On the Economy of Machinery and Manufactures - Charles Babbage (interesting books to read in english .TXT) 📗

Part of its weight

The roughly chiselled floor of its quarry is nearly 2/3

Along a wooden floor 3/5

By wood upon wood 5/9

If the wooden surfaces are soaped 1/6

With rollers on the floor of the quarry 1/32

On rollers on wood 1/40

On rollers between wood 1/50

 

At each increase of knowledge, as well as on the contrivance

of every new tool, human labour becomes abridged. The man who

contrived rollers, invented a tool by which his power was

quintupled. The workman who first suggested the employment of

soap or grease, was immediately enabled to move, without exerting

a greater effort, more than three times the weight he could

before.(5*)

 

6. The economy of human time is the next advantage of

machinery in manufactures. So extensive and important is this

effect, that we might, if we were inclined to generalize, embrace

almost all the advantages under this single head: but the

elucidation of principles of less extent will contribute more

readily to a knowledge of the subject; and, as numerous examples

will be presented to the reader in the ensuing pages, we shall

restrict our illustrations upon this point.

 

As an example of the economy of time, the use of gunpowder in

blasting rocks may be noticed. Several pounds of powder may be

purchased for a sum acquired by a few days’ labour: yet when this

is employed for the purpose alluded to, effects are frequently

produced which could not, even with the best tools, be

accomplished by other means in less than many months.

 

The dimensions of one of the blocks of limestone extracted

from the quarries worked for the formation of the breakwater at

Plymouth were 26 1/2 ft long, 13 ft wide, and 16 ft deep. This

mass, containing above 4,800 cubic feet, and weighing about 400

tons, was blasted three times. Two charges of 50 lbs each were

successively exploded in a hole 13 feet deep, the bore being 3

inches at top and 2 1/2 inches at bottom: 100 lbs of powder were

afterwards exploded in the rent formed by those operations. Each

pound of gunpowder separated from the rock two tons of matter, or

nearly 4,500 times its own weight. The expense of the powder was

L 6, or nearly 7 1/2d. per lb: the boring occupied two men during

a day and a half, and cost about 9s.; and the value of the

produce was, at that time, about L 45.

 

7. The simple contrivance of tin tubes for speaking through,

communicating between different apartments, by which the

directions of the superintendent are instantly conveyed to the

remotest parts of an establishment, produces a considerable

economy of time. It is employed in the shops and manufactories in

London, and might with advantage be used in domestic

establishments, particularly in large houses, in conveying orders

from the nursery to the kitchen, or from the house to the stable.

Its convenience arises not merely from saving the servant or

workman useless journeys to receive directions, but from

relieving the master himself from that indisposition to give

trouble, which frequently induces him to forego a trifling want,

when he knows that his attendant must mount several flights of

stairs to ascertain his wishes, and, after descending, must mount

again to supply them. The distance to which such a mode of

communication can be extended, does not appear to have been

ascertained, and would be an interesting subject for enquiry.

Admitting it to be possible between London and Liverpool, about

seventeen minutes would elapse before the words spoken at one end

would reach the other extremity of the pipe.

 

8. The art of using the diamond for cutting glass has

undergone, within a few years, a very important improvement. A

glazier’s apprentice, when using a diamond set in a conical

ferrule, as was always the practice about twenty years since,

found great difficulty in acquiring the art of using it with

certainty; and, at the end of a seven years’ apprenticeship, many

were found but indifferently skilled in its employment. This

arose from the difficulty of finding the precise angle at which

the diamond cuts, and of guiding it along the glass at the proper

inclination when that angle is found. Almost the whole of the

time consumed and of the glass destroyed in acquiring the art of

cutting glass, may now be saved by the use of an improved tool.

The gem is set in a small piece of squared brass with its edges

nearly parallel to one side of the square. A person skilled in

its use now files away the brass on one side until, by trial, he

finds that the diamond will make a clean cut, when guided by

keeping this edge pressed against a ruler. The diamond and its

mounting are now attached to a stick like a pencil, by means of a

swivel allowing a small angular motion. Thus, even the beginner

at once applies the cutting edge at the proper angle, by pressing

the side of the brass against a ruler; and even though the part

he holds in his hand should deviate a little from the required

angle, it communicates no irregularity to the position of the

diamond, which rarely fails to do its office when thus employed.

 

The relative hardness of the diamond, in different

directions, is a singular fact. An experienced workman, on whose

judgement I can rely, informed me that he has seen a diamond

ground with diamond powder on a cast-iron mill for three hours

without its being at all worn, but that, on changing its

direction with respect to the grinding surface, the same edge was

ground away.

