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errors in the preceding one; and it is

sufficient merely to indicate a few of their sources. They

frequently arise from having neglected to take into consideration

that metals are not perfectly rigid but elastic. A steel cylinder

of small diameter must not be regarded as an inflexible rod; but

in order to ensure its perfect action as an axis, it must be

supported at proper intervals.

 

Again, the strength and stiffness of the framing which

supports the mechanism must be carefully attended to. It should

always be recollected, that the addition of superfluous matter to

the immovable parts of a machine produces no additional momentum,

and therefore is not accompanied with the same evil that arises

when the moving parts are increased in weight. The stiffness of

the framing in a machine produces an important advantage. If the

bearings of the axis (those places at which they are supported)

are once placed in a straight line, they will remain so, if the

framing be immovable; whereas if the framework changes its form,

though ever so slightly, considerable friction is immediately

produced. This effect is so well understood in the districts

where spinning factories are numerous, that, in estimating the

expense of working a new factory, it is allowed that five per

cent on the power of the steamengine will be saved if the

building is fireproof: for the greater strength and rigidity of a

fireproof building prevents the movement of the long shafts or

axes which drive the machinery, from being impeded by the

friction that would arise from the slightest deviation in any of

the bearings.

 

323. In conducting experiments upon machinery, it is quite a

mistake to suppose that any imperfect mechanical work is good

enough for such a purpose. If the experiment is worth making, it

ought to be tried with all the advantages of which the state of

mechanical art admits; for an imperfect trial may cause an idea

to be given up, which better workmanship might have proved to be

practicable. On the other hand, when once the efficiency of a

contrivance has been established, with good workmanship it will

be easy afterwards to ascertain the degree of perfection which

will suffice for its due action.

 

324. It is partly owing to the imperfection of the original

trials, and partly to the gradual improvements in the art of

making machinery, that many inventions which have been tried, and

given up in one state of art, have at another period been

eminently successful. The idea of printing by means of moveable

types had probably suggested itself to the imagination of many

persons conversant with impressions taken either from blocks or

seals. We find amongst the instruments discovered in the remains

of Pompeii and Herculaneum, stamps for words formed out of one

piece of metal, and including several letters. The idea of

separating these letters, and of recombining them into other

words, for the purpose of stamping a book, could scarcely have

failed to occur to many: but it would almost certainly have been

rejected by those best acquainted with the mechanical arts of

that time; for the workmen of those days must have instantly

perceived the impossibility of producing many thousand pieces of

wood or metal, fitting so perfectly and ranging so uniformly, as

the types or blocks of wood now used in the art of printing.

 

The principle of the press which bears the name of Bramah,

was known about a century and a half before the machine, to which

it gave rise, existed; but the imperfect state of mechanical art

in the time of the discoverer, would have effectually deterred

him, if the application of it had occurred to his mind, from

attempting to employ it in practice as an instrument for exerting

force.

 

These considerations prove the propriety of repeating, at the

termination of intervals during which the art of making machinery

has received any great improvement, the trails of methods which,

although founded upon just principles, had previously failed.

 

325. When the drawings of a machine have been properly made,

and the parts have been well executed, and even when the work it

produces possesses all the qualities which were anticipated,

still the invention may fail; that is, it may fail of being

brought into general practice. This will most frequently arise

from the circumstance of its producing its work at a greater

expense than that at which it can be made by other methods.

 

326. Whenever the new, or improved machine, is intended to

become the basis of a manufacture, it is essentially requisite

that the whole expense attending its operations should be fully

considered before its construction is undertaken. It is almost

always very difficult to make this estimate of the expense: the

more complicated the mechanism, the less easy is the task; and in

cases of great complexity and extent of machinery it is almost

impossible. It has been estimated roughly, that the first

individual of any newly invented machine, will cost about five

times as much as the construction of the second, an estimate

which is, perhaps, sufficiently near the truth. If the second

machine is to be precisely like the first, the same drawings, and

the same patterns will answer for it; but if, as usually happens,

some improvements have been suggested by the experience of the

first, these must be more or less altered. When, however, two or

three machines have been completed, and many more are wanted,

they can usually be produced at much less than one-fifth of the

expense of the original invention.

