On the Economy of Machinery and Manufactures by Charles Babbage (english books to improve english TXT) 📕

material to be wrought is firmly grasped by screws, are of this

kind, and are used in almost every workshop; but a more striking

example may be found in the trade of the nail-maker.

Some kinds of nails, such as those used for defending the

soles of coarse shoes, called hobnails, require a particular form

of the head, which is made by the stroke of a die. The workman

holds one end of the rod of iron out of which he forms the nails

in his left hand; with his right hand he hammers the red-hot end

of it into a point, and cutting the proper length almost off,

bends it nearly at a right angle. He puts this into a hole in a

small stake-iron immediately under a hammer which is connected

with a treadle, and has a die sunk in its surface corresponding

to the intended form of the head; and having given one part of

the form to the head with the small hammer in his hand, he moves

the treadle with his foot, disengages the other hammer, and

completes the figure of the head; the returning stroke produced

by the movement of the treadle striking the finished nail out of

the hole in which it was retained. Without this substitution of

his foot for another hand, the workman would, probably, be

obliged to heat the nails twice over.

14. Another, though fortunately a less general substitution

of tools for human hands, is used to assist the labour of those

who are deprived by nature, or by accident, of some of their

limbs. Those who have had an opportunity of examining the

beautiful contrivances for the manufacture of shoes by machinery,

which we owe to the fertile invention of Mr Brunel, must have

noticed many instances in which the workmen were enabled to

execute their task with precision, although labouring under the

disadvantages of the loss of an arm or leg. A similar instance

occurs at Liverpool, in the Institution for the Blind, where a

machine is used by those afflicted with blindness, for weaving

sash-lines; it is said to have been the invention of a person

suffering under that calamity. Other examples might be mentioned

of contrivances for the use, the amusement, or the instruction of

the wealthier classes, who labour under the same natural

disadvantages. These triumphs of skill and ingenuity deserve a

double portion of our admiration when applied to mitigate the

severity of natural or accidental misfortune; when they supply

the rich with occupation and knowledge; when they relieve the

poor from the additional evils of poverty and want.

15. Division of the objects of machinery. There exists a

natural, although, in point of number, a very unequal division

amongst machines: they may be classed as; first, those which are

employed to produce power, and as, secondly, those which are

intended merely to transmit force and execute work. The first of

these divisions is of great importance, and is very limited in

the variety of its species, although some of those species

consist of numerous individuals.

Of that class of mechanical agents by which motion is

transmitted—the lever, the pulley, the wedge, and many others—

it has been demonstrated, that no power is gained by their use,

however combined. Whatever force is applied at one point can only

be exerted at some other, diminished by friction and other

incidental causes; and it has been further proved, that whatever

is gained in the rapidity of execution is compensated by the

necessity of exerting additional force. These two principles,

long since placed beyond the reach of doubt, cannot be too

constantly borne in mind. But in limiting our attempts to things

which are possible, we are still, as we hope to shew, possessed

of a field of inexhaustible research, and of advantages derived

from mechanical skill, which have but just begun to exercise

their influence on our arts, and may be pursued without limit

contributing to the improvement, the wealth, and the happiness of

our race.

16. Of those machines by which we produce power, it may be

observed, that although they are to us immense acquisitions, yet

in regard to two of the sources of this power—the force of wind

and of water—we merely make use of bodies in a state of motion

by nature; we change the directions of their movement in order to

render them subservient to our purposes, but we neither add to

nor diminish the quantity of motion in existence. When we expose

the sails of a windmill obliquely to the gale, we check the

velocity of a small portion of the atmosphere, and convert its

own rectilinear motion into one of rotation in the sails; we thus

change the direction of force, but we create no power. The same

may be observed with regard to the sails of a vessel; the

quantity of motion given by them is precisely the same as that

which is destroyed in the atmosphere. If we avail ourselves of a

descending stream to turn a water-wheel, we are appropriating a

power which nature may appear, at first sight, to be uselessly

and irrecoverably wasting, but which, upon due examination, we

shall find she is ever regaining by other processes. The fluid

which is falling from a higher to a lower level, carries with it

the velocity due to its revolution with the earth at a greater

distance from its centre. It will therefore accelerate, although

to an almost infinitesimal extent, the earth’s daily rotation.

