REESE LIBRARY
OF THI:
UNIVERSITY OF CALIFORNIA.
Received. L//U24&/ .
J^
Accessions No. ^4 <?4^ Shelf No. .
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THE ECONOMY
OF
WORKSHOP MANIPULATION.
THE ECONOMY
WORKSHOP MANIPULATION.
A LOGICAL METHOD OF LEARNING CONSTRUCTIVE
MECHANICS.
ARRANGED WITH QUESTIONS
FOR THE USE OF
APPRENTICE ENGINEERS AND STUDENTS.
BY
J. RICHARDS,
AUTHOR OF "A TREATISE ON THE CONSTRUCTION AND OPERATION OF WOOD-WORKING
MACHINES," "THE OPERATOR'S HANDBOOK," "WOOD CONVERSION BY
MACHINERY," AND OTHER WRITINGS ON MECHANICAL SUBJECTS.
LONDO:
E. & F. N. SPON, 48 CHA
NEW YORK : 446 BROOME STREET.
1876.
[All rights reserved.]
Entered, according to Act of Congress, in the year 1875, by
JOHN RICHARDS,
In the Office of the Librarian of Congress, at Washington.
PREFACE.
THE contents of the present work, except the Intro-
duction and the chapter on Gauges, consist mainly in
a revision of a series of articles published in " Engi-
neering " and the Journal of the Franklin Institute,
under the head of " The Principles of Shop Manipula-
tion," during 1873 and 1874.
The articles alluded to were suggested by observa-
tions made in actual practice, and by noting a " habit
of thought " common among learners, which did not
seem to accord with the purely scientific manner in
which mechanical subjects are now so constantly
treated.
The favourable reception which the articles on
" Shop Manipulation " met with during their serial
publication, and various requests for their reproduc-
tion in the form of a book, has led to the present
edition.
The addition of a few questions at the end of each
chapter, some of which are not answered in the text,
it is thought will assist the main object of the work,
which is to promote a habit of logical investigation on
the part of learners.
b
VI PREFACE.
It will be proper to mention here, what will be more
fully pointed out in the Introduction, that although
workshop processes may be scientifically explained
and proved, they must nevertheless be learned logi-
cally. This view, it is hoped, will not lead to any-
thing in the book being construed as a disparagement
of the importance of theoretical studies.
Success in Technical Training, as in other kinds of
education, must depend greatly upon how well the gene-
ral mode of thought among learners is understood and
followed ; and if the present work directs some attention
to this matter it will not fail to add something to
those influences which tend to build up our industrial
interests.
J. R.
10 JOHN STREET, ADELPHI,
LONDON, 1875.
CONTENTS.
CHAP. PAGE
INTRODUCTION, ...... 1
I. PLANS OF STUDYING, ...... 6
II. MECHANICAL ENGINEERING, . . . . .13
III. ENGINEERING AS A CALLING, . . . . .17
IV. THE CONDITIONS OF APPRENTICESHIP, . . .18
V. THE OBJECT OF MECHANICAL INDUSTRY, . . .25
VI. ON THE NATURE AND OBJECTS OF MACHINERY, . . 28
VII. MOTIVE MACHINERY, . . . . . .29
VIII. WATER POWER, . . . . . .35
IX. WIND POWER, . . . . . .41
X. MACHINERY FOR TRANSMITTING AND DISTRIBUTING POWER, . 42
XI. SHAFTS FOR TRANSMITTING POWER, . . . .44
XII. BELTS FOR TRANSMITTING POWER, . . .. .48
XIII. GEARING AS A MEANS OF TRANSMITTING POWER, . . 51
XIV. HYDRAULIC APPARATUS FOR TRANSMITTING POWER, . . 53
XV. PNEUMATIC MACHINERY FOR TRANSMITTING POWER, . . 55
XVI. MACHINERY OF APPLICATION, . . . .57
XVII. MACHINERY FOR MOVING AND HANDLING MATERIAL, . . 60
XVIII. MACHINE COMBINATION, . . . . .67
XIX. THE ARRANGEMNET OF ENGINEERING ESTABLISHMENTS, . 71
XX. GENERALISATION OF SHOP PROCESSES, . . .74
XXI. MECHANICAL DRAWING, . . . . .78
XXII. PATTERN MAKING AND CASTING, . . . .90
XXIII. FORGING, . . . . . . .100
XXIV. TRIP-HAMMERS, . . . . . .106
XXV. CRANK-HAMMERS, . . . . . .108
VI 11 CONTENTS.
CHAP. PACK
XXVI. STEAM-HAMMERS, . . . . . .109
XXVII. COMPOUND HAMMERS, . . . . .112
XXVIII. TEMPERING STEEL, . . . . . .114
XXIX. FITTING AND FINISHING, ..... 118
XXX. TURNING LATHES, ...... 121
XXXI. PLANING OR REblPROOATING MACHINES, . . . 128
XXXII. SLOTTING MACHINES, ...... 134
XXXIII. SHAPING MACHINES, . . . . . .135
XXXIV. BORING AND DRILLING, . . . . .136
XXXV. MILLING, . . . . . . .140
XXXVI. SCREW-CUTTING, . . . . . .143
XXXVII. STANDARD MEASURES, . . . . .145
XXXVIII. GAUGING IMPLEMENTS, . . . . .147
XXXIX. DESIGNING MACHINks, . . . . .152
XL. INVENTION, . . . . . . .159
XLI. WORKSHOP EXPERIENCE, . . . .165
THE ECONOMY
OF
WORKSHOP MANIPULATION
INTROD UCTION.
IN adding another to the large number of books winch treat
upon Mechanics, and especially of that class devoted to what is
called Mechanical Engineering, it will be proper to explain some
of the reasons for preparing the present work j and as these
explanations will constitute a part of the work itself, and be
directed to a subject of some interest to a learner, they are
included in the Introduction.
First I will notice that among our many books upon mechani-
cal subjects there are none that seem to be directed to the
instruction of apprentice engineers; at least, there are none
directed to that part of a mechanical education most difficult to
acquire, a power of analysing and deducing conclusions from
commonplace matters.
Our text-books, such as are available for apprentices, consist
mainly of mathematical formulae relating to forces, the properties
of material, examples of practice, and so on, but do not deal
with the operation of machines nor with constructive manipula-
tion, leaving out that most important part of a mechanical
education, which consists in special as distinguished from general
knowledge.
The theorems, formulae, constants, tables, and rules, which are
generally termed the principles of mechanics, are in a sense only
symbols of principles ; and it is possible, as many facts will
prove, for a learner to master the theories and symbols of
A.
% WORKSHOP MANIPULATION.
mechanical principles, and yet not be able to turn such knowledge
to practical account.
A principle in mechanics may be known, and even familiar to
a learner, without being logically understood ; it might even be
said that both theory and practice may be learned without the
power to connect and apply the two things. A person may, for
example, understand the geometry of tooth gearing and how to
lay out teeth of the proper form for various kinds of wheels, how
to proportion and arrange the spokes, rims, hubs, and so on ; he
may also understand the practical application of wheels as a
means of varying or transmitting motion, but between this
knowledge and a complete wheel lies a long train of intricate
processes, such as pattern-making, moulding, casting, boring,
and fitting. Farther on comes other conditions connected with
the operation of wheels, such as adaptation, wear, noise, acci-
dental strains, with many other things equally as important, as
epicycloi^al curves or other geometrical problems relating to
wheels.
Text-books, such as relate to construction, consist generally of
examples, drawings, and explanations of machines, gearing, tools,
and so on ; such examples are of use to a learner, no doubt, but
in most cases he can examine the machines themselves, and on
entering a shop is brought at once in contact not only with the
machines but also with their operation. Examples and drawings
relate to how machines are constructed, but when a learner comes
to the actual operation of machines, a new and more interesting
problem is reached in the reasons why they are so constructed.
The difference between how machinery is constructed and why
it is so constructed, is a wide one. This difference the reader
should keep in mind, because it is to the second query that the
present work will be mainly addressed. There will be an
attempt an imperfect one, no doubt, in some cases to deduce
from practice the causes which have led to certain forms of
machines, and to the ordinary processes of workshop manipula-
tion. In the mind of a learner, whether apprentice or student,
the strongest tendency is to investigate why certain proportions
and arrangement are right and others wrong why the opera-
tions of a workshop are conducted in one manner instead of
another ? This is the natural habit of thought, and the natural
course of inquiry and investigation is deductive.
Nothing can be more unreasonable than to expect an apprentice
INTRODUCTION. 3
engineer to begin by an inductive course in learning and reason-
ing about mechanics. Even if the mind were capable of such a
course, which can not be assumed in so intricate and extensive a
subject as mechanics, there would be a want of interest and an
absence of apparent purpose which would hinder or prevent
progress. Any rational view of the matter, together with as
many facts as can be cited, will all point to the conclusion that
apprentices must learn deductively, and that some practice
should accompany or precede theoretical studies. How dull and
objectless it seems to a young man when he toils through " the
sum of the squares of the base and perpendicular of a right-angle
triangle," without knowing a purpose to which this problem is
to be applied ; he generally wonders why such puzzling theorems
were ever invented, and what they can have to do with the
practical affairs of life. But if the same learner were to happen
upon a builder squaring a foundation by means of the rule " six,
eight, and ten," and should in this operation detect the applica-
tion of that tiresome problem of " the sum of the squares," he
would at once awake to a new interest in the matter ; what was
before tedious and without object, would now appear useful and
interesting. The subject would become fascinating, and the learner
would go on with a new zeal to trace out the connection between
practice and other problems of the kind. Nothing inspires a
learner so much as contact with practice ; the natural tendency,
as before said, is to proceed deductively.
A few years ago, or even at the present time, many school-
books in use which treat of mechanics in connection with
natural philosophy are so arranged as to hinder a learner from
grasping a true conception of force, power, and motion ; these
elements were confounded with various agents of transmission,
such as wheels, wedges, levers, screws, and so on. A learner was
taught to call these things " mechanical powers," whatever that
may mean, and to compute their power as mechanical elements.
In this manner was fixed in the mind, as many can bear wit-
ness, an erroneous conception of the relations between power and
the means for its transmission ; the two things were confounded
together, so that years, and often a lifetime, has not served to
get rid of the idea of power and mechanism being the same. To
such teaching can be traced nearly all the crude ideas of mechanics
so often met with among those well informed in other matters. In
the great change from empirical rules to proved constants, from
4 WORKSHOP MANIPULATION
special and experimental knowledge to the application of science
in the mechanic arts, we may, however, go too far. The
incentives to substitute general for special knowledge are so
many, that it may lead us to forget or underrate that part which
cannot come within general rules.
The labour, dirt, and self-denial inseparable from the acquire-
ment of special knowledge in the mechanic arts are strong
reasons for augmenting the importance and completeness of
theoretical knowledge, and while it should be, as it is, the con-
stant object to bring everything, even manipulative processes, so
far as possible, within general rules, it must not be forgotten that
there is a limit in this direction.
In England and America the evils which arise from a false
or over estimate of mere theoretical knowledge have thus far been
avoided. Our workshops are yet, and must long remain, our tech-
nological schools. The money value of bare theoretical training
is so fast declining that we may be said to have passed the point
of reaction, and that the importance of sound practical know-
ledge is beginning to be more felt than it was some years ago.
It is only in those countries where actual manufactures and other
practical tests are wanting, that any serious mistake can be
made as to what should constitute an education in mechanics.
Our workshops, if other means fail, will fix such a standard ;
and it is encouraging to find here and there among the outcry
for technical training, a note of warning as to the means to be
employed.
During the meeting of the British Association in Belfast
(1874), the committee appointed to investigate the means of
teaching Physical Science, reported that "the most serious
obstacle discovered was an absence from the minds of the pupils
of a firm and clear grasp of the concrete facts forming a base of
the reasoning processes they are called upon to study ; and that
the use of text-books should be made subordinate to an attend-
ance upon lectures and demonstrations."
Here, in reference to teaching science, and by an authority
which should command our highest confidence, we have a clear
exposition of the conditions which surround mechanical training,
with, however, this difference, that in the latter " demonstration "
has its greatest importance.
Professor John Sweet of Cornell University, in America, while
delivering an address to the mechanical engineering classes,
INTRODUCTION. 5
during the same year, made use of the following words : " It is
not what you ' know' that you will be paid for ; it is what you
can * perform/ that must measure the value of what you learn
here." These few words contain a truth which deserve to be
earnestly considered by every student engineer or apprentice ;
as a maxim it will come forth and apply to nearly everything in
subsequent practice.
I now come to speak directly of the present work and its
objects. It may be claimed that a book can go no further in
treating of mechanical manipulation than principles or rules will
reach, and that books must of necessity be confined to what
may be called generalities. This is in a sense true, and it is,
indeed, a most difficult matter to treat of machine operations and
shop processes ; but the reason is that machine operations and
shop processes have not been reduced to principles or treated in
the same way as strains, proportions, the properties of material,
and so on. I do not claim that manipulative processes can be
so generalised this would be impossible ; yet much can be done,
and many things regarded as matters of special knowledge can
be presented in a way to come within principles, and thus
rendered capable of logical investigation.
Writers on mechanical subjects, as a rule, have only theoretical
knowledge, and consequently seldom deal with workshop pro-
cesses. Practical engineers who have passed through a success-
ful experience and gained that knowledge which is most difficult
for apprentices to acquire, have generally neither inclination nor
incentives to write books. The changes in manipulation are so
frequent, and the operations so diversified, that practical men have
a dread of the criticisms which such changes and the differences
of opinion may bring forth ; to this may be added, that to be-
come a practical mechanical engineer consumes too great a share
of one's life to leave time for other qualifications required in
preparing books. For these reasons " manipulation " has been
neglected, and for the same reasons must be imperfectly treated
here. The purpose is not so much to instruct in shop processes as
to point out how they can be best learned, the reader for the most
part exercising his own judgment and reasoning powers. It
will be attempted to point out how each simple operation is
governed by some general principle, and how from such opera-
tions, by tracing out the principle which lies at the bottom, it
is possible to deduce logical conclusions as to what is right or
6 WORKSHOP MANIPULATION.
wrong, expedient or inexpedient. In this way, it is thought, can
be established a closer connection between theory and practice,
and a learner be brought to realise that he has only his reasoning
powers to rely on that formula), rules, tables, and even books,
are only aids to this reasoning power, which alone can master
and combine the symbol and the substance.
No computations, drawings, or demonstrations of any kind will
be employed to relieve the mind of the reader from the care of
remembering and a dependence on his own exertions. Drawings,
constants, formulae, tables, rules, with all that pertains to com-
putation in mechanics, are already furnished in many excellent
books, which leave nothing to be added, arid such books can be
studied at the same time with what is presented here.
The book has been prepared with a full knowledge of the fact,
that what an apprentice may learn, as well as the time that is
consumed in learning, are both measured by the personal interest
felt in the subject studied, and that such a personal interest on
the part of an apprentice is essential to permanent success as an
engineer. A general dry ness and want of interest must in this,
as in all cases, be a characteristic of any writing devoted to
mechanical subjects : some of the sections will be open to this
charge, no doubt, especially in the first part of the book ; but it
is trusted that the good sense of the reader will prevent him from
passing hurriedly over the first part, to see what is said, at the
end, of casting, forging, and fitting, and will cause him to read
it as it comes, which will in the end be best for the reader, and
certainly but fair to the writer.
CHAPTER I.
PLANS OF STUDYING.
BY examining the subject of applied mechanics and shop mani-
pulation, a learner may see that the knowledge to be acquired
by apprentices can be divided into two departments, that may be
called general and special. General knowledge relating to tools,
processes and operations, so far as their construction and action
may be understood from general principles, and without special
PLANS OF STUDYING. 7
or experimental instruction. Special knowledge is that which
is based upon experiment, and can only be acquired by special,
as distinguished from general sources.
To make this plainer, the laws of forces, the proportion . of
parts, strength of material, and so on, are subjects of general know-
ledge that may be acquired from books, and understood without
the aid of an acquaintance with the technical conditions of
either the mode of constructing or the manner of operating
machines ; but how to construct proper patterns for castings, or
how the parts of machinery should be moulded, forged, or fitted,
is special knowledge, and must have reference to particular cases.
The proportions of pulleys, bearings, screws, or other regular de-
tails of machinery, may be learned from general rules and prin-
ciples, but the hand skill that enters into the manufacture of
these articles cannot be learned except by observation and
experience. The general design, or the disposition of metal in
machine-framing, can be to a great extent founded upon rules
and constants that have general application ; but, as in the case
of wheels, the plans of moulding such machine frames are not
governed by constant rules or performed in a uniform manner.
Patterns of different kinds may be employed ; moulds may be
made in various ways, and at a greater and less expense ; the
metal can be mixed to produce a hard or a soft casting, a strong
or a weak one ; the conditions under which the metal is poured
may govern the soundness or shrinkage, things that are deter-
mined by special instead of general conditions.
The importance of a beginner learning to divide what he has
to learn into these two departments of special and general, has
the advantage of giving system to his plans, and pointing out
that part of his education which must be acquired in the work-
shop and by practical experience. The time and opportunities
which might be devoted to learning the technical manipulations
of a foundry, for instance, would be improperly spent if devoted
to metallurgic chemistry, because the latter may be studied apart
from practical foundry manipulation, and without the oppor-
tunity of observing casting operations.
It may also be remarked that the special knowledge involved
in applied mechanics is mainly to be gathered and retained by
personal observation and memory, and that this part is the
greater one ; all the formulae relating to machine construction
may be learned in a shorter time than is required to master and
WORKSHOP MANIPULATION.
understand the operations which may be performed on an engine
lathe. Hence first lessons, learned when the mind is interested
and active, should as far as possible include whatever is special ;
in short, no opportunity of learning special manipulation should
be lost. If a wheel pattern come under notice, examine the manure
in which it is framed together, the amount of draught, and how
it is moulded, as well as to determine whether the teeth have
true cycloidal curves.
Once, nearly all mechanical knowledge was of the class termed
special, and shop manipulations were governed by empirical rules
and the arbitrary opinions of the skilled ; an apprentice entered
a shop to learn a number of mysterious operations, which could
not be defined upon principles, and only understood by special
practice and experiment. The arrangement and proportions of
. mechanism were also determined by the opinions of the skilled,
and like the manipulation of the shop, were often hid from tbe
apprentice, and what he carried in his memory at the end of an
apprenticeship was all that he had gained. The tendency of
this was to elevate those who were the fortunate possessors of a
strong natural capacity, and to depress the position of those less
fortunate in the matter of mechanical "genius," as it was called.
Tbe ability to prepare proper designs, and to succeed in original
plans, was attributed to a kind of intuitive faculty of the mind ;
in short, the mechanic arts were fifty years ago surrounded by
a superstition of a different nature, but in its influences the same
as superstition in other branches of knowledge.
But now all is changed : natural phenomena have been ex-
plained as being but the operation of regular laws ; so has
mechanical manipulation been explained as consisting in the
application of general principles, not yet fully understood, but
far enough, so that the apprentice may with a substantial educa-
tion, good reasoning powers, and determined effort, force his way
where once it had to be begged. The amount of special know-
ledge in mechanical manipulation, that which is irregular and
modified by special conditions, is continually growing less as
generalisation and improvement go on.
Another matter to be considered is that the engineering
apprentice, in estimating what he will have to learn, must not
lose sight of the fact that what qualifies an engineer of to-day
will fall far short of the standard that another generation will fix,
and of that period in which his practice will fall. This I men-
PLANS OF STUDYING. 9
tion because it will have much to do with the conceptions that a
learner will form of what he sees around him. To anticipate
improvement and change is not only the highest power to
which a mechanical engineer can hope to attain, but is the key
to his success.
By examining the history of great achievements in the mechanic
arts, it will be seen that success has been mainly dependent upon
predicting future wants, as well as upon an ability to supply
such wants, and that the commercial value of mechanical im-
provements is often measured by conditions that the improve-
ments themselves anticipate. The invention of machine-made
drills, for example, was but a small matter ; but the demand that
has grown up since, and because of their existence, has rendered
this improvement one of great value. Moulded bearings for
shafts were also a trifling improvement when first made, but it
has since influenced machine construction in America in a way
that has given great importance to the invention.
It is generally useless and injudicious to either expect or to
search after radical changes or sweeping improvements in
machine manufacture or machine application, but it is im-
portant in learning how to construct and apply machinery, that
the means of foreseeing what is to come in future should at the
same time be considered. The attention of a learner can, for
example, be directed to the division of labour, improvements in
shop system, how and where commercial interests are influenced
by machinery, what countries are likely to develop manufactures,
the influence of steam-hammers on forging, the more extended
use of steel when cheapened by improved processes for producing
it, the division of mechanical industry into special branches,
what kind of machinery may become staple, such as shafts, pul-
leys, wheels, and so on. These things are mentioned at random,
to indicate what is meant by looking into the future as well as
at the present.
Following this subject of future improvement farther, it may
be assumed that an engineer who understands the application
and operation of some special machine, the principles that
govern its movements, the endurance of the wearing surfaces,
the direction and measure of the strains, and who also under-
stands the principles of the distribution of material, arrange-
ment, and proportions, that such an engineer will be able to
construct machines, the plans of which will not be materially
10 WORKSHOP MANIPULATIONS
departed from so long as the nature of the operations to which
the machines are applied remain the same.
A proof of this proposition is furnished in the case of stand-
ard machine tools for metal-cutting, a class of machinery that
for many years past has received the most thorough attention at
the hands of our best mechanical engineers.
Standard tools for turning, drilling, planing, boring, and so
on, have been changed but little during twenty years past, and
are likely to remain quite the same in future. A lathe or a
planing-machine made by a first-class establishment twenty
years ago has, in many cases, the same capacity, and is worth
nearly as much in value at the present time as machine tools of
modern construction a test that more than any other deter-
mines their comparative efficiency and the true value of the
improvements that have been made. The plans of the framing
for machine tools have been altered, and many improvements in
details have been added ; yet, upon the whole, it is safe to
assume, as before said, that standard tools for metal-cutting have
reached a state of improvement that precludes any radical
changes in future, so long as the operations in metal-cutting
remain the same.
This state of improvement which has been reached in ma-
chine-tool manufacture, is not only the result of the skill expended
on such tools, but because as a notable exception they are the
agents of their own production ; that is, machine tools produce
machine tools, and a maker should certainly become skilled in
the construction of implements which he employs continually
in his own business. This peculiarity of machine-tool manufac-
tures is often overlooked by engineers, and unfair comparisons
made between machines of this class and those directed to wood
conversion and other manufacturing processes, which machinists,
as a rule, do not understand.
Noting the causes and conditions which have led to this perfec-
tion in machine-tool manufacture, and how far they apply in
the case of other classes of machinery, will in a measure indicate
the probable improvements and changes that the future will
produce.
The functions and adaptations of machinery constitute, as
already explained, the science of mechanical engineering. The
functions of a machine are a foundation on which its plans
are based ; hence machine functions and machine effect are
PLANS OF STUDYING. 11
matters to which the attention of an apprentice should first be
directed.
In the class of mechanical knowledge that has been defined as
general, construction comes in the third place : first, machine
functions ; next, plans or adaptation of machines ; and third,
the manner of constructing machines. This should be the order
of study pursued in learning mechanical manipulation. Instead
of studying how drilling-machines, planing-machines or lathes
are arranged, and next plans of constructing them, and then the
principles of their operation, which is the usual course, the
learner should reverse the order, studying, first, drilling, planing,
and turning as operations ; next, the adaptation of tools for the
purposes ; and third, plans of constructing such tools.
Applied to steam-engines, the same rule holds good. Steam,
as a motive agent, should first be studied, then the operation of
steam machinery, and finally the construction of steam-engines.
This is a rule that may not apply in all cases, but the exceptions
are few.
To follow the same chain of reasoning still farther, and to show
what may be gained by method and system in learning mechanics,
it may be assumed that machine functions consist in the applica-
tion of power, and therefore power should be first studied ; of this
there can be but one opinion. The learner who sets out to master
even the elementary principles of mechanics without first having
formed a true conception of power as an element, is in a measure
wasting his time and squandering his efforts.
Any truth in mechanics, even the action of the " mechanical
powers " before alluded to, is received with an air of mystery,
unless the nature of power is first understood. Practical demon-
stration a hundred times repeated does not create a conviction of
truth in mechanical propositions, unless the principles of operation
are understood.
An apprentice may learn that power is not increased or dimin-
ished by being transmitted through a train of wheels which change
both speed and force, and he may believe the proposition without
having a " conviction " of its truth. He must first learn to
regard power as a constant and indestructible element something
that maybe weighed, measured, and transmitted, but not created
or destroyed by mechanism ; then the nature of the mechanism
may be understood, but not before.
To obtain a true understanding of the nature of power is by no
12 WORKSHOP MANIPULATION.
means the difficulty for a beginner that is generally supposed ;
and when once reached, the truth will break upon the mind like
a sudden discovery, and ever afterwards be associated with
mechanism and motion whenever seen. The learner will after-
wards find himself analysing the flow of water, the traffic in the
streets, the movement of ships and trains ; even the act of
walking will become a manifestation of power, all clear and
intelligible, without that air of mystery that is otherwise insepar-
able from the phenomena of motion. If the learner will go on
farther, and study the connection between heat and force, the
mechanical equivalent of heat when developed' into force and
motion, and the reconversion of power into heat, he will have
commenced at the base of what must constitute a thorough
knowledge of mechanics, without which he will have to continu-
ally proceed under difficulties.
I am well aware of the popular opinion that such subjects are
too abstruse to be understood by practical mechanics an assump-
tion that is founded mainly in the fact that the subject of heat
and motion are not generally studied, and have been too recently
demonstrated in a scientific way to command confidence and at-
tention ; but the subject is really no more difficult to understand
in an elementary sense than that of the relation between move-
ment and force illustrated in the " mechanical powers " of school-
books, which no apprentice ever did or ever will understand,
except by first studying the principles of force and motion,
independent of mechanical agents, such as screws, levers, wedges,
and so on.
It is to be regretted that there has not been books especially
prepared to instruct mechanical students in the relations between
heat, force, motion, and practical mechanism. The subject is, of
course, treated at great length in modern scientific works, but is not
connected with the operations of machinery in a way to be easily
understood by beginners. A treatise on the subject, called " The
Correlation and Conservation of Forces," published by D. Appleton
& Co. of New York, is perhaps as good a book on the subject as
can at this time be referred to. The work contains papers con-
tributed by Professors Carpenter, Grove, Helmotz, Faraday, and
others, and has the advantage of arrangement in short sections,
that compass the subject without making it tedious.
In respect to books and reading, the apprentice should supply
himself with references. A single book, and the best one that can
MECHANICAL ENGINEERING. 1 3
be obtained on eacli of the different brandies of engineering, is
enough to begin with. A pocket-book for reference, such as
Molesworth's or Nystrom's, is of use, and should always be at
hand. For general reading, nothing compares with the scientific
and technical journals, which are now so replete with all kinds of
information. Beside noting the present progress of engineering
industry in all parts of the world, they contain nearly all be-
sides that a learner will require.
It will be found that information of improvements and mecha-
nical progress that a learner may gather from serial publications
can always be exchanged for special knowledge in his intercourse
with skilled workmen, who have not the opportunity or means of
reading for themselves ; and what an apprentice may read and
learn in an hour can often be "exchanged" for experimental
knowledge that has cost years to acquire.
(1.) Into what two divisions can a knowledge of constructive
mechanics be divided ? (2.) Give an example of your oAvn to distinguish
between special and general knowledge. (3.) In what manner is special
knowledge mostly acquired ? (4.) What has been the effect of scientific
investigations upon special knowledge 1 (5.) What is meant by the
division of labour ? (6.) Why have engineering tools been less changed
than most other kinds of machinery during twenty years past ?
(7.) What is meant by machine functions ; adaptation ; construction ?
(8.) Why has the name "mechanical powers" been applied to screws,
levers, wedges, and so on ? (9.) Can power be conceived of as an.
element or principle, independent of mechanism ?
CHAPTER II
MECHANICAL ENGINEERING.
THIS work, as already explained, is to be devoted to mechanical
engineering, and in view of the difference of opinion that exists
as to what mechanical engineering comprehends, and the different
sense in which the term is applied, it will be proper to explain
what is meant by it here.
I am not aware that any one has defined what constitutes
civil engineering, or mechanical engineering, as distinguished one
14 WORKSHOP MANIPULATION.
from the other, nor is it assumed to fix any standard here
farther than to serve the purpose of explaining the sense in which
the terms will be used \ yet there seems to be a clear line of
distinction, which, if it does not agree with popular use of the
terms, at least seems to be furnished by the nature of the busi-
ness itself. It will therefore be assumed that mechanical
engineering relates to dynamic forces and works that involve
machine motion, and comprehends the conditions of machine
action, such as torsional, centrifugal, intermittent, and irregular
strains in machinery, arising out of motion ; the endurance of
wearing surfaces, the constructive processes of machine-making
and machine effect in the conversion of material in short, agents
for converting, transmitting, and applying power.
Civil engineering, when spoken of, will be assumed as referring
to works that do not involve machine motion, nor the use of
power, but deal with static forces, the strength, nature, and
disposition of material under constant strains, or under measured
strains, the durability and resistance of material, the construction
of bridges, factories, roads, docks, canals, dams, and so on ; also,
levelling and surveying. This corresponds to the most common
use of the term civil engineering in America, but differs greatly
from its application in Europe, where civil engineering is under-
stood as including machine construction, and where the term
engineering is applied to ordinary manufacturing processes.
Civil engineering, in the meaning assumed for the term, has
become almost a pure mathematical science. Constants are proved
and established for nearly every computation ; the strength and
durability of materials, from long and repeated tests, has come
to be well understood ; and as in the case of machine tools, the
uniformity of practice among civil engineers, and the perfection
of their works, attest how far civil engineering has become a
true science, and proves that the principles involved in the con-
struction of permanent works are well understood.
To estimate how much is yet to be learned in mechanical
engineering, we have only to apply the same test, and when we
contrast the great variance between the designs of machines and
the diversity of their operation, even when applied to similar
purposes, their imperfection is at once apparent. It must, how-
ever, be considered that if the rules of construction were uniform,
and the principles of machine operation as well understood as
the strength and arrangement of material in permanent struc-
MECHANICAL ENGINEERING. 15
tares, still there would remain the difficulty of adaptation to new
processes, which are continually being developed.
If the steam-engine, for instance, had forty years ago been
brought to such a state of improvement as to be constructed
with standard proportions and arrangement for stationary pur-
poses, all the rules, constants, and data of whatever kind that
had been collected and proved, would have been but of little use
in adapting steam-engines to railways and the purposes of
navigation.
Mechanical engineering has -by the force of circumstances
been divided up into branches relating to engineering tools, rail-
way machinery, marine engines, and so on ; either branch of
which constitutes a profession within itself. Most thorough study
will be required to master general principles, and then a further
effort to acquire proficiency in some special branch, without
which there is but little chance of success at the present day.
To master the various details of machine manufacture,
including draughting, founding, forging, and fitting, is of itself
a work equal to most .professional pursuits, to say nothing of
manual skill ; and when we come to add machine functions and
their application, generating and transmitting power, with other
things that will necessarily be included in practice, the task
assumes proportions that makes it appear a hopeless one.
Besides, the work of keeping progress with the mechanic arts
calls for a continual accretion of knowledge and it is no small
labour to keep informed of the continual changes and improve-
ments that are going on in all parts of the world, which may at
any time modify and change both machines and processes. But
few men, even under the most favourable conditions, have been
able to qualify themselves as competent mechanical engineers
sooner than at forty years of age.
One of the earliest cares of an apprentice should be to divest
his mind of what I will call the romance of mechanical
engineering, almost inseparable from such views as are often
acquired in technological schools. He must remember that it
is not a science he is studying, and that mathematics deal only
with one branch of what is to be learned. Special knowledge,
or what does not come within the scope of general principles,
must be gained in a most practical way, at the expense of hard
work, bruised fingers, and a disregard of much that the world
calls gentility.
16 WORKSHOP MANIPULATION.
Looking ahead into the future, the apprentice can see a field
for the mechanical engineer widening on every side. As the con-
struction of permanent works becomes more settled and uniform,
the application of power becomes more diversified, and develops
problems of greater intricacy. No sooner has some great
improvement, like railway and steam navigation, settled into
system and regularity than new enterprises begin. To offset the
undertaking of so great a work as the study of mechanical
engineering, there is the very important advantage of the
exclusiveness of the calling a condition that arises out of its
difficulties. If there is a great deal to learn, there is also much
to be gained in learning it. It is seldom, indeed, that an effi-
cient mechanical engineer fails to command a place of trust and
honour, or to accumulate a competency by means of his calling.
If a civil engineer is wanted to survey railways, construct
docks, bridges, buildings, or permanent works of any kind,
there are scores of men ready for the place, and qualified to dis-
charge the duties ; but if an engineer is wanted to design and
construct machinery, such a person is not easy to be found, and
if found, there remains that important question of competency ;
for the work is not like that of constructing permanent works,
where several men may and will perform the undertaking very
much in the same manner, and perhaps equally well. In the
construction of machinery it is different; the success will be
directly as the capacity of the engineer, who will have but few
precedents, and still fewer principles, to guide him, and generally
has to set out by relying mainly upon his special knowledge of
the operation and application of such machines as he has to
construct.
(1.) How may mechanical be distinguished from civil engineering ?
(2.) What test can be applied to determine the progress made in any
branch of engineering? (3.) What are some of the conditions which
prevent the use of constants in machine construction ? (4.) Is mechani-
cal engineering likely to become more exact and scientific ? (5.) Name
some of the principal branehes of mechanical engineering. (6.) Which
is the most extensive and important ?
ENGINEERING AS A CALLING.
CHAPTER III.
ENGINEERING AS A CALLING.
IT may in the abstract be claimed that the dignity of any
pursuit is or should be as the amount of good it confers, and the
influence it exerts for the improvement of mankind. The social
rank of those engaged in the various avocations of life has, in
different countries and in different ages, been defined by various
standards. Physical strength and courage, hereditary privilege,
and other things that once recommended men for preferment,
have in most countries passed away or are regarded as matters
of but little importance, and the whole civilised world have
agreed upon one common standard, that knowledge and its
proper use shall be the highest and most honourable attainment
to which people may aspire.
It may be useless or even wrong to institute invidious com-
parisons between different callings which are all useful and
necessary, and the matter is not introduced here with any view
of exalting the engineering profession ; it is for some reasons
regretted that the subject is alluded to at all, but there is too
much to be gained by an apprentice having a pride and love
for his calling to pass over the matter of its dignity as a pursuit
without calling attention to it. The gauntlet has been thrown
down and comparison provoked by the unfair and unreasonable
place that the politician, the metaphysician, and the moral
philosopher have in the past assigned to the sciences and con-
structive arts. Poetry, metaphysics, mythology, war, and super-
stition have in their time engrossed the literature of the
world, and formed the subject of what was alone considered
education.
In a half century past all has changed; the application of
the sciences, the utilisation of natural forces, manufacturing,
the transportation of material, the preparation and diffusion of
printed matter, and other great matters of human interest, have
come to shape our laws, control commerce, establish new relations
between people and countries in short, has revolutionised the
world. So rapid has been this change that it has outrun the
powers of conception, and people waken as from a dream to
find themselves governed by a new master.
B
18 WORKSHOP MANIPULATION.
Considering material progress as consisting primarily in the
demonstration of scientific truths, and secondly, in their appli-
cation to useful purposes, we can see the position of the engineer
as an agent in this great work of reconstruction now going on
around us. The position is a proud one, but not to be attained
except at the expense of great effort, and a denial of everything
that may interfere with the acquirement of knowledge during
apprenticeship and the study which must follow.
The mechanical engineer deals mainly with the natural forces,
* and their application to the conversion of material and trans-
port. His calling involves arduous duties; he is brought in
contact with what is rough and repulsive, as well as what is
scientific and refined. He must include grease, dirt, manual
labour, undesirable associations, and danger with apprenticeship,
or else be content to remain without thoroughly understanding
his profession.
(1.) What should determine the social rank of industrial callings ?
(2.) Why have the physical sciences and mechanic arts achieved so
honourable a position ? (3.) How may the general object of the engin-
eering arts be described? (4.) What is the difference between science
and art as the terms are generally employed in connection with practical
industry ?
CHAPTER IV.
THE CONDITIONS OF APPRENTICESHIP.
WERE it not that moral influences in learning mechanics, as in
all other kinds of education, lie at the bottom of the whole mat-
ter, the subject of this chapter would not have been introduced.
But it is the purpose, so far as possible, to notice everything that
concerns an apprentice and learner, and especially what he has
to deal with at the outset; hence some remarks upon the nature
of apprentice engagements will not be out of place. To acquire
information or knowledge of any kind successfully and perma-
nently, it must be a work of free volition, as well as from a sense
of duty or expediency ; and whatever tends to create love and
respect for a pursuit or calling, becomes one of the strongest
THE CONDITIONS OF APPRENTICESHIP. 19
incentives for its acquirement, and the interest taken by an
apprentice in his business is for this reason greatly influenced by
the opinions that he may hold concerning the nature of his
engagement.
The subject of apprentice engagements seems in the abstract to
be only a commercial one, partaking of the nature of ordinary
contracts, and, no doubt, can be so construed so far as being
an exchange of " considerations," but no farther. Its intricacy is
established by the fact that all countries where skilled labour exists
have attempted legislation to regulate apprenticeship, and to
define the terms and conditions between master and apprentice ;
but, aside from preventing the abuse of powers delegated to
masters, and in some cases forcing a nominal fulfilment of con-
ditions defined in contracts, such legislation, like that intended
to control commerce and trade, or the opinions of men, has failed
to attain the objects for which it was intended.
This failure of laws to regulate apprenticeship, which facts
fully warrant us in assuming, is due in a large degree to the
impossibility of applying general rules to special cases ; it may
be attributed to the same reasons which make it useless to fix
values or the conditions of exchange by legislation. What is
required is that the master, the apprentice, and the public should
understand the true relations between them the value of what
is given and what is received on both sides. When this is
understood, the whole matter will regulate itself without any
interference on the part of the law.
The subject is an intricate one, and has been so much affected
by the influence of machine improvement, and a corresponding
decrease in what may be called special knowledge, that rules and
propositions which would fifty years ago apply to the conditions
of apprenticeship, will at the present day be wrong and unjust.
Viewed in a commercial sense, as an exchange of considerations
or values, apprenticeship can be regarded like other engage-
ments ; yet, what an apprentice gives as well as what he receives
are alike too conditional and indefinite to be estimated by ordi-
nary standards. An apprentice exchanges unskilled or inferior
labour for technical knowledge, or for the privilege and means
of acquiring such knowledge. The master is presumed to impart
a kind of special knowledge, collected by him at great expense
and pains, in return for the gain derived from the unskilled
labour of the learner. This special knowledge given by the master
20 WORKSHOP MANIPULATION.
may be imparted in a longer or shorter time; it may be thorough
and valuable, or not thorough, and almost useless. The privileges
of a shop may be such as to offset a large amount of valuable
labour on the part of the apprentice, or these privileges maybe of
such a character as to be of but little value, and teach inferior
plans of performing work.
On the other hand, the amount that an apprentice may earn
by his labour is governed by his natural capacity, and by the in-
terest he may feel in advancing; also from the view he may take
of the equity of his engagement, and the estimate that he places
upon the privileges and instruction that he receives. In many
branches of business, where the nature of the operations carried on
are measurably uniform, and have not for a long time been much
affected by changes and improvements, the conditions of appren-
ticeship are more easy to define ; but mechanical engineering is
the reverse of this, it lacks uniformity both as to practice and
what is produced. To estimate the actual value of apprentice
labour in an engineering-work is not only a very difficult matter,
but to some extent impracticable even by those of long experience
and skilled in such investigations ; and it is not to be expected
that a beginner will under such circumstances be able to under-
stand the value of such labour : he is generally led to the con-
clusion that he is unfairly treated, that his services are not suffi-
ciently paid for, and that he is not advanced rapidly enough.
With these conclusions in his mind, but little progress will be
made, and hence the reason for introducing the subject here.
The commercial value of professional or technical knowledge
is generally as the amount of time, effort, and unpaid labour that
has been devoted to its acquirement. This value is sometimes
modified by the exclusiveness of some branch that has been
made the object of special study. Exclusiveness is, however,
becoming exceptional, as the secrets of manufacture and special
knowledge are supplanted by the application of general prin-
ciples ; it is a kind of artificial protection thrown around certain'
branches of industry, and must soon disappear, as unjust to the
public and unnecessary to success.
In business arrangements, technical knowledge and professional
experience become capital, and offset money or property, not
under any general rule, nor even as a consideration of which the
law can define the value or prescribe conditions for. The
estimate placed upon technical knowledge when rated as capital
THE CONDITIONS OF APPRENTICESHIP, 21
in the organisation of business firms, and wherever it becomes
necessary to give such knowledge a commercial value, furnishes
the best and almost the only source from which an apprentice
can form an opinion of the money value of what he is to acquire
during his apprenticeship.
