 number of turns, and their nearness to the core are 
 the essential qualities of a wireless receiver. The 
 classification of receivers according to resistance is 
 merely a method of showing the number of turns and 
 the fineness of the wire used; i.e., the sensitiveness. 
 All this is true up to a certain point only. The fineness 
 of wire and the great number of turns used to wind 
 receivers of over 3000 ohms does not add to their 
 sensitiveness, the current dispersed over so much wire 
 being incapable of imparting as much strength of 
 magnetism to the core as in the case of receivers of 
 from 2000 to 3000 ohms resistance. 
 
 As will be seen from what has gone before, receivers 
 should be wound with single covered copper wire. 
 Enamelled copper wire may be used for this purpose. 
 A very recent receiver wound with this wire held inside 
 a tiny spark gap in order to prevent burning off the 
 insulation. Some unscrupulous dealers have partly 
 wound the magnets with German silver wire in order 
 to increase the resistance of the receiver, and thus to 
 obtain a high price for it. It will be understood, how- 
 ever, by this time, that such a receiver is no better if 
 as good as one wound with the same number of feet 
 of copper wire, with a resistance usually one-thirteenth 
 that quoted on the fraudulent receiver (the resistance 
 
RECEIVING APPARATUS 55 
 
 of German silver being about thirteen times as great 
 as copper). 
 
 The receiver cases may be of hard rubber or alumi- 
 num. A composition material is most frequently 
 used, and while very much cheaper is more brittle 
 than hard rubber. For wireless work, a receiver must 
 be of the bi-polar type, the single-pole type giving 
 very unsatisfactory results. The diaphragm may be 
 of ordinary thickness, especially in a receiver of a 
 new design which has a small screw to adjust the 
 distance between diaphragm and magnets. Thin 
 gold-plated diaphragms are sometimes used in order 
 to secure sharp signals, while thicker diaphragms will 
 give signals of duller tone. Dull signals can be read 
 in spite of static interference, which would make 
 sharper signals unreadable. The gold-plate is to pre- 
 vent rust, but lacquer serves the same purpose. 
 
 The head band for the receivers may be of nickelled 
 brass or German silver, and may be leather covered 
 for insulation. The convenience of the wearer will 
 determine its shape. Sometimes pure gum rubber 
 tubing is put over the head band, both for its insula- 
 tion, and for the comfort to the operator. Rubber 
 ear cushions over the receivers, which are often used, 
 are not advisable. They increase the distance of the 
 receiver from the ear and may weaken all very faint 
 signals. 
 
 The Tuning Coil is a device by means of which the 
 aerial circuit is increased (or tuned) so as to receive 
 
56 WIRELESS OPERATORS' POCKET BOOK 
 
 incoming waves, whatever their wave length (train 
 frequency). The tuning coil is arranged with one or 
 more variable contacts so that this increase in the 
 aerial circuit may be adapted to the length of any 
 waves we desire to receive. The tuning coil is con- 
 nected with the aerial circuit so as to synchronize 
 (or time) the vibrations of the aerial with the wave 
 length or train frequency of the transmitting station. 
 This increase to the aerial circuit does not depend 
 
 
 TUNING COIL 
 
 entirely upon the length of wire contained in the coil, 
 but upon the amount of coil inductance in the aerial 
 circuit or inductively coupled to it. 
 
 A tuning coil should be wound of soft drawn bare 
 copper wire, approximately no. 22, on a core of 
 unshrinkable highly insulating material, such as hard 
 rubber or cardboard seasoned or soaked in shellac. 
 Fibre is sometimes used, but is not to be depended 
 upon. Bare copper, wire is best, although single 
 covered copper wire may be used if paths are cut 
 
RECEIVING APPARATUS 57 
 
 through the insulation for the slides. Enamelled wire 
 is not good for a tuning coil; not only does it refuse 
 to maintain its close tension around the core and 
 become loose, but the enamel acts as a sort of condenser 
 between turns because of its extreme thinness, and 
 makes the tuning broader or less definitely sharp than 
 is necessary. The wire of the coil must be well insu- 
 lated, by winding in a thread cut in hard rubber, by 
 spacing it on a screw-cutting lathe on cardboard, or 
 by winding it with a thread between each turn. Such 
 a coil should be from three to four inches in diameter 
 and twelve or eight inches long. There is no advan- 
 tage in having a larger coil, as the wave lengths of 
 practically all stations come within this range. If a 
 greater range of tuning is desired, which will be rare 
 unless for the extremely long waves used by the trans- 
 atlantic stations, it is better to have a loading coil 
 which may occasionally be switched into the circuit, 
 and which will not permanently burden it. 
 
 One, two, or three variable contacts (slides, sliders) 
 are used on tuning coils. Although the three-slide 
 form is employed for its greater selectivity and to 
 produce a loose-coupling effect, the one and two slide 
 forms are most popular for general use. The slides 
 should have a phosphor bronze spring, preferably with 
 a rolling contact, and a well insulated handle. 
 
 A Loading Coil is a supplementary coil used to give 
 a greater inductance to the circuit, and thus to give 
 it a greater range of resonance, and to enable it to 
 
58 WIRELESS OPERATORS' POCKET BOOK 
 
 receive longer waves or those of much lower frequency. 
 In form it is merely a single-slide tuning coil. 
 
 The Condenser collects and holds electricity. Its 
 conductors are very close together, and adjacent ones 
 are charged with opposite kinds of electricity one 
 negatively and one positively. An .alternating current 
 passes readily through a condenser, because the charge 
 keeps changing from negative to positive and back 
 
 ALTERNATING- Dl"RECT 
 
 again. A direct current, while it will give the same 
 initial charge to the first plate, cannot pass through 
 the condenser, since only the change of polarity will 
 maintain the charge in the opposite plate. In other 
 words, we have the two plates of a condenser (A and 
 B), through which an alternating current is passing. 
 When A receives a positive charge, it repels the posi- 
 tive charge from B and attracts the negative; thus B 
 is negative. When A reverses and becomes negative, 
 
RECEIVING APPARATUS 59 
 
 B becomes positive for the same reason. The same 
 process goes on; A, constantly changing, forces B to 
 change, and the current continues. When a direct 
 current is led to the condenser it charges A positively. 
 B at once becomes negative and remains so. There 
 is no change of direction in the current after the first 
 connection, and therefore the charge remains fixed 
 and no current can pass. 
 
 For wireless work, there are two kinds of condensers 
 
 those which present a fixed value and those where 
 the condenser value may be varied at the will of the 
 operator. The former is called a Fixed Condenser, 
 the latter a Variable Condenser. 
 
 A Fixed Condenser is used in order to balance one 
 part of the circuit with the other. This is a part of 
 the process of tuning or bringing the circuit into resonance 
 with the transmitting station. Practically the princi- 
 pal use of a fixed condenser for receiving is to short- 
 circuit (shunt) the telephone receivers. For instance, 
 in the circuit shown in Fig. 40 the high frequency 
 
60 WIRELESS OPERATORS' POCKET BOOK 
 
 current set up in the oscillatory circuit will more 
 .readily pass from A to B through the condenser (C) 
 than through the receivers (P), since the latter offer 
 a much higher resistance to it. When a detector 
 rectifies the high frequency alternating current to a 
 direct current, the condenser opposes the passage of 
 this direct current, which therefore passes through the 
 receivers and comes to our ears. A fixed condenser 
 may also be used in the circuit to prevent short- 
 
 circuiting the detector, when the latter is connected 
 across a coil. This latter connection is, however, of 
 less advantage. 
 
 The capacity of a fixed condenser ranges between 
 .002 and .005 microfarads (mf.). Those of large 
 capacity should be used with telephone receivers of 
 low resistance, of smaller capacity with receivers of 
 higher resistance. This is because the larger wire used 
 in the low resistance phone offers an easier passage 
 to the current than the finer wire used in the higher 
 resistance phone, and therefore the low resistance 
 
RECEIVING APPARATUS 
 
 61 
 
 phones need more condenser to balance the circuit 
 than do those of higher resistance. 
 
 Where a potentiometer is used, it should be short- 
 circuited by a fixed condenser and be placed with the 
 phones (see Fig. 42). 
 
 The Variable Condenser is used to enable the operator 
 to tune or bring the circuit into finer resonance than 
 would otherwise be possible. If the point of sharp- 
 
 F I 
 
 est tuning happens to come between the turns of the 
 coil, and where it cannot be reached exactly by any of 
 the slides, the variable condenser makes it possible 
 for the operator to reach the exact point of sharpest 
 tuning, and thus to obtain the most accurate results. 
 
 There are two very good kinds of variable condensers, 
 the Rotary and the Slide Plate types. The Rotary 
 type is the easiest one to manipulate and is the most 
 convenient. If aluminum plates of large diameter, 
 however, are used, there may be some sagging of the 
 
62 WIRELESS OPERATORS' POCKET BOOK 
 
 metal, which will cause the plates to short-circuit. 
 The Slide Plate type, while more troublesome to 
 manipulate, has the advantage of greater stability, 
 and its condenser values are more nearly proportionate 
 to the adjustment. 
 The plates may be of brass or aluminum, and of 
 
 J 
 
 ROTARY CONDENSER 
 
 stock sufficiently heavy to prevent sagging. For this 
 reason brass is more durable. The clearance between 
 the plates should be as little as possible. Many 
 commercial variable condensers have a clearance of 
 TjV of an inch. Those with ^ are better, but are 
 rare. The highest capacity of a variable condenser 
 should not be over .004 mf., .003 mf. being that most 
 often necessary. 
 
RECEIVING APPARATUS 
 
 63 
 
 An Oscillation Transformer is added to a receiving 
 set in order to obtain more selective tuning than the 
 ordinary tuning coil will give. They may be easily 
 
 SLIDE PLATE CONDENSER 
 
 made and at small comparative expense. They are 
 simple to operate, and generally increase the receiving 
 range of a station. 
 
 The best oscillation transformers are wound on 
 
 OSCILLATION TRANSFORMER 
 
64 WIRELESS OPERATORS' POCKET BOOK 
 
 threaded hard rubber, both primary and secondary. 
 Next to hard rubber comes shellacked cardboard, on 
 which the wire may be spaced on a screw-cutting lathe 
 or wound with thread for insulation. In size the 
 primary should be about four inches in diameter and 
 four inches long. No. 22 bare copper wire should 
 be used, twenty-four turns to the inch, about 100 
 turns in all. One slide with rolling contact on the 
 primary is necessary. The clearance between pri- 
 
 mary and secondary should be as small as possible, 
 not more than I inch. The secondary should be about 
 3! inches in diameter, and the winding about three 
 inches long. Nos. 26 to 28 bare or single silk insu- 
 lated wire should be used, about 200 turns in all. 
 The secondary should slide in and out of the primary, 
 and not rotate inside, since by drawing secondary 
 away from primary we vary not only the magnetic of 
 the two coils, but also the mass capacity between the 
 two. In this way we may cut out static effects which 
 
RECEIVING APPARATUS 
 
 65 
 
 interfere with our receiving. With 200 turns on the 
 secondary, taps should be taken out every twenty 
 turns and brought to a many-point switch. 
 
 By the addition of a second oscillation transformer, 
 using a circuit like that shown in Fig. 44, much finer 
 tuning still will be possible, although the difficulty 
 of tuning will at the same time be increased. This is 
 called a Weeding-out Circuit. Indeed it is possible 
 to add another oscillation transformer, to gain still 
 
 finer tuning, and at the same time make tuning more 
 difficult. Neither of these circuits will be used, how- 
 ever, except where the interference is very bad; and 
 then only seldom, as there is a slight loss of energy as 
 each one is added. 
 
 We have now mentioned all the usual instruments 
 for receiving. Only a few out-of-the-way or merely 
 experimental forms have been omitted, and those 
 intentionally. We shall now give a selection of such 
 sets of apparatus as are well fitted for use together, 
 
66 WIRELESS OPERATORS' POCKET BOOK 
 
 and which will be adapted to certain receiving dis- 
 tances, at reasonable prices. 
 
 Receiving Set No. i with Single Slide Tuning Coil. 
 Silicon Detector; one 8o-ohm Receiver; Fixed Con- 
 denser (.004 mf.); Single Slide Tuning Coil, three 
 inches in diameter and twelve inches long; Two- wire 
 
 COMPLETE RECEIVING SET 
 
 Aerial of no. 12 or 14 copper or aluminum wire, 50 feet 
 long and 50 high, of the T or L type. For receiving 
 distance, use table on page 170. 
 
 Receiving Set No. 2 with Double Slide Tuning Coil. 
 Silicon or Electrolytic Detector and Potentiometer; 
 one looo-ohm Receiver with Single Headband; Fixed 
 Condenser (.003 mf.); Double Slide Tuning Coil, same 
 
RECEIVING APPARATUS 67 
 
 dimensions as in Set No. i; Aerial as in Set No. i. 
 For receiving distance, see tables. 
 
 Set No. 3 with Double Slide Tuning Coil. Silicon 
 or Electrolytic Detector and Potentiometer; two 1000- 
 ohm Receivers and Double Headband; Fixed Con- 
 denser; Double Slide Tuning Coil; Variable Condenser, 
 Slide Plate type; Four- wire Aerial, 50 to 75 feet 
 long and 60 feet high, of no. 14 copper, aluminum, 
 or phosphor bronze wire, T, L, or Fan types. For 
 receiving distance, see tables. 
 
 Set No. 4 with Three Slide Tuning Coil. Silicon 
 or Perikon Detector; 2ooo-ohm Receivers, as in 
 Set No. 3; Fixed Condenser as in Set No. 2; Three 
 Slide Tuning Coil, same dimensions as in Set No. i; 
 Variable Condenser, either Slide Plate or Rotary 
 type; Aerial as in Set No. 3. For receiving distance, 
 see tables. 
 
 Set No. 4 with Oscillation Transformer. Perikon 
 Detector; Potentiometer; two i5oo-ohm Receivers 
 and Headband; Fixed Condenser (.0025 mf.); Receiv- 
 ing Oscillation Transformer; two Variable Condensers 
 (.003 mf. each). The receiving range of this set 
 may be increased practically without limit, according 
 to the type of aerial used. For aerial, see Chapter 
 VI and diagrams on page 71. 
 
CHAPTER VI 
 
 AERIALS AND GROUNDS! TYPES AND CONSTRUCTION 
 
 OF first-rate importance in constructing a wireless 
 station is the choice of a type of aerial and a good 
 ground connection for the apparatus. Ground con- 
 nections are usually easy to obtain and cause little 
 difficulty. Not so, however, with the aerial. We must 
 select a type of aerial suitable for our surroundings, 
 and we must decide upon the size necessary for the 
 transmitting and receiving distances we wish to cover, 
 and we must consider the mechanical difficulties of 
 construction, the cheapest kind of wire suitable for the 
 necessary spans, and the proper insulation of it. 
 
 Any aerial which can be used for transmitting makes 
 a good receiving aerial. The converse of this is not 
 always true, for not every good receiving aerial can 
 also be used for transmitting. Therefore the wireless 
 operator will always wish to construct a transmitting 
 aerial, and those described in this chapter are of this 
 kind and may be used indifferently for both purposes. 
 This simply means that there must be a number of 
 strands and that the extreme height of the aerial is 
 somewhat less than its length. 
 
 68 
 
AERIALS AND GROUNDS 
 
 69 
 
 The Straight-away and the Loop are terms used to 
 indicate the method of connecting the aerial. In the 
 straight-away form all the upper wires end dead on 
 an insulator. These upper wires in the loop form 
 are all connected together and divided into two sec- 
 
 STRAIGHT AWAY 
 
 LOOP 
 
 PIG-. * 5" 
 
 tions at the bottom, as shown in Fig. 45. Aerials of 
 almost any type may be erected in either form, but 
 while the loop gives slightly better results on a short 
 aerial, the straight-away is decidedly the more efficient 
 in most cases. 
 
 There are about six types of good aerials, but the 
 combinations of these are almost innumerable. Each 
 
70 WIRELESS OPERATORS' POCKET BOOK 
 
 of the main types, however, is distinct; and it seems 
 best to confine our attention to their principal features. 
 In the order of similarity of construction these are 
 
 P IT* E C T / O 
 
 O F 
 
 D- T=\ El R T El S T EN/ER&Y 
 PIG. 
 
 the r, the Vertical, the L, the F, the Faw, and the 
 Umbrella types. 
 
 Of all these the T is most nearly perfect and gives 
 the best results. For one thing, the I aerial is not 
 directional to any considerable extent, as is the L or 
 the V type. 
 
AERIALS AND GROUNDS 
 
 71 
 
 T RE.RIAL 
 
 LOOP 
 
 VERTICAL 
 
 LOOP 
 
 U MBR ELLA 
 AERIAL 
 
 V A.E.RIAL 
 
 FAN AERIAL 
 
 STRAIGHT 
 
 1.0 OP 
 
 DIAGRAM OF AERIALS 
 
72 WIRELESS OPERATORS' POCKET BOOK 
 
 After the J 1 , the Vertical type has the greatest 
 advantage, then the Umbrella, the Fan, and the L 
 or F types. Questions of location are, however, very 
 important in making this decision for any specified 
 station, and may almost reverse this order. 
 
 T Type Aerials. For all-around work both in 
 transmitting and receiving the T type is generally 
 considered the most efficient. For the very best 
 results the T aerial should be from 100 to 200 feet 
 high and with a horizontal stretch of from 90 to 
 190 feet. From six to ten strands of nos. 8 to 12 
 wire should be used either in the loop or straight- 
 away forms. These dimensions may be varied if 
 the principal of a horizontal slightly shorter than the 
 vertical is adhered to. 
 
 Vertical Type Aerials are not at all directional and 
 are most excellent for general use. They may be in 
 either the loop or straight-away form. This aerial 
 is seldom used because of the difficulty of erecting. 
 One very long pole is necessary. It should be from 
 75 to 200 feet high, of from six to ten strands of nos. 
 8 to 12 wire. . 
 
 Umbrella Type Aerials. These are always good 
 aerials and are inexpensive. They must be in the 
 straight-away form. If instead of a pole, water con- 
 ductor- pipes are used, with four guy-wires at each 
 joint, and both pole and guy-wires are insulated, the 
 latter with strain insulators, the whole thing may be 
 used as an aerial, and is very efficient. In size the 
 
AERIALS AND GROUNDS 73 
 
 umbrella aerial may be from 50 to 150 feet. The guy- 
 wires will have to be proportional to the height of 
 aerial and the strain upon them. Phosphor bronze 
 or galvanized iron wire should be used. For a 50- 
 foot pole nos. 12 or 14 phosphor bronze would be 
 sufficient, while for a i5o-foot pole nos. 4 to 8 
 stranded steel cable is necessary. This type is be- 
 coming very popular. 
 
 The L or Horizontal Type Aerial may be either in 
 the loop or straight-away form. It has the disadvan- 
 tage of being somewhat directional. It should be about 
 100 feet long and 100 feet high, with eight to ten 
 strands of 8 to 12 wire. This type is very common. 
 It has often a length of 200 feet to a height of 50 to 
 75, which is all right for receiving, but is objectionable 
 for sending. 
 
 The V Type of Aerial is used where the highest point 
 must be near the station, with a lower point some 
 distance away. This type is especially good in crowded 
 quarters, and while slightly directional, gives excellent 
 results. It should consist of six to ten strands of 
 nos. 8 to 12 wire, about 100 feet long on each stretch. 
 The height should be over 50 feet, and preferably 75 
 feet. 
 
 The Fan Type is especially good in crowded quarters 
 also. It is not directional and must be of the straight- 
 away form. It should be composed of from fifteen to 
 twenty strands of nos. 12 to 14 wire and should be from 
 30 to 90 feet high. There are two kinds of fan- type 
 
74 WIRELESS OPERATORS' POCKET BOOK 
 
 aerials one consisting of a single fan suspended be- 
 tween two poles, the other formed of four fans sus- 
 pended around four poles, such as is used in the 
 Marconi Station in Wellfleet. 
 
 Almost as important as the comparative efficiency 
 of different forms of aerials is the fitting of those types 
 to the location of a station. All the surroundings 
 must be considered and must have due weight in the 
 final decision. The best location for a station is on 
 a hill and near the seacoast. Directly on the sea- 
 coast or on an inland hill are both good locations. A 
 wireless station in a forest or in the middle of a large 
 city is at the very greatest disadvantage, since the 
 trees and the trolley lines and iron frame buildings of 
 the city absorb waves of almost any wave lengths in 
 use, except the very long waves of a few such stations 
 as Marconi and Fessenden. 
 
 If buildings are crowded together in a city or there 
 are near-by trees, the umbrella type on top of the 
 building will probably be advisable. Where great 
 height cannot be obtained, the loop form should be 
 used. The fan aerial is also very good under these cir- 
 cumstances. Long wave lengths for transmitting are 
 necessary to avoid the absorption which shorter lengths 
 would undergo amid crowded buildings. 
 
 In the country it is most desirable to get a location 
 on a hill-top; and if possible, one free from trees. If 
 guy-wires are attached to trees, a series of strain 
 insulators should be placed between tree and aerial. 
 
AERIALS AND GROUNDS 
 
 75 
 
 MARCONI STATION 
 
76 WIRELESS OPERATORS' POCKET BOOK 
 
 Copper wire is the very best for an aerial. Next 
 in conductivity comes phosphor bronze. Phosphor 
 bronze wire should be used on all stretches of 100 feet 
 and over. Aluminum wire is not as good a conductor 
 as copper, although some of the larger sizes will do 
 just as well. One of its advantages is its cheapness. 
 It is very light also; eight or ten strands of aluminum 
 wire cause very little strain to the cross-arm. Iron 
 wire, because of a certain reactance effect, is a poor 
 conductor and should not be used in the regular 
 aerial, except in the umbrella type, where a great 
 number are used in multiple as guy-wires. Only 
 galvanized wire should be used. 
 
 Following is a list of the best sizes and materials of 
 wires at best advantage in any good aerials. 
 
 Size (B & S) 
 
 Copper wire, stranded, solid, or tinned 8-14 
 
 Phosphor bronze, stranded or solid 6-12 
 
 Aluminum, solid 6-12 
 
 Galvanized iron, solid (for umbrella type only) 4-10 
 
 Insulation for Transmitting and Receiving Stations. 
 The proper insulation of an aerial plays a very im- 
 portant part in the transmitting as well as in the 
 receiving distance. One of the greatest faults in the 
 experimenter's transmitting station is that of leakage 
 from improper or poor insulation. In erecting an 
 aerial, two insulators should be used between each 
 wire and the cross-arms. Not only that, but the ropes 
 holding the cross-arms and all guy-wires should be 
 
AERIALS AND GROUNDS 77 
 
 protected by petticoat strain insulators. The follow- 
 ing is a list of the proper insulators for transmit- 
 ting powers: 
 
 i or 2 inch spark coil ...... wire cleats or spool insulators. 
 
 J kw. set ............... 2 inch strain insulators. 
 
 i " ' ............... 2 ' petticoat strain insulators. 
 
 1 " " ............... 6 " 
 
 2 " " ............... 6 " 
 
 " " .............. 18 " " " " 
 
 To ascertain the total strain (T) upon the insulators, 
 the following equation may be used: 
 
 T _ 
 
 : 
 
 ss 
 
 where L is the length of wire in feet, W the weight per 
 foot in pounds, and 5 the total sag of the wire in feet. 
 For example, if we have the following: Wire, no. 6; 
 weight per foot, 0.112 Ibs. (with insulators); sag, one 
 foot; span, 100 feet, 
 
 (ioo) 2 o.i 12 1120 
 
 T = - 5; - = 5 = 140 Ibs., total strain on 
 o X I o 
 
 insulators. 
 
 If an aerial is selected and erected according to these 
 principles, the operator may be sure that he is getting 
 approximately all the efficiency out of his station. 
 As this is so important, he should take great pains in 
 each part, in order that the result may be as faultless 
 as possible. 
 