The sum of all these increments of velocity, arising from the

descent of all the falling waters on the earth’s surface, would

in time become perceptible, did not nature, by the process of

evaporation, convey the waters back to their sources; and thus

again, by removing matter to a greater distance from the centre,

destroy the velocity generated by its previous approach.

17. The force of vapour is another fertile source of moving

power; but even in this case it cannot be maintained that power

is created. Water is converted into elastic vapour by the

combustion of fuel. The chemical changes which thus take place

are constantly increasing the atmosphere by large quantities of

carbonic acid and other gases noxious to animal life. The means

by which nature decomposes these elements, or reconverts them

into a solid form, are not sufficiently known: but if the end

could be accomplished by mechanical force, it is almost certain

that the power necessary to produce it would at least equal that

which was generated by the original combustion. Man, therefore,

does not create power; but, availing himself of his knowledge of

nature’s mysteries, he applies his talents to diverting a small

and limited portion of her energies to his own wants: and,

whether he employs the regulated action of steam, or the more

rapid and tremendous effects of gunpowder, he is only producing

on a small scale compositions and decompositions which nature is

incessantly at work in reversing, for the restoration of that

equilibrium which we cannot doubt is constantly maintained

throughout even the remotest limits of our system. The operations

of man participate in the character of their author; they are

diminutive, but energetic during the short period of their

existence: whilst those of nature, acting over vast spaces, and

unlimited by time, are ever pursuing their silent and resistless

career.

18. In stating the broad principle, that all combinations of

mechanical art can only augment the force communicated to the

machine at the expense of the time employed in producing the

effect, it might, perhaps, be imagined, that the assistance

derived from such contrivances is small. This is, however, by no

means the case: since the almost unlimited variety they afford,

enables us to exert to the greatest advantage whatever force we

employ. There is, it is true, a limit beyond which it is

impossible to reduce the power necessary to produce any given

effect, but it very seldom happens that the methods first

employed at all approach that limit. In dividing the knotted root

of a tree for fuel, how very different will be the time consumed,

according to the nature of the tool made use of! The hatchet, or

the adze, will divide it into small parts, but will consume a

large portion of the workman’s time. The saw will answer the same

purpose more quickly and more effectually. This, in its turn, is

superseded by the wedge, which rends it in a still shorter time.

If the circumstances are favourable, and the workman skilful, the

time and expense may be still further reduced by the use of a

small quantity of gunpowder exploded in holes judiciously placed

in the block.

19. When a mass of matter is to be removed a certain force

must be expended; and upon the proper economy of this force the

price of transport will depend. A country must, however, have

reached a high degree of civilization before it will have

approached the limit of this economy. The cotton of Java is

conveyed in junks to the coast of China; but from the seed not

being previously separated, three-quarters of the weight thus

carried is not cotton. This might, perhaps, be justified in Java

by the want of machinery to separate the seed, or by the relative

cost of the operation in the two countries. But the cotton

itself, as packed by the Chinese, occupies three times the bulk

of an equal quantity shipped by Europeans for their own markets.

Thus the freight of a given quantity of cotton costs the Chinese

nearly twelve times the price to which, by a proper attention to

mechanical methods, it might be reduced. *

NOTES:

1. ‘The Bandana handkerchiefs manufactured at Glasgow have long

superseded the genuine ones, and are now committed in large

quantities both by the natives and Chines.’ Crawford’s Indian

Archipelago, vol. iii, p. 505.

2. ‘Captain Clapperton, when on a visit at the court of the

Sultan Bello, states, that provisionswere regularly sent me from

the sultan’s table on pewter dishes with the London stamp; and I

even had a piece of meat served up on a white wash-hand basin of

English manufacture.’ Clapperton’s Journey, p. 88.

3. At Calicut, in the East Indies (whence the cotton cloth caled

calico derivesits name), the price of labour is one-seventh of

that in England, yet the market is supplied from British looms.

4. Liverpool, though not itself a manufacturing town, has been

placed in this list, from its connection with Manchester, of

which it is the port.

5. So sensible are the effects of grease in diminishing friction,

that the drivers of sledges in Amsterdam, on which heavy goodsare

transported, cary in their hand a rope soaked in tallow, which

they thrown down from time to time before the sledge, in order

that, by passing over the rope, it may become greased.