An apprentice at first generally forms an exaggerated estimate
of what he has to learn ; it presents to his mind not only a great
undertaking, but a kind of mystery, which he fears that he may
riot be able to master. The next stage is when he has made
some progress, and begins to underrate the task before him, and
imagine that the main difficulties are past, that he has already
mastered all the leading principles of mechanics, which is, after
all, but a "small matter/' In a third stage an apprentice
experiences a return of his first impressions as to the difficulties
of his undertaking ; he begins to see his calling as one that
must involve endless detail, comprehending things which can
only be studied in connection with personal experience ; he sees
" the horizon widen as it recedes," that he has hardly begun
the task, instead of having completed it even despairs of its
final accomplishment.
In the workshop, mechanical knowledge of some kind is con-
tinually and often insensibly acquired by a learner, who observes
the operations that are going on around him ; he is continually
availing himself of the experience of those more advanced, and
learns by association the rules and customs of the shop, of the
business, and of discipline and management. He gathers the
technical terms of the fitting-shop, the forge and foundry; notes
the operations of planing, turning, drilling, and boring, with the
names and application of the machines directed to these oper-
ations. He sees the various plans of .lifting and moving material,
the arrangement and relation of the several departments to
facilitate the course of the work in process ; he also learns where
the product of the works is sold, discusses the merits and adap-
tation of what is constructed, which leads to considering the
wants that create a demand for this product, and the extent and
nature of the market in which it is sold.
All these things constitute technical knowledge, and the
privilege of their acquirement is an element of value. The
common view taken of the matter, however, is that it costs
nothing for a master to afford these privileges the work must
at any rate be carried on, and is not retarded by being watched
22 WORKSHOP MANIPULATION.
and learned by apprentices. Viewed from any point, the pri-
vileges of engineering establishments have to be considered as
an element of value, to be bought at a price, just as a ton
of iron or a certain amount of labour is; and in a commer-
cial sense, as an exchangeable equivalent for labour, material,
or money. In return a master receives the unskilled labour or
service of the learner; this service is presumed to be given at a
reduced rate, or sometimes without compensation, for the privi-
leges of the works and the instruction received.
In forming an estimate of the value of his services, an appren-
tice sees what his hands have performed, compares it with what
a skilled man will do, and estimates accordingly, assuming that
his earnings are in proportion to what has been done ; but this
is a mistake, and a very different standard must be assumed to
arrive at the true value of such unskilled labour.
Apprentice labour, as distinguished from skilled labour, has
to be charged with the extra attention in management, the loss
that is always occasioned by a forced classification of the work,
the influence in lowering both the quality and the amount of
work performed by skilled men, the risk of detention by failure
or accident, and loss of material ; besides, apprentices must be
charged with the same, if not a greater expense than skilled
workmen, for light, room, oil, tools, and office service. Attempts
have been made in some of the best-regulated engineering estab-
lishments to fix some constant estimate upon apprentice labour,
but, so far as known, without definite results in any case. If
not combined with skilled labour, it would be comparatively
easy to determine the value of apprentice labour; but when it
comes up as an item in the aggregate of labour charged to a
machine or some special work constructed, it is difficult, if not
impossible, to separate skilled from unskilled service.
Another condition of apprenticeship that is equally as difficult
to define as the commercial value of mechanical knowledge, or
that of apprentice labour, is the extent and nature of the faci-
lities that different establishments afford for learners.
In speaking of the mechanical knowledge to be gained, and of
the privileges afforded for learners in engineering-works in a
general way, it must, of course, be assumed that such works
afford full facilities for learning some branch of work by the
best practice and in the most thorough manner. Such establish-
ments are, however, graded from the highest class, on the best
THE CONDITIONS OF APPRENTICESHIP. 23
branches of work, where a premium would be equitable, down
to the lowest class, performing only inferior branches of work,
where there can be little if any advantage gained by serving an
apprenticeship.
Besides this want or difference of facilities which establish-
ments may afford, there is the farther distinction to be made
between an engineering establishment and one that is directed
to the manufacture of staple articles. This distinction between
engineering-works and manufacturing is quite plain to engineers
themselves, but in many cases is not so to those who are to enter
as apprentices, nor to their friends who advise them. In every
case where engagements are made there should be the fullest
possible investigation as to the character of the works, not only to
protect the learner, but to guard regular engineering establish-
ments in the advantages to be gained by apprentice labour. A
machinist or a manufacturer who employs only the muscular
strength and the ordinary faculties of workmen in his operations,
can afford to pay an apprentice from the beginning a fair share
of his earnings ; but an engineering-work that projects original
plans, generates designs, and assumes risks based upon skill and
special knowledge, is very different from a manufactory. To
manufacture is to carry on regular processes for converting
material; such processes being constantly the same, or approxi-
mately so, and such as do not demand much mechanical know-
ledge on the part of workmen.
The name of having been an apprentice to a famous firm may
sometimes have an influence in enabling an engineer to form
advantageous commercial connections, but generally an appren-
ticeship is of value only as it has furnished substantial knowledge
and skill ; for every one must sooner or later come down to the
solid basis of their actual abilities and acquirements. The engi-
neering interest is by far too practical to recognise a shadow
instead of true substance, and there is but little chance of
deception in a calling which deals mainly with facts, figures, and
positive demonstration.
It is best, when an apprentice thinks of entering an engineer-
ing establishment, to inquire of its character from disinterested
persons who are qualified to judge of the facilities it affords.
As a rule, every machine-shop proprietor imagines his own
establishment to combine all the elements of an engineering
business and the fewer the facilities for learners, usually the
24 WORKSHOP MANIPULATION.
more extravagant this estimate ; so that opinions in the matter,
to be relied upon, should come from disinterested sources.
In regard to premiums, it is a matter to be determined
by the facilities that a work may afford for teaching apprentices.
To include experience in all the departments of an engineering
establishment, within a reasonable term, none but those of un-
usual ability can make their services of sufficient value to offset
what they receive; and there is no doubt but that premium
engagements, when the amount of the premium is based upon
the facilities afforded for learning, are fair and equitable.
There is, however, this to be remembered, that the considera-
tions which more especially balance premiums such as a term at
draughting, designing, and office service may be mainly acquired
by self-effort, while the practical knowledge of moulding, forging,
and fitting cannot; and an apprentice who has good natural
capacity, may, if industrious, by the aid of books and such
opportunities as usually exist, qualify himself very well without
including the premium departments in his course.
Finally, it must constantly be borne in mind that what will
be learned is no less a question of faculties than effort, and that
the means of succeeding are closed to none who at the beginning
form proper plans, and follow them persistently.
(1.) Why cannot the conditions of apprentice engagements be deter-
mined by law ? (2.) In what manner does machine improvements affect
the conditions of apprenticeship ? (3.) What are the considerations
which pass from a master to an apprentice ? (4.) What from an appren-
tice to a master ? (5.) Why is a particular service of less value when
performed by an apprentice than by a skilled workman ? (6.) In what
manner can technical knowledge be made to balance or become capital ?
(7.) Name two of the principal distinctions between technical know-
ledge and property as constituting capital. (8.) What is the difference
between what is called engineering and regular manufactures 1
THE OBJECT OF MECHANICAL INDUSTRY. 25
CHAPTER Y.
THE OBJECT OF MECHANICAL INDUSTRY.
MECHANICAL engineering, like every other business pursuit, is
directed to the accumulation of wealth and as the attainment
of any purpose is more surely achieved by keeping that purpose
continually in view, there will be no harm, and perhaps consider-
able gain derived by an apprentice considering at the beginning
the main object to which his efforts will be directed after learn-
ing his profession or trade. So far as an abstract principle of
motives, the subject is of course unfit to consider in ' con-
nection with engineering operations, or shop manipulation ; but
business objects have a practical application to be followed
throughout the whole system of industrial pursuits, and are as
proper to be considered in connection with machine-manufactur-
ing as mechanical principles, or the functions and operation of
machines.
The cost of production is an element that continually modifies
or improves manufacturing processes, determines the success of
every establishment, and must be considered continually in
making drawings, patterns, forgings, and castings. Machines
are constructed because of the difference between what they cost
and ivhat they sell for between their manufacturing cost and
market value when they are completed.
It seems hard to deprive engineering pursuits of the romance
that is often attached to the business, and bring it down to a
matter of commercial gain ; but it is best to deal with facts,
especially when such facts have an immediate bearing upon the
general object in view. There is no intention in these remarks
of disparaging the works of many noble men, who have given
their means, their time, and sometimes their lives, to the ad-
vancement of the industrial arts, without hope or desire of any
other reward than the satisfaction of having performed a duty ;
but we are dealing with facts, and no false colouring should
prevent a learner from forming practical estimates of practical
matters.
The following propositions will place this subject of aims and
objects before the reader in the sense intended:
26 WORKSHOP MANIPULATION.
First. The main object of mechanical engineering is commer-
cial gain the profits derived from planning and constructing
machinery.
Second. The amount of gain so derived is as the difference
between the cost of constructing machinery, and the market
value of the machinery when completed.
Third. The difference between what it costs to plan and con-
struct machinery and what it will sell for, is generally as the
amount of engineering knowledge and skill brought to bear in
the processes of production.
This last sentence brings the matter into a tangible form, and
indicates what the subject of gain should have to do with what
an apprentice learns of machine construction. Success in an
engineering enterprise may be temporarily achieved by illegiti-
mate means such as misrepresentation of the capacity and
quality of what is produced, the use of cheap or improper
material, or by copying the plans of others to avoid the expense
of engineering service but in the end the permanent success of
art engineering business must rest upon the knowledge and skill
that is connected with it.
By examining into the facts, an apprentice will find that all
truly successful establishments have been founded and built
upon the mechanical abilities of some person or persons whose
skill formed a base upon which the business was reared, and
that true skill is the element which must in the end lead to
permanent success. The material and the labour which make
up the first cost of machines are, taking an average of various
classes, nearly equally divided ; labour being in excess for the
finer class of machinery, and the material in excess for the
coarser kinds of work. The material is presumed to be purchased
at the same rates by those of inferior skill as by those that are
well skilled, so that the difference in the first, or manufacturing
cost of machinery, is determined mainly by skill.
Skill, in the sense employed here, consists not only in preparing
plans and in various processes for converting and shaping mate-
rial, but also in the general conduct of an establishment, includ-
ing estimates, records, system, and so on, which will be noticed
in their regular order. The amount of labour involved, and
consequently the first cost of machinery, is in a large degree as
the number of mechanical processes required, and the time con-
sumed in each operation j to reduce the number of these processes
THE OBJECT OF MECHANICAL INDUSTRY. 27
or operations, shorten the time in which they may be performed,
and improve the quality of what is produced, is the business of
the mechanical engineer. A careful study of shop operations or
processes, including designing, draughting, moulding, forging,
and fitting, is the secret of success in engineering practice, or in
the management of manufactures. The advantages of an eco-
nomical design, and the most carefully-prepared drawings, are
easily neutralised and lost by careless or improper manipulation
in the workshop ; an incompetent manager may waste ten pounds
in shop processes, while the commercial department of a work
saves one pound by careful buying and selling.
This importance of shop processes in machine construction is
generally realised by proprietors, but not thoroughly understood
in all of its bearings; an apprentice may notice the continual
effort that is made to augment the production of engineering-
works, which is the same thing as shortening the processes.
A machine may be mechanically correct, arranged with sym-
metry, true proportions, and proper movements; but if such a
machine has not commercial value, and is not applicable to
a useful purpose, it is as much a failure as though it were
mechanically inoperative. In fact, this consideration of cost and
commercial value must be continually present ; and a mechanical
education that has not furnished a true understanding of the
relations between commercial cost and mechanical excellence
will fall short of achieving the objects for which such an educa-'
tion is undertaken. By reasoning from such premises as have
been laid down, an apprentice may form true standards by which
to judge of plans and processes that he is brought in contact
with, and the objects for which they are conducted.
(1.) To what general object are all pursuits directed ? (2.) What
besides wealth may be objects in the practice of engineering pursuits ?
(3.) Name some of the most common among the causes which reduce
the cost of production. (4.) Name five of the main elements which go
to make up the cost of engineering products. (5.) Why is commercial
success generally a true test of the skill connected with engineering-
works ?
28 WORKSHOP MANIPULATION.
CHAPTER VI
ON THE NATURE AND OBJECTS OF MACHINERY.
MACHINES do not create or consume, but only transmit and
apply power ; and it is only by conceiving of power as a con-
stant element, independent of every kind of machinery, that the
learner can reach a true understanding of the nature of machines.
When once there is in the mind a fixed conception of power, dis-
sociated from every kind of mechanism, there is laid, so to
speak, a solid foundation on which an understanding of machines
may be built up.
To believe a fact is not to learn it, in the sense that these
terms may be applied to mechanical knowledge ; to believe a
proposition is not to have a conviction of its truth; and what is
meant by learning mechanical principles is, as remarked in a
previous place, to have them so fixed in the mind that they will
involuntarily arise to qualify everything met with that involves
mechanical movement. For this reason it has been urged that
learners should begin by first acquiring a clear and fixed con-
ception of power, and next of the nature arid classification of
machines, for without the first he cannot reach the second.
Machines may be defined in general terms as agents for con-
verting, transmitting, and applying power, or motion and force,
which constitute power. By machinery the natural forces are
utilised, and directed to the performance of operations where
human strength is insufficient, when natural force is cheaper,
and when the rate of movement exceeds what the hands can
perform. The term " agent " applied to machines conveys a true
idea of their nature and functions.
Machinery can be divided into four classes, each constituting
a division that is very clearly defined by functions performed,
as follows :
First. Motive machinery for utilising or converting the
natural forces.
Second. Machinery for transmitting and distributing power.
Third. Machinery for applying power.
Fourth. Machinery of transportation.
Or, more briefly stated
Motive machinery.
MOTIVE MACHINEKY. 29
Machinery of transmission.
Machinery of application.
Machinery of transportation.
These divisions of machinery "will next be treated of separ-
ately, with a view of making the classification more clear, and
to explain the principles of operation in each division. This
dissertation will form a kind of base upon which the prac-
tical part of the treatise will in a measure rest. It is trusted that
the reader will carefully consider each proposition that is laid
down, and on his own behalf pursue the subjects farther than
the limits here permit.
(1.) To what three general objects are machines directed ? (2.) How
are machines distinguished from other works or structures ? (3.) Into
what four classes can machinery be divided ? (4.) Name one principal
type in each of these four divisions.
CHAPTER VII.
MO TI VE MA CHINER Y.
Ix this class belong
Steam-engines.
Caloric or air engines.
Water-wheels or water-engines.
Wind -wheels or pneumatic engines.
These four types comprehend the motive-power in general use
at the present day. In considering different engines for motive-
power in a way to best comprehend their nature, the first view
to be taken is that they are all directed to the same end, and all
deal with the same power ; and in this way avoid, if possible, the
impression of there being different kinds of power, as the terms
water-power, steam-power, and so on, seem to imply. We speak
of steam-power, water-power, or wind-power \ but power is the
same from whatever source derived, and these distinctions merely
indicate different natural sources from which power is derived,
or the different means employed to utilise and apply it.
Primarily, power is a product of heat ; and wherever force
and motion exist, they can be traced to heat as the generating
30 WOKKSHOP MANIPULATION,
element : whether the medium through which the power is
obtained be by the expansion of water or gases, the gravity of
water, or the force of wind, heat will always be found as the
prime source. So also will the phenomenon of expansion be
found a constant principle of developing power, as will again
be pointed out. As steam-engines constitute a large share of
the machinery commonly met with, and as a class of machinery
naturally engrosses attention in proportion, the study of mechanics
generally begins with steam-engines, or steam machinery, as it
may be called.
The subject of steam-power, aside from its mechanical con-
sideration, is one that may afford many useful lessons, by tracing
its history and influence, not only upon mechanical industry,
but upon human interests generally. This subject is often
treated of, and both its interest and importance conceded ; but no
one has, so far as I know, from statistical and other sources,
ventured to estimate in a methodical way the changes that can
be traced directly and indirectly to steam-power.
The steam-engine is the most important, and in England and
America best known among motive agents. The importance of
steam contrasted with other sources of motive-power is due
not so much to a diminished cost of power obtained in this way,
but for the reason that the amount of power produced can be
determined at will, and in most cases without reference to local
conditions ; the machinery can with fuel and water be trans-
ported from place to place, as in the case of locomotives which
not only supply power for their own transit, but move besides
vast loads of merchandise, or travel.
For manufacturing processes, one importance of steam-power
rests in the fact that such power can be taken to the
material ; and beside other advantages gained thereby, is the
difference in the expense of transporting manufactured pro-
ducts and the raw material. In the case of iron manufacture,
for example, it would cost ten times as much to transport the ore
and the fuel used in smelting as it does to transport the manu-
factured iron ; steam-power saves this difference, and without
such power our present iron traffic would be impossible. In a
great many manufacturing processes steam is required for heat-
ing, bleaching, boiling, and so on ; besides, steam is now to a large
extent employed for warming buildings, so that even when water
or other power is employed, in most cases steam-generating
MOTIVE MACHINERY. 31
apparatus has to be set up in addition. In many cases waste
steam or waste heat from a steam-engine can be employed for
the purposes named, saving most of the expense that must be
incurred if special apparatus is employed.
Other reasons for the extended and general use of steam as a
power, besides those already named, are to be found in the fact
that no other available element or substance can be expanded to
a given degree at so small a cost as water; and that its tem-
perature will not rise to a point injurious to machinery, and,
further, in the very important property of lubrication which
steam possesses, protecting the frictional surfaces of pistons and
valves, which it is impossible to keep oiled because of their
inaccessibility or temperature.
The steam-engine, in the sense in which the term is employed,
means not only steam-using machinery, but steam-generating
machinery or plant ; it includes the engine proper, with the
boiler, mechanism for feeding water to the boiler, machinery for
governing speed, indicators, and other details.
An apprentice must guard against the too common impres-
sion that the engine, cylinder, piston, valves, and so on, are the
main parts of steam machinery, and that the boiler and furnace
are only auxiliaries. The boiler is, in fact, the base of the whole,
that part where the power is generated, the engine being merely
an agent for transmitting power from the boiler to work that is
performed. This proposition would, of course, be reached by
any one in reasoning about the matter and following it to a con-
clusion, but the fact should be fixed in the mind at the
beginning.
When we look at a steam-engine there are certain impressions
conveyed to the mind, and by these impressions we are governed
in a train of reflection that follows. We may conceive of a
cylinder and its details as a complete machine with independent
functions, or we can conceive of it as a mechanical device for
transmitting the force generated by a boiler, and this concep-
tion might be independent of, or even contrary to, specific know-
ledge that we at the same time possessed ; hence the importance
of starting with a correct idea of the boiler being, as we may say,
the base of steam machinery.
As reading books of fiction sometimes expands the mind and
enables it to grasp great practical truths, so may a study of
abstract principles often enable us to comprehend the simplest
32 WORKSHOP MANIPULATION.
forms of mechanism. Even Humboldt and Agassiz, it is said,
resorted sometimes to imaginative speculations as a means of
enabling them to grasp new truths.
In no other branch of machinery has so much research and
experiment been made during eighty years past as in steam
machinery, and, strange to say, the greater part of this research
has been directed to the details of engines ; yet there has been
no improvement made during the time which has effected any
considerable saving of heat or expense. The steam-engines of
fifty years ago, considered as steam-using machines, utilised
nearly the same proportion of the energy or power developed by
the boiler as the most improved engines of modern construction
a fact that in itself indicates that an engine is not the vital
part of steam machinery. There is not the least doubt that if
the efforts to improve steam-engines had been mainly directed
to economising heat and increasing the evaporative power of
boilers, much more would have been accomplished with the
same amount of research. This remark, however, does not apply
to the present day, when the principles of steam-power are so well
understood, and when heat is recognised as the proper element
to deal with in attempts to diminish the expense of power.
There is, of course, various degrees of economy in steam-using
as well as in steam-generating machinery j but so long as the
best steam machinery does not utilise but one-tenth or one-
fifteenth part of the heat represented in the fuel burned, there
need be no question as to the point where improvements in
such machinery should be mainly directed.
The principle upon which steam-engines operate may be
briefly explained as follows :
A cubic inch of water, by taking up a given amount of heat,
is expanded to more than five hundred cubic inches of steam,
at a pressure of forty-five pounds to the square inch. This
extraordinary expansion, if performed in a close vessel, would
exert a power five hundred times as great as would be required
to force the same quantity of water into the vessel against this
expansive pressure; in other words, the volume of the water
when put into the vessel would be but one five-hundredth part of
its volume when it is allowed to escape, and this expansion, when
confined in a steam-boiler, exerts the force that is called steam-
power. This force or power is, through the means of the engine
and its details, communicated and applied to different kinds of
MOTIVE MACHINERY. 33
work where force and movement are required. The water
employed to generate steam, like the engine and the boiler, is
merely an agent through which the energy of heat is applied.
This, again, reaches the proposition that power is heat, and heat
is power, the two being convertible, and, according to modern
science, indestructible ; so that power, when used, must give off
its mechanical equivalent of heat, or heat, when utilised, develop
its equivalent in power. If the whole amount of heat repre-
sented in the fuel used by a steam-engine could be applied, the
effect would be, as before stated, from ten to fifteen times as
great as it is in actual practice, from which it must be inferred
that a steam-engine is a very imperfect machine for utilising
heat. This great loss arises from various causes, among which
is that the heat cannot be directly nor fully communicated to
the water. To store up and retain the water after it is expanded
into steam, a strong vessel, called a boiler, is required, and all
the heat that is imparted to the water has to pass through
the plates of this boiler, which stand as a wall between the heat
and its work.
To summarise, we have the following propositions relating to
steam machinery :
1. The steam-engine is an agent for utilising the power of
heat and applying it to useful purposes.
2. The power of a steam-engine is derived by expanding water
in a confining vessel, and employing the force exerted by pres-
sure thus obtained.
3. The power developed is as the difference of volume between
the feed-water forced into the boiler, and the volume of the
steam that is drawn from the boiler, or as the amount of heat
taken up by the water.
4. The heat that may be utilised is what will pass through
the plates of the boiler, and be taken up by the water, and is
but a small share of what the fuel produces.
5. The boiler is the main part, where power is generated, and
the engine is but an agent for transmitting this power to the
work performed.
6. The loss of power in a steam-engine arises- from- the heat
carried off in the exhaust steam, loss by radiation, arid the
friction of the moving parts.
7. By condensing the steam before it leaves the engine, so>
that the steam is returned to the air in the form of water, and
C
34 WORKSHOP MANIPULATION.
of the same volume as when it entered the boiler, there is a gain
effected by avoiding atmospheric pressure, varying according to
the perfection of the arrangements employed.
Engines operated by means of hot air, called caloric engines,
and engines operated by gas, or explosive substances, all act
substantially upon the same general principles as steam-engines ;
the greatest distinction being between those engines wherein the
generation of heat is by the combustion of fuel, and those wherein
heat and expansion are produced by chemical action. With the
exception of a limited number of caloric or air engines, steam
machinery comprises nearly all expansive engines that are
employed at this day for motive-power ; and it may be safely
assumed that a person who has mastered the general principles
of steam-engines will find no trouble in analysing and under-
standing any machinery acting from expansion due to heat,
whether air, gas, or explosive agents be employed.
This method of treating the subject of motive-engines will no
doubt be presenting it in a new way, but it is merely beginning
at an unusual place. A learner who commences with first prin-
ciples, instead of pistons, valves, connections, and bearings, will
find in the end that he has not only adopted the best course,
but the shortest one to understand steam and other expansive
,(1.) What is principal among the details of steam machinery ?
(2.) What has been the most important improvement recently made in
steam machinery ? (3.) What has been the result of expansive engines
generally stated ? (4.) Why has water proved the most successful
among various expansive substances employed to develop power ?
(5.) Why does a condensing engine develop more power than a non-con-
densing one ? (6.) How far back from its development into power can
heat be traced as an element in nature 1 (7.) Has the property of com-
bustion a common source in all substances ?
WATER-POWER. 35
CHAPTER VIII.
WATER-POWER.
WATER-WHEELS, next to steam-engines, are the most common
motive agents. For centuries water-wheels remained without
much improvement or change down to the period of turbine
wheels, when it was discovered that instead of being a very
simple matter, the science of hydraulics and water-wheels
involved some very intricate conditions, giving rise to many
problems of scientific interest, that in the end have produced
the class known as turbine wheels.
A modern turbine water-wheel, one of the best construction,
operating under favourable conditions, gives a percentage of
the power of the water which, after deducting the friction of the
wheel, almost reaches the theoretical coefficient or equals the
gravity of the water; it may therefore be assumed that there
will in the future be but little improvement made in such
water-wheels except in the way of simplifying and cheapening
their construction. There is, in fact, no other class of machines
which seem to have reached the same state of improvement as
water-wheels, nor any other class of machinery that is con-
structed with as much uniformity of design and arrangement, in
different countries, and by different makers.
Water-wheels, or water-power, as a mechanical subject, is
apparently quite disconnected with shop manipulation, but
will serve as an example for conveying general ideas of force
and motion, and, on these grounds, will warrant a more
extended notice than the seeming connection with the general
subject calls for.
In the remarks upon steam-engines it was explained that
power is derived from heat, and that the water and the engine
were both to be regarded as agents through which power was
applied, and further, that power is always a product of heat.
There is, perhaps, no problem in the whole range of mechanics
more interesting than to trace the application of this principle
in machinery ; one that is not only interesting but instructive,
and may suggest to the mind of an apprentice a course of
36 WORKSHOP MANIPULATION.
investigation that will apply to many other matters connected
with power and mechanics.
Power derived from water by means of wheels is due to the
gravity of the water in descending from a higher to a lower
level ; but the question arises, What has heat to do with this 1
If heat is the source of power, and power a product of heat,
there must be a connection somewhere between heat and the
descent of the water. Water, in descending from one level to
another, can give out no more power than was consumed in
raising it to the higher level, and this power employed to raise
the water is found to be heat. Water is evaporated by heat of
the sun, expanded until it is lighter than the atmosphere, rises
through the air, and by condensation falls in the form of rain
over the earth's surface; then drains into the ocean through
streams and rivers, to again resume its round by another
course of evaporation, giving out in its descent power that we
turn to useful account by means of water- wheels. This principle
of evaporation is continually going on ; the fall of rain is
likewise quite constant, so that streams are maintained within
a sufficient regularity to be available for operating machinery.
The analogy between steam-power and water-power is there-
fore quite complete. Water is in both cases the medium
through which power is obtained; evaporation is also the
leading principle in both, the main difference being that in the
case of steam-power the force employed is directly from the
expansion of water by heat, and in water-power the force is an
indirect result of expansion of water by heat.
Every one remembers the classification of water-wheels met
with in the older school-books on natural philosophy, where we
are informed that there are three kinds of wheels, as there were
"three kinds of levers" namely, overshot, undershot, and breast
wheels with a brief notice of Barker's mill, which ran apparently
without any sufficient cause for doing so. Without finding
fault with the plan of describing water-power commonly adopted
in elementary books, farther than to say that some explana-
tion of the principles by which power is derived from the
water would have been more useful, I will venture upon a
different classification of water-wheels, more in accord with
modern practice, but without reference to the special mechanism
of the different wheels, except when unavoidable. Water-wheels
can be divided into four general types.
WATER-POWER. 37
First. Gravity wheels, acting directly from the weight of the
water which is loaded upon a wheel revolving in a vertical
plane, the weight resting upon the descending side until the
water has reached the lowest point, where it is discharged.
Second. Impact wheels, driven by the force of spouting water
that expends its percussive force or momentum against the vanes
tangental to the course of rotation, and at a right angle to the
face of the vanes or floats.
Third. Reaction wheels, that are "enclosed," as it is termed,
and filled with water, which is allowed to escape under pressure
through tangental orifices, the .propelling force being derived
from the unbalanced pressure within the wheel, or from the re-
action due to the weight and force of the water thrown off from
the periphery.
Fourth. Pressure wheels, acting in every respect upon the
principle of a rotary steam-engine, except in the differences that
arise from operating with an elastic and a non-elastic fluid ; thk
pressure of the water resting continually against the vanes and
"abutment," without means of escape except by the rotation of
the wheel.
To this classification may be added combinationUwhe^fej/''
acting partly by the gravity and partly by the percussiaktfhrce "& f
of the water, by impact combined with reaction, or by nW!$5^
and maintained pressure.
Gravity, or "overshot" wheels, as they are called, for some
reasons will seem to be the most effective, and capable of utilis-
ing the whole effect due to the gravity of the water ; but in
practice this is not the case, and it is only under peculiar con-
ditions that wheels of this class are preferable to turbine wheels,
and in no case will they give out a greater per cent, of power
than turbine wheels of the best class. The reasons for this will
be apparent by examining the conditions of their operation.
A gravity wheel must have a diameter equal to the fall of
water, or, to use the technical name, the height of the head.
The speed at the periphery of the wheel cannot well exceed
sixteen feet per second without losing a part of the effect by the
wheel anticipating or overrunning the water. This, from the
large diameter of the wheels, produces a very slow axial speed,
and a train of multiplying gearing becomes necessary in order
to reach the speed required in most operations where power is
33 WORKSHOP MANIPULATION.
applied. This train of gearing, besides being liable to wear and
accident, and costing usually a large amount as an investment,
consumes a considerable part of the power by frictional resist-
ance, especially when such gearing consists of tooth wheels.
Gravity wheels, from their large size and their necessarily ex-
posed situation, are subject to be frozen up in cold climates ;
and as the parts are liable to be first wet and then dry, or warm
and cold by exposure to the air and the water alternately, the
tendency to corrosion if constructed of iron, or to decay if of
wood, is much greater than in submerged wheels. Gravity
wheels, to realise the highest measure of effect from the water,
require a diameter so great that they must drag in the water at
the bottom or delivering side, and are for this reason especially
affected by back-water, to which all wheels are more or less
liable from the reflux of tides or by freshets. These disadvan-
tages are among the most notable pertaining to gravity wheels,
and have, with other reasons such as the inconvenience of con-
struction, greater cost, and so on driven such wheels out of use
by the force of circumstances, rather than by actual tests or
theoretical deductions.
Impact wheels, or those driven by the percussive force of
water, including the class termed turbine water-wheels, are at
this time generally employed for heads of all heights.
The general theory of their action may be explained in the
following propositions :
1. The spouting force of water is theoretically equal to its
gravity.
2. The percussive force of spouting water can be fully utilised
if its motion is altogether arrested by the vanes of a wheel.
3. The force of the water is greatest by its striking against
planes at right angles to its course.
4. Any force resulting from water rebounding from the
vanes parallel to their face, or at any angle not reverse to the
motion of the wheel, is lost.
5. This rebounding action becomes less as the columns of
water projected upon the wheel are increased in number and
diminished in size.
6. To meet the conditions of rotation in the wheel, and to
facilitate the escape of the water without dragging, after it has
expended its force upon the vanes, the reversed curves of the
turbine is the best-known arrangement.
WATER-POWER. 39
It is, of course, very difficult to deal with so complex a subject
as the present one with words alone, and the reader is recom-
mended to examine drawings, or, what is better, water-wheels
themselves, keeping the above propositions in view.
Modern turbine wheels have been the subject of the most
careful investigation by able engineers, and there is no lack of
mathematical data to be referred to and studied after the general
principles are understood. The subject, as said, is one of great
complicity if followed to detail, and perhaps less useful to a
mechanical engineer who does not intend to confine his practice
to water-wheels, than other subjects that may be studied with
greater advantage. The subject of water-wheels may, indeed,
be called an exhausted one that can promise but little return for
labour spent upon it with a view to improvements, at least.
The efforts of the ablest hydraulic engineers have not added
much to the percentage of useful effect realised by turbine wheels
during many years past.
Keaction wheels are employed to a limited extent only, and
will soon, no doubt, be extinct as a class of water-wheels. In
speaking of reaction wheels, I will select what is called Barker's
mill for an example, because of the familiarity with which it is
known, although its construction is greatly at variance with
modern reaction wheels.
There is a problem as to the principle of action in a Barker
wheel, which although it may be very clear in a scientific sense,
remains a puzzle to the minds of many who are well versed in
mechanics, some contending that the power is directly from
pressure, others that it is from the dynamic effect due to
reaction. It is one of the problems so difficult to determine by
ordinary standards, that it serves as a matter of endless debate
between those who hold different views ; and considering the
advantage usually derived from such controversies, perhaps the
best manner of disposing of the problem here is to state the two
sides as clearly as possible, and leave the reader to determine for
himself which he thinks right.
Presuming the vertical shaft and the horizontal arms of a
Barker wheel to be filled with water under a head of sixteen
feet, there would be a pressure of about seven pounds upon each
superficial inch of surface within the cross arm, exerting an equal
force in every direction. By opening an orifice at the sides of
these arms equal to one inch of area, the pressure would at that
40 WORKSHOP MANIPULATION.
point be relieved by the escape of the water, and the internal
pressure be unbalanced to that extent. In other words, opposite
this orifice, and on the other side of the arm, there would be a
force of seven pounds, which being unbalanced, acts as a pro-
pelling power to drive the wheel.
This is one theory of the principle upon which the Barker
wheel operates, which has been laid down in Vogdes' " Mensura-
tion," and perhaps elsewhere. The other theory alluded to is
that, direct action and reaction being equal, ponderable matter
discharged tangentally from the periphery of a wheel must
create a reactive force equal to the direct force with which the
weight is thrown off. To state it more plainly, the spouting
water that issues from the arm of a Barker wheel must react in
the opposite course in proportion to its weight.
The two propositions may be consistent with each other er
even identical, but there still remains an apparent difference.
The latter seems a plausible theory, and perhaps a correct one ;
but there are two facts in connection with the operation of reaction
water-wheels which seem to controvert the latter and favour the
first theory, namely, that reaction wheels in actual practice
seldom utilise more than forty per cent, of useful effect from the
water, and that their speed may exceed the initial velocity of the
water. With this the subject is left as one for argument or
investigation on the part of the reader.
Pressure wheels, like gravity wheels, should, from theoretical
inference, be expected to give a high per cent, of power. The
water resting with the whole of its weight against the vanes or
abutments, and without chance of escape except by turning the
wheel, seems to meet the conditions of realising the whole effect
due to the gravity of the water, and such wheels would no doubt
be economical if they had not to contend with certain mechanical
difficulties that render them impracticable in most cases.
A pressure wheel, like a steam-engine, must include running
contact between water-tight surfaces, and like a rotary steam-
engine, this contact is between surfaces which move at different
rates of speed in the same joint, so that the wear is unequal,
and increases as the speed or the distance from the axis.
When it is considered that the most careful workmanship has
never produced rotary engines that would surmount these diffi-
culties in working steam, it can hardly be expected they can be
overcome in using water, which is not only liable to be filled
WIND-POWER. 41
with grit and sediment, but lacks the peculiar lubricating pro-
perties of steam. A rotary steam-engine is in effect the same as
a pressure water-wheel, and the apprentice in studying one will
fully understand the principles of the other.
(1.) What analogy may be found between steam and water power 1 ?
(2.) What is the derivation of the name turbine ? (3.) To what class
of water-wheels is this name applicable 1 (4.) How may water-wheels
be classified? (5.) Upon what principle does a reaction water-wheel
operate ? (6.) Can ponderable weight and pressure be independently
considered in the case? (7.) Why cannot radial running joints be
maintained in machines ? (8.) Describe the mechanism in common use
for sustaining the weight of turbine wheels, and the thrust of propeller
shafts.
CHAPTER IX,
WIND-POWER.
WIND-POWER, aside from the objections of uncertainty and irreg-
ularity, is the cheapest kind of motive-power. Steam machinery,
besides costing a large sum as an investment, is continually
deteriorating in value, consumes fuel, and requires continual
skilled attention. Water-power also requires a large investment,
greater in many cases than steam-power, and in many places
the plant is in danger of destruction by freshets. Wind-power
is less expensive in every way, but is unreliable for constancy
except in certain localities, and these, as it happens, are for the
most part distant from other elements of manufacturing industry.
The operation of wind- wheels is so simple and so generally under-
stood that no reference to mechanism need be made here. The
force of the wind, moving in right lines, is easily applied to
producing rotary motion, the difference from water-power being
mainly in the comparative weakness of wind currents and the
greater area required in the vanes upon which the wind acts.
Turbine wind-wheels have been constructed on very much the same
plan as turbine water-wheels. In speaking of wind-power, the
propositions about heat must not be forgotten. It has been ex-
plained how heat is almost directly utilised by the steam-engine,
42 WORKSHOP MANIPULATION.
and how the effect of heat is utilised by water-wheels in a less
direct manner, and the same connection will be found between
heat and wind-wheels or wind-power. Currents of air are due
to changes of temperature, and the connection between the heat
that produces such air currents and their application as power is
no more intricate than in the case of water-power.
(1.) What is the difference in general between wind and water wheels 1
(2.) Can the course of wind, like that of water, be diverted and applied
at pleasure ? (3.) On what principle does wind act against the vanes of
a wheel ? (4.) How may an analogy between wind-power and heat be
traced 1
CHAPTER X.
MACHINERY FOR TRANSMITTING AND DISTRIBUTING
POWER.
To construe the term ''transmission of power" in its full sense,
it will, when applied to machinery, include nearly all that has
motion ; for with the exception of the last movers, or where
power passes off and is expended upon work that is performed,
all machinery of whatever kind may be called machinery of
transmission. Custom has, however, confined the use of the
term to such devices as are employed to convey power from one
place to another, without including organised machines through
which power is directly applied to the performance of work.
Power is transmitted by means of shafts, belts, friction wheels,
gearing, and in some cases by water or air, as various conditions
of the work to be performed may require. Sometimes such
machinery is employed as the conditions do not require, because
there is, perhaps, nothing of equal importance connected with
mechanical engineering of which there exists a greater diversity
of opinion, or in which there is a greater diversity of practice,
than in devices for transmitting power.
I do not refer to questions of mechanical construction, although
the remark might be true if applied in this sense, but to the
kind of devices that may be best employed in certain cases.
TRANSMITTING MACHINERY. 43
It is not proposed at tins time to treat of the construction of
machinery for transmitting power, but to examine into the con-
ditions that should determine which of the several plans of
transmitting is best in certain cases whether belts, gearing, or
shafts should be employed, and to note the principles upon
which they operate. Existing examples do not furnish data as
to the advantages of the different plans for transmitting power,
because a given duty may be successfully performed by belts,
gearing, or shafts even by water, air, or steam and the com-
parative advantages of different means of transmission is not
always an easy matter to determine.
Machinery of transmission being generally a part of the fixed
plant of an establishment, experiments cannot be made to insti-
tute comparisons, as in the case of machines ; besides, there are
special or local considerations such as noise, danger, freezing,
and distance to be taken into account, which prevent any rules
of general application. Yet in every case it may be assumed that
some particular plan of transmitting power is better than any
other, and that plan can best be determined by studying, first,
the principles of different kinds of mechanism and its adaptation
to the special conditions that exist ; and secondly, precedents or
examples.
A leading principle in machinery of transmission that more
than- any other furnishes data for strength and proper propor-
tions is, that the stress upon the machinery, whatever it may
be, is inverse as the speed at which it moves. For example, a
belt two inches wide, moving one thousand feet a minute, will
theoretically perform the same work that one ten inches wide
will do, moving at a speed of two hundred feet a minute ; or a
shaft making two hundred revolutions a minute will transmit
four times as much power as a shaft making but fifty revolu-
tions in the same time, the torsional strain being the same in
both cases.
This proposition argues the expediency of reducing the pro-
portions of mill gearing and increasing its speed, a change which
has gradually been going on for fifty years past ; but there are
opposing conditions which make a limit in this direction, such as
the speed at which bearing surfaces may run, centrifugal strain,
jar, and vibration. The object is to fix upon a point between
what high speed, light weight, cheapness of cost suggest, and what
the conditions of practical use and endurance demand.
44 WORKSHOP MANIPULATION.
(1.) "What does the term "machinery of transmission" include, as
applied in common use 1 (2.) Why cannot direct comparisons be made
"between shafts, belts, and gearing? (3.) Define the relation between
speed and strain in machinery of transmission. (4.) What are the
principal conditions which limit the speed of shafts ?
CHAPTER XL
SHAFTS FOR TRANSMITTING POWER.
THERE is no use in entering upon detailed explanations of what
a learner has before him. Shafts are seen wherever there is
machinery ; it is easy to see the extent to which they are
employed to transmit power, and the usual manner of arranging
them. Various text-books afford data for determining the
amount of torsional strain that shafts of a given diameter will
bear ; explain that their capacity to resist torsional strain is as
the cube of the diameter, and that the deflection from transverse
strains is so many degrees ; with many other matters that are
highly useful and proper to know. I will therefore not devote
any space to these things here, but notice some of the
more obscure conditions that pertain to shafts, such as are
demonstrated by practical experience rather than deduced from
mathematical data. What is said will apply especially to what
is called line-shafting for conveying and distributing power in
machine-shops and other manufacturing establishments. The
following propositions in reference to shafts will assist in under-
standing what is to follow :
1. The strength of shafts is governed by their size and the
arrangement of their supports.