78 WIRELESS OPERATORS' POCKETBOOK 
 
 Closely associated with his aerial efficiency is the 
 adequacy of his ground connections. Although a 
 good ground is nearly always easy to obtain, care 
 should be taken in assuring oneself that it is a good 
 ground. 
 
 The ground connections for sets up to one and two 
 kilowatt should be made to water-pipes, with a 
 
 WIRE 
 TO INSTRUMENTS 
 
 V X t 7 ^ jv; s \ \ \ \ XX N 
 
 no. 6 to 8 insulated wire. In all cases this ground 
 connection should be made at or near the street side 
 of the water-pipes, or where it enters the ground. 
 Even a receiving station should be properly grounded 
 in case of thunderstorms. Gas-pipes are not always 
 an efficient ground, because they do not always form 
 a sure connection; a certain red paint used in the 
 joints sometimes acts as insulator. A water-pipe, on 
 the other hand, is always a good ground. 
 
AERIALS AND GROUNDS 79 
 
 A very good method of getting a ground connection 
 for experimental purposes on a water-pipe is to scrape 
 the pipe well and bind it with tin or lead foil. Upon 
 this is wound a bright piece of new wire, the ground- 
 wire. Another sheet of tinfoil outside is then covered 
 with tape, if it is to be used permanently. 
 
 Where water-pipe grounds are not available, several 
 methods may be resorted to. One way is to bury a 
 copper ground plate in charcoal with a good-sized lead 
 (wire 6-8) to the instruments. Another good ground 
 for stations near the water is to throw overboard a 
 large metal plate securely fastened to a substantial 
 lead which runs to the instruments. Still another 
 method, and the best, is to lay several hundred square 
 feet of wire chicken netting over charcoal spread on the 
 surface of the ground. This can be used even on sand, 
 which forms the poorest connection possible. 
 
 When an efficient aerial and a good ground connec- 
 tion are secured, the operator may turn his attention 
 to the installation of his station, which we shall pro- 
 ceed to treat in the following chapter. 
 
CHAPTER VII 
 
 PROTECTION AND INSTALLATION OF A STATION 
 
 HAVING assembled all the separate parts of the 
 wireless station, when the aerial has been erected and 
 a good ground connection made, there still remains 
 the by no means simple task of assembling them and 
 of putting the completed station into working order. 
 The steps in this process are first the protection and 
 then the installation of the instruments in their places. 
 Protection of a station includes both its preservation 
 from lightning and also prevention of injurious effects 
 upon the lighting system or the metres of the household. 
 Installation of a station relates to the wiring of the 
 transmitting apparatus both for alternating current 
 and for direct current with interrupters, and then to 
 the placing and wiring of the receiving apparatus. 
 
 Let us begin with the aerial. As it enters the station 
 the aerial should be protected by a one-piece insulator. 
 If, for instance, the wires are brought through the outer 
 wall of the house, one continuous containing tube of 
 porcelain, hard rubber, or electrose should extend four 
 or five inches beyond either surface of the wall to stop 
 any leakages of current. Small porcelain tubes may 
 
 80 
 
PROTECTION AND INSTALLATION 81 
 
 be used on spark coils operated by battery current, 
 but an electrose or hard rubber tube one inch thick 
 should be used on sets of from J to i kw.; for 
 stations of from i to 3 kw. hard rubber or electrose 
 insulation two inches thick is necessary; while for 
 sets up to 5 kw. electrose insulators at least three 
 inches thick all around the wire will be needed. 
 The wires for all leads from the aerial to the apparatus 
 
 AERIAL. 
 
 
 INSTRUMENTS 
 \ 
 i 
 
 AERIAL LEAT> |OO AMPERE. 
 
 NO. G V\/IT*E: SW/ITCH 
 
 X 
 
 rNo v f INSULATED 
 FJG.^8 GROUND WIRE 
 
 should be of no. 6 copper wire, rubber insulated. 
 Fire Underwriters' Rules declare that all aerial wire 
 going into a station should be connected to a loo-am- 
 pere switch. This switch should be of the single pole 
 double throw order, with the aerial connected to its 
 centre or handle pole. It is advisable to use a double 
 throw switch, since the instruments are entirely cut 
 out when the aerial is grounded, which is not the case 
 if a single throw switch is used. To the lower pole 
 
82 WIRELESS OPERATORS' POCKET BOOK 
 
 should be connected an insulated, no. 4, ground wire, 
 joined to the water-pipe on the street side of the 
 water-metre, or to one of the ground connections 
 described in the previous chapter. The upper pole of 
 the loo-ampere switch is connected to the apparatus 
 through the ordinary switches. In cities, Fire Under- 
 writers' Rules order that this switch and the ground 
 
 O 
 
 <* o 
 
 SMALL TO 110 VOLT 
 
 SPARK &AP MAINS 
 
 |H 5- A/AP. 
 
 y FUSE 
 
 FID. *-<? * AVF-COND 
 
 wire be placed outside the station, and that the aerial 
 be grounded when not in use. 
 
 The protection of a wireless station includes the safe- 
 guarding of the line and metres, of the key, and of the 
 step-up or transmitting transformer. For direct cur- 
 rent, little protection is necessary, but this is not the 
 case where alternating current is used. 
 
 Thorough protection of the line, key, and transformer 
 from i to 5 kw. for alternating current are shown in 
 Figs. 49 and 50. 
 
 The sending or step-up transformer should be 
 shunted with two 5-ampere fuses and one 2-mf. con- 
 
PROTECTION AND INSTALLATION 
 
 83 
 
 denser across which is a small protective spark gap, 
 the whole connected in series across the primary of 
 the transformer. This is the best protective device 
 known, and will prevent all kick-backs. It will be 
 found advisable to use a i or 2 mf. condenser across 
 the contacts of the key, where these are not large 
 enough to prevent its sparking or sticking. 
 The proper protection for the line is shown in Fig. 
 
 TO TRANSFORME-R 
 
 TO TRAN5FOR/AE.R 
 
 "*5T tt/^NPl 1 ! TO MAINS 
 F U SC U 
 
 2M.F.IN i si 
 
 COND- HJ J SI 
 fuSfTlj T0 ^ANS 
 
 i 
 
 Z nF-| 
 , 1 |j 
 
 y AI-VP. Fusey 
 
 I j 
 
 S& f*^ 
 [SD (bO 
 
 2. M F- 1 
 
 i ! 
 
 5- AMP. FUSE J 
 
 TO TRANS FORttEB 
 
 ro 
 
 TRANSFOR/AER 
 
 FHOTE.CTION OF 
 
 RWOTECTIOIM OF 
 *'C- OC.MEBATOR 
 
 F I G. 
 
 50. This device is situated near the metres and con- 
 sists of an arrangement similar to that placed across 
 the transformer; two 5-ampere fuses are connected 
 in series across the main line with a 2-mf. condenser. 
 Across this condenser is placed another protective 
 spark gap with a distance between the gaps of about 
 ^4 of an inch. This device is sufficient to protect 
 the line transformer and metres from any kick-backs 
 in the circuit. 
 
84 WIRELESS OPERATORS' POCKETBOOK 
 
 For the protection of an alternating current generator 
 it is necessary to use a more complex arrangement of 
 fuses, condensers, and spark gaps. Across the gener- 
 ator are placed two 5-ampere fuses and two 2-mf. 
 condensers in series. Across these condensers in turn 
 are two protective spark gaps. A connection between 
 the two condensers is grounded through a third 2-mf. 
 
 n wwwv 
 
 TRANSFORfNCR 
 
 condenser. This device is especially for motor gener- 
 ator sets and affords adequate protection there. 
 
 With direct current somewhat simpler safety devices 
 are necessary. Direct current, however, is not nearly 
 so good as alternating current, for some kind of an 
 interrupter must be used in order to obtain the pul- 
 sating current described in Chapter I. Fig. 51 shows 
 a method of protection for direct current. The key 
 is shunted with a one or two microfarad condenser, 
 while the main line has two 5-ampere fuses in series, 
 with a condenser and protective spark gap. This 
 affords sufficient protection for ordinary circuits. 
 
PROTECTION AND INSTALLATION 
 
 85 
 
 Installation. A broad table is the best thing for 
 mounting the instruments of a wireless station. If this 
 is used the convenient position of the instruments may 
 be easily determined, and by judicious grouping a 
 slight movement of the hands will control them all. 
 All of the switches used in changing from sending to 
 receiving should be beside the key, in order to facili- 
 tate the operator's movements. The most convenient 
 
 MAIN CUT-OUT\ 
 
 DE.TECTOB 
 
 NSTALLATION 
 
 OUTLINE. OF 
 F I C 
 
 arrangement places the transmitting apparatus at the 
 right and that for receiving at the left. 
 
 All connecting wires for the transmitting appara- 
 tus should be rubber insulated, no. 14, stranded, 
 copper wire. Porcelain or hard rubber insulators are 
 necessary where the wires pass through the table. 
 Care must be taken in wiring underneath the table, as 
 well as on top. On the extreme right is the main 
 cut-off for the sending instruments. If an electrolytic 
 
86 WIRELESS OPERATORS' POCKET BOOK 
 
 interrupter or a rotary converter is used, it should be 
 encased beneath the table, where it will be out of the 
 way. Where alternating current is used reactance 
 regulators will cut down the current. With sets from 
 2 to 5 kw. these are of the best advantage. However, 
 reactance regulators are expensive and hard to build, 
 so a bank of lamps may be used for resistance with 
 
 6~ 
 9_ 
 
 c: 
 -o 
 
 
 
 
 oooo 
 
 "1 
 
 AC- 
 
 
 3*. 
 32 
 
 bf 
 16 
 
 C 
 C- 
 
 c 
 
 c 
 
 p 
 p- 
 p 
 p. 
 
 1 A/AP- 
 1 R A\P- 
 
 MS RESISTANCE 
 
 TOTAL 
 
 LAA\PS USED 
 FtCr. 
 
 small sets using either alternating or direct current. 
 An 8-candle-power lamp allows a J-ampere current 
 to pass; one of 16 c.p. allows J ampere; one of 32 c.p. 
 allows a full ampere to pass. If we want a current of 
 4! amperes, then, we place in the circuit one 64 c.p, 
 two 32 c.p., and one 16 c.p. lamps, thus securing the 
 necessary amperage. 
 
 The receiving apparatus, we have decided, will be 
 on the left of the table. In wiring up, rubber covered, 
 
PROTECTION AND INSTALLATION 
 
 87 
 
 no. 1 6 or 18, stranded, copper wire will be necessary. 
 The leading wires of the receiving instruments should 
 be placed on top of the table, so as to leave the under 
 side clear for the transmitting wiring. 
 
 M /=\T 1 M Gr 
 
 FI &. 
 
 All leads both for sending and receiving apparatus 
 should be as short as possible. For these and the 
 connections the operator is strongly advised against 
 using the tinsel telephone cords, their resistance being 
 very high. 
 
 If pains are taken in following these directions, and 
 
88 WIRELESS OPERATORS' POCKET BOOK 
 
 a careful study is made of the diagrams, the operator 
 will find every instrument in his station within easy 
 reach of his hand. Variations may sometimes be 
 advantageous under special circumstances, but for 
 ordinary use experience has shown the placing of every 
 instrument as shown in the diagrams. 
 
 Fire Underwriters' Rules. Following are the regu- 
 lations regarding the matter issued by the Fire Under- 
 writers: 
 
 In setting up wireless telegraph apparatus (so called), 
 all wiring within the building must conform to the 
 rules and requirements of the National Board of Fire 
 Underwriters governing the class of work installed and 
 the following additional specifications: 
 
 I. Aerial conductors to be permanently and effec- 
 tively grounded at all times, when station is not in 
 operation, by a conductor not smaller than no. 4 B. & 
 S. Gauge copper wire run in a direct line to a water- 
 pipe, at a point on the street side of all connections to 
 said water-pipe within the premises; or to some other 
 equally satisfactory earth connection. 
 
 II. Aerial conductors when grounded as above 
 specified must be effectually cut off from all apparatus 
 within the building. 
 
 III. Or the aerial to be permanently connected at 
 all times to earth in the manner specified above, through 
 a short gap or lightning arrester; said arrester to have 
 a gap of not over .015 of an inch between brass or 
 copper plates not less than i\ inches the other way with 
 
PROTECTION AND INSTALLATION 89 
 
 a thickness of not less than f of an inch mounted upon 
 non-combustible non-absorptive insulating material 
 of such dimensions as to give ample strength. Other 
 approved arresters of equally low resistance and equally 
 substantial construction may be used. 
 
 IV. In cases where the aerial is grounded as specified 
 in no. I, the switch employed to join the aerial to the 
 ground connection shall not be smaller than a standard 
 loo-ampere jack-knife switch. 
 
 V. Notice of wiring done for these installations 
 should be sent to the board, the same as for all other 
 electrical work. 
 
CHAPTER VIII 
 
 OPERATION OF A STATION 
 
 IF good care is taken of a station, it will generally 
 work to its highest advantage. The operator should 
 see that his apparatus is carefully handled at all times 
 and that his transmitting apparatus is always in 
 proper resonance. This chapter will take up not only 
 general questions of care of instruments, but it will 
 deal with tuning devices suitable both for fine appa- 
 ratus and for the more inexpensive instruments. Hints 
 on the improvement of a station's working will be no 
 small part of this chapter's interest, and in this 
 respect we are now coming to what is perhaps the most 
 important part of the subject. 
 
 No general suggestions can apply both to transmit- 
 ting and receiving apparatus, since the range of distance 
 covered by the two is always different: Therefore 
 we shall take up the two in turn, dealing with the 
 separate parts of our subject-matter first as applied 
 to sending and then to receiving. 
 
 Transmitting Apparatus. The working of the station 
 depends largely upon the care that is taken of it, and 
 for that reason apparatus should at all times be kept 
 
 90 
 
OPERATION OF A STATION 91 
 
 free from dust. This is especially true of all spark 
 gaps, the large one used for transmitting, and all small 
 protective gaps. If dust collects between the sparking 
 surfaces, it acts as a conductor, the gap is short- 
 circuited, and then the fuses blow or burn out. Once 
 the adjustments of the spark gaps are made, these 
 should be boxed in and left alone. Wherever also 
 there are small contact points, as in the vibrator or 
 key, a particle of dust may cause considerable trouble. 
 
 Operation of transmitting apparatus does not lie in 
 the manipulation of the key so much as in tuning up 
 the helix or condenser. This tuning up of the apparatus 
 brings the helix into resonance with the aerial and with 
 the condenser. It is the most important factor in 
 operation and is one requiring skill and experience. 
 
 The theory of resonating or tuning up the trans- 
 mitting apparatus is as follows: The helix has three 
 contacts, a ground connection, which should be sta- 
 tionary, and two variable connections, one in series 
 with condenser and spark gap, another leading to the 
 aerial (see Fig. 55). The helix is thus divided into 
 two parts or inductive fields, one included between 
 ground and condenser, the other between -ground and 
 aerial. These are called inductances (L 1 and L 2 ). The 
 aerial ordinarily acts as a condenser so that now we 
 have two groups or circuits, consisting, in the first 
 place of the aerial condenser (C 2 ) and helix inductance 
 (L 2 ), which act as a secondary; in the second place of 
 the condenser (C 1 ) and the inductance (L 1 ), which act 
 
92 WIRELESS OPERATORS' POCKET BOOK 
 
 as a primary. These two circuits must be equalized 
 to secure good results, i.e. 
 
 C 2 xL 2 = C l xL\ 
 secondary primary 
 
 Bringing this condition about by manipulating the 
 helix contacts is called tuning. 
 
 The variation in the condenser (C 1 ) and helix (L l ) 
 necessary to secure the same value as the aerial (C 2 ) 
 
 n 
 
 u 
 
 FIG. 
 
 and inductance (L 2 ) may be done theoretically either 
 in the condenser or in the helix. Practically, however, 
 it is so much easier to move the helix contacts than to 
 cut tinfoil off the condenser plates that the helix is 
 almost always made variable, the condenser stationary. 
 Further, it is necessary to notice that the relative 
 position in the circuit of spark gap and condenser is 
 unimportant and may be changed. 
 
 There are several methods of tuning both with the 
 helix and with the oscillation transformer. Two spe- 
 
OPERATION OF A STATION 93 
 
 cial instruments are used in tuning, the Geissler tube 
 and the hot-wire ammeter, the latter being the more 
 efficient. 
 
 The Geissler Tube is a glass tube, in both ends of 
 which are sealed electrodes, generally of platinum. 
 The air in the tube being exhausted or nearly so, a 
 spark will readily jump between the metal electrodes 
 in the rarified air. If a slight current is passed through, 
 a faint light is diffused throughout the tube. Increase 
 in its light marks the passage of a stronger current, 
 
 F I D. $-4 
 
 and the maximum brilliancy marks the highest point 
 of a high frequency current. A Geissler tube of plain 
 design is shown in Fig. 56. 
 
 The Hot-wire Ammeter is a much more delicate 
 instrument. It depends upon the fact that a German 
 silver wire will expand when heated even slightly. 
 A simple form is shown in Fig. 57, but all such instru- 
 ments work on variations of the same principle. A 
 German silver wire is stretched between two points 
 (A and B), to the middle of which is attached another 
 wire connected to the end of a fine aluminum needle 
 (D). This needle turns on a pivot or fulcrum (F) and 
 
94 WIRELESS OPERATORS' POCKET BOOK 
 
 is shown on the dial scale (E). Now if the instru- 
 ment is connected in an electrical circuit, a slight 
 current passing through (A) and (B) expands the g.s. 
 wire, which lets down the wire (C) and causes the 
 aluminum needle (D) to deflect from the point of 
 
 equilibrium (o). Where the needle shows the greatest 
 deflection will be the point of greatest current strength. 
 Since the ammeter is very delicate, a variable resist- 
 ance should be shunted across it, to prevent burning 
 out the wire. 
 
 The first step in tuning is to move the condenser 
 clip (B) on the helix until a desired wave length 
 is obtained. Thereafter this clip will remain fixed. 
 
OPERATION OF A STATION 
 
 95 
 
 Across the helix, between helix and aerial, is now placed 
 this Geissler tube, which shows by its point of greatest 
 brilliancy the exact position for the clip (A).. When 
 
 AER IAL 
 
 n 
 
 F I G .,TS 
 
 tuning-in the circuit, the light in the tube may be 
 lessened in intensity by decreasing the spark gap. 
 By moving the aerial clip (A) on the helix, with a faint 
 light in the Geissler tube, it will be easy to find the 
 point where a perfect balance occurs, by the maximum 
 
 brilliancy of the tube. This is the point of finest 
 tuning or resonance. 
 
 A second method of tuning the helix, by using a 
 hot-wire ammeter, is better and more exact (Fig. 59). 
 
96 WIRELESS OPERATORS' POCKET BOOK 
 
 The ammeter should be placed in the ground circuit, 
 or between ground and aerial, the former method 
 being preferred because the apparatus can then be 
 handled if necessary. This would not be so if it were 
 in the aerial. First fix the wave length desired by the 
 condenser clip (B). Then by moving the aerial clip 
 
 (A) up and down the helix, we find different degrees of 
 deflection in our ammeter needle. Where that deflec- 
 tion is greatest, the current is strongest, and there we 
 will place clip (A). It should be noted in both cases 
 where tuning up with a helix that either clip (A) or (B) 
 may be used to determine the wave length, the varia- 
 tion being made by the other clip. 
 
 With the oscillation transformer the use of tuning 
 instruments is much the same. However, it is possible 
 to secure resonance by the aid of a small auxiliary 
 spark gap, and without special instruments when a 
 transformer is used in place of the helix. This method 
 is shown in Fig. 60. In tuning the oscillation trans- 
 former, a test spark gap is placed across the secondary, 
 i.e. between aerial and ground. The condenser clip 
 
 (B) on the primary of the transformer sets the wave 
 length. The secondary is tuned with the aerial clip 
 (A). By operating the key, and at the same time 
 watching the discharges at the auxiliary spark gap, 
 we will find where they are most rapid. In repeating 
 the process the point, of highest resonance may be 
 found. This method of tuning is, however, by no 
 means easy, and considerable quickness is required to 
 
OPERATION OF A STATION 
 
 97 
 
 count the dots of the key and at the same time note 
 the discharges at the gap. It is advisable only because 
 of the simplicity of the instruments. 
 
 When using the Geissler tube with an oscillation 
 transformer, it should be placed in exactly the same 
 position as the auxiliary spark gap shown in Fig. 60. 
 
 The maximum brilliancy will show the point of highest 
 resonance for the secondary, the primary determining 
 the wave length by the condenser clip (B). 
 
 The hot-wire ammeter is placed in the ground 
 circuit connected with the primary of the oscillation 
 transformer and is used in the same way as with the 
 helix, the condenser clip (B) setting the wave length 
 as in previous examples. 
 
 Still a third method of tuning up is as follows: An 
 
98 
 
 WIRELESS OPERATORS 1 POCKET BOOK 
 
 ordinary ij-volt Tungsten lamp placed in the ground 
 circuit is bridged with a variable resistance. As you 
 press the key and at the same time vary the resistance, 
 the point of brightest light having the lowest resistance 
 
 FIG. 61 
 
 will show best value of balance and the best position 
 for clip (A). 
 
 The coupling between primary and secondary should 
 be carefully regulated, so that the two coils be far 
 enough apart to secure sharp tuning, and at the same 
 time be near enough to prevent too great loss of energy. 
 If the two coils are too far apart, they will lose part 
 of the inductive effect upon each other; that is, they 
 will be out of inductive range. If they are too near 
 
OPERATION OF A STATION 
 
 99 
 
 together the secondary's reactance on the primary will 
 cause a hump in the wave, and two points of tuning 
 will be the result, the stronger point representing the 
 main tuning point, and the weaker one showing the 
 split or division of energy. 
 
 With the transmitting instruments perfectly tuned, 
 
 L 
 
 VERY SMALL 
 "RESISTANCE 
 
 FID. 
 
 \1 VOLT 
 TUN GSTE.N 
 
 it is necessary only to manipulate the key quickly 
 and easily. This is, of course, largely a matter of 
 quickness of movement and practice. The matter of 
 the various codes now in use will be further discussed 
 in Chapter X. 
 
 Receiving Apparatus. The operation of receiving 
 apparatus consists principally of bringing the instru- 
 
100 WIRELESS OPERATORS' POCKET BOOK 
 
 ments into resonance with those of a transmitting 
 station whose messages we desire to receive. In 
 theory the tuning of receiving apparatus is the com- 
 plement of that of transmitting. Waves of a certain 
 length are sent out from the transmitting station, and 
 the receiving station must be able to catch them on 
 its aerial acting again as a condenser. The tuning 
 coil, acting as an inductance, is joined with the aerial 
 and enough additional condenser value to balance the 
 incoming waves. This condenser value may be sup- 
 plied by variable or fixed condensers added to the 
 circuit. 
 
 Operation of the receiving apparatus includes the 
 manipulation of tuning coils and oscillation trans- 
 former, of the variable condenser, and of the detector 
 in order to secure the correct amount of inductance 
 and capacity (aerial condenser and coil inductance) 
 to receive the incoming waves. This manipulation 
 depends upon the type of coil, so that it seems best to 
 consider the tuning of each one independently. In 
 general, it may be said that the slides of the coil or 
 the oscillation transformer should first be brought 
 roughly into tune with the station sending, then the 
 variable condenser should be brought to the point of 
 highest resonance before adjusting the detector. 
 
 The Single Slide Tuning Coil is most frequently 
 used without a variable condenser. Under such cir- 
 cumstances there is only one movement to be made, 
 one slide to be moved. (Fig. 63.) 
 
OPERATION OF A 
 
 101 
 
 The Double Slide Coil should be used with a variable 
 condenser, although of course fair results may be 
 obtained without. The clips are lettered (A) and (B). 
 A rough adjustment is found with (A), and this is made 
 more sharp by (B). The last and finest adjustment is 
 made with the variable condenser (VC). (Fig. 64.) 
 