 

9. Employment of materials of little value. The skins used by

the goldbeater are produced from the offal of animals. The hoofs

of horses and cattle, and other horny refuse, are employed in the

production of the prussiate of potash, that beautiful, yellow,

crystallized salt, which is exhibited in the shops of some of our

chemists. The worn-out saucepans and tinware of our kitchens,

when beyond the reach of the tinker’s art, are not utterly

worthless. We sometimes meet carts loaded with old tin kettles

and worn-out iron coal-skuttles traversing our streets. These

have not yet completed their useful course; the less corroded

parts are cut into strips, punched with small holes, and

varnished with a coarse black varnish for the use of the

trunk-maker, who protects the edges and angles of his boxes with

them; the remainder are conveyed to the manufacturing chemists in

the outskirts of the town, who employ them in combination with

pyroligneous acid, in making a black die for the use of calico

printers.

 

10. Of tools. The difference between a tool and a machine is

not capable of very precise distinction; nor is it necessary, in

a popular explanation of those terms, to limit very strictly

their acceptation. A tool is usually more simple than a machine;

it is generally used with the hand, whilst a machine is

frequently moved by animal or steam power. The simpler machines

are often merely one or more tools placed in a frame, and acted

on by a moving power. In pointing out the advantages of tools, we

shall commence with some of the simplest.

 

11. To arrange twenty thousand needles thrown promiscuously

into a box, mixed and entangled in every possible direction, in

such a form that they shall be all parallel to each other, would,

at first sight, appear a most tedious occupation; in fact, if

each needle were to be separated individually, many hours must be

consumed in the process. Yet this is an operation which must be

performed many times in the manufacture of needles; and it is

accomplished in a few minutes by a very simple tool; nothing more

being requisite than a small flat tray of sheet iron, slightly

concave at the bottom. In this the needles are placed, and shaken

in a peculiar manner, by throwing them up a very little, and

giving at the same time a slight longitudinal motion to the tray.

The shape of the needles assists their arrangement; for if two

needles cross each other (unless, which is exceedingly

improbable, they happen to be precisely balanced), they will,

when they fall on the bottom of the tray, tend to place

themselves side by side, and the hollow form of the tray assists

this disposition. As they have no projection in any part to

impede this tendency, or to entangle each other, they are, by

continually shaking, arranged lengthwise, in three or four

minutes. The direction of the shake is now changed, the needles

are but little thrown up, but the tray is shaken endways; the

result of which is, that in a minute or two the needles which

were previously arranged endways become heaped up in a wall, with

their ends against the extremity of the tray. They are then

removed, by hundreds at a time, with a broad iron spatula, on

which they are retained by the forefinger of the left hand. As

this parallel arrangement of the needles must be repeated many

times, if a cheap and expeditious method had not been devised,

the expense of the manufacture would have been considerably

enhanced.

 

12. Another process in the art of making needles furnishes an

example of one of the simplest contrivances which can come under

the denomination of a tool. After the needles have been arranged

in the manner just described, it is necessary to separate them

into two parcels, in order that their points may be all in one

direction. This is usually done by women and children. The

needles are placed sideways in a heap, on a table, in front of

each operator, just as they are arranged by the process above

described. From five to ten are rolled towards this person with

the forefinger of the left hand; this separates them a very small

space from each other, and each in its turn is pushed lengthwise

to the right or to the left, according to the direction of the

point. This is the usual process, and in it every needle passes

individually under the finger of the operator. A small alteration

expedites the process considerably: the child puts on the

forefinger of its right hand a small cloth cap or fingerstall,

and rolling out of the heap from six to twelve needles, he keeps

them down by the forefinger of the left hand, whilst he presses

the forefinger of the right hand gently against their ends: those

which have the points towards the right hand stick into the

fingerstall; and the child, removing the finger of the left hand,

slightly raises the needles sticking into the cloth, and then

pushes them towards the left side. Those needles which had their

eyes on the right hand do not stick into the finger cover, and

are pushed to the heap on the right side before the repetition of

this process. By means of this simple contrivance each movement

of the finger, from one side to the other, carries five or six

needles to their proper heap; whereas, in the former method,

frequently only one was moved, and rarely more than two or three

were transported at one movement to their place.

 

13. Various operations occur in the arts in which the

assistance of an additional hand would be a great convenience to

the workman, and in these cases tools or machines of the simplest

structure come to our aid: vices of different forms, in