2. The capacity of shafts is governed by their strength and
the speed at which they run taken together.
3. The strains to which shafts are subjected are the torsional
strain of transmission, transverse strain from belts and wheels,
and strains from accidents, such as the winding of belts.
4. The speed at which shafts should run is governed by their
size, the nature of the machinery to be driven, and the kind of
bearings in which they are supported.
5. As the strength of shafts is determined by their size, and
SHAFTS FOR TRANSMITTING POWER. 45
their size fixed by ike strains to which they are subjected,
strains are first to be considered.
There were three kinds of strain mentioned torsional, deflec-
tive, and accidental. To meet these several strains the same
means have to be provided, which is a sufficient size and strength
to resist them hence it is useless to consider each of these dif-
ferent strains separately. If we know which of the three is
greatest, and provide for that, the rest, of course, may be dis-
regarded. This, in practice, is found to be accidental strains to
which shafts are in ordinary use subjected, and they are usually
made, in point of strength, far in excess of any standard that
would be fixed by either torsional or transverse strain due to the
regular duty performed.
This brings us back to the old proposition, that for structures
which do not involve motion, mathematical data will furnish
dimensions ; but the same rule will not apply in machinery. To
follow the proportions for shafts that would be furnished by pure
mathematical data would in nearly all cases lead to error.
Experience has demonstrated that for ordinary cases, where
power is transmitted and applied with tolerable regularity, a
shaft three inches in diameter, making one hundred and fifty
revolutions a minute, its bearings three to four diameters in
length, and placed ten feet apart, will safely transmit fifty horse-
power.
By assuming this or any other well-proved example, and estimat-
ing larger or smaller shafts by keeping their diameters as the
cube root of the power to be transmitted, the distance between
bearings as the diameter, and the speed inverse as the diameter,
the reader will find his calculations to agree approximately with
the modern practice of our best engineers. This is not men-
tioned to give proportions for shafts, so much as to call atten-
tion to accidental strains, such as winding belts, and to call
attention to a marked discrepancy between actual practice
and such proportions as would be given by what has been
called the measured or determinable strains to which shafts are
subjected.
As a means for transmitting power, shafts afford the very
important advantage that power can be easily taken off at any
point throughout their length, by means of pulleys or gear-
ing, also in forming a positive connection between the motive-
power and machines, or between the different parts of machines.
46 WORKSHOP MANIPULATION,
The capacity of shafts in resisting torsional strain is as the cube
of their diameter, and the amount of torsional deflection in shafts
is as their length. The torsional capacity being based upon the
diameter, often leads to the construction of what may be termed
diminishing shafts, lines in which the diameter of the several
sections are diminished as the distance from the driving power
increases, and as the duty to be performed becomes less. This
plan of arranging line shafting has been and is yet quite com-
mon, but certainly was never arrived at by careful observation.
Almost every plan of construction has both advantages and dis-
advantages, and the best means of determining the excess of
either, in any case, is to first arrive at all the conditions as near
as possible, then form a " trial balance," putting the advantages
on one side and the disadvantages on the other, and footing up
the sums for comparison. Dealing with this matter of shafts of
uniform diameter and shafts of varying diameter in this way,
there may be found in favour of the latter plan a little saving of
material and a slight reduction of friction as advantages. The
saving of material relates only to first cost, because the expense
of fitting is greater in constructing shafts when the diameters of
the different pieces vary; the friction, considering that the same
velocity throughout must be assumed, is scarcely worth estimating.
For disadvantages there is, on the other hand, a want of uni-
formity in fittings that prevents their interchange from one part
of a line shaft to the other a matter of great importance, as
such exchanges are frequently required. A line shaft, when
constructed with pieces of varying diameter, is special machinery,
adapted to some particular place or duty, and not a standard
product that can be regularly manufactured as a staple article
by machinists, and thus afforded at a low price. Pulleys,
wheels, bearings, and couplings have all to be specially pre-
pared; and in case of a change, or the extension of lines of
shafting, cause annoyance, and frequently no little expense,
which may all be avoided by having shafts of uniform
diameter. The bearings, besides being of varied strength and
proportions, are generally in such cases placed at irregular inter-
vals, and the lengths of the different sections of the shaft are
sometimes varied to suit their diameter. With line shafts of
uniform diameter, everything pertaining to the shaft such as
hangers, couplings, pulleys, and bearings is interchangeable ;
the pulleys, wheels, bearings, or hangers can be placed at plea-
SHAFTS FOR TRANSMITTING POWER. 47
sure, or changed from one part of the shaft to another, or from
one part of the works to another, as occasion may require. The
first cost of a line of shafting of uniform diameter, strong enough
for a particular duty, is generally less than that of a shaft con-
sisting of sections varying in size. This may at first
strange, but a computation of the number of supports
with the expense of special fitting, will in nearly all cases
saving.
Attention has been called to this case as one wherein t
ditions of operation obviously furnish true data to govern
arrangement of machinery, instead of the determinable strains
which the parts are subjected, and as a good example of the
importance of studying mechanical conditions from a practical and
experimental point of view. If the general diameter of a shaft is
based upon the exact amount of power to be transmitted, or if
the diameter of a shaft at various parts is based upon the torsional
stress that would be sustained at these points, such a shaft
would not only fail to meet the conditions of practical use, but
would cost more by attempting such an adaptation. The regular
working strain to which shafts are subjected is inversely as the
speed at which they run. This becomes a strong reason in favour
of arranging shafts to run at a maximum speed, provided there
was nothing more than first cost to consider ; but there are other
and more important conditions to be taken into account, prin-
cipal among which are the required rate of movement where
power is taken off to machines, and the endurance of bearings.
In the case of line shafting for manufactories, if the speed
varies so much from that of the first movers on machines as to
require one or more intermediate or counter shafts, the expense
would be very great ; on the contrary, if countershafts can be
avoided, there is a great saving of belts, bearings, machinery,
and obstruction. The practical limit of speed for line shafts is
in a great measure dependent upon the nature of the bearings,
a subject that will be treated of in another place.
(1.) What kind of strains are shafts subjected to ? (2.) What deter-
mines the strength of shafts in resisting transverse strain ? (3.) Why
are shafts often more convenient than belts for transmitting power 1
(4.) What is the difference between the strains to which shafts and
belts are subjected ? (5.) What is gained by constructing a line shaft
of sections diminishing in size from the first mover? (6.) What is
gained by constructing line shafts of uniform diameter ?
48 WORKSHOP MANIPULATION.
CHAPTER XII.
BELTS FOR TRANSMITTING POWER.
THE traction of belts upon pulleys, like that of locomotive wheels
upon railways, being incapable of demonstration except by actual
experience, for a long time hindered the introduction of belts as
a means of transmitting motion and power except in cases when
gearing or shafts could not be employed. Motion is named
separately, because with many kinds of machinery that are driven
at high speed such as wood machines the transmission of rapid
movement must be considered as well as power, and in ordinary
practice it is only by means of belts that such high speeds may
be communicated from one shaft to another.
The first principle to be pointed out in regard to belts, to
distinguish them from shafts as a means of transmitting power,
is that power is communicated by means of tensile instead of
torsional strain, the power during transmission being repre-
sented in the difference of tension between the driving and
the slack side of belts. In the case of shafts, their length, or
the distance to which they may be extended in transmitting
power, is limited by torsional resistance ; and as belts are not
liable to this condition, we may conclude that unless there are
other difficulties to be contended with, belts are more suitable
. than shafts for transmitting power throughout long distances.
Belts suffer resistance from the air and from friction in the bear-
ings of supporting pulleys, which are necessary in long horizontal
belts ; with these exceptions they are capable of moving at a
very high rate of speed, and transmitting power without appreci-
able loss.
Following this proposition into modern engineering examples,
we find how practice has gradually conformed to what these
properties in belts suggest. Wire and other ropes of small
diameter, to avoid air friction, and allowed to droop in low curves
to avoid too many supporting pulleys, are now in many cases
employed for transmitting power through long distances, as at
Schaffhausen, in Germany. This system has been very success-
fully applied in some cases for distributing power in large manu-
facturing establishments. Belts, among which are included all
BELTS FOR TRANSMITTING POWER, 49
flexible bands, do not afford the same facilities for taking off
power at different points as shafts, but have advantages in
transmitting power to portable machinery, when power is to
be taken off at movable points, as in the case of portable travel-
ling cranes, machines, and so on.
An interesting example in the use of belts for communicating
power to movable machinery is furnished by the travelling cranes
of Mr Ramsbottom, in the shops of the L. <fc N. W. Railway, at
Crewe, England, where powerful travelling cranes receive both
the lifting and traversing power by means of a cotton rope not
more than three-fourths of an inch in diameter, which moves at a
high velocity, the motion being reduced by means of tangent wheels
and gearing to attain the force required in lifting heavy loads.
Observing the operation of this machinery, a person not familiar
with the relations between force and motion will be astonished at
the effect produced by the small rope which communicates power
to the machinery.
Considered as means for transmitting power, the contrast as to
advantages and disadvantages lies especially between belts and
gearing instead of between belts and shafts. It is true in extreme
cases, such as that cited at Crewe, or in conveying water-power
from inaccessible places, through long distances, the comparison
lies between belts and shafts; but in ordinary practice, especially
for first movers, the problem as to mechanism for conveying
power lies between belts and gear wheels. If experience in
the use of belts was thorough, as it is in the case of gearing,
arid if the quality of belts did not form so important a part in
the estimates, there would be but little difficulty in determining
where belts should be employed and where gearing would be
preferable. Belts are continually taking the place of gearing
even in cases where, until quite recently, their use has been con-
sidered impracticable ; one of the largest rolling mills in Pitts-
burg, Pennsylvania, except a single pair of spur wheels as the
last movers at each train of rolls, is driven by belts throughout.
Leaving out the matter of a positive relative movement between
shafts, which belts as a means of transmitting power cannot in-
sure, there are the following conditions that must be considered
in determining whether belts or other means should be employed
in transmitting power from one machine to another or between
the parts of machines.
1. The distance to which power is to be transmitted.
D
50 WORKSHOP MANIPULATION.
2. The speed at which the transmitting machinery must move-
3. The course or direction of transmission, whether in straight
lines or at angles.
4. The cost of construction and durability.
5. The loss of power during transmission.
6. Danger, noise, vibration, and jar.
In every case where there can be a question as to whether
gearing shafts or belts will be the best means of transmitting
power, the several conditions named will furnish a solution if
they are properly investigated and understood. Speed, noise, or
angles may become determinative conditions, and are such in a
large number of cases ; first cost and loss of power are generally
secondary conditions. Applying these tests to cases where belts,
shafts, or wheels may be employed, a learner will soon find him-
self in possession of knowledge to guide him in his own schemes,
and enable him to judge of the correctness of examples that
come under his notice.
It is never enough to know that any piece of work is commonly
constructed in some particular manner, or that a proposition is
generally accepted as being correct ; a reason should be sought
for. Nothing is learned, in the true sense, until the reasons for
it are understood, and it is by no means sufficient to know from
observation alone that belts are best for high speeds, that gear-
ing is the best means of forming angles in transmitting power, or
that gearing consumes more power, and that belts produce less
jar and noise ; the principles which lie at the bottom must be
reached before it can be assumed that the matter is fairly under-
stood.
(1.) Why have belts been found better than shafts for transmitting
power through long distances ? (2.) What are the conditions which
limit the speed of belts ? (3.) Why cannot belts be employed to com-
municate positive movement ? (4.) Would a common belt transmit
motion positively, if there were no slip on the pulleys ? (5.) Name some
of the circumstances to be considered in comparing belts with gearing or
shafts as a means of transmitting power.
GEARING AS A MEANS OF TRANSMITTING POWER. 51
CHAPTER XIII.
GEARING AS A MEANS OF TRANSMITTING POWER.
THE term gearing, which was once applied to wheels, shafts, and
the general mechanism of mills and factories, has now in com-
mon use become restricted to tooth wheels, and is in this sense
employed here. Gearing as a means of transmitting motion is
employed when the movement of machines, or the parts of
machines, must remain relatively the same, as in the case of the
traversing screw of an engine lathe when a heavy force is
transmitted between shafts that are near to each other, or when
shafts to be connected are arranged at angles with each other.
This rule is of course not constant, except as to cases where
positive relative motion has to be maintained. Noise, and the
liability to sudden obstruction, may be reasons for not employing
tooth wheels in many cases when the distance between and the
position of shafts would render such a connection the most
durable and cheap. Gearing under ordinary strain, within
limited speed, and when other conditions admit of its use, is the
cheapest and most durable mechanism for transmitting power ;
but the amount of gearing employed in machinery, especially in
Europe, is no doubt far greater than it will be in future, when
belts are better understood.
No subject connected with mechanics has been more thoroughly
investigated than that of gearing. Text-books are replete with
every kind of information pertaining to wheels, at least so far
as the subject can be made a mathematical one ; and to judge
from the amount of matter, formulae, and diagrams, relating to
the teeth of wheels that an apprentice will meet with, he will
no doubt be led to believe that the main object of modern
engineering is to generate wheels. It must be admitted that the
teeth of wheels and the proportions of wheels is a very im-
portant matter to understand, and should be studied with the
greatest care ; but it is equally important to know how to pro-
duce the teeth in metal after their configuration has been
denned on paper ; to understand the endurance of teeth under
abrasive wear when made of wrought or cast iron, brass or
steel; how patterns can be constructed from which correct
52 WORKSHOP MANIPULATION.
v/heels may be cast, and Low the teeth of wheels can be cut by
machinery, and so on.
A learner should, in fact, consider the application and
operative conditions of gearing as one of the main parts of the
subject, and the geometry or even the construction of wheels
as subsidiary ; in this way attention will be directed to that
which is most difficult to learn, and a part for which faci-
lities are frequently wanting. Gearing may be classed into
five modifications spur wheels, bevel wheels, tangent wheels,
spiral wheels, and chain wheels; the last I include among
gearing because the nature of their operation is analogous to
tooth wheels, although at first thought chains seem to correspond
more to belts than gearing. The motion imparted by chains
meshing over the teeth of wheels is positive, and not frictional as
with belts ; the speed at which such chains may run, with other
conditions, correspond to gearing.
Different kinds of gearing can be seen in almost every
engineering establishment, and in view of the amount of
scientific information available, it will only be necessary to point
out some of the conditions that govern the use and operation,
of the different kinds of wheels. The durability of gearing,
aside from breaking, is dependent upon pressure and the amount
of rubbing action that takes place between the teeth when in
contact. Spur wheels, or bevel wheels, when the pitch is
accurate and the teeth of the proper form, if kept clean and
lubricated, wear but little, because the contact between the
teeth is that of rolling instead of sliding. In many cases, one
wheel of a pair is filled with wooden cogs ; in this arrangement
there are four objects, to avoid noise, to attain a degree of
elasticity in the teeth, to retain lubricants by absorption in the
wood, and to secure by wear a better configuration of the teeth
than is usually attained in casting, or even in cutting teeth.
Tangent wheels and spiral gearing have only what is termed
line contact between the bearing surfaces, and as the action
between these surfaces is a sliding one, such wheels are subject
to rapid wear, and are incapable of sustaining much pressure, or
transmitting a great amount of power, except the surfaces be
hard and lubrication constant. In machinery the use of tangent
wheels is mainly to secure a rapid change of speed, usually to
diminish motion and increase force.
By placing the axes of tangent gearing so that the threads or
HYDRAULIC APPARATUS FOR TRANSMITTING POWER. 53
teeth of the pinions are parallel to the face of the driven teeth,
us in the planing machines of Messrs Wm. Sellers & Co.,
the conditions of operation are changed, and an interesting
problem arises. The progressive or forward movement of the
pinion teeth may be equal to the sliding movement between the
surfaces ; and an equally novel result is, that the sliding action
is distributed over the whole breadth of the driven teeth.
In spiral gearing the line of force is at an angle of forty-five
degrees with the bearing faces of the teeth, and the sliding
movement equal to the speed of the wheels at their periphery ;
the bearing on the teeth, as before said, is one of line contact
only. Such wheels cannot be employed except in cases where an
inconsiderable force is to be transmitted. Spiral wheels are
employed to connect shafts that cross each other at right angles
but in different planes, and when the wheels can be of the same
size.
It may be mentioned in regard to rack gearing for communi-
cating movement to the carriages of planing machines or other
purposes of a similar nature : the rack can be drawn to the
wheel, and a lifting action avoided, by shortening the pitch of
the rack, so that it will vary a little from the driving wheel.
The rising or entering teeth in this case do not come in contact
with those on the rack until they have attained a position
normal to the line of the carriage movement.
, (1.) Into what classes can gearing be divided ? (2.) What determines
the weaving capacity of gearing 1 (3.) What is the advantage gained
by employing wooden cogs for gear wheels? (4.) Why are tangent or
worm wheels not durable ?
CHAPTER XIV.
HYDRAULIC APPARATUS FOR TRANSMITTING POWER.
ALTHOUGH a system but recently developed, the employment of
hydraulic machinery for transmitting and applying power has
reached an extended application to a variety of purposes, and
gives promise of a still more extensive use in future. Con-
54 WORKSHOP MANIPULATION.
sidered as a means of transmitting regularly a constant amount
of power, water apparatus is more expensive and inferior in
many respects to belts or shafts, and its use must be traced to some
special principle involved which adapts hydraulic apparatus to
the performance of certain duties. This principle will be found
to consist in storing up power in such a manner that it may be
used with great force at intervals ; and secondly, in the facilities
afforded for multiplying force by such simple mechanism as
pumps. An engine of ten-horse-power, connected with machinery
by hydraulic apparatus, may provide for a force equal to one
hundred horse-power for one-tenth part of the time, the power
being stored up by accumulators in the interval ; or in other
words, the motive power acting continuously can be accumulated
and applied at intervals as it may be required for raising
weights, operating punches, compressive forging, or other work
of an intermittent character. Hydraulic machinery employed
for such purposes is more simple and inexpensive than gear-
ing and shafts, especially in the application of a great force
acting for a considerable distance, and where a cylinder and
piston represent a degree of strength which could not be attained
with twice the amount of detail, if gearing, screws, levers, or
other devices were employed instead.
Motion or power may be varied to almost any degree by the
ratio between the pistons of pumps and the pistons which give
off the power, the same general arrangement of machinery
answering in all cases ; whereas, with gearing the quantity of
machinery has to be increased as the motive power and the
applied power may vary in time and force. This as said recom-
mends hydraulic apparatus where a great force is required at
intervals, and it is in such cases that it was first employed, and
is yet for the most part used.
In the use of hydraulic apparatus for transmitting and apply-
ing power, there is, however, this difficulty to be contended with :
water is inelastic, and for the performance of irregular duty,
there is a loss of power equal to the difference between the
duty that a piston may perform and what it does perform ;
that is, the amount of water, and consequently the amount of
power given off, is as the movement and volume of the water,
instead of as the work done. The application of hydraulic
machinery to the lifting and handling of weights will be further
noticed in another place.
PNEUMATIC MACHINERY FOR TRANSMITTING POWER. 05
(1.) Under what conditions is hydraulic apparatus a suitable means
for transmitting power ? (2.) To what class of operations is hydraulic
apparatus mostly applied? (3.) Why is not water as suitable a medium
as air or steam in transmitting power for general purposes ?
CHAPTER XV.
PNEUMATIC MACHINERY FOR TRANSMITTING POWER.
PNEUMATIC machinery, aside from results due to the elasticity
of air, is analogous in operation to hydraulic machinery.
Water may be considered as a rigid medium for transmitting
power, corresponding to shafts and gear wheels ; air as a flexible
or yielding one, corresponding to belts. There is at this time
but a limited use of pneumatic apparatus for transmitting power,
but its application is rapidly extending, especially in transport-
ing material by means of air currents, and in conveying power
to mining machinery.
The successful application of the pneumatic system at the
Mont Cenis Tunnel in Italy, and at the Hoosac Tunnel in
America, has demonstrated the value of the system where the
air not only served to transmit power to operate the machinery
but to ventilate the mines at the same time. Air brakes for
railway trains are another example illustrating the advantages of
pneumatic transmission ; the force being multiplied at the
points where it is applied, so that the connecting pipes are
reduced to a small size, the velocity of the air making up for
a great force that formerly had to be communicated through rods,
chains, or shafts. The principal object attained by the use of
air to operate railway brakes is, however, to maintain a connec-
tion throughout a train by means of flexible pipes that accom-
modate themselves to the varying distance between the carriages.
Presuming that the flow of air in pipes is not materially impeded
by friction or angles, and that there will be no difficulty in
maintaining lubrication for pistons or other inaccessible parts of
machinery when driven by air, there seems to be many reasons
in favour of its use as a means of distributing power in manu-
56 WORKSHOP MANIPULATION.
facturing districts. The diminished cost of motive power when
it is generated on a large scale, and the expense and danger of
maintaining an independent steam power for each separate estab-
lishment where power is employed, especially in cities, are strong
reasons in favour of generating and distributing power by com-
pressed air, through pipes, as gas and water are now supplied.
Air seems to be the most natural and available medium for
transmitting and distributing power upon any general system
like water or gas, and there is every probability of such a system
existing at some future time. The power given out by the
expansion of air is not equal to the power consumed in com-
pressing it, but the loss is but insignificant compared with the
advantages that may be gained in other ways. There is no
subject more interesting, and perhaps few more important for
an engineering student to study at this time, than the trans-
mission of power and the transport of material by pneumatic
apparatus.
In considering pneumatic machinery there are the following
points to which attention is directed :
1. The value of pneumatic apparatus in reaching places where
steam furnaces cannot be employed.
2. The use that may be made of air after it has been applied
as a motive agent.
3. The saving from condensation, to which steam is exposed,
avoidance of heat, and the consequent contraction and expansion
of long conducting pipes.
4. The loss of power by friction and angles in conducting air
through pipes.
5. The lubrication of surfaces working under air pressure,
such as the pistons and valves of engines.
6. The diminished cost of generating power on a large scale,
compared with a number of separate steam engines distributed
over manufacturing districts.
7. The effect of pneumatic machinery in reducing insurance
rates and danger of fire.
8. The expense of the appliances of distribution and their
maintenance.
In passing thus rapidly over so im*portant a subject, and one
that admits of so extended a consideration as machinery of
transmission, the reader can see that the purpose has been to
touch only upon such points as will lead to thought and investi-
MACHINERY OF APPLICATION. 57
gation, and especially to meet such queries as are most likely to
arise in the mind of a learner. In arranging and erecting
machinery of transmission, obviously the first problem must
be, what kind of machinery should be employed, and what
are the conditions which should determine the selection and
arrangement? What has been written has, so far as possible,
been directed to suggesting proper means of solving these ques-
tions.
(1.) In what respect are air and water like belts and gearing, as means
to transmit power 1 (2.) What are some of the principal advantages
gained by employing air to operate railway breaks 1 (3.) Name some
of the advantages of centralising motive power. (4.) Are the conditions
of working an engine the same whether air or steam is employed ?
CHAPTER XVI.
MACHINERY OF APPLICATION'.
THE term application has been selected as a proper one to dis-
tinguish machines that expend and apply power, from those
that are employed in generating or transmitting power. Machines
of application employed in manufacturing, and which expend
their action on material, are directed to certain operations which
are usually spoken of as processes, such as cutting, compressing,
grinding, separating, and disintegrating.
By classifying these processes, it will be seen that there is in
all but a few functions to be performed by machines, and that
they all act upon a few general principles. Engineering tools em-
ployed in fitting are, for example, all directed to the process of
cutting. Planing machines, lathes, drilling machines, and shaping
machines are all cutting machines, acting upon the same general
plan that of a cleaving wedge propelled in straight or curved
lines.
Cutting, as a process in converting material, includes the force
to propel cutting edges, means to guide and control their action,
and mechanism to sustain and adjust the material acted upon.
In cutting with hand tools, the operator performs the two functions
58 WORKSHOP MANIPULATION.
of propelling and guiding the tools with his hands ; but in what
is called power operations, machines are made to perform these
functions. In nearly all processes machines have supplanted
hand labour, and it may be noticed in the history and develop-
ment of machine tools that much has been lost in too closely imi-
tating hand operations when machines were first applied. To be
profitable, machines must either employ more force, guide tools
with more accuracy, or move them at greater speed, than is at-
tainable by hand. Increased speed may, although more seldom,
be an object in the employment of machinery, as well as the
guidance of implements or increased force in propelling them.
The hands of workmen are not only limited as to the power that
may be exerted, and unable to guide tools with accuracy, but are
also limited to a slow rate of movement, so that machines can be
employed with great advantage in many operations where neither
the force nor guidance of tools are wanting.
There is nothing more interesting, or at the same time more
useful, in the study of mechanics, than to analyse the action of
cutting machines or other machinery of application, and to ascer-
tain in examples that come under notice whether the main object
of a machine is increased force, more accurate guidance, or
greater speed than is attainable by hand operations. Cutting
machines as explained may be directed to either of these objects
singly, or to all of them together, or these objects may vary in
their relative importance in different operations ; but in all cases
where machines are profitably employed, their action can be traced
to one or more of the functions named.
To follow this matter further. It will be found in such machines
as are directed mainly to augmenting force or increasing the
amount of power that may be applied in any operation, such as
sawing wood or stone, the effect produced when compared to
hand labour is nearly as the difference in the amount of power
applied ; and the saving that such machines effect is generally in
the same proportion. A machine that can expend ten horse-
power in performing a certain kind of work, will save ten times
as much as a machine directed to the same purpose expending
but one horse-power \ this of course applies to machines for the
performance of the coarser kinds of work, and employed to sup-
plant mere physical effort. In other machines of application, such
as are directed mainly to guidance, or speed of action, such as
sewing machines, dove-tailing machines, gear-cutting machines,
MACHINERY OF APPLICATION. 59
and so on, there is no relation -whatever between the increased
effect that may be produced and the amount of power expended.
The difference between hand and machine operations, and the
labour-saving effect of machines, will be farther spoken of in
another place ; the subject is alluded to here, only to enable the
reader to more fully distinguish between machinery of transmis-
sion and machinery of application. Machinery of application,
directed to what has been termed compression processes, such as
steam hammers, drops, presses, rolling mills, and so on, act upon
material that is naturally soft and ductile, or when it is softened
by heat, as in the case of forging.
In compression processes no material is cut away as in cutting
or grinding, the mass being forced into shape by dies or forms
that give the required configuration. The action of compressing
machines may be either intermittent, as in the case of rolling
mills ; percussive, as in steam hammers, where a great force acts
throughout a limited distance ; or gradual and sustained, as in
press forging. Machines of application, for abrading or grinding,
are constantly coming more into use; their main purpose being to
cut or shape material too hard to be acted upon by compression
or by cutting processes. It follows that the necessity for machines
of this kind is in proportion to the amount of hard material which
enters into manufactures ; in metal work the employment of
hardened steel and iron is rapidly increasing, and as a result,
grinding machines have now a place among the standard machine
tools of a fitting shop.
Grinding, no doubt, if traced to the principles that lie at the
bottom, is nothing more than a cutting process, in which the
edges employed are harder than any material that can be made
into cutters, the edges firmly supported by being imbedded into
a mass as the particles of sand are in grindstones, or the
particles of emery in emery wheels.
Separating machines, such as bolts and screens, which may be
called a class, require no explanation. The employment of mag-
netic machines to separated iron and brass filings or shop waste,
may be noted as a recent improvement of some importance.
Disintegrating machines, such as are employed for pulverising
various substances, grinding grain or pulp, separating fibrous
material, and so on, are, with some exceptions, simple enough to
be readily understood. One of these exceptions is the rotary
" disintegrators," recently introduced, about the action of which
60 WORKSHOP MANIPULATION.
some diversity of opinion exists. The effect produced is cer-
tainly abrasive wear, the result of the pieces or particles strik-
^ng one against another, or against the revolving beaters and
casing. The novelty of the process is in the augmented effect
produced by a high velocity, or, in other words, the rapidity of
the blows.
(1.) Name five machines as types of those employed in the general
processes of converting material. (2.) Name some machines, the object
of which is to augment force One to attain speed One directed to the
guidance of tools. (3.) What is the difference between the hot and cold
treatment of iron as to processes As to dimensions ? (4.)
CHAPTER XVII.
MACHINERY FOR MOVING AND HANDLING MATERIAL.
STEAM and other machinery applied to the transport of material
and travel, in navigation and by railways, comprises the greater
share of what may be called engineering products ; and when we
consider that this vast interest of steam transport is less than a
century old, and estimate its present arid possible future influence
on human affairs, we may realise the relation that mechanical
science bears to modern civilisation.
To follow out the application of power to the propulsion of
vessels and trains, with the many abstruse problems that would
of necessity be involved, would be to carry this work far beyond
the limits within which it is most likely to be useful to the ap-
prentice engineer ; besides, it would be going beyond what can
properly be termed manipulation.
Marine and railway engineering have engrossed the best
talent in the world ; investigation and research has been expended
upon these subjects in a degree commensurate with their im-
portance, and it would be hard to suggest a single want in the
many able text-books that have been prepared upon the subjects.
Marine and railway engineering are sciences that may, in a sense,
be separated from the ordinary constructive arts, and studied at
MACHINERY FOR MOVING AND HANDLING MATERIAL. 61
the end of a course in mechanical engineering, but are hardly
proper subjects for an apprentice to take up at the beginning.
In treating of machinery for transport, as a class, the subject,
as far as noticed here, will be confined to moving and handling
material as one of the processes of manufacturing, and especially
in connection with machine construction. If the amount of
time, expense, labour, and machinery devoted to handling
material in machine shops is estimated, it becomes a matter of
astonishment to as many as have not previously investigated the
subject ; as an item of expense the handling, often exceeds the
fitting on large pieces, and in the heavier class of work demands
the most careful attention to secure economical manipulation.
It will be well for an apprentice to begin at once, as soon as
he commences a shop course, to note the manner of handling
material, watching the operation of cranes, hoists, trucks, tackle,
rollers ; in short, everything that has to do with moving and
handling. The machinery and appliances in ordinary use are
simple enough in a mechanical sense, but the principles of hand-
ling material are by no means as plain or easy to understand.
The diversity of practice seen in various plans of handling and
lifting weights fully attests the last proposition, and it is
questionable whether there is any other branch of mechanical
engineering that is treated less in a scientific way than machinery
of this class. I do not allude to the mechanism of cranes and
other devicas, which are usually well proportioned and generally
well arranged, but to the adaptation of such machinery with
reference to special or local conditions. There are certain
inherent difficulties that have to be encountered in the construc-
tion and operation of machinery, for lifting and handling, that
are peculiar to it as a class among these difficulties is the
transmission of power to movable mechanism, the intermittent
and irregular application of power, severe strains, also the
liability to accidents and breakage from such machinery being
controlled by the judgment of attendants.
Ordinary machinery, on the reverse, is stationary, generally
consumes a regular amount of power, is not subjected to such
uncertain strains, and as a rule acts without its operation being
controlled by the will of attendants.
The functions required in machinery for handling material in
a machine shop correspond very nearly to those of the human
hands. Nature in this, as in all other things, where a comparison.
62 WORKSHOP MANIPULATION.
is possible, Las exceeded man in adaptation ; in fact, we cannot
conceive of anything more perfect than the human hands for
handling material a duty that forms a great share of all that
we term labour.
Considered mechanically as a means of handling material, the
human hands are capable of exerting force in any direction,
vertically, horizontally, or at any angle, moving at various rates
of speed, as the conditions may require, and with varying force
within the limits of human strength. These functions enable us
to pick up or lay down a weight slowly and carefully, to trans-
port it at a rapid rate to save time, to move it in any direction, and
without the least waste of power, except in the case of carrying
small loads, when the whole body has to be moved, as in ascend-
ing or descending stairs. The power travelling cranes, that are
usually employed in machine-fitting establishments, are per-
haps the nearest approach that has been made to the human
frame in the way of handling mechanism ; they, however, lack
that very important feature of a movement, the speed of which is
graduated at will. It is evident that in machinery of any kind for
handling and lifting that moves at a uniform rate of speed, and
this rate of speed adapted, as it must be, to the conditions of
starting or depositing a load, much time must be lost in the
transit, especially when the load is moved for a considerable
distance. This uniform speed is perhaps the greatest defect in
the lifting machinery in common use, at least in such as is driven
by power.
In handling a weight with the hands it is carefully raised, and
laid down with care, but moved as rapidly as possible through-
out the intervening distance ; this lesson of nature has not
been disregarded. We find that the attention of engineers has
been directed to this principle of variable speed to be controlled
at will. The hydraulic cranes of Sir William Armstrong, for
example, employ this principle in the most effective manner, not
only securing rapid transit of loads when lifted, but depositing
or adjusting them with a care and precision unknown to mechan-
ism positively geared or even operated by friction breaks.
The principles of all mechanism for handling loads should be
such as to place the power, the rate of movement, and the direc-
tion of the force, within the control of an operator, which, as
has been pointed out, is the same thing in effect as the action
of the human hands.
MACHINERY FOR MOVING AND HANDLING MATERIAL. 63
The safety, simplicity, and reliable action of hydraulic
machinery has already led to its extensive employment for
moving and lifting weights, and it is fair to assume that the
importance and success of this invention fully entitle it to be
classed as one of the most important that has been made in
mechanical engineering during fifty years past. The applica-
tion of hydraulic force in operating the machinery used in the
processes for steel Bessemer manufacture, is one of the best
examples to illustrate the advantages and principles of
hydraulic system. Published drawings and descripti
Bessemer steel plant explain this hydraulic machinery.
There is, however, a principle in hydraulic machine
must be taken into account, in comparing it with positively
mechanism, which often leads to loss of power that in
cases will overbalance any gain derived from the peculiar
action of hydraulic apparatus. I allude to the loss of power
incident to dealing with an inelastic medium, where the amount
of force expended is constant, regardless of the resistance
offered. A hydraulic crane, for instance, consumes power
in proportion to its movements, and not as the amount of duty
performed ; it takes the same quantity of water to fill the
cylinders of such cranes, whether the water exert much or little
force in moving the pistons. The difference between employing
elastic mediums like air and steam, and an inelastic medium
like water, for transmitting force in performing irregular duty,
has been already alluded to, and forms a very interesting study
for a student in mechanics, leading, as it does, to the solution
of many problems concerning the use and effect of power.
The steam cranes of Mr Morrison, which resemble hydraulic
cranes, except that steam instead of water is employed as a
medium for transmitting force, combine all the advantages of
hydraulic apparatus, except positive movement, and evade the
loss of power that occurs in the use of water. The elasticity of
the steam is found in practice to offer no obstacle to steady and
accurate movement of a load, provided the mechanism is well
constructed, while the loss of heat by radiation is but trifling.
To return to shop processes in manufacturing. Material
operated upon has to be often, sometimes continually, moved
from one place to another to receive successive operations, and
this movement may be either vertically or horizontally as
determined, first, by the relative facility with which the material
64 WORKSHOP MANIPULATION,
may be raised vertically, or moved horizontally, and secondly, by
the value of the ground and the amount of room that may be
available, and thirdly by local conditions of arrangement. In large
cities, where a great share of manufacturing is carried on, the
value of ground is so great that its cost becomes a valid reason
for constructing high buildings of several storeys, and moving
material vertically by hoists, thus gaining surface by floors,
instead of spreading the work over the ground ; nor is there
any disadvantage in high buildings for most kind of manufacture,
including machine fitting even, a proposition that will hardly
be accepted in Europe, where fitting operations, except for small
pieces, are rarely performed on upper floors.
Vertical handling, although it consumes more power, as a rule
costs less, is more convenient, and requires less room than
horizontal handling, which is sure to interfere more or less with
the constructive operations of a workshop. In machine fitting
there is generally a wrong estimate placed upon the value of
ground floors, which are no doubt indispensable for the heaviest
class of work, and for the heaviest tools ; but with an ordinary
class of work, where the pieces do not exceed two tons in
weight, upper floors if strong are quite as convenient, if there
is proper machinery for handling material ; in fact, the records
of any establishment, where cost accounts are carefully made up,
will show that the expense of fitting on upper floors is less than
on ground floors. This is to be accounted for by better light, and
a removal of the fitting from the influences and interference of
other operations that must necessarily be carried on upon
ground floors.
For loading and unloading carts and waggons, the convenience
of the old outside sling is well known ; it is also a well-attested
fact that accidents rarely happen with sling hoists, although
they appear to be less safe than running platforms or lifts. As
a general rule, the most dangerous machinery for handling or
raising material is that which pretends to dispense with the care
and vigilance of attendants, and the safest machinery that
which enforces such attention. The condition which leads to
danger in hoisting machinery is, that the power employed is
opposed to the force of gravity, and as the force of gravity is
acting continually, it is always ready to take advantage of the
least cessation in the opposing force employed, and thus drag
away the weight for which the two forces are contending;
MACHINERY FOR MOVING AND HANDLING MATERIAL. 65
as a weight when under the influence of gravity is moved at an
accelerated velocity, if gravity becomes the master, the result
is generally a serious accident. Lifting may be considered a
case wherein the contrivances of man are brought to bear in over-
coming or opposing a natural force ; the imperfect force of the
machinery is liable to accident or interruption, but gravity never
fails to act. Acting on every piece of matter in proportion to
its weight must be some force opposing and equal to that of
gravity j for example, a piece of iron lying on a bench is opposed
by the bench and held in resistance to gravity, and to move
this piece of iron we have to substitute some opposing force,
like that of the hands or lifting mechanism, to overcome
gravity.
As molecular adhesion keeps the particles of matter together
so as to form solids, so the force of gravity keeps objects in
their place ; and to attain a proper conception of forces, especially
in handling and moving material, it is necessary to familiarise
the mind with this thought.
The force of gravity acts only in one direction vertically,
so that the main force of hoisting and handling machinery
which opposes gravity must also act vertically, while the
horizontal movement of objects may be accomplished by simply
overcoming the friction between them and the surfaces on
which they move. This is seen in practice. A force of a
hundred pounds may move a loaded truck, which it would
require tons to lift ; hence the horizontal movements of
material may be easily accomplished by hand with the aid of
trucks and rollers, so long as it is moved on level planes ; but
if a weight has to be raised even a single inch by reason of
irregularity in floors, the difference between overcoming frictional
contact and opposing gravity is at once apparent.
One of the problems connected with the handling of material
is to determine where hand-power should stop and motive-power
begin what conditions will justify the erection of cranes,
hoists, or tramways, and what conditions will not. Frequent
mistakes are made in the application of power when it is not
required, especially for handling material ; the too common
tendency of the present day being to apply power to every
purpose where it is possible, without estimating the actual
saving that, may be effected. A common impression is that
motive power, wherever applied to supplant hand labour ill
E
66 WORKSHOP MANIPULATION.
handling material, produces a gain ; but in many cases the
fallacy of this will be apparent, when all the conditions are
taken into account.
Considered upon grounds of commercial expediency as a
question of cost alone, it is generally cheaper to move material
by hand when it can be easily lifted or moved by workmen,
when the movement is mainly in a horizontal direction, and
when the labour can be constantly employed ; or, to assume a
general rule which in practice amounts to much the same
thing, vertical lifting should be done by motive power, and
horizontal movement for short distances performed by hand.
There is nothing more unnatural than for men to carry loads up
stairs or ladders ; the effort expended in such cases is one-half
or more devoted to raising the weight of the body, which
is not utilised in the descent, and it is always better to employ
winding or other mechanism for raising weights, even when it is
to be operated by manual labour. Speaking of this matter of
carrying loads upward, I am reminded of the fact that builders
in England and America, especially in the latter country, often
have material carried up ladders, while in some of the older
European countries, where there is but little pretension to
scientific manipulation, bricks are usually tossed from one man
to another standing on ladders at a distance of ten to fifteen feet
apart.
To conclude. The reader will understand that the difficulties
and diversity of practice, in any branch of engineering, create
similar or equal difficulties in explaining or reasoning about the
operations ; and the most that can be done in the limited space
allotted here to the subject of moving material, is to point out
some of the principles that should govern the construction and
adaptation of handling machinery, from which the reader can
take up the subject upon his own account, and follow it through
the various examples that may come under notice.
To sum up We have the following propositions in regard to
moving and handling material :
1. The most economical and effectual mechanism for handling
is that which places the amount of force and rate of movement
continually under the control of an operator.
2. The necessity for, and consequent saving effected by, power-
machinery for handling is mainly in vertical lifting, horizontal
movement being easily performed by hand.
MACHINE COMBINATION. 67
3. The vertical movement of material, although it consumes
more power, is more economical than horizontal handling, because
less floor room and ground surface is required.