 The Three Slide Tuning Coil has an effect similar 
 to the Loose-coupled coil, but it is not so selective; i.e. 
 it will not bring in one station without interference 
 so well as the latter. In Fig. 65 are shown the three 
 slides; the ground clip (A), between which and the 
 aerial is formed a primary circuit; the distance be- 
 tween clips (B) and (C) forming the secondary circuit, 
 while the coupling is regulated by varying the distance 
 
102 WIRELESS OPERATORS' POCKETBOOK 
 
 between (A) and (BC). The first adjustment, which is 
 only approximate, is obtained with (A). Then a more 
 careful tuning is secured by moving (B) and (C) to- 
 gether. The finest adjustment is then made with the 
 variable condenser (VC). Finally a closer adjustment 
 
 of (A) may be made, and this completes the tuning 
 of the circuit. 
 
 The Loose-coupled Tuning Coil or Receiving Oscillation 
 Transformer is much more delicate in its adjustment 
 than any other and is far more easily manipulated. 
 It is the only tuning device to be recommended for 
 good work. The first thing is to obtain the desired 
 station roughly with the slide (A) on the primary. 
 Then the switch (B) on the secondary should be varied, 
 
OPERATION OF A STATION 
 
 103 
 
 followed by the regulation of the coupling (K) between 
 the two coils. After this the variable condenser will 
 be adjusted. And finally a further fine variation on 
 the primary will give us the greatest strength of 
 signals. 
 
 The Use of Two Receiving Oscillation Transformers: 
 The Weeding-out Circuit. By placing a second oscilla- 
 
 tion transformer in series with the first one (see Fig. 
 67), greater selectivity still can be obtained, although 
 at some slight loss of energy in the strength of signals. 
 The first adjustment is made on the primary (A). 
 Then either (C) or (B) should be moved and a finer 
 balance found with the variable condenser (D). The 
 slide (E) on the secondary is then regulated to balance 
 this coil with the previous ones, by an additional 
 
104 WIRELESS OPERATORS' POCKET-BOOK 
 
 movement of the second variable condenser (F). The 
 tuning is so sharp in this circuit that it is necessary 
 to go over the manipulation of these variations a second 
 and even a third time to secure the greatest value. 
 
 A Tertiary Weeding-out Circuit is occasionally 
 used for extreme cases, but the increased loss of energy 
 is a serious drawback to its usefulness, except where 
 
 interference is unusually bad. Adjustment is made 
 by the same routine as in the first weeding-out circuit, 
 with the addition of another oscillation transformer 
 and variable condenser. The circuit is shown in the 
 chapter on diagrams. 
 
 The Detector will be used in every case, as the last 
 and final adjustment. If the surface of the mineral 
 in a silicon or perikon detector be covered with a thin 
 film of Atlas Oil No. 2, its action will be increased and 
 the mineral's rectifying qualities will be preserved. 
 
OPERATION OF A STATION 
 
 105 
 
 Some of the perikon detectors now in use by the 
 government show the mineral entirely immersed in 
 oil, and this form has given great satisfaction when 
 used. Molybdenite, which occurs in closely packed 
 layers, should have a sharp knife-edge resting against 
 the cross-section of these layers. Good silicon should 
 
 & 
 
 be free from flaws. An artificial or polished surface 
 is the best for contact with a spear-point. The oval 
 fractures of iron pyrites or pyrop should come in con- 
 tact with a spear-point such as is used for silicon. 
 There are several kinds of zincite, only one of which 
 is good for use in perikon detectors. This occurs in 
 layers of some thickness, which should be turned edge- 
 wise in contact with a sharply pointed piece of bornite, 
 both of these minerals being used in their natural 
 
106 WIRELESS OPERATORS' POCKET BOOK 
 
 fractures. By adjusting the detector carefully, testing 
 meanwhile with a buzzer, the most sensitive point 
 may be found; and this, as we have already stated, 
 should be retained as long as possible. 
 
 Adjustment and operation of both sending and 
 receiving apparatus is of the highest importance for 
 good results in wireless. The importance of careful- 
 ness and fine manipulation cannot be over-emphasized. 
 Recognition of this and the skill, which are learned only 
 after considerable experience, show the division be- 
 tween the real operator and the amateur, in the worst 
 sense of the word. 
 
CHAPTER IX 
 
 BREAKING-IN SYSTEMS! METHODS OF SIMULTANEOUS 
 RECEIVING AND TRANSMITTING 
 
 IN transmitting wireless signals we have always 
 the sending station, from whose aerial are sent out 
 waves of a definite length in every direction. Now 
 it is as easy to receive such signals to the north as to 
 the south of the station, the only limitations being 
 caused by the limits of power of the sending station's 
 electrical apparatus and its distance from the receiving 
 station. Thus all wireless messages are sent out in 
 circles around the transmitting aerial. If there are 
 many such stations close together, the result would be 
 pandemonium but for the fact that sending stations 
 may regulate their wave lengths and thus avoid inter- 
 ference to some extent. It has long been the ideal of 
 wireless experiment to find some method by which 
 the receiving station may be tuned in to a certain 
 sending station, regardless of the fact that other sta- 
 tions nearer at hand and perhaps of greater power 
 were sending at the same time. To some extent this 
 differential tuning is now possible, but only in cases 
 where waves of very different lengths are coming in 
 107 
 
108 WIRELESS OPERATORS' POCKET BOOK 
 
 at the same time. For instance, if the Marconi 
 Station (Cape Cod, Mass., with a wave length of 1800) 
 is sending at the same time as the Charlestown, Mass., 
 Navy Yard (at a wave length of from 320 to 560), 
 a receiving station in Boston will be able to cut out 
 one or the other, provided he has a Loose-coupled 
 Tuning Coil. But if the Navy Yard is sending at the 
 same time as the Board of Trade Building, Boston 
 
 HAND THROW SWITCH 
 
 (about 700 metres wave length), it will be almost 
 impossible to tune the stronger station out and re- 
 ceive only the weaker one. 
 
 If tuning devices can ever be brought to the per- 
 fection necessary to secure such fine tuning readily, 
 every wireless man will be glad. But meanwhile we 
 have a present condition of affairs, and what can be 
 done to obviate interference or make it less annoying 
 is every man's quest. Breaking-in Systems, while not 
 yet generally popular, seem destined to supply this 
 
BREAKING-IN SYSTEMS 
 
 109 
 
 need, and are increasingly used every day. If they 
 do not prevent interference, they at any rate make it 
 impossible except consciously. 
 
 The Breaking-in System is a method of simultaneous 
 transmitting and receiving wireless signals; that is, 
 a device is placed between the sending and receiving 
 sets so that the operator may receive incoming signals 
 even while he is sending them out. This device con- 
 
 SI/^XPLE BRE.AK KE.Y 
 Fl G. 6r 
 
 sists usually of some attachment to the key which 
 automatically switches in the transmitting circuit 
 every time the key is pressed, and also automatically 
 switches in the receiving circuit every time the key is 
 released, even between the dots and dashes of the code. 
 Its advantages are more or less obvious to every 
 operator. To the government or any commercial 
 station, the breaking-in system has the advantage that 
 if serious interference occurs in the course of a long 
 message, that fact may be signalled to the sending 
 operator. Thus the latter will stop until elimination 
 
110 WIRELESS OPERATORS' POCKET BOOK 
 
 of the interference, and so save the time and current 
 which would otherwise be used in completing a message 
 which the receiving station could not pick up. On 
 the other hand, a breaking-in system will notify an 
 experimenter or private operator when more important 
 
 F I &. 69 
 
 stations are sending. He will, as a matter of course, 
 stop sending with wave lengths near those of the 
 professional stations, and thus will cease to make him- 
 self a nuisance and a subject for hostile legislation. 
 
 Methods of breaking-in are determined partly of 
 course by personal choice, but much more by the 
 power of the transmitting apparatus. Thus we will 
 take up three or four of the best ways, appropriate 
 for different sizes of instruments. 
 
BREAKING-IN SYSTEMS 
 
 111 
 
112 WIRELESS OPERATORS' POCKET BOOK 
 
 For a One-inch Spark Coil a simple mechanical 
 device is all that is necessary. Such an arrangement 
 is shown in Fig. 68. It consists of a short strip of f 
 inch fibre, half an inch wide and four inches long, and 
 an adjustable contact (A) below which is a stationary 
 contact (B). Fig. 69 shows this key in the circuit. 
 When the key is at rest, contact (A) will be on contact 
 (B), thus connecting the. aerial with the receiving set. 
 On pressing the key (K), the contact (A) is raised away 
 from (B), breaking the receiving circuit. Then contact 
 (C) touches (D) and completes the transmitting circuit. 
 The device must be adjusted so that the connection of 
 (A) and (B) will be broken before (C) touches (D), 
 otherwise the current will pass into the receiving 
 set, breaking down the detector and disturbing the 
 operator. A small auxiliary spark gap (E) between 
 helix and aerial connects the latter with the transmit- 
 ting set when the key is closed and insulates it from 
 the same set when the key is open. 
 
 For a Two-inch Coil this method would be inade- 
 quate. An electrical device like that shown in Fig. 70 
 is, however, suitable for such a coil or one somewhat 
 larger. This break consists of an insulating rod (B) 
 supported in the centre. The aerial is connected to con- 
 tacts (C) and (D) on either end of the rod. A spring 
 (E) holds the rod down at one end, the receiving end, 
 where the circuit is made through contacts (D) and 
 (F.) The opposite end of the rod may be pulled down 
 by an electro-magnet (H) operating on an armature (J). 
 
BREAKING-IN SYSTEMS 
 
 113 
 
114 WIRELESS OPERATORS' POCKETBOOK 
 
 When this end of the rod is brought down, three things 
 occur: the contact (D) and (F) is broken, and contact 
 is made between (C) and (L), and (M) and (N). Fig. 
 71 shows this device in the circuit. With the key at 
 rest, the spring (E) holds the contact (D) on (F), thus 
 connecting the aerial with the receiving set; the con- 
 tacts (MN) and (CL) being open and consequently cut- 
 ting out the transmitting set. If the key (K) is pressed, 
 it operates the magnets (H) through the local circuit. 
 Then this magnet, acting on the armature (J), reverses 
 the pull on the rod. Now contact at (D) and (F) is 
 broken, and the receiving side is cut out. Meanwhile 
 connection is made between (M) and (N), and this 
 turns on the primary current, and the aerial is con- 
 nected to the transmitting side through the contacts 
 (C) and (L). This break must be adjusted so that 
 the contacts (D) and (F) be broken, and those of (C) 
 and (L) made before that made at (MN); otherwise 
 the same results as those previously mentioned will 
 follow, and the operator will receive a shock. 
 
 For Transmitting Stations up to i kw. a form of 
 break permitting greater insulation is necessary, and 
 another variation of electrical device has been arranged 
 especially for small transformers. By the addition 
 of more insulation and certain protective devices this 
 break may be used up to 2 kw. 
 
 In the break (Fig. 72) as adapted for a i-kw. trans- 
 former the following description holds good. The 
 key (K) has two sets of contacts (AB and CD), of 
 
BREAKING-IN SYSTEMS 
 
 115 
 
116 WIRELESS OPERATORS' POCKETBOOK 
 
 which the latter are very heavy. When the key is 
 at rest neither of these contacts is closed, but the aerial 
 is connected directly with the receiving side. When 
 the key (K) is pressed, the local circuit is closed 
 through the relay (R), thus grounding the secondary 
 of the oscillation transformer through the relay con- 
 tacts (E). The contact (CD) being formed, closes the 
 primary circuit and operates the transformer. It is 
 necessary, as in previous examples, that contact (AB) 
 be made before (CD), and for the same reason. An 
 adjustable protective spark gap (F), consisting of two 
 knife-edged brass plates mounted on hard rubber 
 blocks, is placed across the relay contacts (E) for pro- 
 tection to the operator in case the contact (CD) should 
 be made before (AB). 
 
 For Stations of 5 kw. the great current requires very 
 complete protective devices, and it is especially neces- 
 sary that the adjustment of the detector be protected 
 from the influence of the powerful transformer. 
 
 This form of break is shown in Fig. 73. When key 
 (K) is at rest, the contacts (AB) and (CD) leading to the 
 transmitting circuit are open, and the aerial is connected 
 to the receiving set through the contacts (EF). When 
 the key is pressed, contacts (AB) close the local relay 
 circuit, thus grounding the aerial by contacts (FH) and 
 protecting the detector by the relays (R^R 2 ). Just 
 afterwards, (CD) being closed, completes the primary 
 of the transmitting circuit. Contacts (AB) should be 
 made before those of (CD) or some of the transmitting 
 
BREAKING-IN SYSTEMS 
 
 117 
 
118 WIRELESS OPERATORS' POCKETBOOK 
 
 current will jump the contacts (EF) and enter the 
 receiving set. However, the knife-edged protective 
 spark gaps (JJ), previously described, are used to 
 prevent this in some measure. 
 
 Great care should be taken to protect the detector 
 in all stations of over i-kw. capacity. Even the 
 pyron and perikon-elektra detectors (whose stability 
 is great) will not retain their most sensitive points 
 beside transmitting stations of this size. A protective 
 device for a detector is shown in Fig. 74. This consists 
 of a relay operating a double pole, double throw switch 
 to cut the detector out of the circuit entirely when 
 sending. At the same time the switch closes the 
 receiving circuit so that no influence will be directed 
 upon the detector, which is screened by a metallic box 
 (E) having two leads (AD) insulated by hard rubber 
 bushings (JJ). The connections (AD) project beyond 
 the bushings about a quarter of an inch to serve as 
 contact points in the relay device. This relay device 
 consists of a magnet (M) which acts on an armature 
 (H) supporting two contacts (BE) which are insulated 
 from each other by a hard rubber standard (K). Two 
 adjustable contact points (C and F) are placed to 
 make contact with (BE) when the key is pressed. Then 
 these points are strapped together or short-circuited. 
 The operation of the break is thus simply explained. 
 If the key is at rest, the magnet (M) is dead, so 
 the spring will hold the contacts (DE) and (AB) 
 closed, connecting the detector in the receiving circuit. 
 
BREAKING-IN SYSTEMS 
 
 119 
 
120 WIRELESS OPERATORS 9 POCKETBOOK 
 
 If, on the other hand, the key is pressed, it will close 
 the local circuit and excite the magnet (M). This 
 pulls the armature (H) forward, disconnecting the 
 detector and closing the receiving circuit by contacts 
 <B and C) and (E and F). These actions break the 
 detector from the circuit and leave it screened or pro- 
 tected from the powerful electrical discharges of the 
 transmitting apparatus. At the same time the receiv- 
 ing circuit is closed and this prevents any influence 
 upon the points (AD) which might occur if the contacts 
 (BE) were open and not closed by CF. 
 
 When the silicon or perikon detectors (zincite and 
 bornite type) are used, it will be necessary always to 
 use this protective device shown in Fig. 74, the 
 stability of these detectors being poor as compared 
 with the sealed point electrolytic, pyron, and perikon- 
 elektra detectors. Any of these latter forms may be 
 used on stations up to i kw. without any protection 
 except a relay to short-circuit them. 
 
 Some of these last diagrams may seem complicated. 
 When the reader, however, stops to think of the prob- 
 lem of switching the aerial between transmitting and 
 receiving, while at the same time protecting himself 
 and the instruments with a single movement of the 
 key, he will understand why such care is taken. It is 
 also necessary that the break work quickly enough to 
 allow incoming signals to be heard even between the 
 dots and dashes of an outgoing message. 
 
CHAPTER X 
 
 CODES 
 
 CODES are merely generally recognized systems of 
 short and long signals, "dots and dashes," arranged to 
 correspond with the letters of the alphabet, numerals, 
 and punctuation marks. By means of these "dots 
 and dashes'," a sending operator is enabled to spell out 
 messages to a receiving operator. As codes are only 
 arbitrary agreements, it might be possible to have 
 as many as there are operators or sets of operators, 
 and every one could use a different one. In practice, 
 however, it has been found convenient to use certain 
 generally recognized systems, which become as familiar 
 as a language to every telegraph operator. 
 
 There are three of these systems in general use in 
 America the American Morse, the Continental, and 
 the Naval Codes. The most popular in America is 
 the Morse, although the Continental is used to a con- 
 siderable extent, especially in wireless telegraphy. The 
 Continental Code is generally used in Europe, and 
 in England is called the Morse, while that code called 
 Morse in America is spoken of as the American Morse. 
 The Naval Code is used officially by the American 
 Navy, but is surpassed in popularity by both the other 
 
 121 
 
122 WIRELESS OPERATORS' POCKETBOOK 
 
 codes even in the Navy. The Continental and the 
 
 Naval Codes have one point of similarity in that 
 
 none 
 
 of 
 
 their letters are spaced (i.e. include spaces as 
 
 well 
 
 as 
 
 dots and dashes), as does the Morse. The 
 
 three 
 
 are shown together on the following pages. 
 
 
 THE CODES 
 
 
 
 MORSE CONTINENTAL NAVY 
 
 
 A 
 
 . A ,_ A 
 
 
 B 
 
 B B 
 
 
 C 
 
 .. . C C ._. 
 
 
 D 
 
 D D 
 
 
 E 
 
 E . E ._ 
 
 
 F 
 
 ._. F F 
 
 
 G 
 
 G G 
 
 
 H 
 
 H .... H 
 
 
 I 
 
 I .. I . 
 
 
 J 
 
 J J 
 
 
 K 
 
 K K 
 
 
 L 
 
 L L 
 
 
 M 
 
 M M 
 
 
 N 
 
 N N .. 
 
 
 O 
 
 . . __. 
 
 
 p 
 
 P P 
 
 
 Q 
 
 Q Q ._.. 
 
 
 R 
 
 . .. R ._. R _.. 
 
 
 S 
 
 S ... S 
 
 
 T 
 
 _ T _ T _ 
 
 
 U 
 
 . U ..__ U . 
 
 
 V 
 
 V V 
 
 
 W 
 
 W W 
 
 
 X 
 
 X X 
 
 
 Y 
 
 .. Y __ Y 
 
 
 Z 
 
 ..VT z z 
 
 
CODES 123 
 
 1 i i 
 
 2 2 2 
 
 3 3 3 
 
 4 4 4 
 
 5 5 5 
 
 6 6 6 
 
 7 . 7 7 
 
 8 8 8 
 
 9 9 9 
 
 o o o 
 
 ;==r. H 
 
 V? ~"~ 
 
 The first necessity for an operator is, of course, to 
 learn thoroughly some one of these codes. As the 
 Morse is so much the more popular, we shall take that 
 for illustrative material, although similar groupings 
 may be made of the Continental. Fig. 76 gives a 
 convenient grouping of the characters which adds to 
 quick memorizing, and acts as an aid to the memory 
 as long as such an aid is of use. 
 
 A CONVENIENT GROUPING OF MORSE CHARACTERS 
 The Dot . E The Dash T 
 
 ALL DOTS 
 CEHIOP R Y Z 6 
 
124 WIRELESS OPERATORS' POCKET BOOK 
 
 ALL DASHES 
 L M T 5 o 
 
 SPACED LETTERS 
 CORY 
 
 FOR MEMORIZING 
 EISHP 6TL 
 
 DASH FOLLOWED BY DOTS 
 N D B 8 
 
 DOTS FOLLOWED BY DASH 
 A U V 4 
 
 CONTRASTING CHARACTERS 
 AN BV CR DU FK GW J, QX 
 
 i ! ! I : ; .' i i .' ! i ! i i i 
 
 : i i ! i i i ! : 
 
 Since every word in telegraphy must be spelled out, 
 certain abbreviations have become generally recognized 
 both in wire and wireless telegraphy. These abbrevia- 
 tions most used in ordinary telegraphy have usually 
 been adopted in wireless, but there are additions, like 
 the famous C. Q. D. (S. O. S.), for special wireless needs. 
 The use of these saves considerable time, and the opera- 
 
CODES 
 
 125 
 
 tor should learn to use them. Every line of business 
 
 has special signs used frequently in its own business. 
 We include here, however, only the general abbre- 
 viations, and the operator will make his own special 
 additions. 
 
 ABBREVIATIONS 
 
 3 or 30 Finish signal 
 
 73 Accept my compliments. 
 
 ANS Answer 
 
 BK Break 
 
 CK Check 
 
 DH Free 
 
 FM From 
 
 GA Go ahead 
 
 GE Good evening 
 
 GM Good morning 
 
 GN Good night 
 
 HR Another message 
 
 IMPT. Important 
 
 MIN. Minute 
 
 NM No more 
 
 NO Number 
 
 OFM Official message (used only by the navy). 
 
 OK or II All right 
 
 OFCorOFS Office 
 
 OPR Operator 
 
 PD Paid (generally in full). 
 
 QN and .QJ Beginning and ending of quotations. 
 
 SIG Signature 
 
 SOS International distress signal. 
 
 SVC Service 
 
 V Test letter. 
 
 X or 99 Interference. 
 
126 WIRELESS OPERATORS 1 POCKETBOOK 
 
 In operating a wireless station, certain forms of 
 messages are absolutely necessary; and in general 
 practice commercial stations have adopted those forms 
 used by the ordinary telegraph companies. Variations 
 are, of course, required, and the following message-form 
 (Fig. 77) will answer the needs of any commercial 
 wireless station. 
 
 Such a form, however, is rather more elaborate 
 than experimenters will ordinarily require for private 
 signalling. For such operators, nevertheless, some 
 formality is advantageous, and a simple question and 
 answer form like the following may be adapted to 
 personal needs. 
 
 1. Call of station wanted (three times) CN, CN. CN. 
 
 2. Sign call of sending station (once) VA 
 
 3. Finish signal 3 or 30 
 
 RECEIVING OPERATOR 
 
 a. call of sending station (three times) VA, VA, VA. 
 
 b. Sign call of receiving station (once) CN. 
 
 c. All right OK. OK. 
 
 d. Go ahead GA . GA . 
 
 e. Call of sending station (once) V A 
 
 f. Sign call of receiving station C N 
 
 g. Finish signal J or 30 
 
 SENDING OPERATOR 
 
 4. Call of station wanted (three times) CN. CN. CN. 
 
 5. Period (repeated two or three times). . . .Period. Period. 
 
 6. Body of message 
 
 7. Period Period. Period. 
 
CODES 
 
 127 
 
 
 S 
 
 X 
 
 Vi 
 
 ' d 
 
 o 
 
 g 
 
 1 
 
 M 9 
 
 M 
 
 tu 
 
 N 
 
 ! 
 
 C/5 
 
 1 
 
 S H 
 
 1 
 
 S 
 
 fc 
 
 
 | 
 
 W 
 
 a 
 
 E?l 
 
 CO 
 
 @ 
 
 w 
 
 M 
 
 O 
 
 H- 
 
 J 
 
 n 
 
 o* 5 
 
 n 
 
 ^ !?* en 
 x 
 
 ?l 
 
 o 
 
 p 
 
 3 
 
 O. 
 
 - 
 C3 OQ 
 
 
 I' 
 
 r H 
 
 p 3 
 
 * S 
 
 Q O 
 
 W 
 
 C-(Ti 
 
 K 
 
 s" >i 
 
 
 w 
 
 
 ^ ^ 
 
 ? ^ 
 
 > 
 
 1 '* - 
 
 H 
 
 ni o^ ^ 
 
 ^^ ^ 
 
 Co "^ 
 
 ^ <j 
 
 & 
 
 ^ 
 
 HR = Message 
 
 i Number of Message 
 SN = Sending Station's Call 
 
 F S = Sending Operator's Sign 
 
 S Y = Receiving Operator's Call. 
 To be filled after the message 
 is copied 
 
 Ck = Check 
 
 7 = Number of words in body of 
 message 
 
 Paid = The message may be either 
 paid, collect, or service. 
 