 

327. The arts of contriving, of drawing, and of executing, do

not usually reside in their greatest perfection in one

individual; and in this, as in other arts, the division of labour

must be applied. The best advice which can be offered to a

projector of any mechanical invention, is to employ a respectable

draughtsman; who, if he has had a large experience in his

profession, will assist in finding out whether the contrivance is

new, and can then make working drawings of it. The first step,

however, the ascertaining whether the contrivance has the merit

of novelty, is most important; for it is a maxim equally just in

all the arts, and in every science, that the man who aspires to

fortune or to fame by new discoveries, must be content to examine

with care the knowledge of his contemporaries, or to exhaust his

efforts in inventing again, what he will most probably find has

been better executed before.

 

328. This, nevertheless, is a subject upon which even

ingenious men are often singularly negligent. There is, perhaps,

no trade or profession existing in which there is so much

quackery, so much ignorance of the scientific principles, and of

the history of their own art, with respect to its resources and

extent, as are to be met with amongst mechanical projectors. The

self-constituted engineer, dazzled with the beauty of some,

perhaps, really original contrivance, assumes his new profession

with as little suspicion that previous instruction, that thought

and painful labour, are necessary to its successful exercise, as

does the statesman or the senator. Much of this false confidence

arises from the improper estimate which is entertained of the

difficulty of invention in mechanics. It is, therefore, of great

importance to the individuals and to the families of those who

are too often led away from more suitable pursuits, the dupes of

their own ingenuity and of the popular voice, to convince both

them and the public that the power of making new mechanical

combinations is a possession common to a multitude of minds, and

that the talents which it requires are by no means of the highest

order. It is still more important that they should be impressed

with the conviction that the great merit, and the great success

of those who have attained to eminence in such matters, was

almost entirely due to the unremitted perseverance with which

they concentrated upon their successful inventions the skill and

knowledge which years of study had matured.

Chapter 28

Proper Circumstances for the Application of Machinery

 

329. The first object of machinery, the chief cause of its

extensive utility, is the perfection and the cheap production of

the articles which it is intended to make. Whenever it is

required to produce a great multitude of things, all of exactly

the same kind, the proper time has arrived for the construction

of tools or machines by which they may be manufactured. If only a

few pairs of cotton stockings should be required, it would be an

absurd waste of time, and of capital, to construct a

stocking-frame to weave them, when, for a few pence, four steel

wires can be procured by which they may be knit. If, on the other

hand, many thousand pairs were wanted, the time employed, and the

expense incurred in constructing a stocking-frame, would be more

than repaid by the saving of time in making that large number of

stockings. The same principle is applicable to the copying of

letters: if three or four copies only are required, the pen and

the human hand furnish the cheapest means of obtaining them; if

hundreds are called for, lithography may be brought to our

assistance; but if hundreds of thousands are wanted, the

machinery of a printing establishment supplies the most

economical method of accomplishing the object.

 

330. There are, however, many cases in which machines or

tools must be made, in which economical production is not the

most important object. Whenever it is required to produce a few

articles parts of machinery, for instance, which must be executed

with the most rigid accuracy or be perfectly alike—it is nearly

impossible to fulfil this condition, even with the aid of the

most skilful hands: and it becomes necessary to make tools

expressly for the purpose, although those tools should, as

frequently happens, cost more in constructing than the things

they are destined to make.

 

331. Another instance of the just application of machinery,

even at an increased expense, arises where the shortness of time

in which the article is produced, has an important influence on

its value. In the publication of our daily newspapers, it

frequently happens that the debates in the Houses of Parliament

are carried on to three and four o’clock in the morning, that is.

to within a very few hours of the time for the publication of the

paper. The speeches must be taken down by reporters, conveyed by

them to the establishment of the newspaper, perhaps at the

distance of one or two miles, transcribed by them in the office,

set up by the compositor, the press corrected, and the paper be

printed off and distributed, before the public can read them.

Some of these journals have a circulation of from five to ten

thousand daily. Supposing four thousand to be wanted, and that

they could be printed only at the rate of five hundred per hour

upon one side of the paper, (which was the greatest number two

journeymen and a boy could take off by the old hand presses),

sixteen hours would be required for printing the complete

edition; and the news conveyed to the purchasers of the latest

portion of the impression, would be out of date before they could

receive it. To obviate this difficulty, it was often necessary to

set up the paper in duplicate, and sometimes, when late, in

triplicate: but the improvements in the printing machines have

been so great, that four thousand copies are now printed on one

side in an hour.

 

332. The establishment of ‘The Times’ newspaper is an

example, on a large scale, of a manufactory in which the division

of labour, both mental and bodily, is admirably illustrated, and

in which also the effect of domestic economy is well exemplified.

It is scarcely imagined by the thousands

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