4. The value of handling machinery, or the saving it effects,
is as the constancy with which it operates ; such machinery may
shorten the time of handling without cheapening the expense.
5. Hydraulic machinery comes nearest to filling the required
conditions in handling material, and should be employed in
cases where the work is tolerably uniform, and the amount of
handling will justify the outlay required.
6. Handling material in machine construction is one of the
principal expenses to be dealt with ; each time a piece is moved
its cost is enhanced, and usually in a much greater degree than
is
(1.) Why has the lifting of weights been made a standard for the
measure of power? (2.) Name some of the difficulties to contend with
in the operation of machinery for lifting or handling material. (3.) What
analogy exists between manual handling and the operation of hydraulic
cranes I (4.) Explain how the employment of overhead cranes saves
room in a fitting shop. (5.) Under what circumstances is it expedient to
move material vertically ? (6.) To what circumstances is the danger
of handling mainly attributable ]
CHAPTER XVIII.
MA CHINE C O MB IN A TI N.
THE combination of several functions in one machine, although
it may not seem an important matter to be considered here, is
nevertheless one that has much to do with the manufacture of
machines, and constitutes what may be termed a principle of
construction.
The reasons that favour combination of functions in machines,
and the effects that such combinations may produce, are so
various that the problem has led to a great diversity of opinions
and practice among both those who construct and even those
who employ machines. It may be said, too, that a great share
68 WORKSHOP MANIPULATION.
of the combinations found in machines, such as those to turn,
mill, bore, slot, and drill in iron fitting, are not due to any deli-
berate plan on the part of the makers, so much as to an opinion
that such machines represent a double or increased capacity.
So far has combination in machines been carried, that in one
case that came under the writer's notice, a machine was arranged
to perform nearly every operation required in finishing the parts
of machinery ; completely organised, and displaying a high order
of mechanical ability in design and arrangement, but practi-
cally of no more value than a single machine tool, because but
one operation at a time could be performed
To direct the attention of learners to certain rules that will
guide them in forming opinions in this matter of machine
combination, I will present the following propositions, and
afterwards consider them more in detail :
First. By combining two or more operations in one machine,
the only objects gained are a slight saving in first cost, one
frame answering for two or more machines, and a saving of floor
room,
Second. In a machine where two or more operations are
combined, the capacity of such a machine is only as a single one
of these operations, unless more than one can be carried on at
the same time without interfering one with another.
Third. Combination machines can only be employed with
success when one attendant performs all the operations, and
when the change from one to another requires but little adjust-
ment and re-arrangement.
Fourth. The arrangement of the parts of a combination
machine have to be modified by the relations between them,
instead of being adapted directly to the work to be performed.
Fifth. The cost of special adaptation, and the usual incon-
venience of fitting combination machines when their parts
operate independently, often equals and sometimes exceeds what
is saved in framing and floor space.
Referring first to the saving effected by combining several
operations in one machine, there is perhaps not one constructor
in twenty that ever stops to consider what is really gained,
and perhaps not one purchaser in a hundred that does the same
thing. The impression is, that when one machine performs two
operations it saves a second machine. A remarkable example
of this exists in the manufacture of combination machines in
MACHINE COMBINATION. 69
Europe for working wood, where it is common to find complicated
machines that will perform all the operations of a joiner's shop,
but as a rule only one thing at a time, and usually in an incon-
venient manner, each operation being hampered and interfered
with by another ; and in changing from one kind of work to
another the adjustments and changes generally equal and some-
times exceed the work to be done. What is stranger still is, that
such machines are purchased, when their cost often equals that
of separate machines to perform the same work.
In metal working, owing to a more perfect division of labour,
and a more intelligent manipulation than in wood-working, there
is less combination in machines in fact, a combination machine
for metal work is rarely seen at this day, and never under
circumstances where it occasions actual loss. The advantage of
combination, as said, can only be in the framing and floor space
occupied by the machines, but these considerations, to be
estimated by a proper standard, are quite insignificant when
compared with other items in the cost of machine operating,
such as the attendance, interest on the invested cost of the
machine, depreciation of value by wear, repairing, and so on.
Assuming, for example, that a machine will cost as much as
the wages of an attendant for one year, which is not far from
an average estimate for iron working machine tools, and that
interest, wear, and repairs amount to ten per cent, on this sum,
then the attendance would cost ten times as much as the
machine \ in other words, the wages paid to a workman to
attend a machine is, on an average, ten times as much as the
other expenses attending its operation, power excepted. This
assumed, it follows that in machine tools any improvement
directed to labour saving is worth ten times as much as an equal
improvement directed to the economy of first cost.
This mode of reasoning will lead to proper estimates of the
difference in value between good tools and inferior tools ; the
results of performance instead of the investment being first con-
sidered, because the expenses of operating are, as before assumed,
usually ten times as great as the interest on the value of a
machine.
In view of these propositions, I need hardly say to what object
machine improvements should be directed, nor which of the con-
siderations named are most affected by a combination of machine
functions ; the fact is, that if estimates could be prepared, show-
70 WORKSHOP MANIPULATION.
ing the actual effect of machine combinations, it would astonish
those who have not investigated the matter, and in many cases
show a loss of the whole cost of such machines each year. The
effect of combination machines is, however, by no means uniform ;
the remarks made apply to standard machines employed in the
regular work of an engineering or other establishment. In ex-
ceptional cases it may be expedient to use combined machines.
In the tool-room of machine-shops, for instance, where one man
can usually perform the main part of the work, and where there
is but little space for machines, the conditions are especially
favourable to combination machines, such as may be used in
milling, turning, drilling, and so on ; but wherever there is a
necessity or an opportunity to carry on two or more of these
operations at the same time, the cost of separate machines is but
a small consideration when compared with the saving of labour
that may be effected by independent tools to perform each opera-
tion. The tendency of manufacturing processes of every kind,
at this time, is to a division of labour, and to a separation of
each operation into as many branches as possible, so that study
spent in " segregating " instead of " aggregating " machine func-
tions is most likely to produce profitable results.
This article has been introduced, not only to give a true under-
standing of the effect and value of machine combination, but to
caution against a common error of confounding machine combi-
nation with invention.
A great share of the alleged improvements in machinery, when
investigated will be found to consist in nothing more than the
combination of several functions in one machine, the novelty of
their arrangement leading to an impression of utility and increased
effect
(1.) What is gained by arranging a machine to perform several
different operations? (2.) What maybe lost by such combination?
(3.) What is the main expense attending the operation of machine
tools ? (4.) What kind of improvement in machine tools produces the
most profitable result 1 (5.) What are the principal causes which have
led to machine combinations.
ARRANGEMENT OF ENGINEERING ESTABLISHMENTS. 71
CHAPTER XIX.
THE ARRANGEMENT OF ENGINEERING
ESTABLISHMENTS.
THE first and, perhaps, the most important matter of all in
founding engineering works is that of arrangement. As a
commercial consideration affecting the cost of manipulation, and
the expense of handling material, the arrangement of an estab-
lishment may determine, in a large degree, the profits that may be
earned, and, as explained in a previous place, upon this matter of
profits depends the success of such works.
Aside from the cost or difficulty of obtaining ground sufficient
to carry out plans for engineering establishments, the diversity
of their arrangement met with, even in those of modern construc-
tion, is no doubt owing to a want of reasoning from general
premises. There is always a strong tendency to accommodate
local conditions, and not unfrequently the details of shop mani-
pulation are quite overlooked, or are not understood by those who
arrange buildings.
The similarity of the operations carried on in all works
directed to the manufacture of machinery, and the kind of
knowledge that is required in planning and conducting such
works, would lead us to suppose that at least as much system
would exist in machine shops as in other manufacturing
establishments, which is certainly not the case. There is,
however, this difference to be considered : that whereas many
kinds of establishments can be arranged at the beginning for a
specific amount of business, machine shops generally grow up
around a nucleus, and are gradually extended as their reputation
and the demands for their productions increase ; besides, the
variety of operations required in an engineering establishment,
and change from one class of work to another, are apt to lead
to a confusion in arrangement, which is too often promoted, or
at least not prevented, by insufficient estimates of the cost of
handling and moving material.
Materials consumed in an engineering establishment consist
mainly of iron, fuel, sand, and lumber. These articles, or their
products, during the processes of manipulation, are continually
72 WORKSHOP MANIPULATION.
approaching the erecting shop, from which finished machinery
is sent out after its completion. This constitutes the erecting
shop, as a kind of focal centre of a works, which should be the
base of a general plan of arrangement. This established, and
the foundry, smithy, finishing, and pattern shops regarded
as feeding departments to the erecting shop, it follows that
the connections between the erecting shop and other depart-
ments should be as short as possible, and such as to allow
free passage for material and ready communication between
managers and workmen in the different rooms. These con-
ditions would suggest a central room for erecting, with
the various departments for casting, forging, and finishing,
radiating from the erecting shop like the spokes of a wheel, or,
what is nearly the same, branching off at right angles on either
side and at one end of a hollow square, leaving the fourth side
of the erecting room to front on a street or road, permitting free
exit for machinery when completed.
The material when in its crude state not only consists of
various things, such as iron, sand, coal, and lumber, that must be
kept separate, but the bulk of such materials is much greater than
their finished product. It is therefore quite natural to receive such
material on the outside or "periphery " of the works where there is
the most room for entrances and for the separate storing of such
supplies. Such an arrangement is of course only possible where
there can be access to a considerable part of the boundary of a
works, yet there are but few cases where a shop cannot be ar-
ranged in general upon the plan suggested. By receiving material
on the outside, and delivering the finished product from the
centre, communications between the departments of an establish-
ment are the shortest that it is possible to have ; by observing
the plans of the best establishments of modern arrangement,
especially those in Europe, it may be seen that this system
is approximated in many of them, especially in establish-
ments devoted to the manufacture of some special class of
work.
Handling and moving material is the principal matter to be
considered in the arrangement of engineering works. The
constructive manipulation can be watched, estimated, and faults
detected by comparison, but handling, like the designs for
machinery, is a more obscure matter, arid may be greatly at
fault without its defects being apparent to any but those who
ARRANGEMENT OF ENGINEERING ESTABLISHMENTS. 73
are highly skilled, and have had their attention especially directed
to the matter.
Presuming an engineering establishment to consist of one-
storey buildings, and the main operations to be conducted on
the ground level, the only vertical lifting to be performed will
be in the erecting room, where the parts of machines are
assembled. This room should be reached in every part by
over-head travelling cranes, that cannot only be used in turning,
moving, and placing the work, but in loading it upon cars or
waggons. One result of the employment of over-head travelling
cranes, often overlooked, is a saving of floor-room ; in ordinary
fitting, from one-third more to twice the number of workmen
will find room in an erecting shop if a travelling-crane is em-
ployed, the difference being that, in moving pieces they may
pass over the top of other pieces instead of requiring long open
passages on the floor. So marked is this saving of room
effected by over-head cranes, that in England, where they are
generally employed, handling is not only less expensive and
quicker, but the area of erecting floors is usually one-half as much
as in America, where travelling-cranes are not employed.
Castings, forgings, and general supplies for erecting can be
easily brought to the erecting shop from the other departments
on trucks without the aid of motive power ; so that the erect-
ing and foundry cranes will do the entire lifting duty required
in any but very large establishments.
The auxiliary departments, if disposed about an erecting shop
in the centre, should be so arranged that material which has to
pass through two or more departments can do so in the order
of the processes, and without having to cross the erecting shop.
Casting, boring, planing, drilling, and fitting, for example,
should follow each other, and the different departments be
arranged accordingly ; whenever a casting is moved twice over
the same course, it shows fault of arrangement and useless ex-
pense. The same rule applies to all kinds of material.
A great share of the handling about an engineering establish-
ment is avoided, if material can be stored and received on a higher
level than the working floors ; if, for instance, coal, iron, and sand
is received from railway cars at an elevation sufficient to allow it
to be deposited where it is stored by gravity, it is equivalent to
saving the power and expense required to raise the material to
such a height, or move it and pile it up, which amounts to the
74 WORKSHOP MANIPULATION.
same thing in the end. It is not proposed to follow the details
of shop arrangement, further than to furnish a clue to some of
the general principles that should be regarded in devising plans
of arrangement. Such principles are much more to be relied
upon than even experience in suggesting the arrangement of
shops, because all experience must be gained in connection with
special local conditions, which often warp and prejudice the
judgment, and lead to error in forming plans under circumstances
different from those where the experience was gained.
(1.) How may the arrangement of an establishment affect its earnings 1
(2.) Why is the arrangement of engineering establishments generally
irregular 1 (3.) Why should an erecting shop be a base of arrangement
in engineering establishments ? (4.) What are the principal materials
consumed in engineering works ? (5.) Why is not special experience a
safe guide in forming plans of shop arrangement ?
CHAPTER XX.
GENERALISATION OF SHOP PROCESSES.
HAVING thus far treated of such general principles and facts
connected with practical mechanics as might properly precede,
and be of use in, the study of actual manipulation in a work-
shop, we come next to casting, forging, and finishing, with other
details that involve manual as well as mental skill, and to which
the term "processes" will apply.
As these shop processes or operations are more or less con-
nected, and run one into the other, it will be necessary at the
beginning to give a short summary of them, stating the general
object of each, that may serve to render the detailed remarks
more intelligible to the reader as he comes to them in their
consecutive order.
Designing, or generating the plans of machinery, may be
considered the leading element in engineering manufactures or
GENERALISATION OF SHOP PROCESSES. 75
machine construction, that one to which all others are sub-
ordinate, both in order and importance, and is that branch
to which engineering knowledge is especially directed. De-
signing should consist, first, in assuming certain results, and,
secondly, in conceiving of mechanical agents to produce these
results. It comprehends the geometry of movements, the
disposition and arrangement of material, the endurance of
wearing surfaces, adjustments, symmetry ; in short, all the con-
ditions of machine operation and machine construction. This
subject will be again treated of at more length in another
section.
Draughting, or drawing, as it is more commonly called, is a
means by which mental conceptions are conveyed from one
person to another ; it is the language of mechanics, and takes
the place of words, which are insufficient to convey mechanical
ideas in an intelligible manner.
Drawings represent and explain the machinery to which they
relate as the symbols in algebra represent quantities, and in a
degree admit of the same modifications and experiments to
which the machinery itself could be subjected if it were already
constructed. Drawings are also an important aid in developing
designs or conceptions. It is impossible to conceive of, and
retain in the mind, all the parts of a complicated machine, and
their relation to each other, without some aid to fix the various
ideas as they arise, and keep them in sight for comparison ; like
compiling statistics, the footings must be kept at hand for
reference, and to determine the relation that one thing may
bear to another.
In the workshop, the objects of drawing are to communicate
plans and dimensions to the workmen, and to enable a division
of the labour, so that the several parts of a machine may be
operated upon by different workmen at the same time also to
enable classification and estimates of cost to be made, and
records kept.
Drawings are, in fact, the base of shop system, upon which
depends not only the accuracy and uniformity of what is
produced, but also, in a great degree, its cost. Complete
drawings of whatever is made are now considered indispensable
in the best regulated establishments ; yet we are not so far
removed from a time when most work was made without
drawings, but what we may contrast the present system with
7(3 WORKSHOP MANIPULATION.
that which existed but a few years ago, when to construct a new
machine was a great undertaking, involving generally many
experiments and mistakes.
Pattern - making relates to the construction of duplicate
models for the moulded parts of machinery, and involves a
knowledge of shrinkage and cooling strains, the manner of
moulding and proper position of pieces, when cast, to ensure
soundness in particular parts. As a branch of machine manu-
facture, pattern-making requires a large amount of special
knowledge, and a high degree of skill ; for in no other depart-
ment is there so much that must be left to the discretion and
judgment of workmen.
Pattern-makers have to thoroughly understand drawings, in
order to reproduce them on the trestle boards with allowance for
shrinkage, and to determine the cores ; they must also under-
stand moulding, casting, fitting, and finishing. Pattern-making
as a branch of machine manufacture, should rank next to
designing and drafting.
Founding and casting relate to forming parts of machinery
by pouring melted metal into moulds, the force of gravity alone
being sufficient to press or shape it into even complicated forms.
As a process for shaping such metal as is not injured by the
high degree of heat required in melting, moulding is the
cheapest and most expeditious of all means, even for forms
of regular outline, while the importance of moulding in pro-
ducing irregular forms is such that without this process the
whole system of machine construction would have to be changed.
Founding operations are divided into two classes, known techni-
cally as green sand moulding, and loam or dry sand moulding ;
the first, when patterns or duplicates are used to form the
moulds, and the second, when the moulds are built by hand
without the aid of complete patterns. Founding involves a
knowledge of mixing and melting metals such as are used in
machine construction, the preparing and setting of cores for
the internal displacement of the metal, cooling and shrinking
strains, chills, and many other things that are more or less
special, and can only be learned and understood from actual
observation and practice.
Forging relates to shaping metal by compression or blows
when it is in a heated and softened condition ; as a process, it is
an intermediate one between casting and what may be called
GENERALISATION OF SHOP PROCESSES. 77
the cold processes. Forging also relates to welding or joining
pieces together by sudden heating that melts the surface
only, and then by forcing the pieces together while in this
softened or semi-fused state. Forging includes, in ordinary
practice, the preparation of cutting tools, and tempering them
to various degrees of hardness as the nature of the work for
which they are intended may require ; also the construction of
furnaces for heating the material, and mechanical devices for
handling it when hot, with the various operations for shaping,
which, as in the case of casting, can only be fully understood by
experience and observation.
Finishing and fitting relates to giving true and accurate
dimensions to the parts of machinery that come in contact with
each other and are joined together or move upon each other, and
consists in cutting away the surplus material which has to be left
in founding and forging because of the heated and expanded con-
dition in which the material is treated in these last processes. In
finishing, material is operated upon at its normal temperature, in
which condition it can be handled, gauged, or measured, and will
retain its shape after it is fitted. Finishing comprehends all
operations of cutting and abrading, such as turning, boring,
planing and grinding, also the handling of material ; it is considered
the leading department in shop manipulation, because it is the
one where the work constructed is organised and brought together.
The fitting shop is also that department to which drawings espe-
cially apply, and other preparatory operations are usually made
subservient to the fitting processes.
Shop system may also be classed as a branch of engineering
work ; it relates to the classification of machines and their parts
by symbols and numbers, to records of weight, the expense of
cast, forged, and finished parts, and apportions the cost of finished
machinery among the different departments. Shop system also
includes the maintenance of standard dimensions, the classification
and cost of labour, with other matters that partake both of a
mechanical and a commercial nature.
In order to render what is said of shop processes more easily
understood, it will be necessary to change the order in which they
have been named. Designing, and many matters connected with
the operation of machines, will be more easily learned and under-
stood after having gone through with what may be called the
constructive operations, such as involve manual skill.
78 WORKSHOP MANIPULATION.
(1.) Name the different departments of an engineering establishment.
(2.) What does the engineering establishment include 1 (3.) What
does the commercial department include? (4.) The foundry depart-
ment ? (5.) The forging department ? (6.) The fitting department 1
(7.) What does the term shop system mean as generally employed ?
CHAPTER XXL
MECHANICAL DRAWING.
MACHINE-DRAWING may in some respects be said to bear the
same relation to mechanics that writing does to literature;
persons may copy manuscript, or write from dictation, of
what they do not understand; or a mechanical draughtsman
may make drawings of a machine he does not understand ; but
neither such writing or drawing can have any value beyond that
of ordinary labour. It is both necessary and expected that a
draughtsman shall understand all the various processes of machine
construction, and be familiar with the best examples that are
furnished by modern practice.
Geometrical drawing is not an artistic art so much as it is a
constructive mechanical one ; displaying the parts of machinery
on paper, is much the same in practice, and just the same in prin-
ciple, as measuring and laying out work in the shop.
Artistic drawing is addressed to the senses, geometrical drawing
is addressed to the understanding. Geometrical drawing may,
however, include artistic skill not in the way of ornamentation,
but to convey an impression of neatness and completeness, that
has by common custom been assumed among engineers, and which
conveys to the mind an idea of competent construction in the
drawing itself, as well as of the machinery which is represented.
Artistic effect, so far as admissible in mechanical drawing, is easy
to learn, and should be understood, yet through a desire to make
pictures, a beginner is often led to neglect that which is more
important in the way of accuracy and arrangement.
It is easy to learn " how " to draw, but it is far from easy to learn
MECHANICAL DRAWING. 79
" what " to draw. Let this be kept in mind, not in the way of
disparaging effort in learning " how " to draw, for this must come
first, but in order that the objects and true nature of the work
will be understood.
The engineering apprentice, as a rule, has a desire to make
drawings as soon as he begins his studies or his work, and there
is not the least objection to his doing so ; in fact, there is a great
deal gained by illustrating movements and the details of machi-
nery at the same time of studying the principles. Drawings if
made should always be finished, carefully inked in, and memo-
randa made on the margin of the sheets, with the date and the
conditions under which the drawings were made. The sheets
should be of uniform size, not too large for a portfolio, and care-
fully preserved, no matter how imperfect they may be. An ap-
prentice who will preserve his first drawings in this manner will
some day find himself in possession of a souvenir that no con-
sideration would cause him to part with.
For implements procure two drawing-boards, forty-two inches
long and thirty inches wide, to receive double elephant paper ;
have the boards plain without elects, or ingenious devices for
fastening the paper ; they should be made from thoroughly sea-
soned lumber, at least one and one-fourth inches thick ; if thinner
they will not be heavy enough to resist the thrust of the T
squares.
It is better to have two boards, so that one may be used for
sketching and drawing details, which, if done on the same sheet
with elevations, dirties the paper, and is apt to lower the
standard of the finished drawing by what may be called bad
association.
Details and sketches, when made on a separate sheet, should
be to a larger scale than elevations. By changing from one scale
to another the mind is schooled in proportion, and the concep-
tion of sizes and dimensions is more apt to follow the finished
work to which the drawings relate.
In working to regular scales, such as one-half, one-eighth, or
one-sixteenth size, a good plan is to use a common rule, instead
of a graduated scale. There is nothing more convenient for a
mechanical draughtsman than to be able to readily resolve dimen-
sions into various scales, and the use of a common rule for
fractional scales trains the mind, so that computations come
naturally, and after a time almost without effort. A plain T
80 WORKSHOP MANIPULATION.
square, with a parallel blade fastened on the side of the head,
but not imbedded into it, is the best ; in this way set squares
can pass over the head of a T square in working at the edges
of the drawing. It is strange that a draughting square should
ever have been made in any other manner than this, and still
more strange, that people* will use squares that do not allow the
set squares to pass over the heads and come near to the edge
of the board.
A bevel square is often convenient, but should be an in-
dependent one; a T square that has a movable blade is not
suitable for general use. Combinations in draughting instruments,
no matter what their character, should be avoided ; such com-
binations, like those in machinery, are generally mistakes, and
their effect the reverse of what is intended.
For set squares, or triangles, as they are sometimes called, no
material is so good as ebonite; such squares are hard, smooth,
impervious to moisture, and contrast with the paper in colour ;
besides they wear longer than those made of wood. For instru-
ments, it is best to avoid everything of an elaborate or fancy
kind ; such sets are for amateurs, not engineers. It is best to
procure only such instruments at first as are really required, of
the best quality, and then to add others as necessity may demand ;
in this way, experience will often suggest modifications of size or
arrangement that will add to the convenience of a set.
One pair each of three and one-half inch and five inch com-
passes, two ruling pens, two pairs of spring dividers, one for
pens and one for pencils, a triangular boxwood scale, a common
rule, and a hard pencil, are the essential instruments for machine-
drawing. At the beginning, when "scratching out" will pro-
bably form an item in the work, it is best to use Whatman's
paper, or the best roll paper, which, of the best manufacture, is
quite as good as any other for drawings that are not water-
shaded.
In mounting sheets that are likely to be removed and replaced,
for the purpose of modification, as working drawings generally
are, they can be fastened very well by small copper tacks driven
along the edges at intervals of two inches or less. The paper can
be very slightly dampened before fastening in this manner, and
if the operation is carefully performed the paper will be quite as
smooth and convenient to work upon as though it were pasted
down ; the tacks can be driven down so as to be flush with, or
MECHANICAL DKAWING.
below the surface of, the paper, and will offer no
squares.
If a drawing is to be elaborate, or to remain long upon
board, the paper should be pasted down. To do this, first
prepare thick mucilage, or what is better, glue, and have it ready
at hand, with some slips of absorbent paper an inch or so wide.
Dampen the sheet on both sides with a sponge, and then apply
the mucilage along the edge, for a width of one-fourth or three-
eighths of an inch. It is a matter of some difficulty to place
a sheet upon a board ; but if the board is set on its edge,
the paper can be applied without assistance. Then, by placing
the strips of paper along the edge, and rubbing over them with
some smooth hard instrument, the edges of the sheet can be
pasted firmly to the board, the paper slips taking up a part of
the moisture from the edges, which are longest in drying. If
left in this condition, the centre will dry first, and the paper be
pulled loose at the edges by contraction before the paste has
time to dry. It is therefore necessary to pass over the centre
of the sheet with a wet sponge at intervals to keep the paper
slightly damp until the edges adhere firmly, when it can be left
to dry, and will be tight and smooth. In this operation much
will be learned by practice, and a beginner should not be dis-
couraged by a few failures. One of the most common diffi-
culties in mounting sheets is in not having the gum or glue
thick enough ; when thin, it will be absorbed by the wood or
the paper, or is too long in drying ; it should be as thick as it
can be applied with a brush, and made from clean Arabic gum,
tragacanth, or fine glue.
Thumb-tacks are of but little use in mechanical drawing
except for the most temporary purposes, and may very well be
dispensed with altogether; they injure the draughting-boards,
obstruct the squares, and disfigure the sheets.
Pencilling is the first and the most important operation in
draughting ; more skill is required to produce neat pencil-work
than to ink in the lines after the pencilling is done.
A beginner, unless he exercises great care in the pencil-
work of a drawing, will have the disappointment to find the
paper soon becoming dirty from plumbago, and the pencil-lines
crossing each other everywhere, so as to give the whole a slovenly
appearance. He will also, unless he understands the nature of
the operations in which he is engaged, make the mistake of
F
82 WORKSHOP MANIPULATION.
regarding the pencil-work as an unimportant part, instead of
constituting, as it does, the main drawing, and thereby neglect
that accuracy which alone can make either a good-looking or a
valuable one.
Pencil-work is indeed the main operation, the inking being
merely to give distinctness and permanency to the lines. The
main thing in pencilling is accuracy of dimensions and stopping
the lines where they should terminate without crossing others.
The best pencils only are suitable for draughting ; if the plumbago
is not of the best quality, the points require to be continually
sharpened, and the pencil is worn away at a rate that more than
makes up the difference in cost between the finer and cheaper
grades of pencils, to say nothing of the effect upon a drawing.
It is common to use a flat point for draughting pencils, but a
round one will often be found quite as good if the pencils are
fine, and some convenience is gained by a round point for free-
hand use in making rounds and fillets. A Faber pencil, that has
detachable points which can be set out as they are worn away,
is convenient for draughting.
For compasses, the lead points should be cylindrical, and fit
into a metal sheath without paper packing or other contrivance
to hold them ; and if a draughtsman has instruments not arranged
in this manner, he should have them changed at once, both for
convenience and economy.
Ink used in drawing should always be the best that can be
procured ; without good ink a draughtsman is continually annoyed
by an imperfect working of pens, and the washing of the lines
if there is shading to be done. The quality of ink can only be
determined by experiment ; the perfume that it contains, or tin-
foil wrappers and Chinese labels, are no indication of quality ;
not even the price, unless it be with some first-class house. To
prepare ink, I can recommend no better plan of learning than to
ask some one who understands the matter. It is better to
waste a little time in preparing it slowly than to be at a continual
trouble with pens, which will occur if the ink is ground too
rapidly or on a rough surface. To test ink, a few lines can be
drawn on the margin of a sheet, noting the shade, how the ink
flows from the pen, and whether the lines are sharp; after the lines
have dried, cross them with a wet brush ; if they wash readily,
the ink is too soft ; if they resist the water for a time, and then
wash tardily, the ink is good. It cannot be expected that inks
MECHANICAL DRAWING. 83
soluble in water can permanently resist its action after drying ;
in fact, it is not desirable that drawing inks should do so, for
in shading, outlines should be blended into the tints where the
latter are deep, and this can only be effected by washing.
Pens will generally fill by capillary attraction; if not, they should
be made wet by being dipped into water ; they should not be
put into the mouth to wet them, as there is danger of poison
from some kinds of ink, and the habit is not a neat one.
In using ruling pens, they should be held nearly vertical, lean-
ing just enough to prevent them from catching on the paper.
Beginners have a tendency to hold pens at a low angle, and drag
them on their side, but this will not produce clean sharp lines,
nor allow the lines to be made near enough to the edges of square
blades or set squares.
In regard to the use of the T square and set squares, no useful
rules can be given except to observe others, and experiment
until convenient customs are attained. A beginner should be
careful of adopting unusual plans, and above all things, of making
important discoveries as to new plans of using instruments,
assuming that common practice is all wrong, and that it is left
for him to develop the true and proper way of drawing. This
is a kind of discovery which is very apt to intrude itself at the
beginning of an apprentice's course in many matters besides draw-
ing, and often leads him to do and say many things which he
will afterwards wish to recall.
It is generally a safe rule to assume that any custom long and
uniformly followed by intelligent people is right ; and, in the
absence of that experimental knowledge which alone enables one
to judge, it is safe to receive such customs, at least for a time,
as being correct.
Without any wish to discourage the ambition of an apprentice
to invent, which always inspires him to laudable exertion, it
is nevertheless best to caution him against innovations. The
estimate formed of our abilities is very apt to be inversely as our
experience, and old engineers are not nearly so confident in their
deductions and plans as beginners are.
A drawing being inked in, the next things are tints, dimen-
sion, and centre lines. The centre lines should be in red ink, and
pass through all points of the drawing that have an axial centre,
or where the work is similar and balanced on each side of the
line. This rule is a little obscure, but will be best understood
84 WORKSHOP MANIPULATION.
if studied in connection with a drawing, arid perhaps as well
remembered without further explanation.
Dimension lines should be in blue, but may be in red. Where
to put them is a great point in draughting. To know where
dimensions are required involves a knowledge of fitting and
pattern-making, and cannot well be explained ; it must be learned
in practice. The lines should be fine and clear, leaving a space
in their centre for figures when there is room. The distribution
of centre lines and dimensions over a drawing must be carefully
studied, for the double purpose of giving it a good appearance
and to avoid confusion. Figures should be made like printed
numerals ; they are much better understood by the workman,
look more artistic, and when once learned require but little if any
more time than written figures. If the scale employed is feet
and inches, dimensions to three feet should be in inches, and above
this in feet and inches ; this corresponds to shop custom, and
is more comprehensive to the workman, however wrong it may
be according to other standards.
In sketches and drawings made for practice, such as are not
intended for the shop, it is suggested that metrical scales be
employed ; it will not interfere with feet and inches, and will
prepare the mind for the introduction of this system of lineal
measurement, which may in time be adopted in England and
America, as it has been in many other countries.
In shading drawings, be careful not to use too deep tints, and
to put the shades in the right place. Many will contend, and
not without good reasons, that working drawings require no
shading ; yet it will do no harm to learn how and where they
can be shaded : it is better to omit the shading from choice than
from necessity. Sections must, of course, be shaded not with
lines, although I fear to attack so old a custom, yet it is certainly
a tedious and useless one : sections with light ink shading of
different colours, to indicate the kind of material, are easier to
make, and look much better. By the judicious arrangement of a
drawing, a large share of it may be in sections, which in almost
every case are the best views to work by. The proper colouring
of sections gives a good appearance to a drawing, and conveys
an idea of an organised machine, or, to use the shop term,
"stands out from the paper." In shading sections, leave a
margin of white between the tints and the lines on the upper and
left-hand sides of the section : this breaks the connection or
MECHANICAL DRAWING. 85
sameness, and the effect is striking; it separates the parts,
and adds greatly to the clearness and general appearance of a
drawing.
Cylindrical parts in the plane of sections, such as shafts and
bolts, should be drawn full, and have a 'round shade,' which
relieves the flat appearance a point to be avoided as much as
possible in sectional views.
Conventional custom has assigned blue as a tint for wrought
iron, neutral or pale pink for cast iron, and purple for steel.
Wood is generally distinguished by " graining," which is easily
done,, and looks well.
The title of a drawing is a feature that has much to do with
its appearance, and the impression conveyed to the mind of an
observer. While it can add nothing to the real value of a drawing,
it is so easy to make plain letters, that the apprentice is urged
to learn this as soon as he begins to draw ; not to make fancy
letters, nor indeed any kind except plain block letters, which can
be rapidly laid out and finished, and consequently employed to a
greater extent. By drawing six parallel lines, making five spaces,
and then crossing them with equidistant lines, the points and
angles in block letters are determined ; after a little practice, it
becomes the work of but a few minutes to put down a title or
other matter on a drawing so that it can be seen and read at a
glance in searching for sheets or details.
In the manufacture of machines, there are usually so many
sizes and modifications, that drawings should assist and determine
in a large degree the completeness of classification and record.
Taking the manufacture of machine tools, for example : we cannot
well say, each time they are to be spoken of, a thirty-six inch lathe
without screw and gearing, a thirty-two inch lathe with screw and
gearing, a forty-inch lathe triple geared or double geared, with a
twenty or thirty foot frame, and so on. To avoid this it is neces-
sary to assume symbols for machines of different classes, consist-
ing generally of the letters of the alphabet, qualified by a single
number as an exponent to designate capacity or different modi-
fications. Assuming, in the case of engine lathes, A to be the
symbol for lathes of all sizes, then those of different capacity and
modification can be represented in the drawings and records aa
A 1 , A 2 , A 3 , A 4 , and so on, requiring but two characters to indicate
a lathe of any kind. These symbols should be marked in large
plain letters on the left-hand lower corner of sheets, so that the
86 WORKSHOP MANIPULATION.
manager, workman, or any one else, can see at a glance what the
drawings relate to. This symbol should run through the time-
book, cost account, sales record, and be the technical name for
machines to which it applies ; in this way machines will always
be spoken of in the works by the name of their symbol.
In making up the time charged to different machines during
their construction, a good plan is to supply each workman with a
slate and pencil, on which he can enter his time as so many hours
or fractions of hours charged to the respective symbols. Instead
of interfering with his time, this will increase a workman's inte-
rest in what he is doing, and naturally lead to a desire to dimmish
the time charged to the various symbols. This system leads to
emulation among workmen where any operation is repeated by
different persons, and creates an interest in classification which
workmen will willingly assist in.
When the dimensions and symbols are added to a drawing,
the next thing is pattern or catalogue numbers. These should
be marked in prominent, plain figures on each piece of casting,
either in red or other colour that will contrast with the general
face of the drawing. These numbers, to avoid the use of symbols
in connection with them, must include consecutively all patterns
employed in the business, and can extend to thousands without
inconvenience.
A book containing the pattern record should be kept, in which
these catalogue numbers are set down, with a short description
to identify the different parts to which the numbers belong, so
that all the various details of any machine can at any time be
referred to. Besides this description, there should be opposite the
catalogue of pattern numbers, ruled spaces, in which to enter
the weight of castings, the cost of the pattern, and also the amount
of turned, planed, or bored surface on each piece when it is
finished, or the time required in fitting, which is the same thing.
In this book the assembled parts of each machine should be set
down in a separate list, so that orders for castings can be made
from the list without other references. This system is the best
one known to the writer, and is in substance a plan now adopted
in many of the best engineering establishments. A complete
system in all things pertaining to drawings and classifications
should be rigidly adhered to ; any plan is better than none, and
the schooling of the mind to be had in the observance of systematic
rules is a matter not to be neglected. New plans for promoting
MECHANICAL DBA WING. 87
system may at any time arise, tut such plans cannot be at any
time understood and adopted except by those who have culti-
vated a taste for order and regularity.
In regard to shaded elevations, it may be said that photography
has superseded them for the purpose of illustrating completed
machines, and but few establishments care to incur the expense
of ink-shaded elevations. Shaded elevations cannot be made
with various degrees of care, and in a longer or shorter time ;
there is but one standard for them, and that is that such drawings
should be made with great care and skill. Imperfect shaded
elevations, although they may surprise and please the unskilled,
are execrable in the eyes of a draughtsman or an engineer ; and
as the making of shaded elevations can be of but little assistance
to an apprentice draughtsman, it is better to save the time that
must be spent in order to make such drawings, and apply the
same study and time to other matters of greater importance.
It is not assumed that shaded elevations should not be made,
nor that ink shading should not be learned, but it is thought
best to point out the greater importance of other kinds of draw-
ing, too often neglected to gratify a taste for picture-making,
which has but little to do with practical mechanics.
Isometrical perspective is often useful in drawing, especially
in wood structures, when the material is of rectangular section,
and disposed at right angles, as in machine frames. One iso-
metrical view, which can be made nearly as quickly as a true
elevation, will show all the parts, and may be figured for dimen-
sions the same as plane views. True perspective, although rarely
necessary in mechanical drawing, may be studied with advantage
in connection with geometry ; it will often lead to the explana-
tion of problems in isometric drawing, and will also assist in
free-hand lines that have sometimes to be made to show parts of
machinery oblique to the regular planes. Thus far the remarks
on draughting have been confined to manipulation mainly. As"
a branch of engineering work, draughting must depend mainly
on special knowledge, and is not capable of being learned or
practised upon general principles or rules. It is therefore impos-
sible to give a learner much aid by searching after principles
to guide him ; the few propositions that follow comprehend
nearly all that may be explained in words.
1. Geometrical drawings consist in plans, elevations, and
sections ; plans being views on the top of the object in a horizon-
88 WORKSHOP MANIPULATION.
tal plane ; elevations, views on the sides of the object in vertical
planes ; and sections, views taken on bisecting planes, at any
angle through an object.
2. Drawings in true elevation or in section are based upon flat
planes, and give dimensions parallel to the planes in which the
views are taken.
3. Two elevations taken at right angles to each other, fix all
points, and give all dimensions of parts that have their axis
parallel to the planes on which the views are taken ; but when
a machine is complex, or when several parts lie in the same plane,
three and sometimes four views are required to display all the
parts in a comprehensive manner.
4. Mechanical drawings should be made with reference to all
the processes that are required in the construction of the work,
and the drawings should be responsible, not only for dimensions,
but for unnecessary expense in fitting, forging, pattern-making,
moulding, and so on.
5. Every part laid down has something to govern it that
may be termed a " base " some condition of function or posi-
tion which, if understood, will suggest size, shape, and relation
to other parts. By searching after a base for each and every
part and detail, the draughtsman proceeds upon a regular sys-
tem, continually maintaining a test of what is done. Every
wheel, shaft, screw or piece of framing should be made with a
clear view of the functions it has to fill, and there are, as
before said, always reasons why such parts should be of a certain
size, have such a speed of movement, or a certain amount of
bearing surface, and so on. These reasons or conditions may be
classed as expedient, important, or essential, and must be esti-
mated accordingly. As claimed at the beginning, the designs
of machines can only in a limited degree be determined by
mathematical data. Leaving out all considerations of machine
operation with which books have scarcely attempted to deal, we
have only to refer to the element of strains to verify the general
truth of the proposition.
Examining machines made by the best designers, it will be
found that their dimensions bear but little if any reference to
calculated strains, especially in machines involving rapid motion.
Accidents destroy constants, and a draughtsman or designer who
does not combine special and experimental knowledge with what
MECHANICAL DRAWING. 89
he may learn from general sources, will find his services to be of
but little value in actual practice.
I now come to note a matter in connection with draughting
to which the attention of learners is earnestly called, and which,
if neglected, all else will be useless. I allude to indigestion,
and its resultant evils. All sedentary pursuits more or less give
rise to this trouble, but none of them so much as draughting.
Every condition to promote this derangement exists. When the
muscles are at rest, circulation is slow, the mind is intensely
occupied, robbing the stomach of its blood and vitality, and, worse
than all, the mechanical action of the stomach is usually arrested
by leaning over the edge of a board. It is regretted that no
good rule can be given to avoid this danger. One who under-
stands the evil may in a degree avert it by applying some of
the logic which has been recommended in the study of me-
chanics. If anything tends to induce indigestion, its opposite
tends the other way, and may arrest it ; if stooping over a
board interferes with the action of the digestive organs, leaning
back does the opposite ; it is therefore best to have a desk as high
as possible, stand when at work, and cultivate a constant habit
of straightening up and throwing the shoulders back, and if
possible, take brief intervals of vigorous exercise. Like rating
the horse-power of a steam-engine, by multiplying the force
into the velocity, the capacity of a man can be estimated by
multiplying his mental acquirements into his vitality.
Physical strength, bone and muscle, must be elements in
successful engineering experience ; and if these things are not
acquired at the same time with a mechanical education, it will
be found, when ready to enter upon a course of practice, that an
important element, the '''propelling power," has been omitted.