 Time = To be filled in by receiving 
 operator, after the message 
 is copied 
 
 If message is relayed 
 
 FIG. 77 
 
128 WIRELESS OPERATORS' POCKET BOOK 
 
 8. Sign call of sending station V A. 
 
 9. Finish signal 3 or 30 
 
 RECEIVING OPERATOR 
 
 h. All right. (If message is received and understood} 
 
 OK. OK. 
 
 i. Call of sending station V A. V A- 
 
 j. Sign call of receiving station C N. C N. 
 
 k. Finish signal 3 or 30 
 
 or, 
 
 Question (if message is not understood and must be repeated} 
 
 DN.DN. 
 
 i. Call of sending station V A. V A. 
 
 j. Sign call of receiving station C. N. C N. 
 
 k. Finish signal 3 or 30 
 
 SENDING OPERATOR 
 
 10. All right (sending operator will repeat) O K. O K. 
 
 11. Call of receiving station CN. CN. 
 
 12. Sign call of sending station V A. 
 
 13. Period Period 
 
 14. Repeats body of message, and ends as before (8, 9) 
 
CHAPTER XI 
 
 THE ETIQUETTE OF WIRELESS AND THE SUBJECT 
 OF INTERFERENCE 
 
 THE air is free to all, or at any rate it has been 
 thought so until discussion upon wireless interference 
 has become of importance. Now we have the knowl- 
 edge that in England a license fee is charged, for the 
 use of the air presumably, whenever a wireless station 
 for transmitting is installed. Many bills on the same 
 subject have been proposed in America, but up to the 
 time of printing, without result. 
 
 There is, moreover, some justice on the part of those 
 who wish to limit the use of the air in this way. Since 
 the loudness of signals depends upon the power of 
 the transmitting instruments and the distance to be 
 covered, it is possible for private persons and com- 
 mercial companies to monopolize the space in certain 
 vicinities, so that a most important government mes- 
 sage cannot be received. It is, of course, to be under- 
 stood that the government should have right of way, 
 not only in the roads, but in the air. 
 
 Interference may be of two kinds, unintentional or 
 malicious. In their effect there is no difference; but 
 129 
 
130 ' WIRELESS OPERATORS' POCKET BOOK 
 
 as a matter of fact, it is the unintentional interfer- 
 ence of experimenters unversed in the code, and with- 
 out adequate breaking-in systems, that has given rise 
 to most of the legislation hostile to them. Malicious 
 interference either on the part of an experimenter or, 
 as frequent complaints bear witness, on that of com- 
 mercial stations, should be dealt with as severely as 
 possible. It would seem that license restrictions would 
 be too mild a treatment for such cases, and in all 
 probability a method of dealing with them will be 
 evolved. 
 
 In cases of unintentional interference, there is usually 
 no remedy, as it is by an experimenter, or where the 
 'station is not properly equipped. No person should 
 operate a transmitting set until he has a proper under- 
 standing of the codes, and, if he has no breaking-in 
 system, without listening-in frequently to learn whether 
 other stations are trying to make themselves heard. 
 It is while a station is trying to receive messages from 
 a distant source that interference is most objectionable. 
 While a powerful station near you is sending, a sending 
 station of less power or different wave length may 
 send without troublesome effect; but when it is trying 
 to get signals from a weaker station, or one at some 
 distance, your interference will be most effective and 
 most disastrous. 
 
 There are, however, some methods of overcoming in- 
 terference. If the experimenter will use an oscillation 
 transformer for sending, he will be able to tune his 
 
THE ETIQUETTE OF WIRELESS 131 
 
 apparatus much more sharply. With a sharply tuned 
 wave length, he will be received only by apparatus 
 tuned in with his instruments most exactly. There- 
 fore, if he is from fifty to one hundred metres either 
 above or below the commercial station, he may be 
 tuned out without trouble at the receiving instruments. 
 
 Another method of overcoming interference is by 
 the new duplex system of wireless, where two aerials 
 are used, one for sending and the other for receiving. 
 The shorter aerial is for sending, thus ensuring a short 
 wave length, much below that of the commercial 
 stations. The longer aerial, for receiving, may be as 
 large as is desired or needed, according to the distance 
 to be covered. 
 
 Still another method is by the use of a breaking-in 
 system, which will enable the experimenter to hear 
 distant sending stations when they call, even while he 
 is sending. 
 
 Where interference occurs with the government or 
 commercial stations, a weeding-out or third (tertiary 
 circuit) should be used. This will make the tuning of 
 the receiving instruments twice as sharp as with the 
 ordinary receiving loose-coupled transformer. 
 
wg 
 c* n 
 
 Q Q 
 ^ H 
 
 
 132 
 
CHAPTER XII 
 
 WIRELESS TELEPHONY 
 
 THE Wireless Telephone is not yet a success. Vari- 
 ous interesting experiments have been made on theo- 
 retical principles, and for short distances speech has 
 been transmitted, or at least musical tones have been 
 identified. Much more experiment, however, is neces- 
 sary before it will be possible to use the wireless tele- 
 phone even to the extent that we can now use the 
 wireless telegraph. 
 
 Distances up to a hundred miles have been claimed 
 by some commercial companies, although it is doubt- 
 ful whether, on test, telephone transmission has been 
 made for such a distance. Moreover, the principle 
 now most popular with experimenters (the so-called 
 "arc method") does not promise much more in the 
 matter of distance even under the best of conditions. 
 For short distances, however, the wireless telephone 
 has been used, and speech has been distinctly heard 
 for twenty miles certainly. Any greater distance 
 than this is a matter for proof and speculation. This 
 was done by using the arc method, which will be 
 later described. By the disruptive discharge method, 
 133 
 
134 WIRELESS OPERATORS' POCKETBOOK 
 
 greater distances can easily be covered, but articula- 
 tion is poor. Professor Fessenden's new system prom- 
 ises improvement in both respects. 
 
 The earliest experiments along the line of telephon- 
 ing without wires were devoted to what we now call 
 
 F I &.7S 
 
 the "conductive" method of wireless telephoning. 
 The connecting medium, in this case, is the ground. 
 The diagram (Fig. 78) will show the working of the 
 system. A plate (A) buried about three feet below 
 the surface of the earth is connected through a set 
 of batteries (B) and a telephone transmitter (T) by a 
 highly insulated lead-wire to another plate (J) buried 
 
WIRELESS TELEPHONY 
 
 135 
 
 in the ground at a distance of some fifteen feet. A 
 duplicate arrangement on the receiving side leads from 
 a plate (A') through a receiver (R) to another plate 
 (JO- When a current is set up in the transmitting 
 side, it is conducted by the surface of the earth from 
 A to A'; after passing through the metallic connec- 
 tions to J' it will find its way back again to J, and a 
 circuit will be established. Now if we speak into the 
 transmitter (T), we will vary the current over this 
 
 FIB. 
 
 circuit, and our speech will be heard in the receiver 
 (R). As a matter of fact, the conductive method 
 really amounts to the circuit shown in Fig. 79, the 
 earth forming the connecting medium between both 
 sets of plates. This method will work up to about 
 three miles. 
 
 Another early form of wireless telephony both in 
 point of original experiment and of electrical impor- 
 tance is the Static Telephone. This form, shown in 
 Fig. 80, works on the principle of the condenser. A 
 wire frame or grid, consisting of lines of wire, and 
 having the effect of an almost solid metallic surface, 
 
136 WIRELESS OPERATORS' POCKETBOOK 
 
 is charged through an induction coil by the human 
 voice. This charge on the grid (A) charges a second 
 grid (B), which is connected to a receiver, and the 
 speech is distinctly transmitted by electro-static in- 
 duction. The effect is represented in our second dia- 
 
 -T- F I G. 8 O -T- 
 
 gram (Fig. 81), the two grids acting as the plates of 
 a condenser. This will work up to a half mile. 
 
 Still another form of wireless telephone works on 
 the principle of the induction coil, by electro-magnetic 
 induction. (See Fig. 82.) A loop of heavy copper wire 
 about five feet in diameter, connected to a telephone 
 transmitter of low resistance and a battery, forms the 
 
WIRELESS TELEPHONY 
 
 137 
 
 transmitting side. The receiving end consists of a simi- 
 lar loop of wire attached to a telephone receiver, which 
 should be of the bi-polar type, and must be wound 
 
 with about no. 18 wire. The transmitting side 
 acts as the primary, the distance between the two 
 loops as the magnetic field, and the receiving loop as 
 the secondary of the induction coil. It is to be noted 
 
 that in both instances we are dealing with low resist- 
 ances. This is to avoid the losses of energy caused 
 by a great number of turns of wire in the circuit. For 
 
138 WIRELESS OPERATORS' POCKETBOOK 
 
 the same reason we use heavy loops of wire, a low 
 resistance telephone transmitter and receiver, and 
 batteries in series multiple. The effect of this form of 
 telephone is shown in Fig. 83. This will work up to 
 three or four miles. 
 
 The smaller illustrative diagrams (Figs. 79, 81, and 
 83) show in graphic manner that no one of these 
 methods of telephony depends upon the action of the 
 high-frequency waves used in wireless telegraphy. In 
 each of these methods the plates must be arranged in 
 
 F t & . 83 
 
 a certain manner. The four grounded plates used in 
 the first, conductive method, must be in a plane, with the 
 upper plates at a similar distance underground, and 
 the lower plates in like manner. The grids of the static 
 form may be different in size and relative position above 
 ground, but it is essential that the transmitting end 
 be higher than the receiving. The loops used in the 
 last, or inductive method, must be either in the same or 
 parallel planes, as no indications will be received if 
 they are at right angles, a fact true of the induction- 
 coil principle. 
 Although none of these use detached electro-mag- 
 
WIRELESS TELEPHONY 
 
 139 
 
 netic waves, there are methods of wireless telephony, 
 or rather we should more properly say Radio-tele- 
 phony, which do make use of those waves. Two or 
 three of these wave methods are of importance, and 
 most of the experiment now going on relates to them. 
 First of these is the Spark Method. In passing 
 from our description of the wireless telegraph, this 
 
 method is simplest. It may be used with an ordinary 
 transmitting circuit (Fig. 84) by the addition of a 
 telephone transmitter of special design in the primary. 
 The vibrations of the voice speaking into this transmit- 
 ter are stepped up to a higher voltage by the spark 
 coil, and are recorded in the spark gap. This gap, 
 which may be of the ordinary form, or may consist 
 of two small carbon rods, should be connected in an 
 oscillatory circuit of almost any design, with aerial and 
 ground connections. Fig. 85 shows a more efficient 
 
140 WIRELESS OPERATORS' POCKET BOOK 
 
 form of telephone working on the same principle. , This 
 is the telephone designed by the author and consists of 
 a special telephone transmitter (A), a variable impe- 
 dence (B), connected with a battery (C) in the primary 
 circuit. Any vibrations received in the transmitter 
 are picked up by the secondary and are discharged 
 through the mercury- vapor spark gap (D). This 
 
 LjJ 
 
 discharge in the mercury-vapor tube sets up oscilla- 
 tions in the circuit, which in turn are picked up by 
 the aerial , circuit and radiated off into space. Such 
 a telephone will transmit messages from five to 
 fifteen miles. The ordinary tones of the human 
 voice both in speech and in singing, and the notes 
 of musical instruments, especially the xylophone, are 
 revealed very clearly through this mercury-vapor 
 spark gap, but articulation is sometimes indistinct. 
 The Arc Method works by the production of un- 
 
WIRELESS TELEPHONY 
 
 141 
 
 damped oscillations. This is most popular at present 
 with experimenters, and several wireless men in 
 America are working with it. A form of arc generator 
 shown in Fig. 86 consists of a singing or musical arc 
 burning in hydrogen gas. This arc will produce 
 oscillations when connected with a coil and condenser, 
 thus forming an oscillatory circuit. An induction 
 
 < ^/wwvwww 
 
 * AAMAMM 
 
 7p 
 
 FI&. 86 
 
 coil (A) is placed in the power circuit between the arc 
 and the power supply. In the primary circuit of this 
 is placed a battery and a telephone transmitter. The 
 vibrations of the voice speaking into the telephone 
 transmitter and varying the current about the arc 
 cause fluctuations in the arc corresponding to those 
 in the transmitter. These variations, communicated 
 to the oscillatory circuit, are picked up by the aerial 
 circuit and radiated from the aerial. Speech is very 
 
142 WIRELESS OPERATORS' POCKETBOOK 
 
 clear when using this method, and it has been used 
 up to fifteen or thirty miles. It is often called the 
 speaking arc. 
 
 Another arc method is illustrated by Fig. 87, con- 
 sisting of an arc generator and a transmitter in the 
 
 t 
 
 FIO. 37 
 
 aerial circuit. An ordinary direct current supply is 
 used and two impedences (JJ). The arc (A) is water 
 cooled, in order to keep down heat disastrous to the 
 production of oscillations. This arc generates best 
 when running on from four to five amperes and not 
 over 220 volts; anything in. excess of this tending to 
 destroy the generating properties for some unknown 
 reason. The arc must be kept at its greatest length, 
 
WIRELESS TELEPHONY 
 
 143 
 
 as at that place it generates best. The frequency of 
 the arc (A) ranging between 100,000 and 200,000 per 
 second, the electro-magnetic waves follow each other 
 so closely that the effect upon the telephone receiver 
 is continuous. Now if we speak into the transmitter, 
 
 placed in the aerial circuit, the vibrations of the voice 
 will interrupt these waves, and the interruptions will 
 be audible in the telephone receivers as words. This 
 is the method used by De Forest. Experiments with 
 this system have covered distances of perhaps twenty 
 or thirty miles, due to the limitations of the current in 
 a secondary circuit. 
 
144 WIRELESS OPERATORS' POCKETBOOK 
 
 Fig. 88 shows Professor Fessenden's Wave-Gener- 
 ator, one of the latest and most ingenious methods 
 yet produced. A direct current dynamo (A), of about 
 5000 volts potential, is connected to a spark gap (S) 
 through a variable resistance (R). Across this gap is 
 placed a coil (inductance) (J) and a condenser (C). 
 The telephone transmitter is placed in the ground cir- 
 cuit. The spark frequency of this device is governed 
 by the resistance (R), so that we can jump from a 
 frequency of one spark to one of 100,000 per second. 
 The working theory of this plan is that the current 
 from the dynamo flowing through the circuit slowly 
 charges the condenser through the resistance (R). 
 When a charge in the condenser becomes great enough 
 to overcome a set distance between the gaps, a spark 
 will jump across and will excite a current in the 
 oscillatory circuit. The greater the resistance in the 
 circuit, the longer it will take to charge the condenser, 
 and the fewer the sparks per second across the arc. 
 If the resistance is low, on the other hand, the con- 
 denser will charge and discharge itself very rapidly 
 across the gap. When a frequency of from 80,000 to 
 160,000 is obtained, the waves, following so rapidly, 
 are inaudible at the receiving end, and an almost 
 continuous current is made. The vibrations of the 
 voice speaking into the transmitter interrupt or vary 
 the intensity of the continuous waves, and speech is 
 thus transmitted. 
 
 In all forms of wireless telephony a special kind of 
 
WIRELESS TELEPHONY 
 
 145 
 
 transmitter is not only advisable, it is actually almost 
 necessary. There has been considerable experiment 
 as to the kind of transmitter best adapted to the 
 purpose, and numerous modifications of the ordinary 
 transmitter are the result. A type which can be used 
 
 FID.8S 
 
 with all the methods of telephony described is shown 
 in Fig. 89. 
 
 This transmitter, which is of the inertia type, works 
 very well for all experimental purposes, although for 
 permanent use the solid back type might perhaps be 
 advisable. This inertia transmitter should have a 
 very massive frame of the ordinary type for long 
 distance use. The diaphragm (B), about .006 inch 
 in thickness, of French steel, should be held firmly in 
 
146 WIRELESS OPERATORS' POCKET BOOK 
 
 place by a metallic ring (C). The mouthpiece (D), 
 of ordinary type, must be so arranged that the distance 
 between it and the diaphragm may be varied. The 
 transmitter button (E), attached to the centre of the 
 diaphragm, is shown separately in Fig. 90. This 
 button consists of a cup or carbon chamber (A), 
 an insulated face-plate (B), and a cap (C). The 
 carbon chamber (D) and the face plate (E) should be 
 made of platinum, although silver-plated brass is 
 
 F) G . 90 
 
 very good. The inside diameter of the carbon chamber 
 (D) should be about f inch, while the distance between 
 the back of this chamber and the face plate should be 
 | inch when the cup is closed. The face-plate, backed 
 with a thin mica washer (F), which supports and 
 insulates it, is held in place by the cap (C). The 
 carbon granules will be large and globular when used 
 in the primary circuit, and the chamber should be well 
 filled with them. When used in the aerial circuit 
 they should be much smaller and should only partially 
 fill the chamber. The thinness of the mica washer is 
 
WIRELESS TELEPHONY 147 
 
 of importance, in order to ensure the greatest amount 
 of vibration reaching the granules. 
 
 For receiving wireless telephone messages, any of 
 the detectors and any of the receiving circuits shown 
 in the back of the book may be used successfully. 
 
APPENDIX 
 
 AERIALS 
 
 The T, the Vertical, the Umbrella are the best types of aerials. 
 
 The L, the V, the Fan are all good types. 
 
 Combinations of types are often best fitted for a specific location. 
 
 TRANSMITTING CIRCUITS. I 
 
 1. Spark Coil, Spark Gap. The simplest circuit. 
 
 2. Spark Coil, Spark Gap, Condenser. The addition of a 
 condenser to give a longer wave. 
 
 3. Spark Coil, Spark Gap, Helix. Addition of a helix to give 
 longer wave. 
 
 4. Spark Coil, Spark Gap, Condenser, and Helix. The com- 
 bination of instruments for the best results. 
 
 Any of these circuits may be used on a one-inch spark coil 
 for distances of from one to two miles; but they are not practical 
 for greater distances, and do not give the full value of the instru- 
 ments. 
 
 TRANSMITTING CIRCUITS. II 
 
 5. Spark Coil, Spark Gap, Helix, and Condenser. A practical 
 circuit for a 3-contact helix. 
 
 6. Spark Coil, Spark Gap, Helix, Condenser, and Anchor 
 Gap. For use with loop aerials and breaking-in systems. A 
 practical circuit. 
 
 149 
 
150 APPENDIX 
 
 7. Spark Coil, Spark Gap, Condenser, 3-Contact Helix. A 
 popular and practical circuit. 
 
 8. Spark Coil, Spark Gap, Condenser, 4-Contact Helix. Circuit 
 especially adapted for the variety of its effects. 
 
 All practical circuits. 
 
 TRANSMITTING CIRCUITS. Ill 
 
 g. Transformer or Spark Coil, Spark Gap, Condenser, 4- 
 Contact Helix, and 3-Point Anchor Gap. For use with loop 
 aerials. As practical as any circuit using a loop aerial. 
 
 10. Transformer or Spark Coil, Spark Gap, Condenser, 3- 
 Contact Helix, and 3-Point Anchor Gap. Highly recommended 
 for loop aerials. 
 
 11. Transformer or Spark Coil, Spark Gap, Condenser, 
 Oscillation Transformer. The most practical and popular 
 circuit known. 
 
 12. Transformer, Spark Gap, three or more Condensers, three 
 or more Oscillation Transformers. A Multiple Transmitting 
 Circuit. For use with very high power. 
 
 The best circuits for commercial and long distance work. 
 
APPENDIX 
 
 151 
 
 T AERIAL 
 
 LOOP 
 
 VERTICAL 
 SERIAL 
 
 LOOP 
 
 UMBRELLA 
 AERIAL 
 
 L ACR I A L 
 
 V AERIAL 
 
 STRAIGHT 
 
 LO OP 
 
 FAN AERIAL 
 
152 
 
 APPENDIX 
 
 6 
 Q 
 
 n 
 
 
 9 
 
 U 
 
 U 
 
APPENDIX 
 
 153 
 
 n 
 
 o- 
 
 -u 
 <r 
 
 "G 
 
 Q 
 
 -n 
 
 U 
 
 6 
 
 u 
 
154 
 
 APPENDIX 
 
 n 
 
 u 
 
 n 
 
APPENDIX 155 
 
 RECEIVING CIRCUITS. I 
 
 SINGLE SLIDE TUNING COILS 
 
 1. Tuning Coil, Detector, and Phones. Simplest circuit. 
 
 2. Tuning Coil, Fixed Condenser, Variable Condenser, De- 
 tector, and Phones. A simple tuned circuit. 
 
 3. Tuning Coil, Fixed Condenser, Detector, and Phones. A 
 practical circuit, but subject to interference. 
 
 4. Tuning Coil, Fixed Condenser, Detector, and Phones. 
 Practical circuit for the beginner. Fairly selective. 
 
 RECEIVING CIRCUITS. II 
 
 DOUBLE SLIDE TUNING COILS 
 
 5. Tuning Coil, Fixed and Variable Condensers, Detector, 
 and Phones. 
 
 6. Tuning Coil, Variable and Fixed Condenser, Detector, and 
 Phones. A practical circuit, but subject to interference. 
 
 7. Tuning Coil, Fixed and Variable Condensers, Detector, 
 and Phones. A selective circuit. 
 
 8. Tuning Coil, Fixed and Variable Condensers, Detector, 
 and Phones. The most selective 2-slide circuit. Will overcome 
 arc-light interference to a measure. 
 
 RECEIVING CIRCUITS. Ill 
 
 THREE SLIDE TUNING COILS 
 
 9. Tuning Coil, Fixed and Variable Condensers, Detector, and 
 Phones. An all-around selective circuit. 
 
 10. Tuning Coil, Fixed and Variable Condensers, Detector, 
 and Phones. Overcomes arc-light interference. 
 
 11. Tuning Coil, Fixed Condenser, two Variable Condensers, 
 Detector, and Phones. Very selective circuit for overcoming 
 static and arc-light interference. 
 
156 APPENDIX 
 
 12. Tuning Coil, Fixed and Variable Condensers, Detector, 
 and Phones. The best 3-Slide circuit known. Has auxiliary 
 loose coupling, which has an effect similar to an oscillation trans- 
 former. Good for overcoming all kinds of interference. 
 
 RECEIVING CIRCUITS. IV 
 
 SPLIT AERIAL CIRCUITS 
 
 13. Two Single Slide Tuning Coils, two Fixed Condensers, 
 Detector, and Phones. Simple interference preventer. 
 
 14. Two Double Slide Tuning Coils, Fixed Condenser, De- 
 tector, and Phones. Adapted to overcome the humming of 
 motor and power wires. 
 
 15. One Single and one 3-Slide Tuning Coil, Fixed Condenser, 
 two Variable Condensers, Detector, and Phones. Will over- 
 come interference from near-by stations. 
 
 16. Two Single Slide Tuning Coils, two Fixed and one Variable 
 Condenser, Detector, and Phones. An all-around interference pre- 
 venter, and a very popular circuit. 
 
 Circuits specially for overcoming different forms of inter- 
 ference. 
 
 RECEIVING CIRCUITS. V 
 
 LOOP AERIALS 
 
 17. Double Slide Tuning Coil, Fixed Condenser, Detector, and 
 Phones. A simple loop circuit. 
 
 18. Double Slide Tuning Coil, Fixed and Variable Condensers, 
 Detector, and Phones. A practical circuit for all-around work. 
 
 19. Two Double Slide Tuning Coils, two Variable Condensers, 
 Detector, and Phones. For overcoming interference. 
 
 20. One Single and one Double Slide Tuning Coil, Fixed and 
 two Variable Condensers, Detector, and Phones. A very selective 
 loop circuit. The best and most popular form. 
 
 Loop aerials somewhat less practical than the straight-away 
 forms for general work. 
 
