_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 methodical
purpose.
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 and 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
useful 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 discovery, 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 engineering
apprentices with a better and more dignified appreciation of their
calling than to confound it with chance invention, and thereby
destroy that confidence in positive results which has in the past
characterised mechanical engineering; also to caution learners
against the loss of time and effort too often expended in searching
after inventions.
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 improvement. 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 supplied 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 invention
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 valves
are connected to the drop by means of links, producing coincident
movement of the piston and valve, and that the movement 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 inductively, 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 available;
the valve and drop must besides be connected, to insure coincident
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 inductive
reasoning, coupled with some knowledge of mechanics, that a steam
hammer, to give a dead blow, requires the following conditions 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 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 proposition
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.
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 inductively. 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 Rumford 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?