(1.) What is the difference between geometric and artistic drawing ?
(2.) What is the most important operation in making a good drawing ?
(3.) Into what three classes can working drawings be divided? (4.)
Explain the difference between elevations and plans. (5.) To what
extent in general practice is the proportion of parts and their arrange-
ment in machines determined mathematically ?
90 WOKKSHOP MANIPULATION.
CHAPTER XXII.
PATTERN-MAKING AND CASTING.
PATTERNS and castings are so intimately connected that it would
be difficult to treat of them separately without continually
confounding them together; it is therefore proposed to speak
of pattern-making and moulding under one head.
Every operation in a pattern-shop has reference to some
operation in the foundry, and patterns considered separately
from moulding operations would be incomprehensible to any but
the skilled. Next to designing and draughting, pattern-making
is the most intellectual of what may be termed engineering
processes the department that must include an exercise of the
greatest amount of personal judgment on the part of the work-
man, and at the same time demands a high grade of hand
skill.
For other kinds of work there are drawings furnished, and
the plans are dictated by the engineering department of machi-
nery-building establishments, but pattern-makers make their
own plans for constructing their work, and have even to repro-
duce the drawings of the fitting-shop to work from. Nearly
everything pertaining to patterns is left to be decided by the
pattern-maker, who, from the same drawings, and through the
exercise of his judgment alone, may make patterns that are
durable and expensive, or temporary and cheap, as the probable
extent of their use may determine.
The expense of patterns should be divided among and charged
to the machines for which the patterns are employed, but there
can be no constant rules for assessing or dividing this cost. A
pattern may be employed but once, or it may be used for years ;
it is continually liable to be superseded by changes and improve-
ments that cannot be predicted beforehand; and in preparing
patterns, the question continually arises of how much ought to
be expended on them a matter that should be determined
between the engineer and the pattern-maker, but is generally
left to the pattern-maker alone, for the reason that but few
mechanical engineers understand pattern-making so well as to
dictate plans of construction.
PATTERN- MAKING AND CASTING. 91
To point out some of the leading points or conditions to be
taken into account in pattern-making, and which must be under-
stood in order to manage this department, I will refer to them
in consecutive order.
First. Durability, plans of construction and cost, which all
amount to the same thing. To determine this point, there is to
be considered the amount of use that the patterns are likely to
serve, whether they are for standard or special machines, and
the quality of the castings so far as affected by the patterns.
A first-class pattern, framed to withstand moisture and rapping,
may cost twice as much as another that has the same outline,
yet the cheaper pattern may answer almost as well to form a few
moulds as an expensive one.
Second. The manner of moulding and its expense, so far as
determined by the patterns, which may be parted so as to be
* rammed up ' on fallow boards or a level floor, or the patterns
may be solid, and have to be bedded, as it is termed ; pieces on
the top may be made loose, or fastened on so as to ' cope off ; '
patterns may be well finished so as to draw clean, or rough so
that a mould may require a great deal of time to dress up after
a pattern is removed.
Third. The soundness of such parts as are to be planed,
bored, and turned in finishing ; this is also a matter that is deter-
mined mainly by how the patterns are arranged, by which is the
top and which the bottom or drag side, the manner of draw-
ing, and provisions for avoiding dirt and slag.
Fourth. Cores, where used, how vented, how supported in
the mould, and I will add how made, because cores that are of
an irregular form are often more expensive than external moulds,
including the patterns. The expense of patterns is often greatly
reduced, but is sometimes increased, by the use of cores, which
may be employed to cheapen patterns,, add to their durability,
or to ensure sound castings.
Fifth. Shrinkage ; the allowance that has to be made for
the contraction of castings in cooling, in other words, the differ-
ence between the size of a pattern and the size of the casting.
This is a simple matter apparently, which may be provided for
in allowing a certain amount of shrinkage in all directions, but
when the inequalities of shrinkage both as to time and degree
are taken into account, the allowance to be made becomes a
problem of no little complication.
92 WORKSHOP MANIPULATION.
Sixth. Inherent, or cooling strains, that may either spring and
warp castings, or weaken them, by maintained tension in certain
parts a condition that often requires a disposition of the metal
quite different from what working strains demand.
Seventh. Draught, the bevel or inclination on the sides of
patterns to allow them to be withdrawn from the moulds without
dragging or breaking the sand.
Eighth. Rapping plates, draw plates, and lifting irons for
drawing the patterns out of the moulds ; fallow and match
boards, with other details* that are peculiar to patterns, and
have no counterparts, neither in names nor uses, outside the
foundry.
This makes a statement in brief of what comprehends a know-
ledge of pattern-making, and what must be understood not only
by pattern-makers, but also by mechanical engineers who under-
take to design machinery or manage its construction success-
fully.
As to the manner of cutting out or planing up the lumber
for patterns, and the manner of framing them together, it is use-
less to devote space to the subject here ; one hour's practical
observation in a pattern-shop, and another hour spent in examin-
ing different kinds of patterns, is worth more to the apprentice
than a whole volume written to explain how these last-named
operations are performed. A pattern, unless finished with paint
or opaque varnish, will show the manner in which the wood is
disposed in framing the parts together.
I will now proceed to review these conditions or principles in
pattern-making and casting in a more detailed way, furnishing
as far as possible reasons for different modes of constructing
patterns, and the various plans of moulding and casting.
In regard to the character or quality of wood patterns, they
can be made, as already, stated, at greater or less expense, and
if necessary, capable of almost any degree of endurance. The
writer has examined patterns which had been used more than two
hundred times, and were apparently good for an equal amount
of use. Such patterns are expensive in their first cost, but are
the cheapest in the end, if they are to be employed for a large
number of castings. Patterns for special pieces, or such as are
to be used for a few times only, do not require to be strong nor
expensive, yet with patterns, as with everything else pertaining
to machinery, the safest plan is to err on the side of strength.
PATTERN-MAKING AND CASTING. 93
For pulleys, gear wheels, or other standard parts of machinery
which are not likely to be modified or changed, iron patterns
are preferable ; patterns for gear wheels and pulleys, when made
of wood, aside from their liability to spring and warp, cannot be
made sufficiently strong to withstand foundry use ; besides, the
greatest accuracy that can be attained, even by metal patterns, is far
from producing true castings, especially for tooth wheels. The
more perfect patterns are, the less rapping is required in draw-
ing them ; and the less rapping done, the more perfect castings
will be.
The most perfect castings for gear wheels and pulleys and
other pieces which can be so moulded, are made by drawing the
patterns through templates without rapping. These templates
are simply plates of metal perforated so that the pattern can be
forced through them by screws or levers, leaving the sand intact.
Such templates are expensive to begin with, because of the
accurate fitting that is required, especially around the teeth of
wheels, and the mechanism that is required in drawing the
patterns, but when a large number of pieces are to be made
from one pattern, such as gear wheels and pulleys, the saving of
labour will soon pay for the templates and machinery required,
to say nothing of the saving of metal, which often amounts to
ten per cent., and the increased value of the castings because of
their accuracy.
Mr Kansome of Ipswich, England, where this system of
template moulding originated, has invented a process of fitting
templates for gear wheels and other kinds of casting by pouring
melted white metal around to mould the fit instead of cutting it
through the templates; this effects a great saving in expense,
and answers in many cases quite as well as the old plan.
The expense of forming pattern-moulds may be considered
as divided between the foundry and pattern-shop. What a
pattern - maker saves a moulder may lose, and what a
pattern-maker spends a moulder may save; in other words,
there is a point beyond which saving expense in patterns is
balanced by extra labour and waste in moulding a fact that is
not generally realised because of inaccurate records of both
pattern and foundry work. What is lost or saved by judicious
or careless management in the matter of patterns and mould-
ing can only be known to those who are well skilled in both
moulding and pattern-making. A moulder may cut all the
94 WORKSHOP MANIPULATION.
fillets in a mould with a trowel ; lie may stop off, fill up, and
print in, to save pattern-work, but it is only expedient to do so
when it costs very much less than to prepare proper patterns,
because patching and cutting in moulds seldom improves them.
The reader may notice how everything pertaining to patterns
and moulding resolves itself into a matter of judgment on the
part of workmen, and how difficult it would be to apply general
rules.
The arrangement of patterns with reference to having certain
parts of castings solid and clean is an important matter, yet one
that is comparatively easy to understand. Supposing the iron
in a mould to be in a melted state, and to contain, as it always
must, loose sand and ' scruff,' and that the weight of the dirt is
to melted iron as the weight of cork is to water, it is easy to
see where this dirt would lodge, and where it would be found
in the castings. The top of a mould or cope, as it is called,
contains the dirt, while the bottom or drag side is generally
clean and sound : the rule is to arrange patterns so that the
surfaces to be finished will come on the bottom or drag side.
Expedients to avoid dirt in such castings as are to be finished
all over or on two sides are various. Careful moulding to
avoid loose sand and washing is the first requisite ; sinking
heads, that rise above the moulds, are commonly employed when
castings are of a form which allows the dirt to collect at one
point. Moulds for sinking heads are formed by moulders as a
rule, but are sometimes provided for by the patterns.
The quality of castings is governed by a great many things
besides what have been named, such as the manner of gating or
flowing the metal into the moulds, the temperature and quality
of the iron, the temperature and character of the mould things
which any skilled foundryman will take pleasure in explaining
in answer to courteous and proper questions.
Cores are employed mainly for what may be termed the
displacement of metal in moulds. There is no clear line of
distinction between cores and moulds, as founding is now
conducted ; cores may be of green sand, and made to surround
the exterior of a piece, as well as to make perforations or to form
recesses within it. The term ' core,' in its technical sense, means
dried moulds, as distinguished from green sand. Wheels or
other castings are said to be cast in cores when the moulds are
made in pieces and dried. Supporting and venting cores, and
PATTERN-MAKING AND CASTING. 95
their expansion, are conditions to which especial attention is
called. When a core is surrounded with hot metal, it gives off,
because of moisture and the burning of the 'wash,' a large
amount of gas which must have free means of escape. In the
arrangement of cores, therefore, attention must be had to some
means of venting, which is generally attained by allowing them
to project through the sides of the mould and communicate with
the air outside.
An apprentice may get a clear idea of this venting process by
inspecting tubular core barrels, such as are employed in mould-
ing pipes or hollow columns, or by examining ordinary cores
about a foundry. Provision of some kind to ' carry off the vent,'
as it is termed by moulders, will be found in every case. The
venting of moulds is even more important than venting cores,
because core vents only carry off gas generated within the core
itself, while the gas from its exterior surface, and from the whole
mould, has to find means of escaping rapidly from the flasks
when the hot metal enters.
A learner will no doubt wonder why sand is used for mould-
ing, instead of some more adhesive material like clay. If he
is not too fastidious for the experiment, and will apply a lump
of damp moulding sand to his mouth and blow his breath
through the mass, the query will be solved. If it were not for the
porous nature of sand-moulds they would be blown to pieces as
soon as the hot metal entered them ; not only because of the
mechanical expansion of the gas, but often from explosion by
combustion. Gas jets from moulds, as may be seen at any time
when castings are poured, will take fire and burn the same as
illuminating gas.
If it were not for securing vent for gas, moulds could be
made from plastic material so as to produce fine castings with
clear sharp outlines.
The means of supporting cores must be devised, or at least
understood, by pattern-makers ; these supports consist of * prints'
and ' anchors.' Prints are extensions of the cores, which project
through the casting and extend into the sides of the mould, to
be held by the sand or by the flask. The prints of cores have
duplicates on the patterns, called core prints, which are, or should
be, of a different colour from the patterns, so as to distinguish one
from the other. The amount of surface required to support
cores is dependent upon their weight, or rather upon their cubic
06 WORKSHOP MANIPULATION.
contents, because the weight of a core is but a trifling matter
compared to its floating force when surrounded by melted metal.
An apprentice in studying devices for supporting cores must
remember that the main force required is to hold them down,
and not to bear their weight. The floating force of a core is as
the difference between its weight and that of a solid of metal of
the same size a matter moulders often forget to consider. It is
often impossible, from the nature of castings, to have prints
large enough to support the cores, and it is then effected by
anchors, pieces of iron that stand like braces between the cores
and the flasks or pieces of iron imbedded in the sand to receive
the strain of the anchors.
In constructing patterns where it is optional whether to employ
cores or not, and in preparing drawings for castings which may
have either a ribbed or a cored section, it is nearly always best
to employ cores. The usual estimate of the difference between
the cost of moulding rib and cored sections, as well as of
skeleton and cored patterns, is wrong. The expense of cores is
often balanced by the advantage of having an ' open mould/
that is accessible for repairs or facing, and by the greater dura-
bility and convenience of the solid patterns. Taking, for ex-
ample, a column, or box frame for machinery, that might be made
either with a rib or a cored section, it would at first thought seem
that patterns for a cored casting would cost much more by
reason of the core-boxes ; but it must be remembered that in
most patterns labour is the principal expense, and what is lost in
the extra lumber required for a core-box or in making a solid
pattern is in many cases more than represented in the greater
amount of labour required to construct a rib pattern.
Cores expand when heated, and require an allowance in their
dimensions the reverse from patterns ; this is especially the case
when the cores are made upon iron frames. For cylindrical
cores less than six inches diameter, or less than two feet long,
expansion need not be taken into account by pattern-makers,
but for large cores careful calculation is required. The expan-
sion of cores is as the amount of heat imparted to them, and the
amount of heat taken up is dependent upon the quantity of
metal that may surround the core and its conducting power.
Shrinkage, or the contraction of castings in cooling, is provided
for by adding from one-tenth to one-eighth of an inch to each
foot in the dimensions of patterns. This is a simple matter, and
PATTERN-MAKING AND CASTING. 97
is accomplished by employing a shrink rule in laying down pat-
tern-drawings from the figured dimensions of the finished work ;
such rules are about one-hundredth part longer than the standard
scale. %
This matter of shrinkage is indeed the only condition in pat-
tern-making which is governed by anything near a constant rule,
and even shrinkage requires sometimes to be varied to suit
special cases. For small patterns whose dimensions do not exceed
one foot in any direction, rapping will generally make up for
shrinkage, and no allowance is required in the patterns, but
pattern-makers are so partial to the rule of shrinkage, as the
only constant one in their work, that they are averse to admitting
exceptions, and usually keep to the shrink rule for all pieces,
whether large or small.
Inherent or cooling strains in castings is much more intricate
than shrinkage : it is, in fact, one of the most uncertain and
obscure matters that pattern-makers and moulders have to con-
tend with. Inherent strains may weaken castings, or cause them
to break while cooling, or sometimes even after they are finished;
and in many kinds of works such strains must be carefully guarded
against, both in the preparation of designs and the arrangement
of patterns, especially for wheels and pulleys with spokes, a.nd for
struts or braces with both ends fixed. The main difficulty result-
ing from cooling strains, however, is that of castings being
warped and sprung ; this difficulty is continually present in the
foundry and machine-shop, and there is perhaps no problem
in the whole range of mechanical manipulation of which there
exists more diversity of opinion and practice than of means to pre-
venting the springing of castings. This being the case, an
apprentice can hardly hope for much information here. There
is no doubt of springing and strains in castings being the result of
constant causes that might be fully understood if it were not for
the ever-changing conditions which exist in casting, both as to
the form of pieces, the temperature and quality of metal, mode
of cooling, and so on.
Castings are of course sprung by the action of unequal strains,
caused by one part cooling or ' setting ' sooner than another.
That far all is clear, but the next step takes us into the dark.
What are the various conditions which induce irregular cooling,
and how is it to be avoided 1
Irregularity of cooling may be the result of unequal conduct-
G
98 WORKSHOP MANIPULATION,
ing power in different parts of a mould or cores, or it may be
from the varying dimensions of the castings, which contain heat
as their thickness, and give it off in the same ratio. As a rule, the
drag or bottom side of a casting cools first, especially if a
mould rests on the ground, and there is not much sand between
the castings and the earth ; this is a common cause of unequal
cooling, especially in large flat pieces. Air being a bad conductor
of heat, and the sand usually thin on the cope or top side, the
result is that the top of moulds remain quite hot, while at the
bottom the earth, being a good conductor, carries off the heat and
cools that side first, so that the iron ' sets ' first on the bottom,
afterwards cooling and contracting on the top, so that castings are
warped and left with inherent strains.
These are but a few of many influences which tend to irregular
cooling, and are described with a view of giving a clue from which
other causes may be traced out. The want of uniformity in sec-
tions which tends to irregular cooling can often be avoided without
much loss by a disposition of the metal with reference to cooling
strains. This, so far as the extra metal required to give unifor-
mity to or to balance the different sides of a casting, is a waste
which engineers are sometimes loth to consent to, and often
neglect in designs for moulded parts ; yet, as before said, the
difficulty of irregular cooling can in a great degree be counteracted
by a proper distribution of the metal, without wasting, if the
matter is properly understood. No one is prepared to make
designs for castings who has not studied the subject of cooling
strains as thoroughly as possible, from practical examples as well
as by theoretical deductions.
Draught, or the taper required to allow patterns to be drawn
readily, is another of those indefinite conditions in pattern-making
that must be constantly decided by judgment and experience. It
is not uncommon to find rules for the draught of patterns laid
down in books, but it would be difficult to find such rules applied.
The draught may be one-sixteenth of an inch to each foot of depth,
or it may be one inch to a foot of depth, or there may be no
draught whatever. Any rule, considered aside from specified
conditions, will only confuse a learner. The only plan to under-
stand the proper amount of draught for patterns is to study the
matter in connection with patterns and foundry operations.
Patterns that are deep, and for castings that require to be
parallel or square when finished, are made with the least possible
PATTERN-MAKING AND CASTING. 99
amount of draught. If a pattern is a plain form, that affords
facilities for lifting or drawing, it may be drawn without taper if
its sides are smooth and well finished. Pieces that are shallow
and moulded often should, as a matter of convenience, have as
much taper as possible ; and as the quantity of draught can be as
the depth of a pattern, we frequently see them made with a taper
that exceeds one inch to the foot of depth.
Moulders generally rap patterns as much as they will stand,
often more than they will stand ; and in providing for draught it is
necessary to take these customs into account. There is no use in
making provision to save rapping unless the rapping is to be
omitted.
Happing plates, draw-irons, and other details of pattern-making
are soon understood by observation. Perhaps the most useful
suggestion which can be given in reference to draw-irons is to
say they should be set on the under or bottom side of
patterns, instead of on the top, where they are generally placed.
A draw-plate set in this way, with a hole bored through the
pattern so as to insert draw-irons from the top, cannot pull
off, which it is apt to do if set on the top side. Every pattern
no matter how small, should be ironed, unless it is some trifling
piece, with dowel-pins, draw and rapping plates. If a system
of draw-irons is not rigidly carried out, moulders will not trouble
themselves to take care of patterns.
In conclusion, I will say on the subject of patterns and cast-
ings, that a learner must depend mainly upon what he can see and
what is explained to him in the pattern-shop and foundry. He
need never fear an uncivil answer to a proper question, applied
at the right time and place. Mechanics who have enough know-
ledge to give useful information of their business, have invari-
ably the courtesy and good sense to impart such information to
those who require it.
An apprentice should never ask questions about simple and
obvious matters, or about such things as he can easily learn
by his own efforts. The more difficult a question is, the more
pleasure a skilled man will take in answering it. In short, a
learner should carefully consider questions before asking them.
A good plan is to write them down, and when information is
wanted about casting, never go to a foundry to interrupt a
manager or moulder at melting time, nor in the morning, when
no one wants to be annoyed with questions.
100 WORKSHOP MANIPULATION.
I will, in connection with this subject of patterns and castings,
suggest a plan of learning especially applicable in such cases,
that of adopting a habit of imagining the manner of mould-
ing, and the kind of pattern used in producing each casting
that comes under notice. Such a habit becomes easy and
natural in a short time, and is a sure means of acquiring an
extended knowledge of patterns and moulding.
A pattern-maker no sooner sees a casting than he imagines
the kind of pattern employed in moulding it ; a moulder will
imagine the plan of moulding and casting a piece ; while an
engineer will criticise the arrangement, proportions, adaptation,
and general design; and if skilled, as he ought to be, will also
detect at a glance any useless expense in patterns or moulding.
(1.) Why cannot the regular working drawings of a machine be
employed to construct patterns by ? (2.) What should determine the
quality or durability of patterns ? (3.) How can the arrangement of
patterns affect certain parts of a casting ? (4.) What means can be
employed to avoid inherent strain in castings ? (5.) Why is the top of a
casting less sound than the bottom or drag side? (6.) What are cores
employed for? (7.) What is meant by venting a mould ? Explain the
difference between green and dry sand mouldings. (8.) Why is sand
employed for moulds 1 (10.) What generally causes the disarrangement
of cores in casting? (11.) Why are castings often sprang or crooked ?
(12.) What should determine the amount of draught given to patterns ?
(13). What are the means generally adopted to avoid cooling strains
in castings ?
CHAPTER XXIII.
FORGING.
WOKKSHOP processes which are capable of being systematised are
the most easy to learn. When a process is reduced to a system
it is no longer a subject of special knowledge, but comes within
general rules and principles, which enable a learner to use his
reasoning powers to a greater extent in mastering it.
To this proposition another may be added, that shop processes
may be systematised or not, as they consist in duplication, or the
FORGING. 101
performance of certain operations repeatedly in the same manner.
It has been shown in the case of patterns that there could be no
fixed rules as to their quality or the mode of constructing them,
and that how to construct patterns is a matter of special know-
ledge and skill.
These rules apply to forging, but in a different way from other
processes. Unlike pattern-making or casting, the general pro-
cesses in forging are uniform ; and still more unlike pattern-
making or casting, there is a measurable uniformity in the articles
produced, at least in machine-forging, where bolts, screws, and
shafts are continually duplicated.
A peculiarity of forging is that it is a kind of hand process,
where the judgment must continually direct the operations, one
blow determining the next, and while pieces forged may be dupli-
cates, there is a lack of uniformity in the manner of producing
them. Pieces may be shaped at a white welding heat or at a low
red heat, by one or two strong blows or by a dozen lighter blows,
the whole being governed by the circumstances of the work as it
progresses. A smith may not throughout a whole day repeat
an operation precisely in the same manner, nor can he, at the
beginning of an operation, tell the length of time required to exe-
cute it, nor even the precise manner in which he will perform it.
Such conditions are peculiar, and apply to forging alone.
I think proper to point out these peculiarities, not so much from
any importance they may have in themselves, but to suggest cri-
tical investigation, and to dissipate any preconceived opinions of
forging being a simple matter, easy to learn, and involving only
commonplace operations.
The first impressions an apprentice forms of the smith-shop
as a department of an engineering establishment is that it is a
black, sooty, dirty place, where a kind of rough unskilled labour is
performed a department which does not demand much attention.
How far this estimate is wrong will appear in after years, when
experience has demonstrated the intricacies and difficulties of
forging, and when he finds the skill in this department is more
difficult to obtain, and costs more relatively than in any other.
Forging as a branch of work requires, in fact, the highest skill,
and is one where the operation continually depends upon the
judgment of the workman, which neither power nor machines can
to any extent supplant. Dirt, hard labour, and heat deter men
from learning to forge, and create a preference for the finishing
102 WORKSHOP MANIPULATION.
shop, which in most places makes a disproportion between the
number of smiths and finishers.
Forging as a process in machine-making includes the forming
and shaping of the malleable parts of machinery, welding or
joining pieces together, the preparation of implements for forging
and finishing, tempering of steel tools, and usually case-hardening.
Considered as a process, forging may be said to relate to shaping
malleable material by blows or compression when it is rendered
soft by heating. So far as hand-tools and the ordinary hand
operations in forging, there can be nothing said that will be of
much use to a learner. In all countries, and for centuries past,
hand implements for forging have remained quite the same; and
one has only to visit any machine forging-shop to see samples
and types of standard tools. There is no use in describing
tongs, swages, anvils, punches, and chisels, when there is nothing
in their form nor use that may not be seen at a glance ; but tools
and machines for the application of motive power in forging pro-
cesses deserve more careful notice.
Forging plant consists of rolling mills, trip-hammers, steam-
hammers, drops, and punches, with furnaces, hearths, and
blowing apparatus for heating. A general characteristic of all
forging machines is that of a great force acting throughout a
short distance. Very few machines, except the largest hammers,
exceed a half-inch of working range, and in average operations
not one-tenth of an inch.
These conditions of short range and great force are best attained
by what may be termed percussion, and by machines which act
by blows instead of positive and gradual pressure; hence we find
that hand and power hammers are the most common tools among
those of the smith-shop.
To exert a powerful force acting through but a short distance,
percussive devices are much more effective and simple than those
acting by maintained or direct pressure. A hammer-head may
give a blow equal to many tons by its momentum, and absorb the
reactive force which is equal to the blow ; but if an equal force
was to be exerted by screws, levers, or hydraulic apparatus, we
can easily see that an abutment would be required to withstand
the reactive force, and that such an abutment would require a
strength perhaps beyond what ingenuity could devise.
This principle is somewhat obscure, and the nature of percussive
forces not generally considered a matter which may be illustra-
FORGING. 103
ted by considering the action of a simple hand-hammer. Few
people, in witnessing the use of a hammer, or in using one them-
selves, ever think of it as an engine giving out tons of force,
concentrating and applying power by functions which, if performed
by other mechanism, would involve trains of gearing, levers, or
screws; and that such mechanism, if employed instead of a
hammer, must lack that important function of applying force in
any direction as the will and hands may direct. A simple hand-
hammer is in the abstract one of the most intricate of mechanical
agents that is, its action is more difficult to analyse than that of
many complex machines involving trains of mechanism ; yet our
familiarity with hammers causes this fact to be overlooked, and
the hammer has even been denied a place among those mechanical
contrivances to which there has been applied the name of "mecha-
nical powers."
Let the reader compare a hammer with a wheel and axle,
inclined plane, screw, or lever, as an agent for concentrating and
applying power, noting the principles of its action first, and then
considering its universal use, and he will conclude that, if there
is a mechanical device that comprehends distinct principles, that
device is the common hammer. It seems, indeed, to be one of
those provisions to meet a human necessity, and without which
mechanical industry could not be carried on. In the manipulation
of nearly every kind of material, the hammer is continually
necessary in order to exert a force beyond what the hands may
do, unaided by mechanism to multiply their force. A carpenter
in driving a spike requires a force of from one to two tons ; a
blacksmith requires a force of from five pounds to five tons to
meet the requirements of his work ; a stonemason applies a force
of from one hundred to one thousand pounds in driving the edge
of his tools; chipping, calking, in fact nearly all mechanical
operations, consist more or less in blows, such blows being the
application of accumulated force expended throughout a limited
distance.
Considered as a mechanical agent, a hammer concentrates the
power of the arms, and applies it in a manner that meets the re-
quirements of various purposes. If great force is required, a long
swing and slow blows accomplish tons ; if but little force is
required, a short swing and rapid blows will serve the degree of
force being not only continually at control, but also the direction
in which it is applied. Other mechanism, if employed instead of
104 WORKSHOP MANIPULATION,
hammers to perform a similar purpose, would require to be com-
plicated machines, and act in but one direction or in one plane.
These remarks upon hammers are not introduced here as a
matter of curiosity, nor with any intention of following mechani-
cal principles beyond where they will explain actual manipulation,
but as a means of directing attention to percussive acting ma-
chines generally, with which forging processes, as before explained,
have an intimate connection.
Machines and tools operating by percussive action, although
they comprise a numerous class, and are applied in nearly all
mechanical operations, have never received that amount of atten-
tion in text-books which the importance of the machines and
their extensive use calls for. Such machines have not even been
set off as a class and treated of separately, although the distinc-
tion is quite clear between machines with percussive action, and
those with what may be termed direct action, both in the man-
ner of operating and in the general plans of construction. There
is, of course, no lack of formulae for determining the measure of
force, and computing the dynamic effect of percussive machines
acting against a measured or assumed resistance, and so on ; but
this is not what is meant. There are certain conditions in the
operation of machines, such as the strains which fall upon sup-
porting frames, the effect produced upon malleable material
when struck or pressed, and more especially of conditions which
may render percussive or positive acting machines applicable to
certain purposes ; but little explanation has been given which is
of value to practical men.
Machines and tools that operate by blows, such as hammers
and drops, produce effect by the impact of a moving mass by
force accumulated throughout a long range, and expending the
sum of this accumulated force on an object. The reactive force
not being communicated to nor resisted by the machine frames,
is absorbed by the inertia of the mass which gave the blow ; the
machinery required in such operations being only a weight, with
means to guide or direct it, and mechanism for connection with
motive power. A hand-hammer, for example, accumulates and
applies the force of the arm, and performs all the functions of
a train of mechanism, yet consists only of a block of metal and a
handle to guide it.
Machines with direct action, such as punches, shears, or rolls,
require first a train of mechanism of some kind to reduce the
FORGING. 105
motion from the driving power so as to attain force ; and secondly,
this force must be balanced or resisted by strong framing, shafts,
and bearings. A punching-machine, for example, must have
framing strong enough to resist a thrust equal to the force applied
to the work ; hence the frames of such machines are always a huge
mass, disposed in the most advantageous way to meet and resist
this reactive force, while the main details of a drop-machine
capable of exerting an equal force consist only of a block and
a pair of guides to direct its course.
Leaving out problems of mechanism in forging machines, the
adaptation of pressing or percussive processes is governed mainly
by the size and consequent inertia of the pieces acted upon. In
order to produce a proper effect, that is, to start the particles of
a piece throughout its whole depth at each blow, a certain pro-
portion between a hammer and the piece acted upon must be
maintained. For heavy forging, this principle has led to the con-
struction of enormous hammers for the performance of such work
as no pressing machinery can be made strong enough to execute,
although the action of such machinery in other respects would
best suit the conditions of the work. The greater share of forg-
ing processes may be performed by either blows or compression,
and no doubt the latter process is the best in most cases. Yet,
as before explained, machinery to act by pressure is much more
complicated and expensive than hammers and drops. The ten-
dency in practice is, however, to a more extensive employment
of press-forging processes.
(1.) What peculiarity belongs to the operation of forging to distinguish
it from most others? (2.) Describe in a general way what forging
operations consist in. (3.) Name some machines having percussive
action. (4.) What may this principle of operating have to do with
the framing of a machine ? (5.) If a steam-hammer were employed as a
punching-machine, what changes would be required in its framing ?
(6.) Explain the functions performed by a hand-hammer.
106 WORKSHOP MANIPULATION.
CHAPTER XXIV.
TRIP- HA MMERS.
TRIP-HAMMERS employed in forging bear a close analogy to, and
were no doubt first suggested by, hand-hammers. Being the
oldest of power-forging machines, and extensively employed, it
will be proper to notice trip-hammers before steam-hammers.
As remarked in the case of other machines treated of. there is no
use of describing the mechanism of trip-hammers ; it is presumed
that every engineer apprentice has seen trip-hammers, or can do
so; and the plan here is to deal especially with what he cannot see,
and would not be likely to learn by casual observation.
One of the peculiarities of trip-hammers as machines is the
mechanical difficulties in connecting them with the driving power,
especially in cases where there are a number of hammers to be
driven from one shaft.
The sudden and varied resistance to line shafts tends to
loosen couplings, destroy gearing, and produce sudden strains
that are unknown in other cases; and shafting arranged with the
usual proportions for transmitting power will soon fail if applied
to driving trip-hammers. Rigid connections or metal attach-
ments are impracticable, and a slipping belt arranged so as to
have the tension varied at will is the usual and almost the only
successful means of transmitting power to hammers. The motion
of trip-hammers is a curious problem ; a head and die weighing,
together with the irons for attaching them, one hundred pounds,
will, with a helve eight feet long, strike from two to three
hundred blows a minute. This speed exceeds anything that
could be attained by a direct reciprocal motion given to the ham-
mer-head by a crank, and far exceeds any rate of speed that
would be assumed from theoretical inference. The hammer-
helve being of wood, is elastic, and acts like a vibrating spring, its
vibrations keeping in unison with the speed of the tripping points.
The whole machine, in fact, must be constructed upon a principle
of elasticity throughout, and in this regard stands as an excep-
tion to almost every other known machine. The framing for
supporting the trunnions, which one without experience would
suppose should be very rigid and solid, is found to answer best
when composed of timber, and still better when this timber is
TRIP-HAMMERS. 107
laid up in a manner that allows the structure to spring and
yield. Starting at the dies, and following back through the
details of a trip-hammer to the driving power, the apprentice
may note how many parts contribute to this principle of elasticity :
First the wooden helve, both in front of and behind the trun-
nion ; next the trunnion bar, which is usually a flat section
mounted on pivot points ; third the elasticity of the framing
called the ' husk/ and finally the frictional belt. This will con-
vey an idea of the elasticity required in connecting the hammer-
head with the driving power, a matter to be borne in mind, as it
will be again referred to.
Another peculiar feature in trip-hammers is the rapidity with
which crystallisation takes place in the attachments for holding
the die blocks to the helves, where no elastic medium can be
interposed to break the concussion of the dies. Bolts to pass
through the helve, although made from the most fibrous Swedish
iron, will on some kinds of work not last for more than ten days'
use, and often break in a single day. The safest mode of attach-
ing die blocks, and the one most common, is to forge them solid,
with an eye or a band to surround the end of the helve.
At the risk of laying down a proposition not warranted by
science, I will mention, in connection with this matter of crystal-
lisation, that metal when disposed in the form of a ring, for some
strange reason seems to evade the influences which produce crystal-
line change. A hand-hammer, for example, may be worn away
and remain fibrous; the links of chains and the tires of wag-
gon wheels do not become crystallised ; even the tires on locomo-
tive wheels seem to withstand this influence, although the con-
ditions of their use are such as to promote crystallisation.
Among exceptions to the ordinary plans of constructing trip-
hammers, may be mentioned those employed in the American
Armoury at Springfield, U.S., where small hammers with rigid
frames and helves, the latter thirty inches long, forged from
Lowmoor iron, are run at a speed of ' six hundred blows a
minute.' As an example, however, they prove the necessity for
elasticity, because the helves and other parts have to be often re-
newed, although the duty performed is very light, such as making
small screws.
(1.) What limits the speed at which the reciprocating parts of
machines may act 1 (2.) What is the nature of reciprocal motion pro-
108 WORKSHOP MANIPULATION.
ducedby cranks? (3.) Can reciprocating movement be uniform in such
machines as power-hammers, saws, or pumps ? (4.) What effect as to
the rate of movement is produced by the elastic connections of a trip-
hammer 1
CHAPTER XXV.
CRANK-HAMMERS.
POWER-HAMMERS operated by crank motion, adapted to the
lighter kinds of work, are now commonly met with in the forg-
ing-shops of engineering establishments. They are usually of
very simple construction, and I will mention only two points in
regard to such hammers, which might be overlooked by an ap-
prentice in examining them.
The faces of the dies remain parallel, no matter how large
the piece may be that is operated upon, while with a trip-
hammer, the top die moves in an arc described from the trun-
nions of the helve, and the faces of the dies can only be parallel
when in one position, or when operating on pieces of a certain
depth. This feature of parallel movement with the dies of
crank-hammers is of great importance on some kinds of work,
and especially so for machine-forgings where the size or depth of
the work is continually being varied.
A second point to be noticed in hammers of this class is the
nature of the connection with the driving power. In all cases
there will be found an equivalent for the elastic helve of the
trip-hammer either air cylinders, deflecting springs, or other
yielding attachments, interposed between the crank and the
hammer-head, also a slipping frictional belt or frictional clutches
for driving, as in the case of trip-hammers.
STEAM-HAMMERS. 109
CHAPTER XXVI.
STEAM-HAMMERS.
THE direct application of steam to forging-hammers is without
doubt the greatest improvement that has ever been made in forg-
ing machinery ; not only has it simplified operations that were
carried on before this invention, but has added many branches.,
and extended the art of forging to purposes which could never
have been attained except for the steam-hammer.
The general principles of hammer-action, so far as already
explained, apply as well to hammers operated by direct steam ;
and a learner, in forming a conception of steam-hammers, must
not fall into the common error of regarding them as machines
distinct from other hammers, or as operating upon new princi-
ples. A steam-hammer is nothing more than the common ham-
mer driven by a new medium, a hammer receiving power through
the agency of steam instead of belts, shafts, and cranks. The
steam-hammer in its most improved form is so perfectly adapted
to fill the different conditions required in power-hammering, that
there seems nothing left to be desired.
Keeping in view what has been said about an elastic connec-
tion for transmitting motion and power to hammers, and cushion-
ing the vibratory or reciprocating parts, it will be seen that
steam as a driving medium for hammers fills the following con-
ditions :
First. The power is connected to the hammer by means of
the least possible mechanism, consisting only of a cylinder, a
piston, and slide valve, induction pipe and throttle valve these
few details taking the place of a steam-engine, shafts, belts,
cranks, springs, pulleys, gearing, in short, all such details as are
required between the hammer-head and the steam-boiler in the
case of trip-hammers or crank-hammers.
Second. The steam establishes the greatest possible elasticity
in the connection between a hammer and the driving power, and
at the same time serves to cushion the blows at both the top
and bottom of the stroke, or on the top only, as occasion may
require.
Third. Each blow given is an independent operation, and
110 WORKSHOP MANIPULATION.
can be repeated at will, while in other hammers such changes
can only be made throughout a series of blows by gradually in-
creasing or diminishing their force.
Fourth. There is no direct connection between the moving
parts of the hammer and the framing, except lateral guides for
the hammer-head ; the steam being interposed as a cushion in
the line of motion, this " reduces the required strength and
weight of the framing to a minimum, and avoids positive strains
and concussion.
Fifth. The range and power of the blows, as well as the
time in which they are delivered, is controlled at will; this
constitutes the greatest distinction between steam and other
hammers, and the particular advantage which has led to their
extended use.
Sixth. Power can be transmitted to steam-hammers through
a small pipe, which may be carried in any direction, and for
almost any distance, at a moderate expense, so that hammers
may be placed in such positions as will best accommodate the
work, and without reference to shafts or other machinery.
Seventh. There is no waste of power by slipping belts or
other frictional contrivances to graduate motion; and finally,
there is no machinery to be kept in motion when the hammer is
not at work.
Keeping these various points in mind, an apprentice will
derive both pleasure and advantage from tracing their applica-
tion in steam-hammers, which may come under notice, and vari-
ous modifications of the mechanism will only render investigation
more interesting.
One thing more must be noticed, a matter of some intricacy,
but without which, all that has been explained would fail to
give a proper idea of steam-hammer-action. The valve motions
are alluded to.
Steam-hammers are divided into two classes one having the
valves moved by hand, and the other class with automatic valve
movement.
The action of steam-hammers may also be divided into what
is termed elastic blows, and dead blows.
In operating by elastic blows, the steam piston is cushioned
at both the up and down stroke, and the action of a steam-ham-
mer corresponds to that of a helve trip-hammer, the steam
filling the office of a vibrating spring ; in this case a hammer
STEAM-HAMMERS. Ill
gives a quick rebounding blow, the momentum being only in part
spent upon the work, and partly arrested by cushioning on the
steam in the bottom of the cylinder under the piston.
Aside from the greater rapidity with which a hammer may
operate when working on this principle, there is nothing gained,
and much lost ; and as this kind of action is imperative in any
hammer that has a * maintained or positive connection ' between
its reciprocating parts and the valve, it is perhaps fair to
infer that one reason why most automatic hammers act with
elastic blows is either because of a want of knowledge as to a,
proper valve arrangement, or the mechanical difficulties in ar-
ranging valve gear to produce dead blows.
In working with dead blows, no steam is admitted under the
piston until the hammer has finished its down stroke, and ex-
pended its momentum upon the work. So different is the effect
produced by these two plans of operating, that on most kinds
of work a hammer of fifty pounds, working with dead blows, will
perform the same duty that one of a hundred pounds will, when
acting by elastic or cushioned blows.
This difference between dead and elastic strokes is so import-
ant that it has served to keep hand-moved valves in use in many
cases where much could be gained by employing automatic acting
hammers.
Some makers of steam-hammers have so perfected the auto-
matic class, that they may be instantly changed so as to work
with either dead blows or elastic blows at pleasure, thereby com-
bining all the advantages of both principles. This brings the
steam-hammer where it is hard to imagine a want of farther
improvement.
The valve gearing of automatic steam-hammers to fill the two
conditions of allowing a dead or an elastic blow, furnishes one of
the most interesting examples of mechanical combination.
It was stated that to give a dead or stamp stroke, the valve
must move and admit steam beneath the piston after the ham-
mer has made a blow and stopped on the work, and that such
a movement of the valve could not be imparted by any main-
tained connection between the hammer-head and valve. This
problem is met by connecting the drop or hammer-head with
some mechanism which will, by reason of its momentum, con-
tinue to ' move after the hammer-head stops.' This mechanism
may consist of various devices. Messrs Massey in England, and
112 WORKSHOP MANIPULATION,
Messrs Ferris & Miles in America, employ a swinging wiper bar,
which is by reason of its weight or inertia retarded, and does not
follow the hammer-head closely on the down stroke, but swings
into contact and opens the valve after the hammer has come to a
full stop.