APPENDIX 157 
 
 RECEIVING CIRCUITS. VI 
 
 LOOSE COUPLED TUNING COILS 
 
 21. Loose Coupled Tuning Coil, Fixed Condenser, Detector, 
 and Phones. Simplest circuit. 
 
 22. Loose Coupled Tuning Coil, Fixed and Variable Conden- 
 sers, Detector, and Phones. An extremely selective and sensitive 
 circuit. The most popular circuit. 
 
 23. Loose Coupled Tuning Coil, Loading Coil, Fixed and two 
 Variable Condensers, Detector, and Phones. The addition of 
 extra inductance in the circuit, when receiving very long waves. 
 By adding the second Variable Condenser alone, short waves 
 may be tuned in. 
 
 24. Loose Coupled Tuning Coil, Single Slide Tuning Coil, 
 Fixed and three Variable Condensers, Detector, and Phones. 
 This is for use in overcoming extreme interference and the hum- 
 ming from high-tension lines. 
 
 The best and most practical circuits for commercial and pro- 
 fessional use. 
 
 RECEIVING CIRCUITS. VII 
 
 25. Loose Coupled Tuning Coil, Fixed and two Variable 
 Condensers, Detector, and Phones. For loop aerials. 
 
 26. Loose Coupled and Loading Coil, Fixed and two Variable 
 Condensers, Detector, and Phones. For loop aerials. A prac- 
 tical circuit. 
 
 27. Two Loose Coupled Tuning Coils, Loading Coil, Fixed 
 and three Variable Condensers, Detector, and Phones. A weeding- 
 out circuit. Extremely selective, and excellent for overcoming 
 all kinds of interference. 
 
 28. Three Loose Coupled Tuning Coils, Loading Coil, Fixed 
 and four Variable Condensers, Detector, and Phones. The 
 tertiary weeding-out circuit. Its selectivity is wonderful, but 
 it is not wholly practical, a slight amount of energy being lost 
 with the addition of each additional loose coupled tuning coil. 
 
158 
 
 APPENDIX 
 
APPENDIX 
 
 159 
 
 1 
 
160 
 
 APPENDIX 
 
 \1J 
 
 \\ 
 
 10 
 
APPENDIX 
 
 161 
 
 IS" 
 
 16 
 
162 
 
 APPENDIX 
 
APPENDIX 
 
 163 
 
164 
 
 APPENDIX 
 
 25- 
 
 2. 8 
 
APPENDIX 165 
 
 COMPLETE SETS. I 
 
 1. Transmitting Apparatus: Spark Coil, Spark Gap, Con- 
 denser, and a i, 2, or 3 Clip Helix. For use with batteries and 
 telegraph key. 
 
 Receiving Apparatus: i, 2, or 3 Slide Tuning Coil, Fixed Con- 
 denser, Detector, and Phones. A Variable Condenser may be 
 added. 
 
 Switch between Sending and Receiving: S.P.D.T. 
 
 A beginner's set. 
 
 COMPLETE SETS. II 
 
 2. Transmitting Apparatus: Spark Coil or Transformer, 
 Spark Gap, Condenser, 3 or 4 Contact Helix. To be run from 
 battery or power, key with durable contacts and adjustable 
 resistance. 
 
 Receiving Apparatus: Loose Coupled Tuning Coil, Fixed and 
 Variable Condenser, Detector, and Phones. 
 
 Switch between Sending and Receiving: D.P.D.T. 
 A practical set. 
 
 COMPLETE SETS. Ill 
 
 3. Transmitting Apparatus: Transformer Spark Gap, Con- 
 denser, Sending Oscillation Transformer, two protective devices 
 for the line and transformer, Rheostat or Reactance Regulator, 
 a Key with heavy contacts. A Condenser across the key points 
 to prevent formation of arc between them. 
 
 Receiving Apparatus: Loose Coupled Tuning Coil, Fixed and 
 Variable Condensers, Detector, and Phones. 
 
 Breaking-in System: Relay with single contact, protective 
 Spark Gap, and Batteries for relay circuit. 
 
 Aerial Switch of 100 amperes. 
 
166 APPENDIX 
 
 COMPLETE SETS. IV 
 
 TWO TO FIVE KILOWATT 
 
 4. Transmitting Apparatus: Transformer, Spark Gap, Con- 
 denser, Oscillation Transformer, three protective devices for the 
 transformer, the switchboard, and for the dynamo, a Reactance 
 Regulator, key with heavy contacts with condenser. 
 
 Receiving Apparatus: Loose Coupled Tuning Coil, Loading 
 Coil, Fixed and two Variable Condensers, Detector with potenti- 
 ometer, Battery and Switch, and Phones. 
 
 Breaking-in System: Aerial Relay with two contacts, two 
 protective Spark Gaps, Relay with six contacts for protecting 
 the detector, and Batteries. 
 
 Switch of 100 amperes. 
 
APPENDIX 
 
 167 
 
 o 
 
 S-F-D-T 
 
168 
 
 APPENDIX 
 
APPENDIX 
 
 169 
 
170 
 
 APPENDIX 
 
 TABLE OF SENDING AND RECEIVING DISTANCES 
 
 In wireless telegraphy the one thing unknown is the distance 
 covered by our instruments. In line telegraphy the distance 
 is regulated by the length of wire. Only the limitations of power 
 limit our transmitting possibilities in wireless; and the degree 
 of sensitiveness shown in our receiving instruments regulates 
 the distances of the stations whose signals we can catch. Every 
 experimenter, indeed every operator, wants to know what those 
 distances are: how far do his signals carry, and how far away is 
 the most distant station whose call he can receive. 
 
 Every instrument in the set, its separate quality, influences 
 this distance, and the result must depend somewhat upon per- 
 sonal judgment. However, the author has made tables which 
 may be used roughly to indicate the range of stations consisting 
 of different sorts of apparatus. They will be found pretty 
 nearly adequate in all cases, if the instruments are carefully 
 judged. 
 
 A TABLE OF RECEIVING DISTANCES 
 AERIALS 
 
 Position 
 
 Hill (within 10 miles of seacoast) i 
 
 " (30 miles or more inland) f 
 
 Low land (sea, coast) ^ 
 
 " " (clear space, inland) f 
 
 " " (city or forest) i 
 
 Type and Value 
 
 Vertical Height 
 
 Horizontal Length 
 
 T L V 
 
 Umbrella, Fan 
 Vertical 
 
 i in feet 
 
 i 
 
 * " " 
 
 t*& in feet 
 \ spread, in feet 
 
 f k 
 
APPENDIX 
 
 171 
 
 CIRCUIT VALUES 
 | 
 
 Circuits in back of book as standards 
 Number 
 
 i, 2, 3, 13- 
 
 4, 5> 14, 15 t 
 
 6, 16, 17, 18 f 
 
 7, 8, 9, 19 T V 
 
 10, II, 12, 20 f 
 
 25, 26, 27, 28 & 
 
 21, 22, 23, 24 I 
 
 DETECTORS AND TELEPHONE RECEIVERS 
 DOUBLE POLE, ALL COPPER WOUND 
 
 Resistance 
 per Pair 
 
 Perikon- 
 Elektra 
 
 Perikon 
 with Bat. 
 
 Perikon 
 No Bat. 
 
 Pyron or 
 Perron 
 
 Electro- 
 lytic 
 
 Silicon 
 
 80 
 
 20 
 
 12 
 
 1O 
 
 IO 
 
 8 
 
 6 
 
 250 
 
 22 
 
 13 
 
 II 
 
 II 
 
 9 
 
 7 
 
 500 
 
 23 
 
 14 
 
 12 
 
 II 
 
 IO 
 
 8 
 
 750 
 
 24 
 
 14 
 
 13 
 
 12 
 
 II 
 
 8 
 
 IOOO 
 
 24 
 
 15 
 
 14 
 
 12 
 
 II 
 
 9 
 
 1500 
 
 25 
 
 15 
 
 14 
 
 13 
 
 12 
 
 9 
 
 2000 
 
 24 
 
 15 
 
 14 
 
 12 
 
 II 
 
 9 
 
 3000 
 
 24 
 
 16 
 
 15 
 
 12 
 
 10 
 
 10 
 
 Explanation of Table. Select conditions of the set 
 in question, and multiply their values together to find 
 total receiving distance of station. These distances 
 may be nearly doubled for special atmospheric condi- 
 tions, and with a good operator. Good between 8 p. M. 
 and 4 A. M. Subtract 20% for day use. 
 
172 
 
 APPENDIX 
 
 Example 
 
 Aerial, Length 180 T V x 180=18 
 
 " Height 90 Jxgo =30 
 
 Value for Aerial 48 
 
 Position, Low, Coast ^ 
 
 Circuit, No. 21 i 
 
 Detector, Pyron, Phones 1500 ohms 13 
 
 48 x y 9 ^ x i x 13 = 560 miles 
 
 SIZES OF AERIAL WIRES 
 
 Material 
 
 Smallest 
 Size 
 
 Largest 
 Size 
 
 Kind 
 
 Copper . 
 
 14. 
 
 8 
 
 Stranded or solid 
 
 Phosphor bronze 
 
 12 
 
 6 
 
 Stranded or solid 
 
 Aluminum 
 
 12 
 
 6 
 
 Solid 
 
 Iron (umbrella type) . . 
 
 IO 
 
 4 
 
 Solid 
 
 AERIAL INSULATION 
 
 Power Size of Insulators 
 
 i and 2 Inch spark coils .............. Porcelain cleats or spools 
 
 kw. set .......................... 2 inch strain insulators 
 
 2 
 
 6 
 
 6 
 
 18 
 
 . .18 
 
 A TABLE OF SENDING DISTANCES 
 
 AERIALS 
 
 Must have two or more strands 
 i. Position 
 
 On seacoast, high land, clear space I 
 
 On coast, low land ' >. 
 
APPENDIX 173 
 
 High land, inland i 
 
 Low land, city or forest i 
 
 2. Size 
 
 Height of aerial over 100 feet i 
 
 60-100 foot aerial t 
 
 40-60 " " J 
 
 30-40 " " i 
 
 CIRCUIT 
 
 3. Numbers from chapter on transmitting diagrams 
 
 11-12 i 
 
 5,7,8 | 
 
 6, 9, 10 i 
 
 1,2,3,4 i 
 
 WAVE LENGTH 
 Not under 400 metres 
 POWER 
 
 Transformers 
 
 
 5 kw 
 
 600 
 
 4 
 
 480 
 
 3 
 
 420 
 
 2! 
 
 370 
 
 2 
 
 300 
 
 l 
 
 290 
 
 I . . 
 
 240 
 
 
 
 2IO 
 
 ^ 
 
 180 
 
 \ 
 
 120 
 
 i 
 
 75 
 
 Battery-operated Spark Coils 
 
 
 50 watts (4 inch spark coil) 
 
 40 
 
 2.; " (2 " " " ) 
 
 25 
 
 15 " (i " " " ) 
 
 12 
 
 10 " (i " " " ) 
 
 8 
 
174 
 
 APPENDIX 
 
 Explanation of Table. Select the conditions of the 
 set in question, and multiply together to obtain send- 
 ing distance of the station. These distances may 
 be nearly doubled when atmospheric conditions are 
 especially favorable. A good operator will also im- 
 prove the distance somewhat. 
 
 Example. A station on the coast, but low land; a loo-foot 
 aerial; a good circuit, using a helix; a one i-kw. transformer. 
 123 4 Result, Distance 
 | x i x f x 240= 135 miles 
 
 COMPARISON OF COPPER AND ALUMINUM 
 
 
 Copper 
 
 Aluminum 
 
 Specific gravity 
 Conductivity 
 
 8.93 
 
 IOO 
 
 2.68 
 63 
 
 Area .... ... 
 
 IOO 
 
 48 
 
 Diameter 
 
 IOO 
 
 126 04 
 
 
 
 
 This shows that aluminum has 63% as great con- 
 ductivity and 48% of the weight of copper; that for 
 wire of equivalent conductivity it has a cross section 
 60% greater and a diameter 26.4% greater than 
 copper. 
 
 It will be noted from the relative diameters that an 
 aluminum wire of equal conductivity with a copper 
 wire will be almost exactly two sizes larger by the 
 B & S Gauge. 
 
 Weight to weight, therefore, the conductivity of 
 aluminum is greater than that of copper by 315% 
 
Table of Dimensions and Resistances of Pure 
 Copper Wire.* 
 
 KEVISED. 
 
 No. 
 B. 
 
 & 
 S. 
 
 Kesistance at 75F. 
 
 bs p. 1000 
 ft. ins'd 
 H.B.&H. 
 ine wire. 
 
 Feet pei 
 Ib. ins'd 
 H.B.&H. 
 ine wire. 
 
 R 
 
 ohms per 
 1000 feet. 
 
 Ohms 
 per 
 mile. 
 
 Feet 
 per 
 ohm. 
 
 Ohms 
 per 
 pound. 
 
 4-0 
 3-0 
 00 
 
 
 .04904 
 .06184 
 .07797 
 .09827 
 
 .25891 
 .32649 
 .41168 
 .51885 
 
 20392.9 
 16172.1 
 12825.4 
 10176.4 
 
 .00007653 
 .00012169 
 .00019438 
 .00030734 
 
 800 
 666 
 500 
 363 
 
 1.25 
 1.50 
 200 
 2.75 
 
 2 
 3 
 4 
 5 
 
 .12398 
 .15633 
 .19714 
 .24858 
 .31346 
 
 .65460 
 .82543 
 1.04090 
 1.31248 
 1.65507 
 
 8066.0 
 6396.7 
 5072.5 
 4022.9 
 3190.2 
 
 .00048920 
 .00077784 
 .0012370 
 .0019666 
 .0031273 
 
 313 
 250 
 200 
 144 
 125 
 
 3.20 
 4.00 ' 
 5.00 
 6.9 
 8.0 
 
 6 
 7 
 8 
 9 
 10 
 
 .39528 
 .49845 
 .62849 
 .79242 
 .99948 
 
 2.08706 
 2.63184 
 3.31843 
 4.18400 
 5.27726 
 
 2529.9 
 2006.2 
 1591.1 
 1262.0 
 1000.5 
 
 .0049728 
 .0079078 
 .0125719 
 .0199853 
 .0317946 
 
 105 
 87 
 69 
 
 50 
 
 9.5 
 11.5 
 14.5 
 
 20.0 
 
 11 
 12 
 13 
 14 
 15 
 
 ~w 
 
 17 
 18 
 19 
 20 
 
 1.2602 
 1.5890 
 2.0037 
 2.5266 
 3.1860 
 
 6.65357 
 8.39001 
 10.5798 
 13.3405 
 16.8223 
 
 793.56 
 629.32 
 499.06 
 395.79 
 313.87 
 
 .0505413 
 .0803641 
 .127788 
 .203180 
 .323079 
 
 31 
 
 22 
 
 32.0 
 45.0 ' 
 
 4.0176 
 5.0660 
 - 6.3880 
 8.0555 
 10.1584 
 
 21.2130 
 26.7485 
 33.7285 
 42.5329 
 53.6362 
 
 248.90 
 197.39 
 156.54 
 124.14 
 98.44 
 
 .513737 
 .816839 
 1.298764 
 2.065312 
 3.284374 
 
 14 
 11 
 
 70.0 
 90.0 
 
 21 
 
 22 
 23 
 24 
 25 
 
 12.8088 
 16.1504 
 20.3674 
 25.6830 
 32.3833 
 
 67.6302 
 85.2743 
 107.540 
 135.606 
 170.984 
 
 78.07 
 61.92 
 49.10 
 38.94 
 30.88 
 
 5.221775 
 8.301819 
 13.20312 
 20.99405 
 33.37780 
 
 
 
 26 
 
 27 
 28 
 29 
 30 
 
 40.8377 
 51.4952 
 64.9344 
 81.8827 
 103.245 
 
 215.623 
 271.895 
 342.854 
 432.341 
 545.133 
 
 24.4y 
 19.42 
 15.40 
 12.21 
 9.686 
 
 53.07946 
 84.39916 
 134.2 '05 
 213.3973 
 339.2673 
 
 
 
 31 
 32 
 33 
 34 
 35 
 36 
 37 
 38 
 39 
 40 
 
 130.176 
 164.174 
 207.000 
 261.099 
 329.225 
 
 687.327 
 866.837 
 1092.96 
 1378.60 
 1738.31 
 
 7.682 
 6.091 
 4.831 
 3.830 
 3.037 
 
 539.3404 
 
 857.8498 
 1363.786 
 2169.776 
 3449.770 
 
 
 
 415.047 
 523.278 
 660.011 
 832.228 
 1049.718 
 
 2191.45 
 2762.91 
 3484.86 
 4394.16 
 5542.51 
 
 2.409 
 1.911 
 1.515 
 1.202 
 .9526 
 
 5482.766 
 8715.030 
 13864.51 
 22043.92 
 35071.11 
 
 
 
 mile pure copper wire 1-16 in. diam.=13.59 ohms at 15.5C. or 59.9F. 
 
Table of Dimensions and Resistances of Pure 
 Copper Wire.* 
 
 No. 
 B. &S. 
 
 Diam. 
 Mils. 
 
 Area. 
 
 W'gt& Length. Sp.gr. 8.9 
 
 Circular 
 Mils. 
 
 Square 
 Inches. 
 
 Lbs. 
 per 
 1000 ft. 
 
 Pounds 
 per 
 mile. 
 
 Feet 
 per 
 pound. 
 
 0000 
 000 
 00 
 
 
 460.000 
 409.640 
 364.800 
 324.950 
 
 211600.0 
 167805.0 
 133079.0 
 105592.5 
 
 166190.2 
 131793.7 
 104520.0 
 82932.2 
 
 640.73 
 508.12 
 402.97 
 319.74 
 
 3383.04 
 2682.85 
 2127.66 
 1688.20 
 
 1.56 
 1.97 
 2.48 
 3.13 
 
 1 
 
 2 
 3 
 4 
 5 
 
 289.300 
 257.630 
 229.420 
 204.310 
 181.940 
 
 83694.5 
 66373.2 
 52633.5 
 41742.6 
 33192.2 
 
 65733.5 
 52129.4 
 41338.3 
 32784.5 
 25998.4 
 
 253.43 
 200.98 
 159.38 
 126.40 
 100.23 
 
 1338.10 
 1061.17 
 841.50 
 667.38 
 529.23 
 
 3.95 
 4.98 
 6.28 
 7.91 
 9.98 
 
 6 
 
 7 
 8 
 9 
 10 
 
 162.020 
 144.280 
 128.490 
 114.430 
 101.890 
 
 26250.5 
 20816.7 
 16509.7 
 13094.2 
 10381.6 
 8234.11 
 6529.94 
 5178.39 
 4106.76 
 3256.76 
 
 20617.1 
 16349.4 
 12966.7 
 10284.2 
 8153.67 
 
 79.49 
 63.03 
 49.99 
 39.65 
 31.44 
 
 419.69 
 332.82 
 263.96 
 209.35 
 165.98 
 
 12.58 
 15.86 
 20.00 
 25.22 
 31.81 
 
 11 
 12 
 13 
 14 
 15 
 
 90.742 
 80.808 
 71.961 
 64.084 
 57.068 
 
 6467.06 
 5128.60 
 4067.09 
 3225.44 
 2557.85 
 
 24.93 
 19.77 
 15.68 
 12.44 
 9.86 
 
 131.65 
 104.40 
 82.792 
 65.658 
 52.069 
 
 40.11 
 
 50.58 
 63.78 
 80.42 
 101.40 
 
 16 
 
 17 
 18 
 19 
 20 
 
 50.820 
 45.257 
 40.303 
 35.890 
 31.961 
 
 2582.67 
 2048.20 
 1624.33 
 1288.09 
 1021.44 
 
 2028.43 
 1608.65 
 1275.75 
 1011.66 
 802.24 
 
 7.82 
 6.20 
 4.92 
 3.90 
 3.09 
 
 41.292 
 32.746 
 25.970 
 20594 
 16.331 
 
 127.87 
 161.24 
 203.31 
 256.89 
 323.32 
 
 21 
 22 
 23 
 24 
 25 
 
 28.462 
 25.347 
 22.571 
 20.100 
 17.900 
 
 810.09 
 642.47 
 509.45 
 404.01 
 320.41 
 
 636.24 
 504.60 
 400.12 
 317.31 
 251.65 
 
 2.45 
 1.95 
 1.54 
 1.22 
 .97 
 
 12.952 
 10.272 
 8.1450 
 6.4593 
 5.1227 
 41)623" 
 3.2215 
 2.5548 
 2.0260 
 1.6068 
 
 407.67 
 514.03 
 648.25 
 817.43 
 1030.71 
 
 26 
 27 
 28 
 29 
 30 
 
 15.940 
 14.195 
 12.641 
 11.257 
 10.025 
 
 254.08 
 201.50 
 159.80 
 126.72 
 100.50 
 
 199.56 
 158.26 
 125.50 
 99.526 
 78.933 
 
 .77 
 .61 
 .48 
 .38 
 .30 
 
 1299.77 
 1638.97 
 2066.71 
 2606.13 
 3286.04 
 
 31 
 32 
 33 
 34 
 35 
 
 8.928 
 7.950 
 7.080 
 6.304 
 5.614 
 
 79.71 
 63.20 
 50.13 
 39.74 
 31.52 
 
 62.603 
 49.639 
 39.369 
 31.212 
 24.753 
 
 .24 
 .19 
 .15 
 .12 
 .10 
 
 1.2744 
 1.0105 
 .8014 
 .6354 
 .5039 
 
 4143.18 
 5225.26 
 6588.33 
 8310.17 
 10478.46 
 
 36 
 37 
 38 
 39 
 
 40 
 
 5.000 
 4.453 
 3.965 
 3.531 
 3.144 
 
 25.00 
 19.83 
 15.72 
 12.47 
 
 9.88 
 
 19.635 
 15.574 
 12.347 
 9.7923 
 
 7.7365 
 
 .08 
 .06 
 .05 
 .04 
 .03 
 
 .3997 
 .3170 
 .2513 
 .1993 
 .1580 
 
 13209.98 
 16654.70 
 21006.60 
 26427.83 
 33410.05 
 
 "1 mile pure copper wire 1-16 in. diam.=13.59 ohms at 15.5C or 59.9F. 
 
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 I5MJHSHSS3S328SSJ 
 
BUBIER PUBLISHING CO. 
 
 ESTABLISHED 1889 
 
 LYNN MASS. 
 
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 Direct Current Dynamo Designs Watson i oo 
 
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 Arithmetic of Magnetism and Electricity, Morrow and Reid i oo 
 
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 SEND FOR CATALOGUE CONTAINING COMPLETE LIST 
 
"H-C" 
 
 Wireless 
 Operator's 
 
 Head 
 Receivers 
 
 IN wireless telephone receivers the important points to be considered 
 are, first, their sensitiveness; second, the degree of comfort with 
 which they can be worn; third, their permanence of adjustment 
 and construction. 
 
 There are many points in the design of receivers which affect their 
 sensitiveness. The coils must be wound so as to give the greatest 
 possible number of turns with the least resistance. Many people assume 
 that high resistance means great sensitiveness. This is not necessarily 
 the case. The most efficient winding is the one having the greatest 
 number of turns of wire nearest the cores for a given ohmic resistance. 
 It would be possible, for instance, to wind the cores with German silver 
 wire and get a very high resistance, but it would give a very poor receiver. 
 The amount of iron in the cores and the quality of the iron are also 
 important factors. 
 
 The diameter and thickness of the diaphragm and the quality of the 
 iron from which it is made also greatly affect the sensitiveness. 
 
 Another feature that must be watched is the strength of the perma- 
 nent magnets. These must be just the right strength to give the best 
 results with the cores and diaphragms with which they are used. Per- 
 manence of adjustment can be secured only by mounting all the parts 
 mentioned on some material which will be unaffected by heat or moisture. 
 
