_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 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 business 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 understood 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
construction 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, however,
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 structures,
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 purposes, 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, railway
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 improvements 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.
Looking ahead into the future, the apprentice can see a field
for the mechanical engineer widening on every side. As the
construction 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
efficient 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 discharge
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 mechanical engineering likely to become
more exact and scientific?--(5.) Name some of the principal
branches of mechanical engineering.--(6.) Which is the most
extensive and important?