By holding this wiper bar continuously in contact with the
hammer-drop, elastic or rebounding blows are given, and by
adding weight in certain positions to the wiper bar its motion is
so retarded that a hammer will act as a stamp or drop. A Ger-
man firm employs the concussion of the blow to disengage valve
gear, so that it may fall and effect this after movement of the
valves. Other engineers effect the same end by employing the
momentum of the valve itself, having it connected to the drop
by a slotted or yielding connection, which allows an independent
movement of the valve after the hammer stops.
(1.) In comparing steam-hammers with trip or crank hammers what
mechanism does steam supplant or represent ? (2.) What can be called
the chief distinction between steam and other hammers? (3.) Under
what circumstances is an automatic valve motion desirable ? (4.) Why
is a dead or uncushioned blow most effective? -(5.) Will a hammer
operate with air the same as with steam ?
CHAPTER XXVII.
COMPOUND HAMMERS.
ANOTHER principle to be noticed in connection with hammers
and forging processes is that of the inertia of the piece operated
upon a matter of no little importance in the heavier kinds of
work.
When a piece is placed on an anvil, and struck on the top side
with a certain force, the bottom or anvil side of the piece
does not receive an equal force. A share of the blow is absorbed
by the inertia of the piece struck, and the effect on the bottom
side is, theoretically, as the force of the blow, less the cushion-
ing effect and the inertia of the pieces acted upon.
COMPOUND HAMMERS. 113
In practice this difference of effect on the top and bottom, or
between the anvil and hammer sides of a piece, is much greater
than would be supposed. The yielding of the soft metal on the
top cushions the blow and protects the under side from the force.
The effect produced by a blow struck upon hot iron cannot be
estimated by the force of the blow ; it requires, to use a technical
term, a certain amount of force to " start " the iron, and any-
thing less than this force has but little effect in moving the
particles and changing the form of a piece.
From this it may be seen that there must occur a great loss of
power in operating on large pieces, for whatever force is absorbed
by inertia has no effect on the underside. By watching a
smith using a hand hammer it will be seen that whenever a piece
operated upon is heavier than the hammer employed, but little if
any effect is produced on the anvil or bottom surface, nor is
this loss of effect the only one. The expense of heating, which
generally exceeds that of shaping forgings, is directly as the
amount of shaping that may be done at each heat ; and con-
sequently, if the two sides of a piece, instead of one, can be
equally acted upon, one-half the heating will be saved.
Another object gained by equal action on both sides of large
pieces is the quality of the forgings produced, which is generally
improved by the rapidity of the shaping processes, and injured
by too frequent heating.
The loss of effect by the inertia of the pieces acted upon
increases with the weight of the work ; not only the loss of
power, but also the expense of heating increases with the size
of the pieces. There is, however, such a difference in the
mechanical conditions between light and heavy forging that for
any but a heavy class of work there would be more lost than
gained in attempting to operate on both sides of pieces at the
same time.
To attain a double effect, and avoid the loss pointed out, Mr
Ramsbottom designed what may be called compound hammers,
consisting of two independent heads or rams moving in opposite
directions, and acting simultaneously upon pieces held between
them.
It would be inferred that the arrangement of these double acting
hammers must necessarily be complicated and expensive, but the
contrary is the fact. The rams are simply two masses of iron
mounted on wheels that run on ways, like a truck, and the im-
K
114 WORKSHOP MANIPULATION.
pact of the hammers, so far as not absorbed in the work, is
neutralised by each other. No shock or jar is communicated to
framing or foundations as in the case of single acting hammers that
have fixed anvils. The same rule applies in the back stroke of
the hammers as the links which move them are connected together
at the centre, where the power is applied at right angles to the
line of the hammer movement. The links connecting the two
hammers constitute, in effect, a toggle joint, the steam piston
being attached where they meet in the centre.
The steam cylinder which moves the hammers is set in the
earth at some depth below the plane upon which they move,
and even when the heaviest work is done there is no per-
ceptible jar when one is standing near the hammers, as there
always is with those which have a vertical movement and are
single acting.
(1.) Why is the effect produced different on the top and bottom of a
piece when struck by a hammer 1 ? (2.) Why does not a compound
hammer create jar and concussion 1 (3.) What would be a mechanical
difficulty in presenting the material to such hammers ? (4.) Which is
most important, speed or weight, in the effect produced on the under
side of pieces, when struck by single acting hammers ?
CHAPTER XXVIII.
TEMPERING STEEL.
TEMPERING may be called a mystery of the smith-shop ; this
operation has that attraction which characterises every process
that is mysterious, especially such as are connected with, or belong
to mechanical manipulation. A strange and perhaps fortunate
habit of the mind is to be greatly interested in what is not well
understood, and to disregard what is capable of plain demon-
stration.
An old smith who has stood at the forge for a score of years
will take the same interest in tempering processes that a novice will.
When a piece is to be tempered which is liable to spring or break,
and the risk is great, he will enter upon it with the same zeal
and interest that he would have done when learning his trade.
TEMPERING STEEL. 115
No one has been able to explain clearly why a sudden change
of temperature hardens steel, nor why it assumes various shades
of colour at different degrees of hardness ; we only know the fact,
and that steel fortunately has such properties.
Every one who uses tools should understand how to temper
them, whether they be for iron or wood. Experiments with tem-
pered tools is the only means of determining the proper degree
of hardness, and as smiths, except with their own tools, have to
rely upon the explanations of others as to proper hardening, it
follows that tempering is generally a source of complaint.
Tempering, as a term, is used to Comprehend both hardening
and drawing ; as a process it depends mainly upon judgment
instead of skill, and has no such connection with forging as to
be performed by smiths only. Tempering requires a different
fire from those employed in forging, and also more care and pre-
cision than blacksmiths can exercise, unless there are furnaces
and baths especially arranged for tempering tools.
A difficulty which arises in hardening tools is because of the
contraction of the steel which takes place in proportion to the
change of temperature ; and as the time of cooling is in propor-
tion to the thickness or size of a piece, it follows, of course,
that there is a great strain and a tendency to break the thinner
parts before the thicker parts have time to cool ; this strain may
take place either from cooling one side first, or more rapidly than
another.
The following propositions in regard to tempering, compre-
hend the main points to be observed :
The permanent contraction of steel in tempering is as the
degree of hardness imparted to it by the bath.
The time in which the contraction takes place is as the tem-
perature of the bath and the cross section of the piece ; in
other words the heat passes off gradually from the surface to
the centre.
Thin sections of steel tools being projections from the mass
which supports the edges, are cooled first, and if provision is not
made to allow for contraction they are torn asunder.
The main point in hardening and the most that can be done
to avoid irregular contraction, is to apply the bath so that it
will act first and strongest on the thickest parts. If a piece is
tapering or in the form of a wedge, the thick end should enter
the bath first ; a cold chisel for instance that is wide enough to
] 1 6 WORKSHOP MANIPULATION.
endanger cracking should be put into the bath with the head
downward.
The upflow of currents of warmed water are a common cause
of irregular cooling and springing of steel tools in hardening ;
the water that is heated, rises vertically, and the least inclination
of a piece from a perpendicular position, allows a warm current
to flow up one side.
The most effectual means of securing a uniform effect from a
tempering bath is by violent agitation, either of the bath or the
piece ; this also adds to the rapidity of cooling.
The effect of tempering baths is as their conducting power \
chemicals except as they may contribute to the conducting
properties of a bath, may safely be disregarded. For baths,
cold or ice water loaded with salt for extreme hardness, and warm
oil for tools that are thin and do not require to be very hard, are
the two extremes outside of which nothing is required in ordi-
nary practice.
In the case of tools composed partly of iron and partly of
steel, steel laid as it is called, the tendency to crack in hardening
may be avoided in most cases by hammering the steel edge at a
low temperature until it is so expanded that when cooled in
hardening it will only contract to a state of rest and correspond
to the iron part ; the same result may be produced by curving
a piece, giving convexity to the steel side before hardening.
Tools should never be tempered by immersing their edges or
cutting parts in the bath, and then allowing the heat to " run
down " to attain a proper temper at the edge. I am well aware
that this is attacking a general custom, but it is none the less
wrong for that reason. Tools so hardened have a gradually
diminishing temper from their point or edge, so that no part
is properly tempered, and they require continual re-hardening,
which spoils the steel j besides, the extreme edge, the only part
which is tempered to a proper shade, is usually spoiled by
heating and must be ground away to begin with. No lathe-
man who has once had a set of tools tempered throughout by
slow drawing, either in an oven, or on a hot plate, will ever
consent to point hardening afterwards. A plate of iron, two
to two and one-half inches thick, placed over the top of a tool
dressing fire, makes a convenient arrangement for tempering
tools, besides adding greatly to the convenience of slow heating,
which is almost as important as slow drawing. The writer has
TEMPERING STEEL. 117
by actual experiment determined that the amount of tool dressing
and tempering, to say nothing of time wasted in grinding tools,
may in ordinary machine fitting be reduced one-third by " oven
tempering."
As to the shades that appear in drawing temper, or tempering
it is sometimes called, it is quite useless to repeat any of the old
rules about " straw colour, violet, orange, blue," and so on ; the
learner knows as much after such instruction as before. The
shades of temper must be seen to be learned, and as 110 one is
likely to have use for such knowledge before having opportunities
to see tempering performed, the following plan is suggested for
learning the different shades. Procure eight pieces of cast
steel about two inches long by one inch wide and three-eighths of
an inch thick, heat them to a high red heat and drop them into
a salt bath ; preserve one without tempering to show the white
shade of extreme hardness, and polish one side of each of the
remaining seven pieces ; then give them to an experienced work-
man to be drawn to seven varying shades of temper ranging
from the white piece to the dark blue colour of soft steel. On
the backs of these pieces labels can be pasted describing the
technical names of the shades and the general uses to which 'tools
of corresponding hardness are adapted.
This will form an interesting collection of specimens and
accustom the eye t6 the various tints, which after some experience
will be instantly recognised when seen separately.
It may be remarked as a general rule that the hardness of
cutting tools is " inverse as the hardness of the material to be
cut," which seems anomalous, and no doubt is so, if nothing but
the cutting properties of edges is considered ; but all cutting edges
are subjected to transverse strain, and the amount of this strain
is generally as the hardness of the material acted upon ; hence
the degree of temper has of necessity to be such as to guard
against breaking the edges. Tools for cutting wood, for example,
can be much harder than for cutting iron, or to state it better,
tools for cutting wood are harder than those usually employed
for cutting iron ; for if iron tools were always as carefully formed
and as carefully used as those employed in cutting wood, they
could be equally hard.
Forges, pneumatic machinery for blast, machinery for hand-
ling large pieces, and other details connected with forging, are
easily understood from examples.
118 WORKSHOP MANIPULATION.
(1.) What causes tools to bend or break in hardening ? (2.) What
means can be employed to prevent injury to tools in hardening ? (3.)
Can the shades of temper be produced on a piece of steel without
hardening ? (4.) What forms a limit of hardness for cutting tools ?
(5.) What are the objects of steel-laying tools instead of making them of
solid steel ?
CHAPTER XXIX.
FITTING AND FINISHING.
THE fitting or finishing department of engineering establishments
is generally regarded as the main one.
Fitting processes, being the final ones in constructing machin-
ery, are more nearly in connection with its use and application \
they consist in the organisation or bringing together the results
of other processes carried on in the draughting room, pattern
shop, foundry, and smith shop.
To the unskilled, or to those who do not take a comprehen-
sive view of an engineering business as a whole, the finishing
and fitting department seems to constitute the whole of machine
manufacture an impression which a learner should guard against,
because nothing but a true understanding of the importance and
relations of the different divisions of an establishment can enable
them to be thoroughly or easily learned.
Finishing, therefore, it must be borne in mind, is but one
among several processes, and that the fitting department is but
one out of four or more among which attention is to be divided.
Finishing as a process is a secondary and not always an
essential one ; many parts of machinery are ready for use when
forged or cast and do not require fitting ; yet a finishing shop
must in many respects be considered the leading department
of an ehgineering establishment. Plans, drawings and esti-
mates are always based on finished work, and when the parts
have accurate dimensions; hence designs, drawings and estimates
may be said to pass through the fitting shop and follow back to
the foundry and smith shop, so that finishing, although the last
process in the order of the work, is the first one after the draw-
ings in every other sense even the dimensions in pattern-making
which seems farthest removed from finishing, are based upon
FITTING AND FINISHING. 119
fitting dimensions, and to a great extent must be modified by
the conditions of finishing.
In casting and forging operations the material is treated while
in a heated and expanded condition ; the nature of these opera-
tions is such that accurate dimensions cannot be attained, so that
both forgings and castings require to be made enough larger than
their finished dimensions to allow for shrinkage and irregularities.
Finishing as a process consists in cutting away this surplus ma-
terial, and giving accurate dimensions to the parts of machinery
when the material is at its natural temperature. Finishing oper-
ations being performed as said upon material at its normal temper-
ature permits handling, gauging and fitting together of the parts
of machinerjr, and as nearly all other processes involve heating,
finishing may be called the cold processes of metal work.
The operations of a fitting shop consist almost entirely of
cutting, and grinding or abrading ; a proposition that may seem
novel, yet these operations comprehend nearly all that is performed
in what is called fitting.
Cutting processes may be divided into two classes : cylindrical
cutting, as in turning, boring, and drilling, to produce circular
forms; and plane cutting, as in planing, shaping, slotting and
shearing, to produce plane or rectangular forms. Abrading or
grinding processes may be applied to forms of any kind.
To classify further cutting machines may be divided into those
wherein the tools move and the material is fixed, and those
wherein the material is moved and the tools fixed, and machines
which involve a compound movement of both the tools and the
material acted upon.
There is also a distinction between machine and hand cutting
that may be noted. In machine cutting it is performed in true
geometrical lines, the tools or material being moved by positive
guides as in planing and turning ; in hand operations, such as
filing, scraping or chipping, the tools are moved without positive
guidance, and act in irregular lines.
To attempt a generalisation of the operations of the fitting
shop in this manner may not seem a very practical means of
understanding them, yet the application will be better understood
as we go farther on.
Cutting tools include nearly all that are employed in finishing ;
lathes, planing machines, drilling and boring machines, shaping,
slotting and milling machines, come within this class. The
120 WORKSHOP MANIPULATION.
machines named make up what are called standard tools, such as
are essential and are employed in all establishments where general
machine manufacture is carried on. Such machines are constructed
upon principles substantially the same in all countries, and have
settled into a tolerably uniform arrangement of movements and
parts.
Besides the machine tools named, there are special machines to
be found in most works, machines directed to the performance
of certain work ; by a particular adaptation such machines are
rendered more effective, but they are by such adapation unfitted
for general purposes.
General engineering work cannot consist in the production of
duplicate pieces, nor in operations performed constantly in the
same manner as in ordinary manufacturing ; hence there has been
much effort expended in adapting machines to general purposes
machines, which seldom avoid the objections of combination,
pointed out in a previous chapter.
The principal improvements and changes in machine fitting at
the present time is in the application of special tools. A lathe,
a planing machine, or drilling machine as a standard machine,
must be adapted to a certain range of work, but it is evident
that if such tools were specially arranged for either the largest
or the smallest pieces that come within their capacity, more
work could be performed in a given time and consequently at
less expense. It is also evident that machine tools must be
kept constantly at work in order to be profitable, and when
there are not sufficient pieces of one kind to occupy a machine,
it must be employed on various kinds of work ; but whenever
there are sufficient pieces of the same size upon which certain
processes of a uniform character are to be performed, there is
a gain by having machines constructed to conform as nearly
as possible to the requirements of special work, and without
reference to any other.
It is now proposed to review the standard tools of a fitting
shop, noticing the general principles of their construction and
especially of their operation ; not by drawings nor descriptions
to show what a lathe or a planing machine is, nor how some
particular engineer has constructed such tools, but upon the
plan explained in the introduction, presuming the reader to be
familiar with the names and purposes of standard machine tools.
If he has not learned this much, and does not understand the
TURNING LATHES. 121
names and general objects of the several operations carried on
in a fitting shop, he should proceed to acquaint himself thus
far before troubling himself with books of any kind.
(1.) Why cannot the parts of machinery be made to accurate dimen-
sions by forging or casting ? (2.) What is the difference between hand
tool and machine tool operation as to truth ? (3.) Why cannot hand-
work be employed in duplicating the parts of machinery ? (4.) What
is the difference between standard and special machine tools ?
CHAPTER XXX.
TURNING LATHES.
Ix machinery the ruling form is cylindrical ; in structures other
than machinery, those which do not involve motion, the ruling
form is rectangular.
Machine motion is mainly rotary ; and as rotary motion is
accomplished by cylindrical parts such as shafts, bearings, pulleys
and wheels, we find that the greater share of machine tools are
directed to preparing cylindrical forms. If we note the area of
the turned, bored and drilled surface in ordinary machinery, and
compare with the amount of planed surface, we will find the
former not less than as two to one in the finer class of machinery,
and as three to one in the coarser class ; from this may be esti-
mated approximately the proportion of tools required for ope-
rating on cylindrical surfaces and plane surfaces ; assuming the
cutting tools to have the same capacity in the two cases, the
proportion will be as three to one. This difference between the
number of machines required for cylindrical and plane surfaces
is farther increased, when we consider that tools act continually
on cylindrical surfaces and intermittently on plane surfaces.
In practice, the truth of this proposition is fully demonstrated
by the excess in the number of lathes and boring tools compared
with those for planing.
An engine lathe is for many reasons called the master tool in
machine fitting. It is not only the leading tool so far as per-
forming a greater share of the work ; but an engine lathe as an
organised machine combines, perhaps, a greater number of useful
122 WORKSHOP MANIPULATION.
and important functions, than any machine which has ever been
devised. A lathe may be employed to turn, bore, drill, mill, or
cut screws, and with a strong screw r -feed may be employed to
some extent for planing; what is still more strange, notwith-
standing these various functions, a lathe is comparatively a
simple machine without complication or perishable parts, and
requires no considerable change in adapting it to the various
purposes named.
For milling, drilling or boring ordinary work within its range,
a lathe is by no means a makeshift tool, but performs these
various operations with nearly all the advantages of machines
adapted to each purpose. An ingenious workman who under-
stands the adaptation of a modern engine lathe can make almost
any kind of light machinery without other tools, except for
planing, and may even perform planing when the surfaces are
not too large ; in this way machinery can be made at an expense
not much greater than if a full equipment of different tools is
employed. This of course can only be when no division of labour
is required, and when one man is to perform all the several
processes of turning, drilling, and so on.
The lathe as a tool for producing heliacal forms would occupy
a prominent place among machine tools, if it were capable of per-
forming no other work ; the number of parts of machinery which
have screw-threads is astonishing ; clamping-bolts to hold parts
together include a large share of the fitting on machinery of all
kinds, while screws are the most common means for increasing
power, changing movements and performing adjustments.
A finisher's engine lathe consists essentially of a strong inflexi-
ble shear or frame, a running spindle with from eight to sixteen
changes of motion, a sliding head, or tail stock, and a sliding
carriage to hold and move the tools.
For a half century past no considerable change has been made
in engine lathes, at least no new principle of operation has been
added, but many improvements have been made in their adapta-
tion and capacity for special kinds of work. Improvements have
been made in the facilities for changing wheels in screw cutting
and feeding, by frictional starting gear for the carriages, an
independent feed movement for turning, arrangements to adjust
tools, cross feeding and so on, adding something, no doubt,
to the efficiency of lathes ; but the improvements named have
been mainly directed to supplanting the skill of lathemen.
TURNING LATHES. 123
A proof of this last proposition is found in the fact that a
thorough hitheman will perform nearly as much work and do it
as well on an old English lathe with plain screw feed, as can be
performed on the more complicated lathes of modern construc-
tion ; but as economy of skill is sometimes an equal or greater
object than a saving of manual labour, estimates of tool capacity
should be made accordingly. The main points of a lathe, such
as may most readily affect its performance, are first truth in
the bearings of the running spindle which communicates a dupli-
cate of its shape to pieces that are turned, second, coincidence
between the line of the spindle and the movement of the carriage,
third, a cross feed of the tool at a true right angle to the spindle
and carriage movement, fourth, durability of wearing surfaces,
especially the spindle bearings and sliding ways. To these may
be added many other points, such as the truth of feeding screws,
rigidity of frames, and so on, but such requirements are obvious.
To avoid imperfection in the running spindles of lathes, or
any lateral movement which might exist in the running bearings,
there have been many attempts to construct lathes with still
centres at both ends for the more accurate kinds of work. Such
an arrangement would produce a true cylindrical rotation, but
must at the same time involve mechanical complication to
outweigh the object gained. It has besides been proved by prac-
tice that good fitting and good material for the bearings and
spindles of lathes will insure all the accuracy which ordinary work
demands.
It may be noticed that the carriages of some lathes move on
what are termed V tracks which project above the top of lathe
frames, and that in other lathes the carriages slide on top of the
frames with a flat bearing. As these two plans of mounting
lathe carriages have led to considerable discussion on the part
of engineers, and as its consideration may suggest a plan of
analysing other problems of a similar nature, I will notice some
of the conditions existing in the two cases, calling the different
arrangements by the names of flat shears and track shears.
These different plans will be considered first in reference to the
effect produced upon the movement of carriages ; this includes
friction, endurance of wear, rigidity of tools, convenience of
operating and the cost of construction. The cutting point in both
turning and boring on a slide lathe is at the side of a piece, or nearly
level with the lathe centres, and any movement of a carriage
124 WORKSHOP MANIPULATION.
horizontally across the lathe affects the motion of the tool and
the shape of the piece acted upon, directly to the extent of such
deviation, so that parallel turning and boring depend mainly
upon avoiding any cross movement or side play of a carriage.
This, in both theory and practice, constitutes the greatest differ-
ence between flat top and track shears ; the first is arranged
especially to resist deviation in a vertical plane, which is of
secondary importance, except in boring with a bar ; the second
is arranged to resist horizontal deviation, which in nine-tenths
of the work done on lathes becomes an exact measure of the in-
accuracy of the work performed.
A true movement of carriages is dependent upon the amount
or wearing power of their bearing surface, how this surface is
disposed in reference to the strain to be resisted, and the condi-
tions under which the sliding surfaces move ; that is, how kept
in contact. The cutting strain which is to be mainly considered,
falls usually at an angle of thirty to forty degrees downward
toward the front, from the centre of the lathe. To resist such
strain a flat top shear presents no surface at right angles to the
strain; the bearings are all oblique, and not only this, but all
horizontal strain falls on one side of the shear only ; for this
reason, flat top shears have to b$ made much heavier than
would be required if the sum of their cross section could be em-
ployed to resist transverse strain. This difficulty can, however,
be mainly obviated by numerous cross girts, which will be found
in most lathe frames having flat tops.
A carriage moving on angular ways always moves steadily and
easily, without play in any direction until lifted from its bearing,
which rarely happens, and its lifting is easily opposed by adjust-
able gibs. A carriage on a flat shear is apt to have play in a
horizontal direction because of the freedom which must exist to
secure easy movement. In the case of tracks, it may also be
mentioned that the weight of a carriage acts as a constant force
to hold it steady, while with a flat shear the weight of a carriage
is in a sense opposed to the ways, and has no useful effect in
steadying or guiding. The rigidity and steadiness of tool move-
ment is notoriously in favour of triangular tracks, so much so that
nearly all American machine tool-makers construct lathes in this
manner, although it adds no inconsiderable cost in fitting.
It may also be mentioned that lathes constructed with angular
guides, have usually such ways for the moving heads as well
TURNING LATHES. 125
as for the carriages ; this gives the advantage of firmly bindii] ) g/ : ^e-
two sides of the frame together in fastening the moving %f ad,
which in effect becomes a strong girt across the frame ; the car-
riages also have an equal and independent hold on both
a shear. In following this matter thus far, it may be
many conditions may have to be considered in reasoning ?
so apparently simple a matter as the form of ways for lathe
riages ; we might even go on to many more points that have not
been mentioned ; but what has been explained will serve to
show that the matter is not one of opinion alone, and that with-
out practical advantages, machine tool-makers will not follow the
most expensive of these two modes of mounting lathe carriages.
Lathes in common use for machine fitting are screw-cutting
engine lathes, lathes for turning only, double-geared, single-
geared, and back-geared lathes, lathes for boring, hand-lathes,
and pulley-turning lathes ; also compound lathes with double
heads and two tool carriages.
These various lathes, although of a widely varied construction
and adapted to uses more or less dissimilar, are still the engine
lathe either with some of its functions omitted to simplify and
adapt it to some special work, or with some of the operative parts
compounded to attain greater capacity.
In. respect to lathe manipulation, which is perhaps the most
difficult to learn of all shop operations, the following hints are
given, which may prove of service to a learner: At the begin-
ning the form of tools should be carefully studied ; this is one of
the great points in lathe work ; the greatest distinction between
a thorough and indifferent latheman is that one knows the
proper form and temper of tools and the other does not. The
adjustment and presenting of tools is soon learned by experience,
but the proper form of tools is a matter of greater difficulty.
One of the first things to study is the shape of cutting edges, both
as to clearance below the edge of the tool, and the angle of the
edge, with reference to both turning and boring, because the
latter is different from turning. The angle of lathe tools is
clearly suggested by diagrams, and there is no better first lesson
in drawing than to construct diagrams of cutting angles for
plane and cylindrical surfaces.
A set of lathe tools should consist of all that are required
for every variety of work performed, so that no time will be
lost by waiting to prepare tools after they are wanted. An
126 WORKSHOP MANIPULATION.
ordinary engine lathe, operating on common work not exceeding
twenty inches of diameter, will require from twenty -five to thirty-
five tools, which will serve for every purpose if they are kept in
order and in place. A workman may get along with ten tools or
even less, but not to his own satisfaction, nor in a speedy way.
Each tool should be properly tempered and ground, ready for
use ' when put away;' if a tool is broken, it should at once be
repaired, no matter when it is likely to be again used. A work-
man who has pride in his tools will always be supplied with as
many as he requires, because it takes no computation to prove
that fifty pounds of extra cast steel tools, as an investment, is but
a small matter compared to the gain in manipulation by having
them at hand.
To an experienced mechanic a single glance at the tools on a
lathe is a sufficient clue to the skill of the operator. If the tools
are ground ready to use, of the proper shape, and placed in order
so as to be reached without delay, the latheman may at once be set
down as having two of the main qualifications of a first-class
workman, which are order, and a knowledge of tools ; while on
the contrary, a lathe board piled full of old waste, clamp bolts,
and broken tools, shows a want of that system and order, without
which no amount of hand skill can make an efficient workman.
It is also necessary to learn as soon as possible the technical-
ities pertaining to lathe work, and still more important to learn
the conventional modes of performing various operations.
Although lathe work includes a large range of operations which
are continually varied, yet there are certain plans of performing
each that has by long custom become conventional ; to gain an
acquaintance with these an apprentice should watch the practice
of the best workmen, and follow their plans as near as he can,
not risking any innovation or change until it has been very
carefully considered. Any attempt to introduce new methods,
modes of chucking work, setting and grinding tools, or other of
the ordinary operations in turning, may not only lead to awkward
mistakes, but will at once put a stop to useful information that
might otherwise be gained from others. The technical terms
employed in describing lathe work are soon learned, generally
sooner than they are needed, and are often misapplied, which is
worse than to be ignorant of them.
In cutting screws it is best not to refer to that mistaken con-
venience called a wheel list, usually stamped on some part of
TURNING LATHES. 127
engine lathes to aid in selecting wheels. A screw to be cut is to
the lead screw on a lathe as the wheel on the screw is to the
wheel on the spindle, and every workman should be familiar with
so simple a matter as computing wheels for screw cutting, when
there is but one train of wheels. Wheels for screw cutting may
be computed not only quite as soon as read from an index, but
the advantage of being familiar with wheel changes is very
important in other cases, and frequently such combinations have
to be made when there is not an index at hand.
The following are suggested as subjects which may be studied
in connection with lathes and turning : the rate of cutting move-
ment on iron, steel, and brass ; the relative speed of the belt
cones, whether the changes are by a true ascending scale from
the slowest ; the rate of feed at different changes estimated like
the threads of a screw at so many cuts per inch ; the proportions
of cone or step pulleys to insure a uniform belt tension, the
theory of the following rest as employed in turning flexible
pieces, the difference between having three or four bearing
points for centre or following rests ; the best means of testing
the truth of a lathe. All these matters and many more are
subjects not only of interest but of use in learning lathe
manipulation, and their study will lead to a logical method of
dealing with problems which will continually arise.
The use of hand tools should be learned by employing them
on every possible occasion. A great many of the modern im-
provements in engine lathes are only to evade hand tool work,
and in many cases effect no saving except in skill. A latheman
who is skilful with hand tools will, on many kinds of light work,
perform more and do it better on a hand lathe than an engine
lathe ; there is always more or less that can be performed
to advantage with hand tools even on the most elaborate engine
lathes.
It is no uncommon thing for a skilled latheman to lock the
slide rest, and resort to hand tools on many kinds of work when
he is in a hurry.
(1.) Why does machinery involve so many cylindrical forms ? (2.)
Why is it desirable to have separate feed gear for turning and
screw cutting? (3.) What is gained by the frictional starting gearing
now applied to the nner class of lathes ? (4.) How may the alignment
of a lathe be tested 1 (5.) What kind of deviation with a lathe carriage
will most aiFect the truth of work performed ? (6.) How may an oval
128 WORKSHOP MANIPULATION.
hole be bored on a common slide lathe ? (7.) How can the angular
ways of a lathe and the corresponding grooves in a carriage be planed to
fit without employing gauges ? (8.) Give the number of teeth in two
wheels to cut a screw of ten threads, when a leading screw is four threads
per inch?
CHAPTER XXXI.
PLANING OR RECIPROCATING MACHINES.
THE term planing should properly be applied only to machines
that produce planes or flat surfaces, but the technical use of the
term includes all cutting performed in right lines, or by what
may be called a straight movement of tools.
As no motion except rotary can be continuous, and as rotary
movement of tools is almost exclusively confined to shaping
cylindrical pieces, a proper distinction between machine tools
which operate in straight lines, and those which operate with
circular movement, will be to call them by the names of rotary
and reciprocating.
It may be noticed that all machines, except milling machines,
which act in straight lines and produce plane surfaces have
reciprocating movement ; the class includes planing, slotting and
shaping machines ; these, with lathes, constitute nearly the whole
equipment of an ordinary fitting shop.
It is strange, considering the simplicity of construction and
the very important office filled by machines for cutting on plane
surfaces, that they were not sooner invented and applied in metal
work. Many men yet working at finishing, can remember when
all flat surfaces were chipped and filed, and that long after engine
lathes had reached a state of efficiency and were generally
employed, planing machines were not known. This is no doubt
to be accounted for in the fact that reciprocal movement, except
that produced by cranks or eccentrics, was unknown or regarded
as impracticable for useful purposes until late years, and when
finally applied it was thought impracticable to have such move-
ments operate automatically. This may seem quite absurd to
even an apprentice of the present time, yet such reciprocating
movement, as a mechanical problem, is by no means so simple
as it may at first appear.
PLANING OR RECIPROCATING MACHINES. 129
A planing machine platen, for instance, moves at a uniform
rate of speed each way, and by its own motion shifts or reverses
the driving power at each extreme of the stroke. Presuming
that there were no examples to be examined, an apprentice
would find many easier problems to explain than how a planing
machine can shift its own belts. If a platen or table disengages
the power that is moving it, the platen stops ; if the momentum
carries it enough farther to engage or connect other mechanism
to drive the platen in the opposite direction, the moment such
mechanism comes into gear the platen must stop, and no move-
ment can take place to completely engage clutches or shift belts.
This is a curious problem that will be referred to again.
Reciprocating tools are divided into those wherein the cutting
movement is given to the tools, as in shaping and slotting
machines, and machines wherein the cutting movement is given
to the material to be planed, as in a common planing machine.
Yery strangely we find in general practice that machine tools
for both the heaviest and the lightest class of work, such as
shaping, and butting, operate upon the first principle, while pieces
of a medium size are generally planed by being moved in con-
tact with stationary tools.
This problem of whether to move the material or to move the
tools in planing, is an old one ; both opinion and practice
vary to some extent, yet practice is fast settling down into con-
stant rules.
Judged upon theoretical grounds, and leaving out the
mechanical conditions of operation, it would at once be con-
ceded that a proper plan would be to move the lightest body ;
that is, if the tools and their attachments were heavier than the
material to be acted upon, then the material should be moved
for the cutting action, and vice versa. But in practice there are
other conditions to be considered more important than a
question of the relative weight of reciprocating parts ; and it
must be remembered that in solving any problem pertaining to
machine action, the conditions of operation are to be con-
sidered first and have precedence over problems of strain,
arrangement, or even the general principles of construction ; that
is, the conditions of operating must form a base from which
proportions, arrangements, arid so on, must be deduced. A stan-
dard planing machine, such as is employed for most kinds of
work, is arranged with a running platen or -carriage upon which
I
130 WORKSHOP MANIPULATION.
the material is fastened and traversed beneath the cutting tools.
The uniformity of arrangement and design in machines of this
kind in all countries wherever they are made, must lead to the
conclusion that there are substantial reasons for employing
running platens instead of giving a cutting movement to the
tools.
A planing machine with a running platen occupies nearly
twice as much floor space, and requires a frame at least one-
third longer than if the platen were fixed and the tools performed
the cutting movement. The weight which has to be traversed,
including the carriage, will in nearly all cases exceed what it
would be with a tool movement ; so that there must exist some
very strong reasons in favour of a moving platen, which I will
now attempt to explain, or at least point out some of the more
prominent causes which have led to the common arrangement of
planing machines.
Strains caused by cutting action, in planing or other
machines, fall within and are resisted by the framing ; even
when the tools are supported by one frame and the material by
another, such frames have to be connected by means of founda-
tions which become a constituent part of the framing in such
cases.
Direct action and reaction are equal ; if a force is exerted in
any direction there must be an equal force acting in the opposite
direction ; a machine must absorb its own strains.
Keeping this in view, and referring to an ordinary planing
machine with which the reader is presumed to be familiar, the
focal point of the cutting strain is at the edge of the tools, and
radiates from this point as from a centre to the various parts of
the machine frame, and through the joints fixed and movable
between the tools and the frame ; to follow back from this cutting
point through the mechanism to the frame proper; first starting
with the tool and its supports and going to the main frame;
then starting from the material to be planed, and following back
in the other direction, until we reach the point where the
strains are absorbed by the main frame, examining the joints
which intervene in the two cases, there will appear some reasons
for running carriages.
Beginning at the tool there is, first, a clamped joint between
the tool and the swing block; second, a movable pivoted joint
between the block and shoe piece ; third, a clamped joint between
PLANING OR RECIPROCATING MACHINES. 131
the shoe piece and the front saddle ; fourth, a moving joint
where the front saddle is gibed to the swing or quadrant plate ;
fifth, a clamp joint between the quadrant plate and the main
saddle ; sixth, a moving joint between the main saddle and the
cross head ; seventh, a clamp joint between the cross head and
standards ; and eighth, bolted joints between the standards and
the main frame ; making in all eight distinct joints between the
tool and the frame proper, three moving, four clamped, and one
bolted joint.
Starting again from the cutting point, and going the other
way from the tool to the frame, there is, first, a clamped and
stayed joint between the material and platen, next, a running
joint between the platen and frame ; this is all ; one joint that
is firm beyond any chance of movement, and a moving joint
that is not held by adjustable gibs, but by gravity; a force
which acts equally at all times, and is the most reliable means
of maintaining a steady contact between moving parts.
Reviewing these mechanical conditions, we may at once see
sufficient reasons for the platen movement of planing machines ;
and that it would be objectionable, if not impossible, to add a
traversing or cutting action to tools already supported through
the medium of eight joints. To traverse for cutting would require
a moving gib joint in place of the bolted one, between the
standards and main frame, leading to a complication of joints
and movements quite impracticable.
These are, however, not the only reasons which have led to a
running platen for planing machines, although they are the most
important.
If a cutting movement were performed by the tool supports, it
would necessarily follow that the larger a piece to be planed,
and the greater the distance from the platen to the cutting point,
the farther a tool must be from its supports ; a reversal of the
conditions required ; because the heavier the work the greater
the cutting strain will be, and the tool supports less able to
withstand the strains to be resisted.
It may be assumed that the same conditions apply to the
standards of a common planing machine, but the case is dif-
ferent ; the upright framing is easily made strong enough by
increasing its depth ; but the strain upon running joints is as
the distance from them at which a force is applied, or to employ
a technical phrase, as the amount of overhang. With a moving
132 WORKSHOP MANIPULATION,
platen the larger and heavier a piece to be planed, the more firmly
a platen is held down ; and as the cross section of pieces usually
increases with their depth, the result is that a planing machine
properly constructed will act nearly as well on thick as thin
pieces.
The lifting strain at the front end of a platen is of course in-
creased as the height at which the cutting is done above its top,
but this has not in practice been found a difficulty of any im-
portance, and has not even required extra length or weight of
platens beyond what is demanded to receive pieces to be planed
and to resist flexion in fastening heavy work. The reversing
movement of planing machine platens already alluded to is one
of the most complex problems in machine tool movement.
Platens as a rule run back at twice the forward or cutting
movement, and as the motion is uniform throughout each
stroke, it requires to be stopped at the extremes by meeting
some elastic or yielding resistance which, to use a steam phrase,
" cushions " or absorbs the momentum, and starts the platen back
for the return stroke.
This object is attained in planing machines by the friction of
the belts, which not only cushions the platen like a spring, but
in being shifted opposes a gradually increasing resistance until
the momentum is overcome and the motion reversed. By
multiplying the movement of the platen with levers or other
mechanism, and by reason of the movement that is attained by
momentum after the driving power ceases to act, it is found
practicable to have a platen ' shift its own belts/ a result that
would never have been reached by theoretical deductions, and was
no doubt discovered by experiment, like the automatic movement
of engine valves is said to have been.
It is not intended to claim that this platen-reversing motion
cannot, like any other mechanical movement, be resolved mathe-
matically, but that the mechanical conditions are so obscure and
the invention made at a time that warrants the supposition of
accidental discovery.
In the driving gearing of planing machines, conditions which
favour the reversing movement are high speed and narrow
driving belts. The time in which belts may be shifted is as
their speed and width ; to be shifted a belt must be deflected or
bent edgewise, and from this cause wind spirally in order to
pass from one pulley to another. To bend or deflect a belt edge-
PLANING OR RECIPROCATING MACHINES. 133
wise there will be required a force in proportion to its width, and
the time of passing from one pulley to another is as the number
of revolutions made by the pulleys.
Planing machines of the most improved construction are driven
by two belts instead of one, and many mechanical expedients
have been adopted to move the belts differentially, so that both
should not be on the driving pulley at the same time, but
move one before the other in alternate order. This is easily
attained by simply arranging the two belts with the distance
between them equal to one and one-half or one and three-fourth
times the width of the driving pulley. The effect is the same as
that accomplished by differential shifting gearing, with the ad-
vantage of permitting an adjustment of the relative movement of
the belts.
Another principle in planing machines which deserves notice
is the manner of driving carriages or platens ; this is usually
performed by means of "spur wheels and a rack. A rack move-
ment is smooth enough, and effective enough so far as a mechani-
cal connection between the driving gearing and a platen, but
there is a difficulty met with from the torsion and elasticity of
cross-shafts and a train of reducing gearing. In all other
machines for metal cutting, it has been a studied object to have
the supports for both the tools and the material as rigid as
possible ; but in the common type of planing machines, such as
have rack and pinion movement, there is a controversion of this
principle, inasmuch as a train of wheels and several cross-shafts
constitute a very effective spring between the driving power and
the point of cutting, a matter that is easily proved by planing
across the teeth of a rack, or the threads of a screw, on a machine
arranged with spur wheels and the ordinary reducing gearing.
It is true the inertia of a platen is interposed and in a measure
overcomes this elasticity, but in no degree that amounts to a
remedy.
A planing machine invented by Mr Bodmer in 1841, and
since improved by Mr William Sellers of Philadelphia, is free
from this elastic action of the platen, which is moved by a tangent
wheel or screw pinion. In Bodmer' s machine the shaft carrying
the pinion was parallel to the platen, but in Sellers' machine is set
on a shaft with its axis diagonal to the line of the platen move-
ment, so that the teeth or threads of the pinion act partly by a
screw motion, and partly by a progressive forward movement
134 WORKSHOP MANIPULATION.
like the teeth of wheels. The rack on the platen of Mr Sellers'
machine is arranged with its teeth at a proper angle to balance
the friction arising from the rubbing action of the pinion, which
angle has been demonstrated as correct at 5, the ordinary co-
efficient of friction ; as the pinion-shaft is strongly supported
at each side of the pinion, and the thrust of the cutting force
falls mainly in the line of the pinion shaft, there is but little if
any elasticity, so that the motion is positive and smooth.