 H-C Head Receivers have been designed with all of the above points 
 in view. The windings are all made with silk covered copper wire. The 
 magnets are made from a special quality of steel and are of the proper 
 strength to give best results with the diaphragms used. The spools and 
 magnets are mounted in a metal cup which supports the diaphragm. 
 The cores are ground to a proper height so that the adjustment is per- 
 manent. The metal cup is enclosed in a hard rubber shell. The two 
 receivers are mounted on an adjustable leather covered head band. 
 There are no nuts or screws to work loose on this band, and nothing to 
 catch the hair. Large pneumatic rubber cushions are provided with 
 each set, which not only shut out extraneous noises but also make the 
 set more comfortable. These cushions are readily detachable. A six- 
 foot two conductor green silk tinsel cord is supplied with each set also. 
 
 These sets may be wound to resistance up to 4,000 ohms. 
 
 HOLTZER-CABOT ELECTRIC CO. 
 
 BROOKLINE, MASS., U. S. A. 
 
T 
 
 4 
 
 TRANSMITTING 
 SET 
 
 WIRELESS TELEGRAPH 
 APPARATUS 
 
 OF 
 
 ABSOLUTE RELIABILITY 
 
 FOR 
 
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 INSTALLATION 
 
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 CLAPP-EASTHAM CO. 
 
 139 MAIN STREET .... CAMBRIDGE, MASS. 
 
 CABINET 
 
 TYPE 
 RECEIVING 
 
 SET 
 
IMPROVED NAVY 
 
 THE BEST WIRELESS RECEIVER MADE FOR 
 LONG DISTANCE WORK 
 
 THE REASONS 
 
 SENSITIVENESS ^ SOFT AND DISTINCT 
 
 TONE ^ SAME PITCH IN BOTH 
 
 RECEIVERS jt IS THE LIGHTEST AND 
 
 MOST COMFORTABLE SET MADE 
 
 Complete outfit weighs only 10 ounces 
 
 LET US PROVE OUR CLAIMS :: SEND FOR A PAIR ON TRIAL 
 Send for catalogue and record bulletin F. D. 
 
 C. BRANDES 1 1 1 BROADWAY, NEW YORK 
 
SUPPLEMENT 
 
 Wireless Operators' Pocket-book 
 
 Information and Diagrams 
 
 LEON W. BISHOP 
 
 LATEST CALL LIST OF 
 WIRELESS STATIONS 
 
 ALPHABETICALLY ARRANGED' 
 
 1911 
 
 BUBIER PUBLISHING COMPANY 
 
 LYNN, MASS., U.S.A. 
 
WIRELESS OPERATORS' POCKET-BOOK 
 
 OF 
 
 Information and Diagrams 
 
 SUPPLEMENT 
 LATEST GALL LIST OF STATIONS 
 
 S. S. Roanoke AQ 
 
 S. S. San Jacinto AS 
 
 S. S. Admiral Sampson AS 
 Amsterdam navy-yard ASD 
 U. S. Army transport Buford 
 
 ATB 
 U. S. Army transport Dix 
 
 ATD 
 IT. S. Army transport Sumner 
 
 ATH 
 
 U. S. Army transport Kilpat- 
 rick ATK 
 
 U. S .Army transport Logan 
 
 ATL 
 
 U. S. Army transport Sher- 
 man ATR 
 U. S. Army transport Sheri- 
 dan ATS 
 U. S. Army transport Thomas 
 
 ATU 
 
 S. S. Dolphin 
 Chatham, Mass. 
 S. S. Seward 
 S. S. Olympia 
 S. S. Kansas City 
 Atlantic City, N.J. 
 S. S. Geo. W. Elder 
 S. S. Brazos 
 
 Avalon, Catalina Island, Cal. 
 A2 
 
 Tug Tyee A3 
 
 Baltimore, Md. (American 
 
 Building) B 
 
 Bocas del Toro, Panama B 
 
 Isles of Shoals, N.H. A 
 
 S. S. Alabama AB 
 
 S. S. Sabine AB 
 
 S. S. Chicago AB 
 
 S. S. Aberdeen ABD 
 
 S. S. Concho AC 
 
 S. S. Denver AD 
 
 S. S. Victoria AD 
 
 Amsterdam, Holland ADM 
 
 S. S. Colorado AF 
 
 S. S. Rio Grande AG 
 
 S. S. Yucatan AG 
 
 S. S. Nueces AH 
 
 S. S. Pennsylvania AH 
 
 S. S. Alamo AJ 
 
 German pilot steamer Jade 
 
 AJA 
 
 S. S. San Marcos AK 
 
 S. S. Santa Clara AK 
 
 S. S. Loftus Cuddy AL 
 
 Algiers, Algeria ALG 
 
 Almeria, Spain ALM 
 
 S. S. America AM 
 
 S. S. Comal AM 
 
 S. S. Riverside AM 
 Kamalo, Molokai, Hawaiian 
 
 Islands AM 
 
 S. S. Northwestern AN 
 
 Antivari, Montenegro AN 
 
 S. S. Minda AND 
 
 S. S. Ohio AO 
 
 S. S. Lampasas AP 
 S. S. City of Benton Harbor 
 AQ 
 
 AU 
 AU 
 AV 
 AW 
 AX 
 AX 
 AY 
 AZ 
 
WIRELESS OPERATORS' POCKETBOOK 
 
 S. S. Bermudian BA 
 
 Buenos Aires, Argentine Re- 
 public BA 
 Batavia, Dutch East Indies 
 
 BA 
 
 Abo, Russia BAG 
 
 S. S. Batavier IV BBF 
 
 S. S. Batavier II BBS 
 
 S. S. Batavier III BBT 
 
 S. S. Batavier V BBV 
 
 S. S. Virginia BC 
 
 S. S. W. S. Porter BD 
 
 S. S. Trinidad BD 
 
 New York, N.Y. BD 
 
 Buffalo, N.Y. (News Build- 
 ing) BF 
 Philadelphia, Pa. BF 
 Bridgeport, Conn. BG 
 S. S. Iroquois BG 
 Helsingfors. Finland BGF 
 Quincy, Mass. BH 
 S. S. Chippewa BH 
 Benton Harbor, Mich. BH 
 Blaavands Huk, Denmark 
 
 BH 
 
 S. S. Indianapolis Bl 
 
 S. S.John J. Barium BJ 
 
 Leckte, Russia BLH 
 
 Libau, Russia BLW 
 
 S. S. Nyack BM 
 
 S. S. Boston BX 
 
 S. S. Rosecrans BX 
 
 Nikolaistadt, Russia BNCh 
 S. S. Nann Smith BO 
 
 Brant, Rock Mass. BO 
 
 S. S. Hermosa BP 
 
 Preste, Russia BPS 
 
 S. S. Bruce BR 
 
 S. S. Thomas Barium BR 
 Britz, Germany BR 
 
 Overtoom, Holland BRBR 
 Reval, Russia BRW 
 
 Philadelphia, Pa. ( Belle vue- 
 Stratford) BS 
 
 Washington, B.C., Bureau of 
 Standards BS 
 
 U. S . Army cableship Burn- 
 side BS 
 Sevastapol, Russia BSP 
 S. S. Nyades BT 
 Butt of Lewis, Scotland BTL 
 S. S. Rupert City BU 
 S. S. Cabrillo BV 
 S. S. Alliance BW 
 Vladivostok, Siberia BWT 
 S. S. City of South Haven 
 
 BX 
 
 Shoeburyness, England BY 
 Babylonia, Brazil BYN 
 
 Bombay, India BYR 
 
 Bessemer Barge No. 2 B2 
 Tug Goliah B3 
 
 Camaguey, Cuba C 
 
 S. S. City of Alpena CA 
 
 S. S. Coamo CA 
 
 S. S. Priscilla CA 
 
 Cambridge, England CA 
 
 Saginaw, Mich. CAN 
 
 S. S. Ashtabula CAR 
 
 S. S. Regele Carol I CAR 
 S.S.Carolina CB 
 
 Buffalo, N.Y. CB 
 
 Boca del Colorado, Costa Rica 
 CB 
 
 Cheribon. Dutch East Indies 
 CB 
 
 S. S. Sierra CBJ 
 
 S. S. City of Cleveland CC 
 S. S. City of Detroit CD 
 
 Duluth, Minn. CD 
 
 Olifden, Ireland CDN 
 
 Detroit, Mich. CF 
 
 Chicago, 111 CG 
 
 Cape May, N.J. CG 
 
SUPPLEMENT 
 
 S. S. City of St. Ignace CG 
 Charlottenburg, Germany 
 
 CG 
 
 S. S. Quadra CGS 
 
 Port Huron, Mich. CH 
 
 San Franciso, Cal. (Chronicle 
 
 CH 
 
 Chamartin, Spain CH 
 
 S. S. Harmonic CHA 
 
 S. S. Huronic CHN 
 
 Erie, Pa. CI 
 
 Sault Ste. Marie, Mich. CJ 
 S. S. San Juan CJ 
 
 S. S. Juanita CJA 
 
 Detroit, Mich. (Detroit 
 
 Journal) CJL 
 
 S. S. Charlois CLS 
 
 Calumet, Mich. CM 
 
 Milwaukee, Wis. CM 
 
 Buenos Aires, Argentine Re- 
 public CM 
 S. S. Hugh Kennedy CMA 
 S. S. Jos. Sellewood CMB 
 S. S. S. M. Clement CMD 
 S. S. Pendenis White CMF 
 S. S. Moses Taylor CMG 
 S. S. James Gayley CMH 
 S. S. W. H. Gratwick CMI 
 S. S. J. J, Albright CMJ 
 S. S. Walter Scranton CMK 
 S. S. E. A. S. Clarke CMN 
 S S. Wm. E. Reis CMP 
 S. S. N. A. Hanna CMQ 
 S. S. H. S.Houlden CMR 
 S. S. Lagonda CMS 
 S. S. J. J. Me Williams CMU 
 S. S. Major CMV 
 S. S. Robt. L. Fryer CMW 
 Bishop, Boston, Mass. CN 
 Cleveland, Ohio CN 
 Ashtabula, Ohio CO 
 Cayo Criso, Cuba CO 
 
 Coruna, Italy CO 
 
 Marion, Mass. CON 
 
 Corvo, Azores COR 
 
 S. S. Ponce CP 
 
 Port Arthur, Ontario CPA 
 S. S. Princess Charlotte CPC 
 
 S. S. Princess May CPM 
 
 S. S. Princess Royal CPR 
 
 Tug Tees CPT 
 
 S. S. Princess Victoria CPV 
 
 Marquette, Mich. CQ 
 
 S. S. City of Erie CR 
 
 S. S. Senaca CS 
 
 S. S. Eastern States CS 
 
 St. Thomas, Ontario CST 
 
 S. S. Canada CT 
 
 Toledo, Ohio CT 
 
 S. S. Tionesta CTA 
 
 S. S. City of Buffalo CU 
 
 S. S. Commonwealth CW 
 
 S. S. Western States CW 
 
 Detroit, Mich. CW 
 
 S. S. St. Croix CX 
 
 Cleveland, Ohio CX 
 
 Bay City, Mich. CY 
 
 Seattle, Wash. (Hotel Perry) 
 DA 
 
 Santa Clara, Cuba DA 
 
 S. S. Philadelphia DA 
 
 S. S. Admiral DAA 
 S. S. Augustus B. Wolvin 
 
 DAB 
 
 S. S. Burgomaster DAB 
 
 S. S. Dacia DAC 
 
 S. S. Field Marshal DAF 
 
 S. S. Adeline DAH 
 
 S. S. Anni DAI 
 
 S. S. Kronprinz DAK 
 
 S. S. James H. Hoyt DAM 
 
 S. S. Frank H. Peavey DAN 
 
 S. S. Neubau DAN 
 
 S. S. Prinz Regent DAP 
 
WIRELESS OPERATORS' POCKET BOOK 
 
 S. S. Adolf Woennann DAW 
 S. S. Prinzessin DAZ 
 
 Tacoma, Wash. DB 
 
 S. S. Caracas DB 
 
 American schooner Dorothy 
 B. Barrett DBB 
 
 S. S. Birkenfels DBB 
 
 Durban, Hatal DBN 
 
 S. S. Bremen DBR 
 
 S. S. Bulow DBW 
 
 Washington, D.C. (Eighth 
 
 and Water streets) DC 
 S. S. Iowa DC 
 
 S. S. Cap Arcona DCA 
 
 S. S. Cap Blanco DCB 
 
 S S. Cap Verde DCE 
 
 S. S. Cap Frio DCF 
 
 S. S. Tietgen DCF 
 
 S. S. Clare DCH 
 
 S. S. Kronprinzessin Cecile 
 
 DCI 
 
 S. S. Clara Blumenfeld DCL 
 S. S. Cap Ortegal DCO 
 
 S. S. Cap Roca DCR 
 
 S. S. Cap Vilabo DCV 
 
 S. S. Kaiserin Augusta Vic- 
 toria DDA 
 S. S. Bleucher DDE 
 S. S. Cincinnati DDC 
 S. S. Bulgaria DDG 
 S.S.Pisa DDF 
 S. S. Hamburg DDK 
 S. S. President Lincoln DDI 
 S S. Batavia DDJ 
 S. S. Deutschland DDL 
 S S. Moltke DDM 
 S. S. Pennsylvania DDN 
 S. S. Prinz Oscar DDO 
 S. S. Patricia DDP 
 S. S Pallanza DDQ 
 S. S. Amerika DDR 
 S. S. President Grant DDS 
 
 S. S. Pretoria DDT 
 
 S. S. Cleveland DDV 
 
 S. S. Graf Waldersee DDW 
 S. S. Prinz Adalbert DDZ 
 Pasadena, Cal. DE 
 
 S. S. Edmund DEH 
 
 S. S. Derfflinger DER 
 
 S. S. Elenore Woermann 
 
 DEW 
 
 Santa Barbara, Cal. (Hotel 
 
 Potter) DF 
 
 Vancouver, British Columbia 
 
 DF 
 
 S. S. Furst Bismarck DFB 
 S. S. Fred. B. Wells DFB 
 S. S. Fritz DFH 
 
 Sacramento, Cal. DG 
 
 S. S. D. G. Kerr DGK 
 
 S S. Grosserog von Olden- 
 burg DGO 
 S. S. Goeben DGN 
 S. S. Gneisenau DGU 
 S. S. Gertrude Woermann 
 
 DGW 
 
 S. S. Kingfisher DH 
 
 S. S. Helene Blumenfeld 
 
 DHB 
 
 S. S. Camerones DHC 
 
 S. S. Heluan DHE 
 
 S. S. Habsburg DHG 
 
 S. S. Mendoza DHM 
 
 S. S. Hohenstauffen DHN 
 S. S. Frank T. Heffelinger 
 
 DHN 
 
 S. S. Hellig Olav DHO 
 
 S. S. Presidente de Mintre 
 
 DHP 
 S. S. Presidente'Quintana 
 
 DHQ 
 
 S. S. Holger DHR 
 
 S. S. Kingsway DI 
 
 S. S. Imperator DIR 
 
SUPPLEMENT 
 
 San Pedro, Cal. DJ 
 
 S. S. James C. Wallace DJC 
 S. S. James H. Reed DJR 
 Everett, Wash. DK 
 
 S. S. Kronprinzessin 
 
 Cecile DKA 
 
 S. S. Berlin DKB 
 
 Ikeda Head, Wash. DKD 
 S S. Friedrich der Grosse 
 
 DKD 
 
 S. S. Princess Irene DKE 
 S. S. Prinz Friedrich 
 
 August DKF 
 
 S. S. Konig Friedrich 
 
 August DKF 
 
 S. S. Konig Wilhelm II DKG 
 S. S. Grosser Kurfurst DKG 
 S. S. Main DKI 
 
 S. S. Neckar DKK 
 
 S S. Konigen Luise DKL 
 S. S. Kaiser Wilhelm II DK 
 S. S. George Washington 
 
 DKN 
 
 S. S. Konig Albert DKO 
 S. S. Kronprinz Wilhelm 
 
 DKP 
 
 S. S. Rhein DKR 
 
 S. S. Barbarossa DKS 
 
 S. S. Kaiser Wilhelm der 
 
 Grosse DKW 
 
 S. S. Princess Alice DKZ 
 S. S. Lutzow DLO 
 
 S. S. Lucile Woermann DLW 
 Duluth, Minn. . DM 
 
 S. S. Meteor DMR 
 
 S. S. Mainz DMZ 
 
 San Luis Obispo, Cal. DN 
 Drogden, Denmark DN 
 
 S. S. Nora DNH 
 
 S. S. Moskwa DOA 
 
 S. S. Oscar second DOR 
 
 Dieppe, France DP 
 
 S. S. Prince Adalbert DPA 
 S. S. Prinz Eitel Fried- 
 rich DPE 
 S. S. Prinz Ludwig DPL 
 S. S. Prince Sigismund DPS 
 S. S. Prince Waldemar DPW 
 Eugene, Oreg. DR 
 Detroit, Mich. DR 
 S. S. Corcovado DRC 
 S. S. Prinz Regent Luit- 
 
 pold DRL 
 
 S. S. Roon DRN 
 
 South Haven, Mich. DS 
 
 Port Townsend, Wash DS 
 S. S. Scharnhorst DSA 
 
 S. S. Senator Holthusen DSH 
 S. S. Sarnia DSM 
 
 S. S. H. P. Bope DSO 
 
 S. S. Senator Refardt DSR 
 S. S. Kleist DST 
 
 S. S. Siberia DSV 
 
 S. S. Seyditz DSZ 
 
 S. S. Titania DTG 
 
 S. S. Admiral ' DTP 
 
 Wilmington, Del. DU 
 
 Juneau, Alaska DU 
 
 S. S. Geo. W. Peavey DUF 
 S. S. United States DUS 
 Chehalis, Wash. DV 
 
 Newport, Oreg. DW 
 
 S. S. Ward Ames DWA 
 
 Toledo, Ohio (Hotel Secor) 
 
 DX 
 
 S. S. Ypiranga DYA 
 
 S. S.Yorck DYK 
 
 Lansing, Mich. DZ 
 
 Portland, Oreg. DZ 
 
 S. S. Ziethan DZN 
 
 American schooner Pendleton 
 Sisters Dl 
 
 Port Townsend, Wash. D2 
 
8 
 
 WIRELESS OPERATORS' POCKET BOOK 
 
 S. S. Earl Grey EG 
 
 S. S. El Norte EN 
 
 S. S. Easton ES 
 
 Cerritos de Sinaloa, 
 
 Mexico EY 
 
 U. S. Army cable boat 
 
 Field FA 
 
 S. S. City of Columbus FA 
 Malabang, P. I. FA 
 
 Fayal. Azores FAL 
 
 Outer Jade lightship, Ger- 
 many FAU 
 S. S. City of Atlanta FB 
 Fairbanks, Alaska FB 
 Borkum Reef lightship, Ger- 
 many FBR 
 Fort Andrews, Mass. FC 
 S. S. City of Macon FC 
 Fort Wood, N. Y. FD 
 S. S. City of Memphis FD 
 Nome, Alaska FD 
 Ferrol, Spain FE 
 Kotlik, Alaska FE 
 Elbe I lightship, Ger- 
 many FEF 
 S. S. Naomi FG 
 Fort Gibbon, Alaska FG 
 Corregidor Island, P. I. FH 
 Eider lightship, Germany 
 
 FIF 
 
 S. S. City of Augusta FJ 
 Fort Stevens, Oreg. FJ 
 
 S. S. City of Savannah FK 
 Circle City, Alaska FK 
 
 Fort Leavenworth, Kans. FL 
 Flores, Azores FLO 
 
 Flekkero, Norway FLK 
 
 Fort St. Michael, Alaska FM 
 Fort Morgan, Ala. FM 
 
 Zamboanga, P. I. FM 
 
 Fort Hancock, N. J. FN 
 
 Flannon, Isle, Scotland FNL 
 
 Fastnet, Ireland FNT 
 
 Fort Monroe, Va. FO 
 
 S. S. Nacoochee EP 
 
 Petersburg, Alaska FP 
 
 Fort Egbert, Alaska FQ 
 
 U. S. Army Cable Ship 
 
 Joseph Henry FR 
 
 Fort Omaha, Nebr. FS 
 
 Jolo, P. I. FS 
 
 Fort Totten, N. Y. FT 
 
 Fort Levett, Me. FV 
 
 Villegignon, Brazil FVG 
 Fort H. G. Wright, N.Y. FW 
 Wrangell, Alaska FW 
 
 Wesser lightship, Germany 
 
 S. S. City of St. Louis FX 
 Fort Worden, Wash. FX 
 S. S. City of Montgomery FY 
 U. S. Artillery harbor tug, 
 
 General R. B. Ay res FY 
 Yacht Lydonia FZ 
 
 Fort Riley, Kans. FZ 
 
 S. S. City of Seattle GA 
 
 S. S. Capt. A. F. Lucas CB 
 Cape Breton, Glace Bay, 
 
 Nova Scotia GB 
 
 Bolt Head, England GBA 
 S. S. Georgia GC 
 
 Brow Head, Ireland GCK 
 Caistor, England GCS 
 
 Standard Oil barge 91 GD 
 Graady lightship, Den- 
 mark GD 
 S. S. City of Everett GF 
 S. S. Falcon GF 
 S. S. Maverick GH 
 Grand Haven, Mich. GH 
 Gjedser, Denmark GJ 
 S. S. Cottage City GK 
 Standard Oil barge 94 GK 
 Karlskrona, Sweden GK 
 
SUPPLEMENT 
 
 9 
 
 The Lizard, England OLD 
 Liverpool, England GLV 
 Grand Marians, Minn. GM 
 S. S. Asuncion GM 
 
 S. S. Pilgrim GM 
 
 Malin Head, Ireland GMH 
 S. S. Atlas GN 
 
 North Foreland, England 
 
 GNF 
 
 Niton, England GNI 
 
 Chicago, 111. (Congress 
 
 Hotel) GO 
 
 Standard Oil barge 95 GP 
 S.S. City of Pueblo GQ 
 
 Copenhagen, Denmark GRA 
 Guaraliba, Brazil GRA 
 
 Rosslare, Ireland GRL 
 
 Grand Rapids, Mich. GRM 
 S. S. Astral GS 
 
 S. S. Senator GS 
 
 S. S. Umatilla GU 
 
 Guernsey, England GU 
 
 Guadalajara, Spain GU 
 
 Galveston, Texas GV 
 
 S. S. Governor GV 
 
 Grand Island, La. GW 
 
 S. S. President GW 
 
 S. S. Queen GX 
 
 Los Angeles, Cal. G2 
 
 Holland, Mich. H 
 
 Horten, Norway H 
 
 Cape Hatteras, N. C. HA 
 New Orleans, La. (United 
 
 Fruit Co.) HB 
 
 U. S. Army Artillery harbor 
 
 tug Harvey Brown HB 
 
 Heysham, England HER 
 
 S. S. Arizona HC 
 
 Carlobago, Austiia-Hungary 
 
 HC 
 
 S. S. Alameda HD 
 
 Elizabeth City, N.C. HD 
 
 Helder, Holland HDR 
 
 Fiume, Austria-Hungary HF 
 S. S. Mariposa HK 
 
 New Orleans, La. HK 
 
 Cape d'Aguilar, Hongkong 
 
 Haaks Lightship, Holland 
 
 HKS 
 
 S. S. Jefferson HM 
 
 S. S. Hanalia HN 
 
 S. S. Chester W. Chapin HN 
 S. S. Missouri HN 
 
 Hunstanton, England HNU 
 S. S. Corwin HO 
 
 S. S. Chicago HO 
 
 Hoek van Holland HOK 
 Trinidad (High Post) HP 
 Mackinac Island, Mich. HQ 
 Horns Reef lightship, Den- 
 mark 
 
 Cabo Haro, Mexico HR 
 
 Tug Savage HS 
 
 S. S. Londonderry HSM 
 
 Nak Nek, Alaska HT 
 
 Kahuku, Oahu, Hawaiian Is- 
 lands HU 
 Havana, Cuba (Vedado) HV 
 S. S. Grant HV 
 S. S. Mackinaw HW 
 Cuban Revenue Cutter 
 