The gearing of these machines is alluded to here mainly for
the purpose of calling attention to what constitutes a new and
singular mechanical movement, one that will furnish a most
interesting study, and deserves a more extended application in
producing slow reciprocating motion.
(1.) Can the driving power be employed directly to shift the belts of a
planing machine ? (2.) Why are planing machines generally con-
structed with a running carriage instead of running tools'? (3.) What
objection exists in employing a train of spur wheels to drive a planing
machine carriage 1 (4.) What is gained by shifting the belts of a plan-
ing machine differentially ? (5.) What produces the screeching of belts
so common with planing machines ? (6.) What conditions favour the
shifting of planing machine belts ?
CHAPTER XXXII.
SL O TTING MA CHINES.
SLOTTING machines with vertical cutting movement differ from
planing machines in several respects, to which attention may be
directed. In slotting, the tools are in most cases held rigidly
and do not swing from a pivot as in planing machines. The
tools are held rigidly for two reasons ; because the force of
gravity cannot be employed to hold them in position at starting,
and because the thrust or strain of cutting falls parallel, and not
transverse to the tools as in planing. Another difference
between slotting and planing is that the cutting movement is
performed by the tools and not by movement of the material.
The cutting strains are also different, falling at right angles to
the face of the table, in the same direction as the force of gravity,
SHAPING MACHINES. 135
and not parallel to the face of the table, as in planing and
shaping machines.
The feed motion in slotting machines, because of the tools
being held rigidly, has to operate differently from that of planing
machines. The cross-feed of a planing machine may act during
the return stroke, but in slotting machines, the feed movement
should take place at the end of the up- stroke, or after the tools
are clear of the material ; so much of the stroke as is made
during the feeding action is therefore lost; and because of this,
mechanism for operating the feed usually has a quick abrupt
action so as to save useless movement of the cutter bar.
The relation between the feeding and cutting motion of
reciprocating machines is not generally considered, and forms an
interesting problem for investigation.
(1.) Name some of the differences between planing arid slotting
machines. (2.) Why should the feed motion of a slotting machine act
abruptly ? (3.) To what class of work are slotting machines especially
adapted ?
CHAPTER XXXIII.
SHAPING MACHINES.
SHAPING machines as machine tools occupy a middle place
between planing and slotting machines ; their movements cor-
respond more to those of slotting machines, while the operation
of the tools is the same as in planing. Some of the advantages
of shaping over planing machines for certain kinds of work are,
because of the greater facilities afforded for presenting and
holding small pieces, or those of irregular shape ; the supports or
tables having both vertical and horizontal faces to which pieces
may be fastened, and the convenience of the mechanism for
adjusting and feeding tools.
Shaping machines are generally provided with adjustable
vices, devices for planing circular forms, and other details which
cannot be so conveniently employed with planing machines.
Another feature of shaping machines is a positive range of the
cutting stroke produced by crank motion, which permits tools to
136 WORKSHOP MANIPULATION.
be stopped with precision at any point ; this admits of planing
slots, keyways, and such work as cannot well be performed upon
common planing machines.
Shaping machines are divided into two classes, one modifica-
tion with a lateral feed of the tools and cutter bar, technically
called " travelling head machines," the other class with a feed
motion of the table which supports the work, called table-feeding
machines. The first modification is adapted for long pieces to
be planed transversely, such as toothed racks, connecting rods,
and similar work ; the second class to shorter pieces where much
hand adjustment is required.
An interesting study in connection with modern shaping
machines is the principle of various devices called ' quick return '
movements. Such devices consist of various modifications of
slotted levers, and what is known as Whitworth's quick return
motion.
The intricacy of the subject renders it a difficult one to deal
with except by the aid of diagrams, and as such mechanism may
be inspected in almost any machine fitting shop, attention is
called to the subject as one of the best that can be chosen for
demonstration by diagrams. Problems of these variable speed
movements are not only of great interest, but have a practical
importance not found in many better known problems which take
up time uselessly and have no application in a practical way.
The remarks, given in a former place, relating to tools for
turning, apply to those for planing as well, except that in planing
tools greater rigidity and strength are required.
(1.) Why are shaping machines better adapted than planing machines
for planing slots, key-ways, and so on ? (2.) What objects are gained
by a quick return motion of the cutter bar of shaping machines ?
CHAPTER XXXIV.
BORING AND DRILLING.
BORING, as distinguished from drilling, consists in turning out
annular holes to true dimensions, while the term drilling is
applied to perforating or sinking holes in solid material. In
BORING AND DRILLING. 137
boring, tools are guided by axial support independent of the
bearing of their edges on the material, while in drilling, the
cutting edges are guided and supported mainly from their contact
with and bearing on the material drilled.
Owing to this difference in the manner of guiding and
supporting the cutting edges, and the advantages of an axial
support for tools in boring, it becomes an operation by which
the most accurate dimensions are attainable, while drilling is a
comparatively imperfect operation ; yet the ordinary conditions
of machine fitting are such that nearly all small holes can be
drilled with sufficient accuracy.
Boring may be called internal turning, differing from external
turning, because of the tools performing the cutting movement,
and in the cut being made on concave instead of convex surfaces ;
otherwise there is a close analogy between the operations
of turning and boring. Boring is to some extent performed on
lathes, either with boring bars or by what is termed chuck-
boring, in the latter the material is revolved and the tools
are stationary.
Boring may be divided into three operations as follows :
chuck-boring on lathes ; bar-boring, when a boring bar runs on
points or centres, and is supported at the ends only ; and bar-
boring when a bar is supported in and fed through fixed bear-
ings. The principles are different in these operations, each one
being applicable to certain kinds of work. A workman who can
distinguish bet ween these plans of boring, and can always determine
from the nature of a certain work which is the best to adopt,
has acquired considerable knowledge of fitting operations.
Chuck-boring is employed in three cases ; for holes of shallow
depth, taper holes, and holes that are screw-threaded. As pieces
are overhung in lathe-boring there is not sufficient rigidity
neither of the lathe spindle nor of the tools to admit of deep
boring. The tools being guided in a straight line, and capable
of acting at any angle to the axis of rotation, the facilities for
making tapered holes are complete; and as the tools are
stationary, and may be instantly adjusted, the same conditions
answer for cutting internal screw-threads ; an operation cor-
responding to cutting external screws, except that the cross
motions of the tool slide are reversed.
The second plan of boring by means of a bar mounted on
points or centres is one by which the greatest accuracy is
138 WORKSHOP MANIPULATION.
attainable ; it is like chuck-boring a lathe operation, and one
for which no better machine than a lathe has been devised, at
least for the smaller kinds of work. It is a problem whether in
ordinary machine fitting there is not a gain by performing all
boring in this manner whenever the rigidity of boring bars is
sufficient without auxiliary supports, arid when the bars can
pass through the work. Machines arranged for this kind of
boring can be employed in turning or boring as occasion may
require.
When a tool is guided by turning on points, the movement is
perfect, and the straightness or parallelism of holes bored in this
manner is dependent only on the truth of the carriage move-
ment. This plan of boring is employed for small steam
cylinders, cylindrical valve seats, and in cases where accuracy is
essential.
The third plan of boring with bars resting in bearings is more
extensively practised, and has the largest range of adaptation.
A feature of this plan of boring is that the form of the boring-
bar, or any imperfection in its bearings, is communicated to the
work ; a want of straightness in the bar makes tapering holes.
This, of course, applies to cases where a bar is fed through fixed
bearings placed at one or both ends of a hole to be bored. If
a boring-bar is bent, or out of truth between its bearings, the
diameter of the hole being governed by the extreme sweep of the
cutters is untrue to the same extent, because as the cutters move
along and come nearer to the bearings, the bar runs with more
truth, forming a tapering hole diminishing toward the rests or
bearings. The same rule applies to some extent in chuck-boring,
the form of the lathe spindle being communicated to holes bored ;
but lathe spindles are presumed to be quite perfect compared
with boring bars.
The prevailing custom of casting machine frames in one piece,
or in as few pieces as possible, leads to a great deal of bar-boring,
most of which can be performed accurately enough by boring
bars supported in and fed through bearings. By setting up
temporary bearings to support boring-bars, and improvising means
of driving and feeding, most of the boring on machine frames can
be performed on floors or sole plates and independent of boring
machines and lathes. There are but few cases in which the im-
portance of studying the principles of tool action is more clearly
demonstrated than in this matter of boring ; even long practical
BORING AND DRILLING. 139
experience seldom leads to a thorough understanding of the
various problems which it involves.
Drilling differs in principle from almost every other operation
in metal cutting. The tools, instead of being held and directed
by guides or spindles, are supported mainly by the bearing of the
cutting edges against the material.
A common angular-pointed drill is capable of withstanding a
greater amount of strain upon its edges, and rougher use than
any other cutting implement employed in machine fitting. The
rigid support which the edges receive, and the tendency to press
them to the centre, instead of to tear them away as with other
tools, allows drills to be used when they are imperfectly shaped,
improperly tempered, and even when the cutting edges are of
unequal length.
Most of the difficulties which formerly pertained to drilling
are now removed by machine-made drills which are manufactured
and sold as an article of trade. Such drills do not require
dressing and tempering or fitting to size after they are in use,
make true holes, are more rigid than common solid shank drills,
and will drill to a considerable depth without clogging.
A drilling machine, adapted to the usual requirements of a
machine fitting establishment, consists essentially of a spindle ar-
ranged to be driven at various speeds, with a movement for
feeding the drills ; a firm table set at right angles to the spindle,
and arranged with a vertical adjustment to or from the spindle, and
a compound adjustment in a horizontal plane. The simplicity
of the mechanism required to operate drilling tools is such that
it has permitted various modifications, such as column drills,
radial drills, suspended drills, horizontal drills, bracket drills,
multiple drills, and others.
Drilling, more than any other operation in metal cutting, re-
quires the sense of feeling, and is farther from such conditions as
admit of power feeding. The speed at which a drill may cut
without heating or breaking is dependent upon the manner in
which it is ground and the nature of the material drilled, the
working conditions may change at any moment as the drilling
progresses ; so that hand feed is most suitable. Drilling machines
arranged with power feed for boring should have some means of
permanently disengaging the feeding mechanism to prevent its
use in ordinary drilling.
I am well aware how far this opinion is at variance with prac-
140 WORKSHOP MANIPULATION.
tice, especially in England ; yet careful observation in a workshop
will prove that power feed in ordinary drilling effects no saving
of time or expense.
(1.) What is the difference between boring and drilling ? (2.) Why
will drills endure more severe use than other tools ? (3.) Why is hand
feeding best suited for drills? (4.) What is the difference between
boring with a bar supported on centres and one fed through journal
bearings ?
CHAPTER XXXV.
MILLING.
MILLING relates to metal cutting with serrated rotary cutters, and
differs in many respects from either planing or turning. The move-
ment of the cutting edges can be more rapid than with tools which
act continuously, because the edges are cooled during the intervals
between each cut ; that is, if a milling tool has twenty teeth, any
single tooth or edge acts only from a fifteenth to a twentieth
part of the time ; and as the cutting distance or time of cutting is
rarely long enough to generate much heat, the speed of such tools
may be one-half greater than for turning, drilling, or planing
tools. Another distinction between milling and other tools is the
perfect and rigid manner in which the cutting edges are supported ;
they are short and blunt, besides being usually carried on short
rigid mandrils. A result of this rigid support of the tools is seen
in the length of the cutting edges that can be employed, which
are sometimes four inches or more in length. It is true the
amount of material cut away in milling is much less than the
edge movement will indicate when compared with turning or
planing ; yet the displacing capacity of a milling machine exceeds
that of either a lathe or a planing machine. Theoretically the
cutting or displacing capacity of any metal or wood cutting
machine, is as the length of the edges multiplied into the speed
of their cutting movement ; a rule which applies very uniformly
in wood cutting, and also in metal cutting within certain limits ;
but the strains that arise in metal cutting are so great that they
may exceed all means of resisting them either in the material
acted upon, or in the means of supporting tools, so that the length
MILLING. 141
of cutting edges is limited. In turning chilled rolls at Pittsburg,
tools to six inches wide are employed, and the effect produced is
as the length of the edge ; but the depth of the cut is slight, and
the operation is only possible because of the extreme rigidity of
the pieces turned, and the tools being supported without movabte
joints as in common lathes.
Under certain conditions a given quantity of soft iron or steel
may be cut away at less expense, and with greater accuracy, by
milling than by any other process.
A milling tool with twenty edges should represent as much
wearing capacity as a like number of separate tools, and may
be said to equal twenty duplicate tools ; hence, in cutting grooves,
notches, or similar work, a milling tool is equivalent to a large
number of duplicate single tools, which cannot be made or set
with the same truth ; so that milling secures accuracy and duplica-
tion, objects which are in many cases more important than speed.
Milling, as explained, being a more rapid process than either
planing or turning, it seems strange that so few machines of this
kind are employed in engineering shops. This points to some
difficulty to be contended with in milling, which is not altogether
apparent, because economic reasons would long ago have led to a
more extended use of milling processes, if the results were as
profitable as the speed of cutting indicates. This is, however,
not the case, except on certain kinds of material, and only for
certain kinds of work.
The advantages gained by milling, as stated, are speed,
duplication, and accuracy ; the disadvantages are the expense of
preparing tools and their perishability.
A solid milling cutter must be an accurately finished piece of
work, made with more precision than can be expected in the
work it is to perform. This accuracy cannot be attained by
ordinary processes, because such tools, when tempered, are liable
to become distorted in shape, and frequently break. When
hardened they must be finished by grinding processes, if intended
for any accurate work ; in fact, no tools, except gauging imple-
ments, involve more expense to prepare, and none are so liable
to accident when in use.
Such tools consist of a combination of cutting edges, all of
which may be said to depend on each one ; because if one breaks,
the next in order will have a double duty to perform, and will
142 WORKSHOP MANIPULATION.
soon follow a reversal of the old adage, that ' union is strength,'
if by strength is meant endurance.
In planing and turning, the tools require no exact form ; they
can be roughly made, except the edge, and even this, in most
cfises, is shaped by the eye. Such tools are maintained at a
trifling expense, and the destruction of an edge is a matter of no
consequence. The form, temper, and strength can be continu-
ally adapted to the varying conditions of the work and the hard-
ness of material. The line of division between planing and
milling is fixed by two circumstances the hardness and uni-
formity of the material to be cut, and the importance of duplica-
tion. Brass, clean iron, soft steel, or any homogeneous metal
not hard enough to cause risk to the tools, can be milled at less
expense than planed, provided there is enough work of a uniform
character to justify the expense of milling tools. Cutting the
teeth of wheels is an example where milling is profitable, but not
to the extent generally supposed. In the manufacture of small
arms, sewing machines, clocks, and especially watches, where
there is a constant and exact duplication of parts, milling is in-
dispensable. Such manufactures are in some cases founded on
milling operations, as will be pointed out in another chapter.
Milling tools large enough to admit of detachable cutters being
employed, are not so expensive to maintain as solid tools. Edge
movement can sometimes be multiplied in this way, so as to
greatly exceed what a single tool will perform.
Milling tools are employed at Crewe for roughing out the slots
in locomotive crank axles. A number of detachable tools are
mounted on a strong disc, so that four to six will act at one
time ; in this way the displacement exceeds what a lathe can
perform when acting continuously with two tools. Kotary planing
machines constructed on the milling principle, have been tried
for plane surfaces, but with indifferent success, except for rough
work.
There is nothing in the construction or operation of milling
machines but what will be at once understood by a learner who
sees them in operation. The whole intricacy of the process lies
in its application or economic value, and but very few, even
among the most skilled, are able in all cases to decide w r hen
milling can be employed to advantage. Theoretical conclusions,
aside from practical experience, will lead one to suppose that
SCREW-CUTTING. 143
milling can be applied in nearly all kinds of work, an opinion
which has in many cases led to serious mistakes.
(1.) If milling tools operate faster than planing or turning tools, why
are they not more employed? (2) How may the effect produced by
cutting tools generally be computed ? (3.) To what class of work are
milling machines especially suited 1 (4.) Why do milling processes
produce more accurate dimensions than are attainable by turning or
planing 1 (5.) Why can some branches of manufacture be said to
depend on milling processes 1
CHAPTER XXXVI.
SCJRE W-CUTTING.
THE tools employed for cutting screw threads constitute a sepa-
rate class among the implements of a fitting shop, and it is
considered best to notice them separately.
Screw-cutting is divided into two kinds, one where the blanks
or pieces to be threaded are supported on centres, the tools held
and guided independently of their bearing at the cutting edges,
called chasing ; the other process is where the blanks have no
axial support, and are guided only by dies or cutting tools, called
die-cutting.
The first of these operations includes all threading processes
performed on lathes, whether with a single tool, by dies carried
positively by slide rests, or by milling.
The second includes what is called threading in America and
screwing in England. Machines for this purpose consist
essentially of mechanism to rotate either the blank to be cut or
the dies, and devices for holding and presenting the blanks.
Chasing produces screws true with respect to their axis, and is
the common process of threading all screws which are to have a
running motion in use, either of the screw itself, or the nut.
Die-cutting produces screws which may not be true, but are
still sufficiently accurate for most uses, such as clamping and
joining together the parts of machinery or other work.
Chasing operations being lathe work, and involving no
principles not already noticed, what is said further will be in
reference to die-cutting or bolt-threading machines, which,
144 WORKSHOP MANIPULATION.
simple as they may appear to the unskilled, involve, neverthe-
less many intricacies which will not appear upon superficial
examination.
Screw- cutting machines may be divided into modifications as
follows : (1) Machines with running dies mounted in what is
called the head ; ( 2) Machines with fixed dies, in which motion
is given to the rod or blank to be threaded ; ( 3) Machines with
expanding dies which open and release the screws when finished
without running back ; (4) Machines with solid dies, in which
the screws have to be withdrawn by changing the motion of the
driving gearing ; making in all four different types.
If these various plans of arranging screw-cutting machines had
reference to different kinds of work, it might be assumed that all
of them are correct, but they are as a rule all applied to the same
kind of work ; hence it is safe to conclude that there is one arrange-
ment better than the rest, or that one plan is right and the others
wrong. This matter may in some degree be determined by
following through the conditions of use and application.
Between a running motion of the dies, or a running motion of
the blanks, there are the following points which may be noticed.
If dies are fixed, the clamping mechanism to hold the rods
has to run with the spindle ; such machines must be stopped
while fastening the rods or blanks. Clamping jaws are usually
as little suited for rotation on a spindle as dies are, and gener-
ally afford more chances for obstruction and accident. To
rotate the rods, if they are long, they must pass through the
driving spindle, because machines cannot well be made of
sufficient length to receive long rods. In machines of this class,
the dies have to be opened and closed by hand instead of by the
driving power, which can be employed for the purpose when the
dies are mounted in a running head.
With running dies, blanks may be clamped when a machine is
in motion, and as the blank does not revolve, it may, when long,
be supported in any temporary manner. The dies can be opened
and closed by the driving power also, and no stopping of a
'machine is necessary \ so that several advantages of considerable
importance may be gained by mounting the dies in a running
head, a plan which has been generally adopted in late years by
machine tool makers both in England and America.
In respect to the difference between expanding and solid dies
it consists mainly in the time required to run back, and the
STANDARD MEASURES. 145
injury to dies which this operation occasions. Uniformity of size
is within certain limits insured by solid dies, but they are more
liable to derangement and less easy to repair than expanding or
independent dies.
Another difference between solid and expanding dies, which
may be pointed out, is in the firmness with which the cutting
edges are held. With a solid die, the edges or teeth being all
combined in one solid piece, are firmly held in a fixed position ;
while with expanding dies their position has to be maintained by
mechanical devices which are liable to yield under the pressure
which arises in cutting. The result is, that the precision with
which a screwing machine with movable dies will act, is depen-
dent upon the strength of the * abutment ' behind the dies,
which should be a hard unyielding surface with as much area
as possible.
Connected with screw dies, there are various problems, such
as clearance behind the cutting edge ; whether an odd or even
number of edges are bestj how many threads require to be
bevelled at the starting point ; and many other matters about
which there are no determined rules. The diversity of opinion
that will be met with on these points, and in reference to taps,
the form of screw-threads, and so on, will convince a learner of
the intricacies in this apparently simple matter of cutting screw-
threads.
(1.) Describe the different modifications of screw- cutting machines.
(2.) What is gained by revolving the dies instead of the rods ? (3.)
What is gained by expanding dies ? (4.) What is the difference be-
tween screws cut by chasing and those cut on a screw-cutting machine I
CHAPTER XXXVII.
STANDARD MEASURES.
MACHINES are composed of parts connected together by rigid and
movable joints ; rigid joints are necessary because of the expense,
and in most cases the impossibility, of constructing framing and
other fixed detail in one piece.
K
146 WORKSHOP MANIPULATION.
All moving parts must of course be independent of fixed
parts, the relation between the two being maintained by what
has been called running joints.
It is evident that when the parts of a machine are joined to-
gether, each piece which has contact on more than one side must
have specific dimensions ; it is farther evident that as many of the
joints in a machine as are to accommodate the exigencies of con-
struction must be without space, that is, they represent continued
sections of what should be solid material, if it were possible to
construct the parts in that manner. This also demands specific
dimensions.
In arranging the details of machines, it is impossible to have
a special standard of dimensions for each case, or even for each
shop ; the dimensions employed are therefore made to conform
to some general standard, which by custom becomes known
and familiar to workmen and to a country, or as we may now
say to all countries.
A standard of lineal measures, however, cannot be taken from
one country to another, or even transferred from one shop to an-
other without the risk of variation ; and it is therefore necessary
that such a standard be based upon something in nature to which
reference can be made in cases of doubt.
In ages past, various attempts were made to find some constant
in nature on which measures could be based. Some of these
attempts were ludicrous, and all of them failures, until the vibra-
tions of a pendulum connected length and space with time. The
problem was then more easy. The changes of seasons and the
movement of heavenly bodies had established measures of time,
so that days, hours, and minutes became constants, proved and
maintained by the unerring laws of nature.
A pendulum vibrating in uniform time regardless of distance,
but always as its length, if arranged to perform one vibration
in a given time, gave a constant measure of length. Thus
lineal measure comes from time ; cubic or solid measures from
lineal measure, and standards of weight from the same source ;
because when a certain quantity of a substance of any kind could
be determined by lineal measurement, and this quantity was
weighed, a standard of weight would be reached, provided there
was some substance sufficiently uniform, to which reference
could be made in different countries. Such a substance is sea
or pure water ; weighed in vacuo, or with the air at an assumed
GAUGING IMPLEMENTS. 147
density, water gives a result constant enough for a standard of
weight.
It is a strange thought that with all the order, system, and
regularity, existing in nature, there is nothing but the move-
ments of the heavenly bodies constant enough to form a base for
gauging tests. The French standard based upon the calculated
length of the meridian may be traced to this source".
Nothing animate or inanimate in nature is uniform ; plants,
trees, animals, are all different ; even the air we breathe and the
temperature around us is constantly changing ; only one thing
is constant, that is time, and to this must we go for all our
standards.
I am not aware that the derivation of our standard measures
has been, in an historical way, as the foregoing remarks will indi-
cate, nor is it the purpose here to follow such history. A
reader, whose attention is directed to the subject, will find no
trouble in tracing the matter from other sources. The present
object is to show what a wonderful series of connections can be
traced from so simple a tool as a measuring gauge, and how
abstruse, in fact, are many apparently simple things, often re-
garded as not worth a thought beyond their practical application.
(1.) Why are machine frames constructed in sections, instead of
being in one piece? (2.) Why must parts which have contact on
opposite sides have specific dimensions ? (3.) What are standards of
measure based upon in England, America, and France? (4.) How
can weight be measured by time ? (5.) Has the French metre provel
a standard admitting of test reference ?
CHAPTER XXXVIII.
GAUGING IMPLEMENTS.
AMONG the improvements in machine fitting which have in recent
years come into general use, is the employment of standard
gauges, by means of which uniform dimensions are maintained,
and within certain limits, an interchange of the parts of
machinery is rendered possible.
Standard gauging implements were introduced about the year
148 WORKSHOP MANIPULATION.
1840, by tlie celebrated Swiss engineer, John G. Bodmer, a man
\vho for many reasons deserves to be considered as the founder of
machine tool manufacture. He not only employed gauges in his
works to secure duplicate dimensions, but also invented and
put in use many other reforms in manipulation ; among these
may be mentioned the decimal or metrical division of measures,
a system of detail drawings classified by symbols, the mode of
calculating wheels by diametric pitch, with many other things
which characterise the best modern practice.
The importance of standard dimensions, and the effect which a
system of gauging may have in the construction of machines,
will be a matter of some difficulty for a learner to understand.
The interchangeability of parts, which is the immediate object
in employing gauges, is plain enough, and some of the advantages
at once apparent, yet the ultimate effects of such a system
extend much farther than will at first be supposed.
The division of labour, that system upon which we may say
our great industrial interests are founded, is in machine fitting
promoted in a wonderful degree by the use of gauging imple-
ments. If standard dimensions can be maintained, it is easy to
see that the parts of a machine can be constructed by different
workmen, or in different shops, and these parts when assembled
all fit together, without that tedious and uncertain plan of try-
fitting which was once generally practised. There are, it is true,
certain kinds of fitting which cannot well be performed by
gauges ; moving flat surfaces, such as the bearings of lathe
slides or the faces of steam engine valves, are sooner and better
fitted by trying them together and scraping off the points of
contact ; but even in such cases the character of the work will be
improved, if one or both surfaces have been first levelled by
gauging or surface plates.
In cylindrical fitting, which as before pointed out, constitutes
the greater part in machine fitting, gauges are especially impor-
tant, because trial-fitting is in most cases impossible.
Flat or plane joints nearly always admit of adjustment between
the fitted surfaces ; that is, the material scraped or ground away
in fitting can be compensated by bringing the pieces nearer
together; but parallel cylindrical joints cannot even be tried
together until finished, consequently, there can be nothing
cut away in trying them together. Tapering, or conical joints,
can of course be trial-fitted, and even parallel fits are sometimes
GAUGING IMPLEMENTS. 149
made by trial, but it is evident that the only material that can
be cut away in such cases, is what makes the difference between
a fit too close, and one which will answer in practice.
As to the practical results which may be attained by a
gauging system, it may be said that they are far in advance of
what is popularly supposed, especially in Europe, where gauges
were first employed.
The process of milling, which has been so extensively adopted
in the manufacture of guns, watches, sewing-machines, and
similar work in America, has, on principles explained in the
chapter on milling, enabled a system of gauging which it is difficult
to comprehend without seeing the processes carried on. And so
important is the effect due to this duplicating or gauging
system, that several important branches of manufacture have
been controlled in this way, when other elements of production,
such as the price of labour, rent, interest, and so on, have been
greatly in favour of countries where the trying system is
practised.
As remarked, the gauging system is particularly adapted to,
or enabled by milling processes, and of course must have its
greatest effect in branches of work directed to the production of
uniform articles, such as clocks, watches, sewing-machines, guns,
hand tools, and so on. That is, the direct effect on the cost of
processes will be more apparent and easily understood in such
branches of manufacture ; yet in general engineering work, where
each machine is more or less modified, and made to special
plans, the commercial gain resulting from the use of gauges is
considerable.
In respect to repairing alone, the consideration of having the
parts of machinery fitted to standard sizes is often equal to its
whole value.
Machinery subjected to destructive wear, and to be operated
at a distance from machine shops locomotive engines for
example if not constructed with standard dimensions, may, by
the detention due to repairing, cause a loss and inconvenience
equal to their value ; if a shaft wheel bearing, or even a fitted
screw bolt is broken, time must be allowed to make the parts
new ; and in order to fit them, the whole machine, or such of its
details as have connection with the broken parts, must be taken
to a shop in order to fit by trial.
The duplicate system has gradually made its way in loco-
150 WORKSHOP MANIPULATION.
motive engineering, and will no doubt extend to the whole of
railway equipment, as constants for dimensions are proved and
agreed upon.
The gauging system has been no little retarded by a selfish
and mistaken opinion that an engineering establishment may
maintain peculiar standards of its own ; in fact, relics of this
spirit are yet to be met with in old machines, where the pitch of
screw-threads has been made to fractional parts of an inch, so
that engineers, other than the original makers, could not well per-
form repairing, or replace broken parts.
One of the effects of employing gauges in machine fitting is
to inspire confidence in workmen. Instead of a fit being regarded
as a mysterious result more the work of chance than design, men
accustomed to gauges come to regard precision as something both
attainable and indispensable. A learner, after examining a set
of well fitted cylindrical gauges, will form a new conception of
what a fit is, and will afterwards have a new standard fixed in
his mind.
The variation of dimensions which are sensible to the touch
at one ten- thousandth part of an inch, furnishes an example of how
important the human senses are even after the utmost precision
attainable by machine action. Pieces may pass beneath the
cutters of a milling machine under conditions, which so far as
machinery avails will produce uniform sizes, yet there is no
assurance of the result until the work is felt by gauges.
The eye fails to detect variations in size, even by comparison,
long before we reach the necessary precision in common fitting.
Even by comparison with figured scales or measuring with rules,
the difference between a proper and a spoiled fit is not discern-
ible by sight.
Many of the most accurate measurements are, however, per-
formed by sight, with vernier calipers for example, the variation
being multiplied hundreds or thousands of times by mechanism,
until the least differences can be readily seen.
In multiplying the variations of a measuring implement by
mechanism, it is obvious that movable joints must be employed ; it
is also obvious that no positive joint, whether cylindrical or fiat,
could be so accurately fitted as to transmit such slight movement
as occurs in gauging or measuring. This difficulty is in most
measuring instruments overcome by employing a principle not
GAUGING IMPLEMENTS. 151
before alluded to, but common in many machines, that of elastic
compensation.
A pair of spring calipers will illustrate this principle. The
points are always steady, because the spring acting continually in
one direction compensates the loose play that may be in the
screw. In a train of tooth wheels there is always more or less
play between the teeth ; and unless the wheels always revolve in
one direction, and have some constant resistance offered to their
motion, ' backlash ' or irregular movement will take place ; but
if there is some constant and uniform resistance such as a spring
would impart, a train of wheels will transmit the slightest motion
throughout.
The extreme nicety with which gauging implements are fitted
seems at first thought to be unnecessary, but it must be remem-
bered that a cylindrical joint in ordinary machine fitting involves
a precision almost beyond the sense of feeling, and that any
sensible variation in turning gauges is enough to spoil a fit.
Opposed to the maintenance of standard dimensions are the
variations in size due to temperature. This difficulty applies alike
to gauging implements and to parts that are to be tested ; yet in
this, as in nearly every phenomenon connected with matter, we
have succeeded in turning it to some useful purpose. Bands of
iron, such as the tires of wheels when heated, can be * shrunk ' on,
and a compressive force and" security attained, which would be
impossible by forcing the parts together both at the same
temperature. Shrinking has, however, been almost entirely
abandoned for such joints as can be accurately fitted.
(1.) How may gauging implements affect the division of labour ?
(2.) In what way does standard dimensions affect the value of machinery ?
(3.) Why cannot cylindrical joints be fitted by trying them together ?
(4.) Under what circumstances is it most important that the parts of
machinery should have standard dimensions? (5.) Which sense is
n.ost acute in testing accurate dimensions 1 (6.) How may slight varia-
tions in dimensions be made apparent to sight ?
152 WORKSHOP MANIPULATION.
CHAPTER XXXIX.
DESIGNING MACHINES.
IT will scarcely be expected that any part of the present work,
intended mainly for apprentice engineers, should relate to de-
signing machines, yet there is no reason why the subject should
not to some extent be treated of; it is one sure to engage more
or less attention from learners, and the study of designing
machines, if properly directed, cannot fail to be of advantage.
There is, perhaps, no one who has achieved a successful ex-
perience as an engineer but will acknowledge the advantages
derived from early efforts to generate original designs, and
none who will not admit that if their first efforts had been
more carefully directed, the advantages gained would have been
greater.
It is exceedingly difficult for an apprentice engineer, without
experimental knowledge, to choose plans for his own education,
or to determine the best way of pursuing such plans when they
have been chosen ; and there is nothing that consumes so much
time, or is more useless than attempting to make original designs,
if there is not some systematic method followed.
There is but little object in preparing designs, when their
counterparts may already exist, so that in making original plans,
there should be a careful research as to what has been already
done in the same line. It is not only discouraging, but annoying,
after studying a design with great care, to find that it has been
anticipated, and that the scheme studied out has been one of
reproduction only. For this reason, attempts to design should at
first be confined to familiar subjects, instead of venturing upon
unexplored ground.
Designing is in many respects the same thing as invention,
except that it deals more with mechanism than principles, although
it may, and often does include both. Like invention, designing
should always be attempted for the attainment of some definite
object laid down at the beginning, and followed persistently
throughout.
It is not always an easy matter to hit upon an object to which
designs may be directed ; and although at first thought it may
seem that any machine, or part of a machine, is capable of im-
DESIGNING MACHINES. 153
provement, it will be found no easy matter to detect existing
i'aults or to conceive plans for their remedy.
A new design should be based upon one of two suppositions
either that existing mechanism is imperfect in its construction, or
that it lacks functions which a new design may supply ; and if
those who spend their time in making plans for novel machinery
would stop to consider this from the beginning, it would save no
little of the time wasted in what may be called scheming without
a purpose.
After determining the ultimate objects of an improvement,
and laying down the general principles which should be followed
in the preparation of a design, there is nothing connected with
constructive engineering that can be more nearly brought within
general rules than arranging details. I am well aware of how
far this statement is at variance with popular opinion among
mechanics, and of the very thorough knowledge of machine
application and machine operation required in making designs,
and mean that there are certain principles and rules which may
determine the arrangement and distribution of material, the
position and relation of moving parts, bearings, and so on, and
that a machine may be built up with no more risk of mistakes
than in erecting a permanent structure.
Designing machines must have reference to adaptation, endur-
ance, and the expense of construction. Adaptation includes the
performance of machinery, its commercial value, or what the
machinery may earn in operating; endurance, the time that
machines may operate without being repaired, and the constancy
of their performance; expense, the investment represented in
machinery.
The adaptation, endurance, and cost of machines in designing
become resolved into problems of movements, the arrangement of
parts, and proportions.
Movements and strains may be called two of the leading con-
ditions upon which designs for machines are based: movements
determine general dimensions, and strains determine the propor-
tions and sizes of particular parts. Movement and strain together
determine the nature and area of bearings or bearing surfaces.
The range and speed of movement of the parts of machines are
elements in designing that admit of a definite determination from
the work to be accomplished, but arrangement cannot be so
154 WORKSHOP MANIPULATION.
determined, and is the most difficult to find data for. To sum
up these propositions we have :
1. A conception of certain functions in a machine, and some
definite object which it is to accomplish.
2. Plans of adaptation and arrangement of the component
parts of the machinery, or organisation as it may be called.
3. A knowledge of specific conditions, such as strains, the
range and rate of movements, and so on.
4. Proportions of the various parts, including the framing,
bearing surfaces, shafts, belts, gearing, and other details.
5. Symmetry of appearance, which is often more the result of
obvious adaptation than ornamentation.
To illustrate the practical application of what has preceded,
let it be supposed, for example, that a machine is to be made for
cutting teeth in iron racks J in. pitch and 3 in. face, and that a
design is to be prepared without reference to such machines as
may already be in use for the purpose.
It is not assumed that an actual design can be made which by
words alone will convey a comprehensive idea of an organised ma-
chine; it is intended to map out a course which will illustrate a plan
of reasoning most likely to attain a successful result in such cases.
The reader, in order to better understand what is said, may
keep in mind a common shaping machine with crank motion, a
machine which nearly fills the requirements for cutting tooth
racks.
Having assumed a certain work to do, the cutting of tooth
racks J in. pitch, and 3 in. face, the first thing to be considered
will be, is the machine to be a special one, or one of general
adaptation ? This question has to do, first, with the functions
of the machine in the way of adapting it to the cutting of racks
of various sizes, or to performing other kinds of work, and
secondly, as to the completeness of the machine; for if it were
to be a standard one, instead of being adapted only to a special
purpose, there are many expensive additions to be supplied which
can be omitted in a special machine. It will be assumed in the
present case that a special machine is to be constructed for
a particular duty only.
The work to be performed consists in cutting away the metal
between the teeth of a rack, leaving a perfect outline for the teeth ;
and as the shape of teeth cannot well be obtained by an adjust-
ment of tools, it must be accomplished by the shape of the tools.
DESIGNING MACHINES. 155
The shape of the tools must, therefore, be constantly maintained,
and as the cross section of the displaced metal is not too great, it
may be assumed that the shape of the tools should be a profile
of the whole space between two teeth, and such a space be cut
away at one setting or one operation. By the application of
certain rules laid down in a former place in reference to cutting
various kinds of material, reciprocating or planing tools may be
chosen instead of rotary or milling tools.
Movements come next in order, and consist of a reciprocating
cutting movement of the tools or material, a feed movement to
regulate the cutting action, and a longitudinal movement of the
rack, graduated to pitch or space, the distance between the teeth.
The reciprocating cutting movement being but four inches or
less, a crank is obviously the best means to produce this motion,
and as the movement is transverse to the rack, which may be
long and unwieldy, it is equally obvious that the cutting motion
should be performed by the tools instead of the rack.
The feed adjustment of the tool being intermittent and the
amount of cutting continually varying, this movement should be
performed by hand, so as to be controlled at will by the sense of
feeling. The same rule applies to the adjustment of the rack
for spacing ; being intermittent and irregular as to time, this
movement should also be performed by hand. The speed of the
cutting movement is known from ordinary practice to be from
sixteen feet to twenty feet a minute, and a belt two and a half
inches wide must move two hundred feet a minute to propel an
ordinary metal cutting tool, so that the crank movement or cutter
movement must be increased by gearing until a proper speed of
the belt is reached j from this the speed of intermediate movers
will be found.
Arrangement comes next in this the first matter to be con-
sidered is convenience of manipulation. The cutting position
should be so arranged as to admit of an easy inspection of the
work. An operator having to keep his hand on the adjusting or
feed mechanism, which is about twelve inches above the work,
it follows that if the cutting level is four feet from the floor, and
the feed handle five feet from the floor, the arrangement will be
convenient for a standing position. As the work requires con-
tinual inspection and hand adjustments, it will for this reason
be a proper arrangement to overhang both the supports for the
rack and the cutting tools, placing them, as we may say, outside
156 WORKSHOP MANIPULATION.
the machine, to secure convenience of access and to allow of in-
spection. The position of the cutting bar, crank, connections,
gearing, pulleys, and shafts, will assume their respective places
from obvious conditions, mainly from the position of the opera-
tor and the work.
Next in order are strains. As the cutting action is the source
of strains, and as the resistance offered by the cutting tools is as
the length or width of the edges, it will be found in the present
case that while other conditions thus far have pointed to small
proportions, there is now a new one which calls for large propor-
tions. In displacing the metal between teeth of three-quarters
of an inch pitch, the cutting edge or the amount of surface acted
upon is equal to a width of one inch and a half. It is true, the
displacement may be small at each cut. but the strain is rather
to be based upon the breadth of the acting edge than the actual
displacement of metal, and we find here strains equal to the
average duty of a large planing machine. This strain radiates
from the cutting point as from a centre, falling on the supports of
the work with a tendency to force it from the framing. Between
the rack and the crank-shaft bearing, through the medium of the
tool, cutter bar, connection, and crank pin, and in various direc-
tions and degrees, this strain may be followed by means of a
simple diagram. Besides this cutting strain, there are none of
importance ; the tension of the belt, the side thrust in bearings,
the strain from the angular thrust of the crank, and the end
thrust of the tool, although not to be lost sight of, need not
have much to do with problems of strength, proportion, and
arrangement.
Strains suggest special arrangement, which is quite a distinct
matter from general arrangement, the latter being governed
mainly by the convenience of manipulation. Special arrangement
deals with and determines the shape of framing, following the
strains throughout a machine. In the present case we have a
cutting strain which may be assumed as equal to one ton, exerted
between the bracket or jaws which support the work, and the
crank-shaft. It follows that between these two points the metal
in the framing should be disposed in as direct a line as possible,
and provision be made to resist flexion by deep sections parallel
with the cutting motion.
Lastly, proportions ; having estimated the cutting force re-
quired at one ton, although less than the actual strain in a
DESIGNING MACHINES. 157
machine of this kind, we proceed upon this to fix proportions,
beginning with the tool shank, and following back through the
adjusting saddle, the cutting bar, connections, crank pins, shafts,
and gear wheels to the belt. Starting again at the tool, or point
of cutting, following through the supports of the rack, the jaws
that clamp it, the saddle for the graduating adjustment, the connec-
tions with the main frame, and so on to the crank-shaft bearing
a second time, dimensions may be fixed for each piece to with-
stand the strains without deflection or danger of breaking. Such
proportions cannot, I am aware, be brought within the rules of
ordinary practice by relying upon calculation alone to fix them,
and no such course is suggested ; calculation may aid, but can-
not determine proportions in such cases ; besides, symmetry,
which cannot be altogether disregarded, modifies the form and
sometimes the dimensions of various parts.
I have in this way imperfectly indicated a methodical plan of
generating a design, as far as words alone will serve, beginning
with certain premises based upon a particular work to be per-
formed, and then proceeding to consider in consecutive order the
general character of the machine, mode of operation, movements
and adjustments, general arrangement, strains, special arrange-
ment, and proportions.
With a thorough knowledge of practical machine operation,
and an acquaintance with existing practice, an engineer proceed-
ing upon such a plan, will, if he does not overlook some of the
conditions, be able to generate designs which may remain with-
out much modification or change, so long as the purpose to which
the machinery is directed remains the same.
Perseverance is an important trait to be cultivated in first
efforts at designing ; it takes a certain amount of study to under-
stand any branch of mechanism, no matter what natural capacity
may be possessed by a learner. Mechanical operations are not
learned intuitively, but are always surrounded by many peculiar
conditions which must be learned seriatim, and it is only by an
untiring perseverance at one thing that there can be any hope of
improving it by new designs.
A learner who goes from gearing and shafts to steam and
hydraulics, from machine tools to cranes and hoisting machinery,
will not accomplish much. The best way is to select at first an
easy subject, one that admits of a great range of modification,
and if possible, one that has not assumed a standard form of
158 WORKSHOP MANIPULATION.
construction. Bearings and supports for shafts and spindles, is
a good subject to begin with.
In designing supports for shafts the strains are easily defined
and followed, while the vertical and lateral adjustment, lubrication
of bearings, symmetry of supports and hangers, and so on, will
furnish grounds for endless modification, both as to arrangement
and mechanism.
In making designs it is best to employ no references except such
as are carried in the memory. The more familiar a person is
with machinery of any class, the more able he may be to prepare
designs, but not by measuring and referring to other people's
plans. Dimensions and arrangement from examples are, by such
a course, unconsciously carried into a new drawing, even by the
most skilled ; besides, it is by no means a dignified matter to
collect other people's plans, and by a little combination and mo-
dification produce new designs. It may be an easy plan to acquire
a certain kind of proficiency, but will most certainly hinder an
engineer from ever rising to the dignity of an original designer.
Symmetry, as an element in designs for machinery, is one of
those unsettled matters which may be determined only in con-
nection with particular cases ; it may, however, be said that for
ail engineering implements and manufacturing machinery of
every kind, there should be nothing added for ornament, or any-
thing that has no connection with the functions of the machinery.
Modern engineers of the abler class are so thoroughly in accord
in this matter of ornamentation, both in opinion and practice, that
the subject hardly requires to be mentioned, and it will be no
disadvantage for a learner to commence by cultivating a contempt
for whatever has no useful purpose. Of existing practice it may
be said, that in what may be called industrial machinery, the
amount of ornamentation is inverse as the amount of engineering
skill employed in preparing designs.
A safe rule will be to assume that machinery mainly used and
seen by the skilled should be devoid of ornament, and that
machinery seen mainly by the unskilled, or in public, should
have some ornament. Steam fire engines, sewing machines, and
works of a similar kind, which fall under the inspection of the
unskilled, are usually arranged with more or less ornament.
As a rule, ornament should never be carried further than
graceful proportions ; the arrangement of framing should follow
as nearly as possible the lines of strain. Extraneous decoration,
INVENTION. 1 59
such as detached filagree work of iron, or painting in colours, is
so repulsive to the taste of the true engineer and mechanic that
it is unnecessary to speak against it.
(1.) Name some of the principal points to be kept in view in preparing
designs 1 (2.) Why should attempts at designing be confined to one
class of machinery ? (3.) What objection exists to examining references
when preparing designs ?
CHAPTER XL.
INVENTION.
THE relation between invention and the engineering arts, and
especially between invention and machines, will warrant a short
review of the matter here ; or even if this reason were wanting,
there is a sufficient one in the fact that one of the first aims of
an engineering apprentice is to invent something ; and as the
purpose here is, so far as the limits will permit, to say something
upon each subject in which a beginner has an interest, invention
must not be passed over.
It has been the object thus far to show that machines, processes,
and mechanical manipulation generally may be systematised and
generalised to a greater or less extent, and that a failure to
reduce mechanical manipulation and machine construction to
certain rules and principles can mainly be ascribed to our want of
knowledge, and not to any inherent difficulty or condition which
prevents such solution. The same proposition is applicable to
invention, with the difference that invention, in its true sense,
may admit of generalisation more readily than machine processes.
Invention, as applied to mechanical improvements, should not
mean chance discovery. Such a meaning is often, if not generally,
attached to the term invention, yet it must be seen that results
attained by a systematic course of reasoning or experimenting
can have nothing to do with chance or even discovery. Such
results partake more of the nature of demonstrations, a name
peculiarly suitable for such inventions as are the result of metho-
dical purpose
ICO WORKSHOP MANIPULATION,
In such sciences as rest in any degree upon physical experiment,
like chemistry, to experiment without some definite object may
be a proper kind of research, and may in the future, as it has in
the past, lead to great and useful results ; but in mechanics the
case is different ; the demonstration of the conservation of force,
and the relation between force arid heat, have supplied the last
link in a chain of principles which may be said to comprehend all
that we are called upon to deal with in dynamical science, and
there remains but little hope of developing anything new or use-
ful by discovery alone. The time has been, and has not yet
passed away, when even the most unskilled thought their ability
to invent improvements in machinery equal with that of an
engineer or skilled mechanic ; but this is now changed ; new
schemes are weighed and tested by scientific standards, in many
cases as reliable as actual experiments. A veil of mystery which
ignorance of the physical sciences had in former times thrown
around the mechanic arts, has been cleared away ; chance dis-
covery, or mechanical superstition, if the term may be allowed,
has nearly disappeared. Many modern engineers regard their
improvements in machinery as the exercise of their profession
only, and hesitate about asking for protective grants to secure an
exclusive use of that which another person might and often does
demonstrate, as often as circumstances call for such improvement.
There are of course new articles of manufacture to be discovered,
and many, improvements in machinery which may be proper
subject matter for patent rights ; improvements which in all
chance would not be made for the term of a patent, except by
the inventor ; but such cases are rare ; and it is fair to assume that
unless an invention is one which could not have been regularly
deduced from existing data, and one that would not in all
probability have been made for a long term of years by any other
person than the inventor, such an invention cannot in fairness
become the property of an individual without infringing the rights
of others.
It is not the intention to discuss patent law, nor even to estimate
what benefits have in the past, or may in the future, be gained to
technical industry, by the patent system, but to impress engineer-
ing apprentices with a better and more dignified appreciation of
their calling than to confound it with chance invention, and there-
by destroy that confidence in positive results which has in the
past characterised mechanical engineering ; also to caution
INVENTION.
learners against the loss of time and effort too often
in searching after inventions. ~^?} y>
It is well for an apprentice to invent or demonstrate all that
he can the more the better ; but as explained in a previous- ''
place, what is attempted should be according to some system, and
with a proper object. Time spent groping in the dark after
something of which no definite conception has been formed, or
for any object not to fill an ascertained want, is generally time
lost. To demonstrate or invent, one should begin methodically,
like a bricklayer builds a wall, as he mortars and sets each brick,
so should an engineer qualify, by careful study, each piece or
movement that is added to a mechanical structure, so that when
done, the result may be useful and enduring.
As remarked, every attempt to generate anything new in
machinery should be commenced by ascertaining a want of im-
provement. When such a want has been ascertained, attention
should be directed first to the principles upon which such want
or fault is to be remedied. Proper mechanism can then be sup-
plied like the missing links in a chain. Propositions thus stated
may fail to convey the meaning intended ; this systematic plan
of inventing may be better explained by an example.
Presuming the reader to remember what was said of steam
hammers in another place, and to be familiar with the uses
and general construction of such hammers, let it be supposed
steam-hammers, with the ordinary automatic valve action, those
that give an elastic or steam-cushioned blow, are well known.
Suppose further that by analysing the blows given by hammers
of this kind, it is demonstrated that dead blows, such as are
given when a hammer comes to a full stop in striking, are
more effectual in certain kinds of work, and that steam-hammers
would be improved by operating on this dead-stroke principle.
Such a proposition would constitute the first stage of an inven-
tion by demonstrating a fault in existing hammers, and a want
of certain functions which if added would make an improvement.
Proceeding from these premises, the first thing should be to
examine the action of existing valve gear, to determine where
this want of the dead-stroke function can best be supplied, and
to gain the aid of such suggestions as existing mechanism may
offer, also to see how far the appliances in use may become a part
of any new arrangement.
By examining automatic hammers it will be found that their
L
] 62 WORKSHOP MANIPULATION.
valves are connected to the drop by means of links, producing
coincident movement of the piston and valve, and that the move-
ment of one is contingent upon and governed by the other. It
will also be found that these connections or links are capable of
extension, so as to alter the relative position of the piston and
valve, thereby regulating the range of the blow, but that the
movement of the two is reciprocal or in unison. Reasoning in-
ductively, not discovering or inventing, it may be determined
that to secure a stamp blow of a hammer-head, the valve must
not open or admit steam beneath the piston until a blow is
completed and the hammer has stopped.
At this point will occur one of those mechanical problems which
requires what may be called logical solution. The valve must be
moved by the drop ; there is no other moving mechanism avail-
able ; the valve and drop must besides be connected, to insure co-
incident action, yet the valve requires to move when the drop is
still. Proceeding inductively, it is clear that a third agent must
be introduced, some part moved by the drop, which will in turn
move the valve, but this intermediate agent so arranged that
it may continue to move after the hammer-drop has stopped.
This assumed, the scheme is complete, so far as the relative
movement of the hammer-drop and the valve, but there must be
some plan of giving motion to this added mechanism. In many
examples there may be seen parts of machinery which continue
in motion after the force which propels them has ceased to act ;
cannon balls are thrown for miles, the impelling force acting for
a few feet only ; a weaver's shuttle performs nearly its whole
flight after the driver has stopped. In the present case, it is
therefore evident that an independent or subsequent movement
of the valves may be obtained by the momentum of some part
set in motion during the descent of the hammer-head.
To sum up, it is supposed to have been determined by induc-
tive reasoning, coupled with some knowledge of mechanics, that a
steam hammer, to give a dead blow, requires the following con-
ditions in the valve gearing :
1. That the drop and valve, while they must act relatively,
cannot move in the same time, or in direct unison.
2. The connection between the hammer drop and valve cannot
be positive, but must be broken during the descent of the drop.
3. The valve must move after the hammer stops.
4. To cause a movement of the valve after the hammer stops
INVENTION. 163
there must be an intermediate agent, that will continue to act
after the movement of the hammer drop has ceased.
5. The obvious means of attaining this independent movement
of the valve gear, is by the momentum of some part set in motion
by the hammer-drop, or by the force of gravity reacting on this
auxiliary agent.
The invention is now complete, and as the principles are all
within the scope of practical mechanism, there is nothing left to
do but to devise such mechanical expedients as will carry out the
principles laid down. This mechanical scheming is a second, and
in some sense an independent part of machine improvement, and
should always be subservient to principles ; in fact, to separate
mechanical scheming from principles, generally constitutes what
has been called chance invention.
Referring again to the hammer problem, it will be found by
examining the history that the makers of automatic-acting
steam-hammers capable of giving the dead stamp blow, have
employed the principle which has been described. Instead of
employing the momentum, or the gravity of moving parts, to
open the valve after the hammer stops, some engineers have
depended upon disengaging valve gear by the concussion and
jar of the blow, so that the valve gearing, or a portion of it, fell
and opened the valve. The ' dead blow gear,' fitted to the earlier
Nasmyth, or Wilson, hammers, was constructed on the latter plan,
the valve spindle when disengaged being moved by a spring.
I will not consume space to explain the converse of this system
of inventing, nor attempt to describe how a chance schemer would
proceed to hunt after mechanical expedients to accomplish the
valve movement in the example given.
Inventions in machine improvement, no matter what their
nature, must of course consist in and conform to certain fixed
modes of operating, and no plan of urging the truth of a pro-
position is so common, even with a chance inventor, as to trace
out the ' principles ' which govern his discovery.
In studying improvements with a view to practical gain, a
learner can have no reasonable hope of accomplishing much in
fields already gone over by able engineers, nor in demonstrating
anything new in what may be called exhausted subjects, such as
steam-engines or water-wheels ; he should rather choose new and
special subjects, but avoid schemes not in some degree confirmed
by existing practice.
164 WORKSHOP MANIPULATION.
It has been already remarked that the boldness of young
engineers is very apt to be inversely as their experience, not to
say their want of knowledge, and it is only by a strong and
determined effort towards conservatism, that a true balance
is maintained in judging of new schemes.
The life of George Stephenson proves that notwithstanding
the novelty and great importance of his improvements in steam
transit, he did not " discover" these improvements. He did not
discover that a floating embankment would carry a railway across
Chat Moss, neither did he discover that the friction between the
wheels of a locomotive and the rails would enable a train to be
drawn by tractive power alone. Everything connected with his
novel history shows that all of his improvements were founded
upon a method of reasoning from principles and generally in-
ductively. To say that he " discovered " our railway system,
according to the ordinary construction of the term, would be to
detract from his hard and well-earned reputation, and place him
among a class of fortunate schemers, who can claim no place in
the history of legitimate engineering.
Count Eumford did not by chance develope the philosophy of
forces upon which we may say the whole science of dynamics
now rests ; he set out upon a methodical plan to demonstrate
conceptions that were already matured in his mind, and to
verify principles which he had assumed by inductive reasoning.
The greater part of really good and substantial improvements,
such as have performed any considerable part in developing
modern mechanical engineering, have come through this course
of first dealing with primary principles, instead of groping about
blindly after mechanical expedients, and present circumstances
point to a time not far distant when chance discovery will quite
disappear.
(1.) What change has taken place in the meaning of the name
" invention " as applied to machine improvement ? (2.) What should
precede an attempt to invent or improve machinery? (3.) In what
sense should the name invention be applied to the works of such men
as Bentham, Bodmer, or Stephenson ?
WORKSHOP EXPERIENCE. 165
CHAPTER XLL
WORKSHOP EXPERIENCE.
To urge the necessity of learning practical fitting as a part of
an engineering education is superfluous. A mechanical engineer
who has not been " through the shop " can never expect to attain
success, nor command the respect even of the most inferior work-
men ; without a power of influencing and controlling others,
he is neither fitted to direct construction, nor to manage details
of any kind connected with engineering industry. There is
nothing that more provokes a feeling of resentment in the mind
of a skilled man than to meet with those who have attempted to
qualify themselves in the theoretical and commercial details of
engineering work, and then assume to direct labour which they
do not understand ; nor is a skilled man long in detecting an
engineer of this class ; a dozen words in conversation upon any
mechanical subject is generally enough to furnish a clue to the
amount of practical knowledge possessed by the speaker.
As remarked in a previous place, no one can expect to prepare
successful designs for machinery, who does not understand the
details of its construction ; he should know how each piece is
moulded, forged, turned, planed, or bored, and the relative cost of
these processes by the different methods which may be adopted.
An engineer may direct and control work without a know-
ledge of practical fitting, but such control is merely a commercial
one, and cannot of course extend to mechanical details which are
generally the vital part; the obedience that may thus be enforced
in controlling others is not to be confounded with the respect
which a superior knowledge of work commands.
A gain from learning practical fitting is the confidence which
such knowledge inspires in either the direction of work or the
preparation of plans for machinery. An engineer who hesitates
in his plans for fear of criticism, or who does not feel a perfect
confidence in them, will never achieve much success.
Improvements, which have totally changed machine fitting
during thirty years past, have been of a character to dispense in
a great measure with hand skill, and supplant it with what may
be termed mental skill. The mere physical effect produced by a
man's hands has steadily diminished in value, until it has now
166 WORKSHOP MANIPULATION.
almost come to be reckoned in foot-pounds ; but the necessity
for practical knowledge instead of being diminished is increased.
Formerly an apprentice entered a shop to learn hand skill, and
to acquaint himself with a number of mysterious processes ; to
learn a series of arbitrary rules which might serve to place him
at a disadvantage even with those whose capacity was inferior
and who had less education ; but now the whole is changed.
An engineer apprentice enters the shop with a confidence that he
may learn whatever the facilities afford if he will put forth the
required efforts ; there are no mysteries to be solved ; nearly all
problems are reached and explained by science, leaving a greater
share of the shop-time of a learner to be devoted to studying
what is special.
This change in engineering pursuits has also produced a change
in the workmen almost as thorough as in manipulation. A man
who deals with special knowledge only and feels that the secrets
of his calling are not governed by systematic rules, by which
others may qualify themselves without his assistance, is always
more or less narrow-minded and ignorant. The nature of his re-
lations to others makes him so ; of this no better proof is wanted
than to contrast the intelligence of workmen who are engaged in
what may be termed exclusive callings with people whose
pursuits are regulated by general rules and principles. A machi-
nist of modern times, having outgrown this exclusive idea, has
been raised thereby to a social position confessedly superior
to that of most other mechanics, so that shop association once so
dreaded by those who would otherwise have become mechanics,
is no longer an obstacle.
Some hints will 'now be given relating to apprentice experience
in a workshop, such matters being selected as are most likely to
be of interest and use to a learner.
Upon entering a shop the first thing to be done is to gain the
confidence and the respect of the manager or foreman who has
charge of the work ; to gain such confidence and respect is
different from, and has nothing to do with, social relations and
must depend wholly upon what transpires in the works. To
inspire the confidence of a friend one must be kind, faithful, and
honourable ; but to command the confidence of a foreman one
must be punctual, diligent, and intelligent. There are no more
kindly sentiments than those which may be founded on a regard
for industry and earnest effort. A learner may have the
WORKSHOP EXPERIENCE. 167
misfortune to break tools, spoil work, and fail in every way to
satisfy himself, yet if he is punctual, diligent, and manifests an
interest in the work, his misfortunes will not cause unkind
resentment.
It must always be remembered that what is to be learned
should not be estimated according to a learner's ideas of its im-
portance. A manager and workmen generally look upon fitting
as one of the most honourable and intelligent of pursuits, deserv-
ing of the respect and best efforts of an apprentice j and while a
learner may not think it a serious thing to make a bad fit, or to
meet with an accident, his estimate is not the one to judge from.
The least word or act which will lead workmen to think that an
apprentice is indifferent, at once destroys interest in his success,
and cuts off one of the main sources from which information may
be derived.
An apprentice in entering the workshop should avoid every-
thing tending to an appearance of fastidiousness, either of manner
or dress ; nothing is more repulsive to workmen, and it may be
added, nothing is more out of place in a machine shop than to
divide one's time between the work and an attempt to keep clean.
An effort to keep as neat as the nature of the work will admit is
at all times right, but to dress in clothing not appropriate, or to
allow a fear of grease to interfere with the performance of work,
is sure to provoke derision.
The art of keeping reasonably clean even in a machine shop is
worth studying \ some men are greased from head to foot in a
few hours, no matter what their work may be ; while others will
perform almost any kind of work, and keep clean without sacrific-
ing convenience in the least. This difference is the result of
habits readily acquired and easily retained.
Punctuality costs nothing, and buys a great deal ; a learner
who reaches the shop a quarter of an hour before starting time,
and spends that time in looking about, manifests thereby an
interest in the work, and avails himself of an important privilege,
one of the most effectual in gaining shop knowledge. Ten minutes
spent in walking about, noting the changes wrought in the work
from day to day, furnishes constant material for thought, and ac-
quaints a learner with many things which would otherwise escape
attention. It requires, however, no little care and discrimination
to avoid a kind of resentment which workmen feel in having
their work examined, especially if they have met with an accident
168 WORKSHOP MANIPULATION.
or made a mistake, and when such inspection is thought to be
prompted by curiosity only. The better plan in such cases is to
ask permission to examine work in such a way that no one will
hear the request except the person addressed such an applica-
tion generally will secure both consent and explanation.
Politeness is as indispensable to a learner in a machine shop as
it is to a gentleman in society. The character of the courtesy
may be modified to suit the circumstances and the person, but
still it is courtesy. An apprentice may understand differential
calculus, but a workman may understand how to bore a steam
cylinder ; and in the workman's estimation a problem in cal-
culus is a trivial thing to understand compared with the boring
of a steam engine cylinder. Under these circumstances, if a work-
man is not allowed to balance some of his knowledge against
politeness, an apprentice is placed at a disadvantage.
Questions and answers constitute the principal medium for ac-
quiring technical information, and engineering apprentices should
carefully study the philosophy of questions arid answers, just as
he does the principles of machinery. Without the art of ques-
tioning but slow progress will be made in learning shop manipu-
lation. A proper question is one which the person asked will
understand, and the answer be understood when it is given ; not
an easy rule, but a correct one. The main point is to consider
questions before they are asked ; make them relevant to the work
in hand, and not too many. To ask frequent questions, is to
convey an impression that the answers are not considered, an in-
ference which is certainly a fair one, if the questions relate to a
subject demanding some consideration. If a man is asked one
minute what diametrical pitch means, and the next minute how
much cast iron shrinks in cooling, he is very apt to be disgusted,
and think the second question not worth answering.
It is important, in asking questions, to consider the mood and
present occupation of the person addressed ; one question asked
when a man's mind is not too much occupied, and when he is in
a communicative humour, is worth a dozen questions asked when
he is engaged, and not disposed to talk.
It is a matter of courtesy in the usages of a shop, and one of
expediency to a learner, to ask questions from those who are
presumed to be best informed on the subject to which the
questions relate ; and it is equally a matter of courtesy to ask
questions of different workmen, being careful, however, never to
WORKSHOP EXPERIENCE. 169
ask two different persons the same question, nor questions that
may call out conflicting answers.
There is not a more generous or kindly feeling in the world
than that with which a skilled mechanic will share his knowledge
with those who have gained his esteem, and who he thinks merit
and desire the aid that he can give.
An excellent plan to retain what is learned, is to make notes.
There is nothing will assist the memory more in learning
mechanics than to write down facts as they are learned, even if
such memoranda are never referred to after they are made.
It is not intended to recommend writing down rules or tables
relating to shop manipulation so much as facts which require
remark or comment to impress them on the memory writing
notes not only assists in committing the subjects to memory, but
cultivates a power of composing technical descriptions, a very
necessary part of an engineering education. Specifications for
engineering work are a most difficult kind of composition and
may be made long, tedious, and irrelevant, or concise and lucid.
There are also a large number of conventional phrases and
endless technicalities to be learned, and to write them will assist
in committing them to memory and decide their orthography.
In making notes, as much as possible of what is written should
be condensed into brief formulae, a form of expression which is
fast becoming the written language of machine shops. Reading
formulae is in a great degree a matter of habit, like studying
mechanical drawings ; that which at the beginning is a maze of
complexity, after a time becomes intelligible and clear at a
glance.
Upon entering the shop, a learner will generally, to use a shop
phrase, " be introduced to a hammer and chisel ; " he will, per-
haps, regard these hand tools with a kind of contempt. Seeing
other operations carried on by power, and the machines in charge
of skilled men, he is likely to esteem chipping and filing as of
but little importance and mainly intended for keeping apprentices
employed. But long after, when a score of years has been added
to his experience, the hammer, chisel, and file, will remain the
most crucial test of his hand skill, and after learning to mani-
pulate power tools of all kinds in the most thorough manner, a
few blows with a chipping hammer, or a half-dozen strokes with
a file, will not only be a more difficult test of skill, but one
most likely to be met with.
170 WORKSHOP MANIPULATION.
To learn to chip and file is indispensable, if for no other
purpose, to be able to judge of the proficiency of others or to
instruct them. Chipping and filing are purely matters of han
skill, tedious to learn, but when once acquired, are never forgotten.
The use of a file is an interesting problem to study, and one of
no little intricacy; in filing across a surface one inch wide, with
a file twelve inches long, the pressure required at each end to
guide it level may change at each stroke from nothing to twenty
pounds or more ; the nice sense of feeling which determines this
is a matter of habit acquired by long practice. It is a wonder
indeed that true surfaces can be made with a file, or even that
a file can be used at all, except for rough work.
If asked for advice as to the most important object for an
apprentice to aim at in beginning his fitting course, nine out of
ten experienced men will say, "to do work well." As power is
measured by force and velocity, work is measured by the two
conditions of skill and time. The first consideration being, how
well a thing may be done, and secondly, in how short a time may
it be performed ; the skill spent on a piece of work is the measure
of its worth ; if work is badly executed, it makes no difference
how short the time of performance has been; this can add nothing
to the value of what is done although the expense is diminished.
A learner is apt to reverse this proposition at the beginning,
and place time before skill, but if he will note what passes around
him, it will be seen that criticism is always first directed to the
character of work performed. A manager does not ask a workman
how long a time was consumed in preparing a piece of work until
its character has been passed upon ; in short, the quality of work
is its mechanical standard, and the time consumed in preparing
work is its commercial standard. A job is never properly done
when the workman who performed it can see faults, and in
machine fitting, as a rule, the best skill that can be applied is no
more than the conditions call for ; so that the first thing to be
learned is to perform work well, and afterwards to perform it
rapidly.
Good fitting is often not so much a question of skill as of the
standard which a workman has fixed in his mind, and to which
all that he does will more or less conform. If this standard is
one of exactness and precision, all that is performed, whether it
be filing, turning, planing, or drawing, will come to this standard.
This faculty of mind can be defined no further than to say that
WORKSHOP EXPERIENCE. 171
it is an aversion to whatever is imperfect, and a love for what is
exact and precise. There is no faculty which has so much to do
with success in mechanical pursuits, nor is there any trait more
susceptible of cultivation. Methodical exactness, reasoning, and
persistence are the powers which lead to proficiency in engineer-
ing pursuits.
There is, perhaps, no more fitting conclusion to these sugges-
tions for apprentices than a word about health and strength. It
was remarked in connection with the subject of drawing, that the
powers of a mechanical engineer were to be measured by his
education and mental abilities, no more than by his vitality and
physical strength, a proposition which it will be well for an
apprentice to keep in mind.
One not accustomed to manual labour will, after commencing,
find his limbs aching, his hands sore ; he will feel exhausted both
at the beginning and at the end of a day's work. These are not
dangerous symptoms. He has only to wait until his system is
built up so as to sustain this new draught upon its resources, and
until nature furnishes a power of endurance, which will in the
end be a source of pride, and add a score of years to life.
Have plenty of sleep, plenty of plain, substantial food, keep the
skin clean and active, laugh at privations, and cultivate a spirit
of self-sacrifice and a pride in endurance that will court the
hardest and longest efforts. An apprentice who has not the
spirit and firmness to endure physical labour, and adapt himself
to the conditions of a workshop, should select some pursuit of a
nature less aggressive than mechanical engineering.
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The Principles of Graphic Statics. By GEORGE
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Practical Geometry, Perspective, and Engineering
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The Elements of Graphic Statics. By Professor
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Breweries and Mailings : their Arrangement, Con-
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Mining Machinery: a Descriptive Treatise on the
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Machinery for Prospecting, Excavating, Hauling, and Hoisting Ventilation Pumping
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Coal, Sulphur, China Clay, Brick Earth, etc.
Tables for Setting out Curves for Railways, Canals,
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The B oiler-maker s andiron Ship-builder s Companion,
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A Practical Treatise on the Steam Engine, con-
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Great Britain and America. The laws relating to the action and precautions to be observed
in the construction of the various details, such as Cylinders, Pistons, Piston-rods, Connecting-
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A Practical Treatise on the Science of Land and
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Theodolite Mining and Town Surveying Railroad Surveying Mapping Division and
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graph Merrett's Improved Quadrant Improved Computation Scale The Diagonal Scale
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Electricity: its Theory, Sources, and Applications.
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The Practice of Hand Turning in Wood, Ivory, Shell,
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Treatise on Watchwork, Past and Present. By the
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Algebra Self -Taught. By W. P. HIGGS, M.A.,
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Spans' Dictionary of Engineering, Civil, Mechanical,
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Notes in Mechanical Engineering. Compiled prin-
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Canoe and Boat Building: a complete Manual for
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Proceedings of the National Conference of Electricians,
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Dynamo - Electricity, its Generation, Application,
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Domestic Electricity for Amateurs. Translated from
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WHARTON, Assoc. Soc. Tel. Eng. Numerous illustrations. Demy 8vo,
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Wrinkles in Electric Lighting. By VINCENT STEPHEN.
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The Practical Flax Spinner ; being a Description of
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Foundations and Foundation Walls for all classes of
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Ten Years Experience in Works of Intermittent
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Steam Making, or Boiler Practice. By CHARLES A.
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tures, 23 pp. 17 figs. Silk, 8 pp.
Cements. Clay.
Ink, 17 pp.
Silk Manufactures, 9 pp..
Coal-tar Products, 44 pp.
Ivory.
II figS.
14 figs.
Jute Manufactures, n Skins, 5 pp.
Cocoa, 8 pp.
pp., 1 1 figs. i Small Wares, 4 pp.
Coffee, 32 pp. 13 figs.
Knitted Fabrics Soap and Glycerine, 39
Cork, 8 pp. 17 figs.
Hosiery, 15 pp. 13 figs.
pp. 45 figs.
Cotton Manufactures, 62
Lace, 13 pp. 9 fi gs-
Spices, 1 6 pp.
PP- 57 ngs.
Leather, 28 pp. 31 figs.
Sponge, 5 pp.
Drugs, 38 pp.
Linen Manufactures, 16 Starch, 9 pp. 10 figs.
Dyeing and Calico
pp. 6 figs. Sugar, 155 pp. 134
Printing, 28 pp. 9 figs.
Manures, 21 pp. 30 figs. figs.
Dyestuffs, 16 pp.
Matches, 1 7 pp. 38 figs. Sulphur.
Electro-Metallurgy, 13
Mordants, 13 pp. i Tannin, 18 pp.
pp.
Narcotics, 47 pp.
Tea, 12 pp.
Explosives, 22 pp. 33 figs.
Nuts, 10 pp.
Timber, 13 pp.
Feathers.
Oils and Fatty Sub-
Varnish, 15 pp.
Fibrous Substances, 92
stances, 125 pp.
Vinegar, 5 pp.
pp. 79 figs.
Paint.
Wax, 5 pp.
Floor-cloth, 1 6 pp. 21
Paper, 26 pp. 23 figs.
Wool, 2 pp.
figs.
Paraffin, 8 pp. 6 figs.
Woollen Manufactures,
Food Preservation, 8 pp.
Pearl and Coral, 8 pp.
58 pp. 39 figs.
Fruit, 8 pp.
Perfumes, 10 pp.
London : E. & F. N. SPON, 125, Strand.
New York : 35, Murray Street.
Crown 8vo, cloth, with illustrations, 5.5-.
WORKSHOP RECEIPTS,
FIRST SERIES.
BY ERNEST SPON.
SYNOPSIS OF CONTENTS.
Bookbinding.
Bronzes and Bronzing
Candles.
Cement.
Cleaning.
Colourwashing.
Concretes.
Dipping Acids.
Drawing Office Details.
Drying Oils.
Dynamite.
Electro - Metallurgy
{Cleaning, Dipping,
Scratch-brushing, Bat-
teries, Baths, and (
Deposits of every j
description).
Enamels.
Engraving on Wood,
Copper, Gold, Silver, '
Steel, and Stone.
Etching and Aqua Tint.
Firework Making j
(Rockets, Stars, Rains, \
Gerbes, Jets, Tour- j
billons, Candles, Fires, |
Lances,Lights, Wheels, !
Fire-balloons, and'
minor Fireworks).
Fluxes.
Foundry Mixtures.
Besides Receipts relating to the lesser Technological matters and processes,
such as the manufacture and. use of Stencil Plates, Blacking, Crayons, Paste,
Putty, Wax, Size, Alloys, Catgut, Tunbridge Ware, Picture Frame and
Architectural Mouldings, Compos, Cameos, and others too numerous to
mention.
Freezing.
Fulminates.
Furniture Creams, Oils,
Polishes, Lacquers,
and Pastes.
Gilding.
Glass Cutting, Cleaning,
Frosting, Drilling,
Darkening, Bending,
Staining, and Paint-
ing.
Glass Making.
Glues.
Gold.
Graining.
Gums.
Gun Cotton.
Gunpowder.
Horn Working.
Indiarubber.
Japans, Japanning, and
kindred processes.
Lacquers.
Lathing.
Lubricants.
Marble Working.
Matches.
Mortars.
Nitre-Glycerine.
Oils.
Paper.
Paper Hanging.
Painting in Oils, in Water
Colours, as well as
Fresco, House, Trans-
parency, Sign, and
Carriage Painting.
Photography.
Plastering.
Polishes.
Pottery (Clays, Bodies,
Glazes, Colours, Oils,
Stains, Fluxes, Ena-
mels, and Lustres).
Scouring.
Silvering.
Soap.
Solders.
Tanning.
Taxidermy.
Tempering Metals.
Treating Horn, Mother-
o'- Pearl, and like sub-
stances.
Varnishes, Manufacture
and Use of.
Veneering.
Washing.
Waterproofing.
Welding.
London: E. & F. N. SPON, 125, Strand.
New York: 35, Murray Street.
Crown 8vo, cloth, 485 pages, with illustrations, 5-r.
WORKSHOP RECEIPTS,
SECOND SERIES.
BY ROBERT HALDANE.
SYNOPSIS OF CONTENTS.-
Acidimetry and Alkali- Disinfectants.
Isinglass.
metry. Dyeing, Staining, and
Ivory substitutes.
Albumen. Colouring.
Leather.
Alcohol. Essences.
Luminous bodies.
Alkaloids. Extracts.
Magnesia.
Baking-powders.
Fireproofing.
Matches.
Bitters.
Gelatine, Glue, and Size.
Paper.
Bleaching.
Glycerine.
Parchment.
Boiler Incrustations.
Gut.
Perchloric acid.
Cements and Lutes.
Hydrogen peroxide.
Potassium oxalate.
Cleansing.
Ink.
Preserving.
Confectionery.
Iodine.
Copying.
lodoform.
Pigments, Paint, and Painting : embracing the preparation of
Pigments^ including alumina lakes, blacks (animal, bone, Frankfort, ivory,
lamp, sight, soot), blues (antimony, Antwerp, cobalt, cseruleum, Egyptian r
manganate, Paris, Peligot, Prussian, smalt, ultramarine), browns (bistre 7
hinau, sepia, sienna, umber, Vandyke), greens (baryta, Brighton, Brunswick,
chrome, cobalt, Douglas, emerald, manganese, mitis, mountain, Prussian,
sap, Scheele's, Schweinfurth, titanium,' verdigris, zinc), reds (Brazilwood lake,
carminated lake, carmine, Cassius purple, cobalt pink, cochineal lake, colco-
thar, Indian red, madder lake, red chalk, red lead, vermilion), whites (alum r
baryta, Chinese, lead sulphate, white lead by American, Dutch, French r
German, Kremnitz, and Pattinson processes, precautions in making, and
composition of commercial samples whiting, Wilkinson's white, zinc white),
yellows (chrome, gamboge, Naples, orpiment, realgar, yellow lakes) ; Paint
(vehicles, testing oils, driers, grinding, storing, applying, priming, drying,
filling, coats, brushes, surface, water-colours, removing smell, discoloration - T
miscellaneous paints cement paint for carton-pierre, copper paint, gold paint,
iron paint, lime paints, silicated paints, steatite paint, transparent paints,
tungsten paints, window paint, zinc paints) ; Painting (general instructions,
proportions of ingredients, measuring paint work ; carriage painting priming,
paint, best putty, finishing colour, cause of cracking, mixing the paints, oils,
driers, and colours, varnishing, importance of washing vehicles, re-varnishing,.
how to dry paint ; woodwork painting).
London : E. & F. N. SPON, 125, Strand,
New York : 35, Murray Street.
JUST PUBLISHED.
Crown 8vo, cloth, 480 pages, with 183 illustrations, $j.
WORKSHOP RECEIPTS,
THIRD SERIES.
BY C. G. WARNFORD LOCK.
Uniform with the First and Second Series.
Alloys.
Aluminium.
Antimony.
Barium.
Beryllium.
Bismuth.
Cadmium.
Caesium.
Calcium.
Cerium.
Chromium.
Cobalt.
Copper.
Didymium.
Electrics.
Enamels and Glazes.
Erbium.
Gallium.
Glass.
Gold.
London : E. & F. N. SPON, 125, Strand.
New York: 35, Murray Street.
SYNOPSIS OF CONTENTS.
Indium. ; Rubidium.
Iridium.
Ruthenium.
Iron and Steel.
Selenium.
Lacquers and Lacquering.
Silver.
Lanthanum.
Slag.
Lead.
Sodium.
Lithium.
Strontium.
Lubricants.
Tantalum.
Magnesium. , Terbium.
Manganese. Thallium.
Mercury. Thorium.
Mica.
Tin.
Molybdenum.
Titanium.
Nickel.
Tungsten.
Niobium.
Uranium.
Osmium.
Vanadium.
Palladium.
Yttrium.
Platinum.
Zinc.
Potassium.
Zirconium.
Rhodium.
WORKSHOP RECEIPTS,
FOURTH SERIES,
DEVOTED MAINLY TO HANDICRAFTS & MECHANICAL SUBJECTS.
BY C. G. WARNFORD LOCK.
250 Illustrations, with Complete Index, and a General Index to the
Four Series, 5s.
Waterproofing rubber goods, cuprammonium processes, miscellaneous
preparations.
Packing and Storing articles of delicate odour or colour, of a deliquescent
character, liable to ignition, apt to suffer from insects or damp, or easily
broken.
Embalming and Preserving anatomical specimens.
Leather Polishes.
Cooling Air and Water, producing low temperatures, making ice, cooling
syrups and solutions, and separating salts from liquors by refrigeration.
Pumps and Siphons, embracing every useful contrivance for raising and
supplying water on a moderate scale, and moving corrosive, tenacious,
and other liquids.
Desiccating air- and water-ovens, and other appliances for drying natural
and artificial products.
Distilling water, tinctures, extracts, pharmaceutical preparations, essences,
perfumes, and alcoholic liquids.
Emulsifying as required by pharmacists and photographers.
Evaporating saline and other solutions, and liquids demanding special
precautions.
Piltering water, and solutions of various kinds.
Percolating and Macerating.
Electrotyping.
Stereotyping by both plaster and paper processes.
Bookbinding in all its details.
Straw Plaiting and the fabrication of baskets, matting, etc.
Musical Instruments the preservation, tuning, and repair of pianos,
harmoniums, musical boxes, etc.
Clock and Watch Mending adapted for intelligent amateurs.
Photography recent development in rapid processes, handy apparatus,
numerous recipes for sensitizing and developing solutions, and applica-
tions to modern illustrative purposes.
London : E. & F. N. SPON, 125, Strand.
New York : 35, Murray Street.
JUST
In demy 8vo, cloth, 600 pages, and 1420 Illustrations, 6s.
SPONS'
MECHANICS' OWN BOOK;
A MANUAL FOR HANDICRAFTSMEN AND AMATEURS.
CONTENTS.
Mechanical Drawing Casting and Founding in Iron, Brass, Bronze,
and other Alloys Forging and Finishing Iron Sheetmetal Working
Soldering, Brazing, and Burning Carpentry and Joinery, embracing
descriptions of some 400 Woods, over 200 Illustrations of Tools and
their uses, Explanations (with Diagrams) of 116 joints and hinges, and
Details of Construction of Workshop appliances, rough furniture,
Garden and Yard Erections, and House Building Cabinet-Making
and Veneering Carving and Fretcutting Upholstery Painting,
Graining, and Marbling Staining Furniture, Woods, Floors, and
Fittings Gilding, dead and bright, on various grounds Polishing
Marble, Metals, and Wood Varnishing Mechanical movements,
illustrating contrivances for transmitting motion Turning in Wood
and Metals Masonry, embracing Stonework, Brickwork, Terracotta,
and Concrete Roofing with Thatch, Tiles, Slates, Felt, Zinc, &c.
Glazing with and without putty, and lead glazing Plastering and
Whitewashing Paper-hanging Gas-fitting Bell-hanging, ordinary
and electric Systems Lighting Warming Ventilating Roads,
Pavements, and Bridges Hedges, Ditches, and Drains Water
Supply and Sanitation Hints on House Construction suited to new
countries.
London : E. & F. N. SPON, 125, Strand.
New York : 35, Murray Street.
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.
1945
LD 21-y5m-7,'37
v/jr*> i r^o^ /-
YB i ooou
UNIVERSITY OF CALIFORNIA LIBRARY