 Hatuey HY 
 
 Ludington, Mich. HX 
 
 S. S. Humboldt HX 
 
 Amesbury, Mass HY 
 
 S. S. Plymouth HY 
 
 Zengg, Austria-Hungary HZ 
 S. S. Rose City H2 
 
 Brest, France (arsenal) IBF 
 Ilha das Cobras, Brazil ICL 
 Inistrahull, Ireland IH 
 
 S. S. Illinois IN 
 
 Toulon, France ITF 
 
10 WIRELESS OPERATORS' POCKET BOOK 
 
 S. S. Imparatul Traian ITR 
 Port Vendres, France IVF 
 S. S. City of Racine JC 
 
 Kingston, Jamaica JCA 
 
 Chosi, Japan JCS 
 
 S. S. North Land JD 
 
 Jersey, England JE 
 
 S. S. Horato Hall JH 
 
 S. S. Manhattan JM 
 
 Otchishi, Japan JO I 
 
 Ose Saki, Japan JOS 
 
 S. S. North Star JS 
 
 Shiomizaki, Japan JSM 
 
 Tsunoshima, Japan JTS 
 
 S. S. James Whalen JW 
 
 Jacksonville, Fla. JX 
 
 S. S. Antilles KA 
 
 Puako, Hawaiian Islands KA 
 Angaur, Caroline Islands 
 
 KAN 
 
 Spokane, Wash. - KB 
 Bremerhaven, Lloyd Hall, 
 
 Germany KBH 
 
 Arkona, Germany KAR 
 
 Bwlk, Germany KBK 
 
 Borkum, Germany KBM 
 Brunsbuttelkoog, Germany 
 
 KBR 
 
 S. S. Christopher Colum- 
 bus KC 
 Cuxhaven, Germany KCX 
 S. S. Comus KD 
 St. Helens. Oreg, KE 
 S. S. King Harold KGH 
 Helgoland, Germany KHG 
 Yap, Caroline Islands KJA 
 S. S. Momus KM 
 Marienleuchte, Germany 
 
 KMR 
 
 Erie, Pa. KN 
 
 Norddeich, Germany KND 
 
 Pachena Point, British 
 
 Columbia KPD 
 
 S. S. Creole KR 
 
 S. S. Santa Cruz KS 
 
 Constanca, Roumania KST 
 The Dalles, Oreg. KT 
 
 Tsingtau, China KTS 
 
 Signalberg, Germany KTS 
 Walla Walla, Wash. KU 
 Key West, Fla. KW 
 
 S. S. Kentucky KY 
 
 Lahaina, Maui, Hawaiian Is- 
 lands " LH 
 Machrihanish Bay, Scot- 
 land LK(D) 
 Cullercoats, England LNS 
 S. S. Lady Laurier LR 
 Castelneuvo, Austria- 
 Hungary LRC 
 Pola, Austria-Hungary LRP 
 Sebenico, Austria-Hungary 
 
 LRS 
 
 Loch Boisdale, Scotland LSG 
 Lussin, Austria-Hungary LU 
 Havana, Cuba. (Morro 
 
 Castle) M 
 
 Messina, Italy M 
 
 S. S. Alliance MA 
 
 S. S. Maine MA 
 
 S. S:Carmania MAA' 
 
 S. S. Lombardia MAB 
 
 S. S. Sicilia MAC 
 
 S. S. Duca Degli Abruzzi 
 
 MAD 
 
 S. S. Duca di Geneva MAE 
 S. S. Mendoza MAF 
 
 S. S. Cordova MAG 
 
 S. S. Virginia MAH 
 
 S. S. Caledonia MAI 
 
 S. S. Indiana MAK 
 
 S. S. Liguria MAL 
 
 S. S. Lusiania MAM 
 
SUPPLEMENT 
 
 11 
 
 S. S. Niagara MAN 
 
 S. S. Duca d'Aosta MAO 
 S. S. Sardegna MAS 
 
 Steam yacht Atalanta MAT 
 American Tickle. Labrador 
 
 MAT 
 
 Asinara, Sardinia, Italy MAS 
 S. S. Umbria MAU 
 
 S. S. Florida MAV 
 
 S. S. Alva MAV 
 
 S. S. Antony MAY 
 
 Mobile, Ala. MB 
 
 Cable steamer Mackay-Ben- 
 nett MB 
 
 S. S. Asturias MBB 
 
 S. S. Baltic MBC 
 
 Bardera, Italy MBD 
 
 Cape Bear, Prince Edward Is- 
 land MBE 
 S. S. Araguay MBG 
 Battle Harbor, Labrador 
 
 MBH 
 Belle Isle, Newfoundland 
 
 MBI 
 Bernal. Argentine Republic 
 
 MBL 
 
 S. S. Arragon MEN 
 
 S. S. Avon MBO 
 
 S. S. Ben My Chree MBQ 
 Bloomfield, England MBR 
 Palm Beach. Fla. MBS 
 
 Becco di Vela, Caprera, 
 
 Italy MBV 
 
 S. S. Athenie MBW 
 
 Brava, Italy MBW 
 
 S. S. Old Colony MC 
 
 S. S. Sheboygan MC 
 
 S. S. Campania MCA 
 
 Chateau Bay, Labrador MCB 
 Cape Cod, Mass. MCC 
 
 Steam yacht Cassandra MCD 
 S. S. Cambria MCG 
 
 Mocangue, Brazil MCG 
 
 S. S. California MCI 
 
 Point Rich. Nova Scotia 
 
 MCH 
 
 S. S. Chili MCI 
 
 Clarke City, Seven Islands, 
 
 Canada MCK 
 
 Cable ship Colonia MCL 
 Capo Mele, Liguria, Italy 
 
 MCM 
 
 S. S. Corsican MCN 
 
 S. S. Chaco MCO 
 
 Monte Capuccini, Ancona, 
 
 Italy MCP 
 
 Cape Ray, Newfoundland 
 
 MCR 
 
 S. S. Bucaneer MCT 
 
 Cape May, N. J. MCY 
 
 Cozzo Spadaro, Cape Passaro, 
 
 Sicily MCZ 
 
 S. S. Cristobal MD 
 
 S. S. Shinnecock- MD 
 
 S. S. Cedric MDC 
 
 S. S. Dominion MDF 
 
 S. S. Devonian MDL 
 
 S. S. Sardinian MDN 
 
 Domino Island, Labrador 
 
 MDO 
 
 Steam yacht Electra ME 
 S. S. Etruria MEA 
 
 S. S. Tarnarac MEB 
 
 S. S. Narragansett MEG 
 
 S. S. Cassandra MED 
 
 S. S. Iroquois MEI 
 
 Merka, Italy MEK 
 
 S. S. Bohemian MEL 
 
 Melilla, Morocco MEL 
 
 S. S. Navahoe MEN 
 
 S. S. Empress Queen MEQ 
 S. S. Royal Edward MER 
 S. S. Satrustegin MES 
 
 S. S. Alfonse XII MET 
 
12 WIRELESS OPERATORS' POCKET BOOK 
 
 S. S. Finance 
 S. S. Lusitania 
 S. S. Arabic 
 S. S. Canada 
 S. S. Finland 
 
 MF 
 MFA 
 MFC 
 MFC 
 MFD 
 
 S. S. W. H. Gratwick MFD 
 Fraserburgh, Scotland MFH 
 S. S. Furnessia MFI 
 
 S. S. Winifredian MFL 
 
 S. S. Pretorian MFN 
 
 Fame Point, Quebec MFP 
 Fort Spuria, Messina, Italy 
 
 MFS 
 
 Tug Tatoosh MG 
 
 S. S. Mauretania MGA 
 
 Steam yacht Lysistrata MGB 
 S. S. Cymric MGC 
 
 S. S. Saturnia MGD 
 
 S. S. Germania MGE 
 
 S. S. Harvard MGH 
 
 Grosse Isle, Quebec MGI 
 S. S. Canadian MGL 
 
 S. S. Virginian MGN 
 
 Giumbo, Italy MGO 
 
 S. S. Royal George MGR 
 S. S. Yale MGY 
 
 S. S. Panama MH 
 
 S. S. Noordan MHA 
 
 S. S. New Amsterdam MHB 
 S. S. Adriatic MHC 
 
 New Haven, England MHH 
 S. S. Cestrian MHL 
 
 S. S. Potsdam MHM 
 
 S. S. Cartheginian MHN 
 
 Heath Point, Anticosti Island, 
 
 Canada MHP 
 
 S. S. Rotterdam MHR 
 
 S. S. Statendam MHS 
 
 Camperdown, Halifax, Nova 
 
 Scotia MHX 
 
 S. S. Rijndam MHY 
 
 S. S. Minnesota MI 
 
 S. S. Ivernia 
 S. S. Laurent ic 
 S. S. Inanda 
 S. S. Inkosi 
 S. S. lolanda 
 
 MIA 
 MIC 
 MID 
 MIK 
 MIL 
 
 S. S. Principesa Mafalda MIM 
 
 S. S. Ionian MIN 
 S. S. Principesa lolanda MIO 
 
 Itala, Italy MIT 
 
 S. S. Suevic MJC 
 
 S. S. Haverford MJH 
 
 S. S. Merion MJM 
 
 S. S. Millinocket MK 
 
 Milwaukee, Wis. MK 
 
 S. S. Olympic MKC 
 
 S. S. Kroonland MKD 
 
 S. S. Frisia MKF 
 
 S. S. Hollarfd MKH 
 
 S. S. Corinthian MKN 
 
 S. S. Makura MKU 
 
 S. S. Killarney MKY 
 
 S. S. Montcalm ML 
 
 S. S. Guadeloupe MLA 
 
 S. S. La Bretagne MLB 
 
 S. S. Celtic MLC 
 
 S. S. Leopold II MLD 
 
 S. S. Lake Erie MLE 
 
 S. S. Milwaukee MLF 
 
 S. S. La Flandre MLF 
 
 S. S. La Gascoyne MLG 
 
 S. S. Lake Michigan MLH 
 
 S. S. Montreal MLI 
 
 S. S. Montrose MLJ 
 
 S. S. Montezuma MLK 
 
 S. S. La Lorraine MLL 
 
 S. S. Lake Manitoba MLM 
 
 S. S. Lake Champlain MLN 
 
 S. S. Mount Royal MLO 
 
 S. S. La Provence MLP 
 
 S. S. Mount Temple MLQ 
 
 S. S. La Navarre MLR 
 
 S. S. La Savoie MLS 
 
SUPPLEMENT 
 
 13 
 
 S. S. La Touraine 
 
 S. S. La Champagne 
 
 Lugh, Italy 
 
 S. S. Montfort 
 
 S. S. Monmouth 
 
 S. S. Chicago 
 
 S. S. Montcalm 
 
 S. S. Minnehaha 
 
 S. S. Madonna 
 
 S. S. Majestic 
 
 S. S. Ma'lwa 
 
 S. S. Mantua 
 
 S. S. Morea 
 
 S. S. Egypt 
 
 S. S. Moldavia 
 
 S. S. Marie Henriette 
 
 S. S. Charles Roux 
 
 S. S. Mongolia 
 
 S. S. Minnetonka 
 
 S. S. Macedonia 
 
 S. S. Mooltan 
 
 S. S. Minneapolis 
 
 MLT 
 MLU 
 MLU 
 MLW 
 MLX 
 MLY 
 MLZ 
 MMA 
 MMB 
 MMC 
 MMD 
 MME 
 MMF 
 MMG 
 MMH 
 MMH 
 MMI 
 MMJ 
 MMK 
 MML 
 MMM 
 MMN 
 
 Punta del Este, Uragua 
 
 S. S. Persia 
 S. S. Marmora 
 
 MMO 
 MMQ 
 MMR 
 
 San Guilano di Trapani, 
 
 Italy MMS 
 
 S. S. Salsette MMT 
 
 S. S. China MMU 
 
 S. S. Perou MMV 
 
 S. S. Mesaba MMV 
 
 S. S. Minnewaska MMW 
 
 S. S. India MMY 
 
 S. S. Arabia MMZ 
 
 Tug Lome MN 
 
 S. S. Manitou MN 
 
 S. S. Pannonia MNA 
 
 S. S. Romanic MNC 
 
 North Sydney. Canada MND 
 S. S. Menominee MNE 
 
 S. S. Grotius MNG 
 
 S. S. New York MHK 
 
 S. S. Manitou MNM 
 
 S. S. Numidian MNN 
 
 S. S. Oranje MNO 
 
 S. S. Prinses Juliana MNP 
 S. S. Marquette MNQ 
 
 S. S. Rembrandt MNR 
 
 Indian Harbor, Labrador 
 
 MNR 
 
 S. S. Konig Wilhelm III MNT 
 S. S. Vondel MNV 
 
 S. S. Konig Wilhelm I MNW 
 S. S. Ancona MOA 
 
 S. S. Bologna MOB 
 
 S. S. Oceanic MOC 
 
 S. S. Otrato MOO 
 
 S. S. Sienna MOE 
 
 S. S. Columbia MOI 
 
 S. S. Mongolian MON 
 
 S. S. Ravenna MOR 
 
 S. S. Toscana MOS 
 
 S. S. Taormina MOT 
 
 S. S. Verona MOV 
 
 S. S. Carpathia MPA 
 
 S. S. Empress of Britain MPB 
 S. S. Canopic MFC 
 
 S. S. Princess Clementine 
 
 MFC 
 
 Poldhu, England MPD 
 
 S. S. Lapland MPD 
 
 S. S. Princess Elizabeth MPE 
 S. S. Empress of China MPG 
 S. S. Philadelphia MPH 
 
 S. S. Princess Henriette MPH 
 S. S. Empress of India MPI 
 S. S. Empress of Japan MPJ 
 S. S. Princess Josephine MPL 
 S. S. Empress of Ireland MPL 
 Palmaria, Italjt MPM 
 
 Capo Sperone, Sardinia, 
 
 Italy MPN 
 
 Point Amour, Labrador MPR 
 
14 WIRELESS OPERATORS' POCKETBOOK 
 
 Ponza Island, Italy MPS 
 S. S. Patris MPT 
 
 S. S. Balmoral Castle MPW 
 S. S. Persic MQC 
 
 S. S. Bunker Hill MR 
 
 S. S. Caronia MRA 
 
 S. S. Roma MRB 
 
 S. S.Cretic MRC- 
 
 S. S. Sindoro MRD 
 
 S. S. Regina Elena MRE 
 S. S. Sannio MRF 
 
 S. S. Regina d'ltalia MRG 
 S. S. Campania MRH 
 
 S. S. Re d'ltalia MRI 
 
 S. S. Ophir MRJ 
 
 S. S. Kawi MRK 
 
 Monte Mario, Rome, Italy 
 
 MRM 
 
 S. S. Grampian MRN 
 
 S. S. Re Vittorip MRO 
 
 S. S. Principe di Piedmonte 
 
 MRP 
 
 S. S. Soentuer MRQ 
 
 S. S. Rindjani MRM 
 
 S. S. Tomasodi Savoia MRS 
 Three Rivers, Canada MRS 
 Father Point, Quebec MRT 
 S. S. Principe Umberto MRU 
 S. S. Principe di' Udine MRV 
 S. S. Willis MRW 
 
 S. S. Tambora MRY 
 
 S. S. Lazio MRZ 
 
 S. S. Ancon MS 
 
 S. S. Massachusetts MS 
 
 S. S. Saxonia MSA 
 
 Cape Sable, Nova Scotia 
 
 MSB 
 
 Siasconsett, Mass. MSC 
 
 Sable Island, Nova Scotia 
 
 MSB 
 
 Sea Gate, N. Y . MSE 
 
 S. S San Giovanni MSF 
 
 S. S. San Georgio . MSH 
 
 St. John, Pattridge Island, 
 
 New Brunswick MSJ 
 
 Sagaponack, N. Y. MSK 
 Santa Maria di Leuca, 
 
 Italy MSL 
 
 S. S. St. Louis MSL 
 
 S. S. San Guiseppi MSN 
 
 S. S. Hesperian MSN 
 
 S. S. San Gugliemo MSO 
 S. S. St. Paul MSP 
 
 Wellfleet, Cape Cod, Mass. 
 
 MSW 
 
 S. S. Minto MT 
 
 S. S. Ultonia MTA 
 
 S. S. Teutonic MTC 
 
 Cross Sand lightship, 
 
 England MTD 
 
 East Goodwin lightship Eng- 
 land MTE 
 Gull lightship, England MTG 
 S. S. Themistocles MTH 
 S. S. Athinai MTI 
 Steam yacht Florence MTK 
 Sunk lightship, "England 
 
 MTK 
 
 Montreal, Quebec MTL 
 
 S. S. Tunisian MTN 
 
 Torre Pilot! di Malamocco, 
 
 Italy MTP 
 
 S. S. Trotona MTR 
 
 South Goodwin lightship, 
 
 England MTS- 
 
 Tongue lightship. England 
 
 MTT 
 
 Murdock, Chelsea, Mass. MU 
 Musil, Austria-Hungary MU 
 S. S. Umbria MUA 
 
 S. S. Titanic MUG 
 
 S. S. Francesca MUF 
 
 S. S. Argentina MUG 
 
 S. S. Alice MUL 
 
SUPPLEMENT 
 
 S. S. Sicilian MUN 
 
 S. S. Oceania MUO 
 
 S. S. Laura MUR 
 
 S. S. Sophia MUS 
 
 S. S. Martha Washington 
 
 MUW 
 
 S. S. Advance MV 
 
 S. S. New Haven MV 
 
 S. S. Argentina MVA 
 
 S. S. Bresilia MVB 
 
 S. S. Italia MVC 
 
 S. S. Vaderland MVD 
 
 Montevideo, Uruguay MVD 
 S. S. Europa MVE 
 
 S. S. Savoia MVF 
 
 Venison Island, Labrador 
 
 MVI 
 Steam yacht The Viking 
 
 S. S. Victorian MVN 
 
 S. S. Oceania MVO 
 
 S. S. Viking MVQ 
 
 S. S. Nord America MVR 
 S. S. America . MVS 
 
 Viesti, Mount Gargano, 
 
 Italy MVT 
 
 S. S. Venezia MVZ 
 
 S. S. Maurence MW 
 
 Manitowoc, Wis. MW 
 
 Wilhelmshaven, Germany 
 
 MW 
 
 Vladivostok, Siberia MW 
 S. S. Aaro MWA 
 
 S. S. Runic MWC 
 
 S. S. Ionic MWI 
 
 S. S. Athenic MWN 
 
 S. S. Oslo MWO 
 
 Whittle Rocks, Quebec MWR 
 Withernsea, England MWS 
 S. S. Corinthic MWT 
 
 S. S. Colon MX 
 
 S. S. Medic MXC 
 
 S. S. Afric MYC 
 
 Mazatlan, Mexico MZ 
 
 S. S. Zealandia MZA 
 
 S. S. Bornu MZB 
 
 S. S. Megantic MZC 
 
 S. S. Zeeland MZD 
 
 S. S. Florizal MZL 
 
 S. S. Parisian MZN 
 
 S. S. Rosalind MZR 
 
 Venice, Italty (Arsenal) 
 
 MZV 
 
 Gjedser Reef lightship, Den- 
 mark N 
 Nauen, Germany NA 
 Cape Elizabeth, Me. (naval 
 
 station) NAB 
 
 Portsmouth, N. H., (navy 
 
 yard) NAC 
 
 Boston, Mass, (navy-yard) 
 
 NAD 
 Cape Cod, Highland Light, 
 
 Mass, (naval station) NAE 
 Newport, R. I. (naval 
 
 station) NAF 
 
 Fire Island, N. Y. (naval 
 
 station) NAG 
 
 Brooklyn, N. Y. (navy- 
 yard) NAH 
 Philadelphia, Pa. (navy- 
 yard) NAI 
 Cape Henlopen, Lewes, DeL 
 (naval station) NAJ 
 Annapolis, Md. ((Naval 
 
 Academy) NAK 
 
 Washington, D. C. (navy- 
 yard) NAL 
 Norfolk, Va. (navy-yard) 
 
 NAM 
 
 Pivers Island, Beaufort, N.C. 
 (naval station) NAN 
 
 Charleston, S. C. (navy- 
 yard) NAO 
 
16 WIRELESS OPERATORS' POCKET BOOK 
 
 St. Augustine Fla. (naval 
 
 statiqn) NAP 
 
 Jupiter Inlet, Neptune, Fla. 
 
 (naval station) NAQ 
 
 Key West, Fla. (naval 
 
 station) NAR 
 
 Pensacola, Fla. (navy- 
 yard) ' NAS 
 New Orleans, La. (naval 
 
 station) NAT 
 
 San Juan, P. R. (naval 
 
 station) NAU 
 
 Culebra, W.I. (naval 
 
 station) NAV 
 
 Guantanamo, Cuba (U. S. 
 
 naval station) NAW 
 
 Colon, Isthmian Canal Zone 
 
 (naval station) NAX 
 
 Porto Bello, Isthmian Canal 
 
 Zone (naval station) NAY 
 U. S. S. Ajax NBH 
 
 U. S. S. Alabama NBI 
 
 U. S. S. Albany NBJ 
 
 U. S. S. Alexander NBM 
 U. S. S. Arethusa NBU 
 
 U. S. S. Bailey NCF 
 
 U. S. S. Bainbridge NCG 
 U. S. S. Baltimore NCH 
 
 U. S. S. Barry NCK 
 
 U. S. S. Biddle NCM 
 
 U. S S. Birmingham NCN 
 U. S. S. Brutus NCT 
 
 U. S. S. Buffalo NCU 
 
 U. S. S. Burrows NCV 
 
 U. S. S. Caesar NCY 
 
 U. S. S. California NCZ 
 
 S. S. Northland ND 
 
 U. S. S. Castine NBA 
 
 U. S. S. Celtic NDB 
 
 U. S. S. Charleston NDC 
 U. S. S. Chattanooga NDE 
 U. S. S. Chauncey NDF 
 
 U. S. S. Chester NDG 
 
 U. S. S. Chicago NDI 
 
 U. S. S. Cincinnati NDL 
 
 U. S. S. Cleveland NDM 
 
 U. S. S. Colorado NDN 
 
 U. S. S. Connecticut NDQ 
 
 U. S. S. Culgoa NDU 
 
 U. S. S. Cyclops NDY 
 S. S. Nushagak NE 
 
 U. S. S. Dale NEH 
 
 U. S. S. Decatur NEJ 
 
 U. S. S. Delaware NEK 
 
 U. S. S. Denver NEM 
 
 U. S. S. Des Moines NEN 
 
 U. S. S. Dixie NEP 
 
 U. S. S. Dolphin NEQ 
 U. S. S. Don Juan de Austria 
 
 (Michigan Naval Militia 
 
 NER 
 
 U. S. S. Drayton NET 
 
 U. S. S. Dubuque NEU 
 
 U. S. S. Eagle NFC 
 
 U. S. S. Farragut NFP 
 
 U. S. S. Flusser NFS 
 
 U. S. S. Galveston NGD 
 
 U. S. S. Georgia NGF 
 
 U. S. S. Glacier NGH 
 
 U. S. S. Goldsborough NGJ 
 U. S. S. Gopher (Minnesota 
 
 Naval Militia) NGK 
 
 U. S. S. Hannibal NGU 
 
 U. S. S. Hartford NGV 
 
 U. S. S. Hector NGX 
 
 U. S. S. Helena NGY 
 S. S. Wilhelmina NH 
 
 U. S. S. Hopkins NHC 
 
 U. S. S. Hull NHE 
 
 U. S. S. Idaho NHN 
 
 U. S. S. Illinois NHO 
 
 U. S. S. Indiana NHQ 
 
 U. S. S. Iowa NHT 
 
 U. S. S. Isis NHU 
 
SUPPLEMENT 
 
 17 
 
 S. S. Klamath NI 
 U. S. S. Jupiter NIE 
 U. S. S. Justin NIF 
 U. S. S. Kansas NIO 
 U. S. S. Kearsarge NIP 
 U. S. S. Kentucky NIQ 
 U. S. S. Lamson NIW 
 U. S. S: Lawrence NIY 
 U. S. S. Lebanon NIZ 
 U. S. S. Leonidas NJA 
 U. S. S. Louisiana NJB 
 U' S. S. Macdonough NJH 
 U. S. S. Machias NJI 
 U. S. S. Maine NJL 
 U. S. S. Marietta NJQ 
 U. S. S. Mars NJR 
 U. S. S. Maryland NJS 
 U. S. S. Massachusetts NJT 
 U. S. S. Mayrant NJU 
 U. S. S. Mayflower NJV 
 U. S. S. McCall NJW 
 U. S: S. Michigan NJZ 
 S. S. Pequonock NK 
 U. S. S. Milwaukee NKA 
 U. S. S. Minnesota NKD 
 U. S. S. Mississippi NKE 
 U. S. S. Missouri NKF 
 U. S. S. Montana NKM 
 U. S. S. Monterey NKN 
 U. S. S. Montgomery NKO 
 U. S. S. Nanshan NKV 
 Nantucket Shoals light- 
 ship NLA 
 Diamond Shoals light- 
 ship NLB 
 Frying Pan Shoals light- 
 ship NLC 
 U. S. S. Nebraska NMA 
 U. S. S. Nero NMB 
 U. S. S. New Hampshire 
 
 NME 
 
 U. S. S. New Jersey NMF 
 
 U. S. S. New Orleans NMG 
 New York nautical school 
 
 ship Newport NMH 
 
 U. S. S. New York NMI 
 
 U. S. S. North Carolina NMN 
 U. S. S. North Dakota NMO 
 U. S. S. Ohio NMW 
 
 U. S. S. Olympia NMX 
 
 Nonendamm, Germany NO 
 U. S. S. Paducah NOG 
 
 U. S. S. Panther NOJ 
 
 U. S. S. Patapsco NOL 
 
 U. S. S. Patuxent NOM 
 
 U. S. S. Paulding NON 
 
 U. S. S. Paul Jones NOP 
 U. S. S. Pennsylvania NOT 
 U. S. S. Perkins NOX 
 
 U. S. S. Perry NOY 
 
 Cordova, Alaska (naval 
 
 station) NPA 
 
 Sitka, Alaska (naval 
 
 station) NPB 
 
 Bremerton, Wash, (navy- 
 yard) NPC 
 Tatoosh Island, Wash, (naval 
 station) NPD 
 North Head, Wash, (naval 
 
 station) NPE 
 
 Cape Blanco, Oreg. (naval 
 
 station) NPF 
 
 Table Bluff, Cal. (naval 
 
 station) NPG 
 
 North Post, Trinidad NPG 
 Mare Island, Cal. (navy- 
 yard) NPH 
 Farallon Islands, Cal. (naval 
 station) NPI 
 Yerba Buena Island, Cal. 
 
 (naval station) NPJ 
 
 Point Arguello, Cal. (naval 
 station) NPK 
 
18 WIRELESS OPERATORS' POCKET BOOK 
 
 Point Loma, Cal. (naval 
 
 station) NPL 
 
 Honolulu, Hawaii (naval sta- 
 tion) NPM 
 Guam. Marianas (naval sta- 
 tion) NPN 
 Cavite, P. I. (naval station) 
 NPO 
 
 Nieuport, Belgium ^ 
 
 S. S. HoUand 
 U. S. S. Pompey 
 U. S. S. Prairie 
 U. S. S. Preble 
 U, S. S. Preston 
 U. S. S. Princeton 
 U. S. S. Prometheus 
 U. S. S. Rainbow NRA 
 
 U. S. S. Raleigh NRB 
 
 Massachusetts nautical 
 
 school ship Ranger NRG 
 U. S. S. Reid NRE 
 
 U. S. S. Rhode Island NRI 
 U. S. S. Decatur NRJ 
 
 U. S. S. Roe NRM 
 
 U. S. S. Salem NRZ 
 
 .S. S. New Hampshire NS 
 U. S. S. Saturn NSF 
 
 U. S. S. Scorpion NSG 
 
 U. S. S. Smith NSQ 
 
 U. S. S. Solace NST 
 
 U. S. S. South Carolina NSW 
 U. S. S. South Dakota . NSX 
 U. S. S. Sterling NTA 
 
 IT. S. S. Sterrett NTB 
 
 U. S. S. Stewart NTC 
 
 U. S. S. St. Louis NTF 
 
 U. S. S. Stringham NTI 
 
 U. S. S. Supply NTK 
 
 S. S. J. S. Chanslor NU 
 
 U. S. S. Tacoma NUA 
 
 U. S. S. Tennessee NUG 
 
 U. S. S. Terry NUI 
 
 U. S. S. Tonopah NUN 
 
 U. S. S. Truxtun NUS 
 
 S. S. Charles S. Nelson NV 
 U. S. S. Vermont NVK 
 
 U. S. S. Vestal NVL 
 
 U. S. S. Vicksburg NVN 
 U. S, S. Virginia NVR 
 
 U. S. S. Vulcan NVT 
 
 S. S. Northwest NW 
 
 Nawiliwili, Kauai, Hawaiian 
 Islands NW 
 
 U. S. S. Warrington NWD 
 U. S. S. Washington NWE 
 U. S. S. West Virginia NWG 
 U. S. S. Wheeling NWH 
 U. S. S. Whipple NWI 
 
 U. S. S. Wilmington NWK 
 U. S. S. Wisconsin NWM 
 U. S. S. Worden NWP 
 
 U. S. S. Yankton NXB 
 
 U. S. S. Yorktown NXD 
 New York ,N. Y. (42 Broad- 
 way) NY 
 Tug Fearless N2 
 S. S. Hamilton OA 
 S. S. Atlanta OAA 
 S. S Columbia OAC 
 S. S. Sophia Hohenberg OAH 
 S. S. Princess Anne OB 
 S. S. Jamestown OC 
 S. S. Jefferson OD 
 New York, N. Y. (Herald 
 ship news office, The 
 Battery) OHX 
 S. S. KayoMaru OKY 
 Pernambuco, Brazil OL 
 S. S. Monroe OM 
 U. S. Artillery harbor tug 
 
 General Randall OR 
 
 S. S. Olivette OV 
 
 S. S. Mascotte OW 
 
 Berlin, Germany OW 
 
SUPPLEMENT 
 
 19 
 
 Oxford, England OX 
 
 S. S. Miami OZ 
 
 New York, N. Y. (Hotel 
 
 Plaza) P 
 
 Isle of Pines, Cuba P 
 
 Seattle, Wash. (University 
 grounds) PA 
 
 S. S. Prince Albert PA 
 
 Ketchikan, Alaska PB 
 
 Pemba Island, Zanzibar PB 
 Astoria, Oreg. PC 
 
 Tampa, Fla. PD 
 
 Friday Harbor, Wash. PD 
 Port Said, Egypt PD 
 
 Providence, R. I. PF 
 
 Aberdeen, Wash. PF 
 
 Westport, Wash. PG 
 
 Payo Obispo, Mexico PG 
 Point Grey, British Colum- 
 bia PGD 
 San Francisco, Cal PH 
 Avalon, Catalina Island. 
 
 Cal. PI 
 
 Fort Frank, P. I. PI A 
 
 Fort Drumm, P. I. PIB 
 
 Fort Wint, P. I. PIC 
 
 Fort William McKinley, 
 
 P. I. PID 
 
 Point Judith, R. I. PJ 
 
 Los Angeles, Cal. (Boyle 
 
 Heights) PJ 
 
 San Diego, Cal. PK* 
 
 Porthcuno, Cornwall Eng- 
 land PK 
 Port Tewfik, Egypt PK 
 Peking, China (Italian em- 
 bassy) PK 
 Eureka, Cal. PM 
 Bahia Blanca, Argentine Re- 
 public PM 
 Pere Marquette car ferry 
 No. 5 PM5 
 
 
 Alpena, Mich. PN 
 
 Katalla, Alaska PN 
 
 Manila, P. I. PN 
 
 Ponta Negra, Brazil PNA 
 Cordova, Alaska PO . 
 
 Kronstadt (Fort Menschi- 
 
 koff), Russia PPZ 
 
 Monterey, Cal. PQ 
 
 S. S. City of Chicago PQ 
 
 Parkeston Quay, England 
 
 PQL 
 North Vancouver, British 
 
 Columbia PR 
 
 Prince Rupert, British Co- 
 lumbia PRD 
 San Francisco, Cal. (Presidio) 
 PS 
 
 Port of Spain, Trinidad PS 
 Port Bragg, Cal. PT 
 
 St. Petersburg, Russia PTB 
 Bellingham, Wash. PU 
 
 S. S. Mobilla PU 
 
 S. S. Providence PV 
 
 Victoria, British Columbia 
 
 PW 
 
 Los Angeles, Cal. (Exam- 
 iner) PX 
 Olympia. Wash, PY 
 S. S. Enterprise PI 
 S. S. Hilonian P2 
 S. S. Portland P3 
 S. S. Col. E. L. Drake P4 
 Standard Oil barge 3 P5 
 S S, Buckman P7 
 S. S. Watson P8 
 S. S. Bertha P9 
 Quebec Q 
 Bluefields, Nicaragua Q 
 Alderney, England QDH 
 Washington, D. C (Elliott 
 
 Woods) QK 
 
 Antwerp, Belgium QR 
 
20 WIRELESS OPERATORS' POCKET BOOK 
 
 Bermuda QWC 
 
 Reggio, Italy R 
 
 S. S. Algerie RAG 
 
 S. S. Governor Cobb RB 
 
 Lightship Recalada, La Plata 
 River, Argentine Re- 
 public RC 
 
 II. S. revenue cutter Algon- 
 quin RCA 
 
 U. S. revenue cutter Bear 
 
 RGB 
 
 U. S. revenue cutter Andros- 
 coggin ROD 
 
 U. S. revenue cutter Seneca 
 RCE 
 
 U. S. revenue cutter Sno- 
 homish RCF 
 
 U. S. revenue cutter Gres- 
 ham RCG 
 
 U. S. revenue cutter McCul- 
 lough RCH 
 
 U. S. revenue cutter Itasca 
 RCI 
 
 U. S. revenue cutter Wood- 
 bury RCJ 
 
 U. S. revenue cutter Tahoma 
 RCK 
 
 U. S. revenue cutter Tusca- 
 rora RCL 
 
 U. S. revenue cutter Mo- 
 hawk ROM 
 
 U. S. revenue cutter Mann- 
 ing RCN 
 
 U. S. revenue cutter Onon- 
 daga RCO 
 
 U. S. revenue cutter Apache 
 RCP 
 
 U. S. revenue cutter Perry 
 
 RCQ 
 
 U. S. revenue cutter Rush 
 
 RCR 
 
 U. S. revenue cutter Semi- 
 
 nole RCS 
 
 U. S. revenue cutter Thetis 
 
 RCT 
 
 U. S. revenue cutter Acush- 
 
 net RCU 
 
 U. S. revenue cutter Win- 
 
 dom RCW 
 
 U. S. revenue cutter Yama- 
 
 craw RCY 
 
 S. S. La Rapide RD 
 
 S. S. France RFR 
 
 S. S. Formosa RFS 
 
 New Haven, England RHN 
 
 S. S. Ile-de-France RIF 
 
 S. S. Russie RIO 
 
 S. S. Italic RIT 
 
 Tug Relief RJ 
 
 Rio de Janeiro, Brazil RJ 
 
 Rijo, Brazil RJI 
 
 Corkbeg, England RJF 
 
 Santa Rosalia, Mexico RH 
 
 S. S. Plata RLA 
 
 S. S. Puritan RN 
 
 S. S. Calvin Austin RN 
 
 S. S. Atrato RNA 
 
 Magdalena RND 
 
 S. S. Nile RNJ 
 
 S. S. Clyde RNK 
 
 S. S. Thames RNM 
 
 S. S. Orinoco RNO 
 
 S. S. Ortona RNQ 
 
 S. S. Trent RNR 
 
 S. S. Tagus RNS 
 
 S. S. Orotava RNV 
 
 S. S. Oruba RNU 
 
 S. S. Berbice RNX 
 
 S. S. Premier RP 
 
 S. S. Pampa RPP 
 
 S. S. Parana RPR 
 
 S. S. I. J. Merritt RQ 
 
 S. S. Marquette RQ 
 
SUPPLEMENT 
 
 21 
 
 Dover, England RQW 
 
 Rixhoft, Germany RRX 
 S. S. Rescue RS 
 
 Pinar del Rio, Cuba RS 
 
 Rost, Norway RST 
 
 Port Arthur, Tex. RU 
 
 S. S. Governor Dingley RV 
 IT. S. Artillery Harbor Tug 
 
 Captain Rowell RW 
 
 Mexican cable ship Relay RX 
 S. S. Yale RY 
 
 Raza, Brazil RZA 
 
 Cambridge, Mass. S 
 
 8. S. Salvor SAL 
 
 S. S. Satellite SAT 
 
 S. S. Prinz August Wil- 
 
 helm SB 
 
 S. S. Birma SBA 
 
 S. S. Indiana SC 
 
 S. S. Tasco SC 
 
 Bari, Italy SC 
 
 S. S. J. F. Tietgen SCF 
 
 Scheveningen, Holland SCH 
 Felixstowe, England -SCQ 
 S. S. Estonia . SEA 
 
 n Franciso, Cal. SF 
 
 S. S. Prinz Eitel Frederich SF 
 S. S. Prinz Sigismund SG 
 Sault Ste. Marie, Mich. SH 
 S. S. Oceana SK 
 
 Cape Lazo, B. C. SKD 
 
 Skegness, England SKE 
 
 San Jose del Cabo, Mexico SJ 
 S. S. Litunia SLA 
 
 S. S. Sierra SM 
 
 Ponta Delgado, San Miguel, 
 
 Azores SMG 
 
 Windmill Hill, Gibraltar SMP 
 Charleston, S. C. (Hampton 
 
 Park) SN 
 
 Santiago de Cuba, Cuba SN 
 Barge Shenango SNA 
 
 S. S. Wm. P. Porter SND 
 S. S. Wilpen SNW 
 
 S.S.King Oscar 1 1 SOR 
 Sorvaagen, Norway SOT 
 S. S. Prinz Joachim SP 
 
 S. S. Russia SRN 
 
 S. S. Puritan SQ 
 
 S. S. Stanley ST 
 
 Santa Maria, Azores STM 
 Savannah, Ga. SV 
 
 Southwest Pass, La. SW 
 Seattle, Wash. S2 
 
 Cherbourg, France TCF 
 
 S. S. Chito Maru TOY 
 
 Dunkerque, France TDF 
 Tobermory Island, Scot- 
 land THM 
 S. S. Hong Kong Maru THN 
 Triangle Island, British Co- 
 lumbia TLD 
 Lorient, France TLF 
 Port Patrick, England TLK 
 S. S. America Maru TMC 
 Tjomo, Norway TMO 
 Rame Head, England TMP 
 S. S. Tennessee TN 
 Tienstin, China TN 
 S. S. Nippon Maru TNP 
 Oran, Algeria TOF 
 Brest, France TQF 
 S. S. Rosina TR 
 Rochefort, France TRF 
 S. S. Tenyo Maru TTY 
 Tempelhofer, Germany TU 
 Kiel, Germany (torpedo 
 
 station) TVK 
 
 Scilly Islands, England TVP 
 Tangier, Morocco TW 
 
 Portland, England TWQ 
 New York, N. Y., (Ill Broad 
 way) TWT 
 
 S. S. Jos. Vacarro TY 
 
22 WIRELESS OPERATORS' POCKET BOOK 
 
 Tacoma, Wash. T2 
 
 S. S. Ellis UA 
 
 S. S. Preston UB 
 
 Boulogne, France UBL 
 
 S S. Buffalo UBO 
 
 8 S. Cartago WC 
 
 S. S. Ucayali UCL 
 
 S. S. Lansing UD 
 
 S. S. Parisiana UD 
 
 S. S. Idaho UDI 
 
 Rama, Nicaragua UE 
 
 S. S. Admiral Schley UG 
 
 S. S. Galilee UGO 
 
 S. S. Heredia UH 
 
 S. S. Herman Frasch UHF 
 
 S. S. Noruega URG 
 S. S. Highland Laddie UHL 
 
 S. S. Highland Pride UHP 
 
 S. S. Highland Rover UHR 
 Cape San Antonio, Cuba UJ 
 
 S. S. Acre UJA 
 
 S. S. Sergipe UJB 
 
 S. S. Orion UJC 
 
 S. S. Bahia UJG 
 
 S. S. Marnhao UJH 
 
 S. S. Olinda UJI 
 
 S. S. Brazil UJK 
 
 S. S. San Salvador UJM 
 
 S. S. Goyaz UJN 
 
 S. S. Para UJO 
 
 S. S. Saturno UJP 
 
 S. S. Manaos UJQ 
 
 S. S. Jupiter UJR 
 
 S. S. Ceara UJV 
 
 S. S. Alagoas UJY 
 
 S. S. Sirio UJZ 
 
 S. S. Turralba. UK 
 
 S. S. Huallaga ULA 
 
 S. S. Santa Maria UM 
 
 S. S. Antenas UM 
 
 S.S.Druid UMD 
 
 Ouessant, France UOS 
 
 S. S. Prince George UPG 
 Porquerolies France UPQ 
 S. S. Prince Rupert UPR 
 S. S. Santa Rita t'S 
 
 Estevan Point, B. C. USD 
 S. S. Eskimo USK 
 
 St. Marie de la Mer, France 
 
 USM 
 
 S. S. St. Vincent USV 
 
 S. S. Admiral Dewey CV 
 S. S. Verdi UVD 
 
 S. S. Vasari UVR 
 
 S. S. Admiral Farragut UW 
 S. S. Pectan l"\Y 
 
 S. S. San Paulo UWK 
 
 S. S. Minas Geraes I \V\ 
 S. S. Rio de Janeiro UWR 
 S.S.Texas 1 \s 
 
 S. S. Lurline U2 
 
 San Giovanni, Italy V 
 
 S. S. Apache VA 
 
 S. S. Arapahoe VB 
 
 S. S. Comanche VC 
 
 S. S. Villa de Douvres VD 
 Yacht Vanadis YDS 
 
 S. S. Iroquois VF 
 
 Sheerness, England VFM 
 S. S. Algonquin VG 
 
 S. S. Huron VH 
 
 S. S. Seminole VJ 
 
 S. S. Cherokee VK 
 
 Wyl lightship, Denmark VL 
 S. S. Mohawk VM 
 
 Victoria, British Columbia 
 
 VSD 
 
 Victoria, British Columbia V2 
 New York, N. Y. (Waldorf- 
 Astoria) WA 
 S. S. China WA 
 S. S. W. B. Davock WB 
 S. S. Beaver WB 
 Wiborg, Italy WB 
 
SUPPLEMENT 
 
 S. S. Morro Castle WC 
 
 S. S. Bear WD 
 
 Bayonne, NJ. WD 
 
 S. S. City of Lowell WE 
 
 S. S. Manchuria WK 
 
 Escuela Naval, Chile WEN 
 Playa Ancha, Chile WFT 
 S. S. Seguranca WG 
 
 S. S. Havana WH 
 
 S. S. Korea WK 
 
 Las Salinas, Chile WLS 
 S. S. Merida WM 
 
 S. S. Mongolia WN 
 
 Wilsons Point, Conn. WN 
 Eastport, Me. WQ 
 
 S. S. City of Traverse WQ 
 New London, Conn. WS 
 
 S. S. Asia WT 
 
 S. S. Siberia WU 
 
 S. S. Vigilancia WV 
 
 S. S. Mexico WX 
 
 S. S. Monterey WY 
 
 Motor yacht Sea Otter WY 
 S. S. Esperanza WZ 
 
 U. S. Artillery harbor tug 
 
 Reno X 
 
 Port Limon, Costa Rico X 
 S. S. Hendrick Hudson XA 
 S. S. Arizona XA 
 
 S. S. City of Philadelphia XA 
 New York, N. Y. (66 Broad- 
 way) XAS 
 New York, N. Y. (Metropo- 
 litan tower) XAV 
 S. S. City of Wilmington XB 
 S. S. Robert Fulton XB 
 Philadelphia, Pa. XBG 
 Washington, D. C. (Evans 
 
 Building) XBM 
 
 S. S. Walter Adams XD 
 
 S. S. Florida XF 
 
 23- 
 
 S. S. Alabama GX 
 
 S. S. Virginia XK 
 
 S. S. Alaska XK 
 
 Duluth, Minn. XKA 
 
 Houghton, Mich. XKD 
 
 Sault Ste. Marie, Mich. XKG 
 
 Cheboygan, Mich. XKJ 
 
 Toledo, Ohio XKS 
 
 Cleveland, Ohio XKW 
 
 S. S. Mindora XM 
 
 Escanaba, Wis. XMB 
 
 Milwaukee, Wis. XMH 
 
 Chicago, 111. XMJ 
 
 Michigan City, Ind. XMQ 
 
 Ludington, Mich. XMV 
 
 S. S. J. L. Lawrence XN 
 
 S. S. City of Norfolk XN 
 
 S. S. City of Baltimore XO 
 
 Xcalac, Mexico XP 
 
 S. S. Louise XQ 
 
 S. S. Quick Step XQ 
 
 S. S. Jos. Whartori XW 
 S. S. S. V. Luckenbach YA 
 
 S. S. Paraguay YA 
 
 S.S.Thalia " YA 
 
 S. S. Aki Maru YAK 
 
 S. S. Awa Maru YAW 
 
 S. S. Toledo YD 
 
 S. S. Inaba Maru YIB 
 
 S. S. lyo Maru YIY 
 
 S. S. Kaga Maru YKG 
 
 S. S. Illinois YN 
 
 S. S. Shinano Maru YSN 
 
 S. S. Tamba Maru -YTB 
 
 S. S. Tango Maru YTG 
 
 S. S. Toso Maru YTS 
 
 S. S. Ossabow ZB 
 
 S. S. Ogeechee ZK 
 
 S. S.Satilla ZM 
 
 S. S. Altamaha --ZQ 
 
 Zanzibar ZR ' 
 
 S. S Ocmulgee ZU 
 
RELIABLE 
 WIRELESS APPARATUS 
 
 OUR POLICY To manufacture wireless apparatus of 
 advanced scientific design, easily operated and thorough 
 in every detail of workmanship. 
 
 OUR STOCK Includes complete sending sets, receiv- 
 ing sets, head receivers, tuneing coils, detectors, spark 
 gaps, condensers, keys, supplies apparatus parts, etc. 
 
 OUR PRICE Much less than generally charged for 
 instruments of the same quality. 
 
 Complete Receiving Sets (as shown in the cut) 
 $5.95. Also various grades up to $85.00 for finest pro- 
 fessional set. Sending sets for all distances and all 
 prices. 
 
 Send stamp for catalogue. 
 
 ALDEN WIRELESS COMPANY 
 
 1210 Montello Street : Campello, Mass. 
 
THIS BOOK IS DUE ON THE LAST DATE 
 STAMPED BELOW 
 
 AN INITIAL FINE OF 25 CENTS 
 
 WILL BE ASSESSED FOR FAILURE TO RETURN 
 THIS BOOK ON THE DATE DUE. THE PENALTY 
 WILL INCREASE TO SO CENTS ON THE FOURTH 
 DAY AND TO $1.OO ON THE SEVENTH DAY 
 OVERDUE. 
 
 AN ~ 
 
 . 
 
 No 30*5 5, * 
 
 HORARY USE 
 
 'I 23 1955 
 
5627 
 
 < 
 
 222658