Saving Time In Natural Operations





47. The process of tanning will furnish us with a striking

illustration of the power of machinery in accelerating certain

processes in which natural operations have a principal effect.

The object of this art is to combine a certain principle called

tanning with every particle of the skin to be tanned. This, in

the ordinary process, is accomplished by allowing the skins to

soak in pits containing a solution of tanning matter: they remain

in the pits six, twelve, or eighteen months; and in some

instances (if the hides are very thick), they are exposed to the

operation for two years, or even during a longer period. This

length of time is apparently required in order to allow the

tanning matter to penetrate into the interior of a thick hide.

The improved process consists in placing the hides with the

solution of tan in close vessels, and then exhausting the air.

The effect is to withdraw any air which may be contained in the

pores of the hides, and to aid capillary attraction by the

pressure of the atmosphere in forcing the tan into the interior

of the skins. The effect of the additional force thus brought

into action can be equal only to one atmosphere, but a further

improvement has been made: the vessel containing the hides is,

after exhaustion, filled up with a solution of tan; a small

additional quantity is then injected with a forcing-pump. By

these means any degree of pressure may be given which the

containing vessel is capable of supporting; and it has been found

that, by employing such a method, the thickest hides may be

tanned in six weeks or two months.



48. The same process of injection might be applied to

impregnate timber with tar, or any other substance capable of

preserving it from decay, and if it were not too expensive, the

deal floors of houses might thus be impregnated with alumine or

other substances, which would render them much less liable to be

accidentally set on fire. In some cases it might be useful to

impregnate woods with resins, varnish, or oil; and wood saturated

with oil might, in some instances, be usefully employed in

machinery for giving a constant, but very minute supply of that

fluid to iron or steel, against which it is worked. Some idea of

the quantity of matter which can be injected into wood by great

pressure, may be formed, from considering the fact stated by Mr

Scoresby, respecting an accident which occurred to a boat of one

of our whaling-ships. The harpoon having been struck into the

fish, the whale in this instance, dived directly down, and

carried the boat along with him. On returning to the surface the

animal was killed, but the boat, instead of rising, was found

suspended beneath the whale by the rope of the harpoon; and on

drawing it up, every part of the wood was found to be so

completely saturated with water as to sink immediately to the

bottom.



49. The operation of bleaching linen in the open air is one

for which considerable time is necessary; and although it does

not require much labour, yet, from the risk of damage and of

robbery from long /exposure, a mode of shortening the process was

highly desirable. The method now practised, although not

mechanical, is such a remarkable instance of the application of

science to the practical purposes of manufactures, that in

mentioning the advantages derived from shortening natural

operations, it would have been scarcely pardonable to have

omitted all allusion to the beautiful application of chlorine, in

combination with lime, to the art of bleaching.



50. Another instance more strictly mechanical occurs in some

countries where fuel is expensive, and the heat of the sun is not

sufficient to evaporate the water from brine springs. The water

is first pumped up to a reservoir, and then allowed to fall in

small streams through faggots. Thus it becomes divided; and,

presenting a large surface, evaporation is facilitated, and the.

brine which is collected in the vessels below the faggots is

stronger than that which was pumped up. After thus getting rid of

a large part of the water, the remaining portion is driven off by

boiling. The success of this process depends on the condition of

the atmosphere with respect to moisture. If the air, at the time

the brine falls through the faggots, holds in solution as much

moisture as it can contain in an invisible state, no more can be

absorbed from the salt water, and the labour expended in pumping

is entirely wasted. The state of the air, as to dryness, is

therefore an important consideration in fixing the time when this

operation is to be performed; and an attentive examination of its

state, by means of the hygrometer, might be productive of some

economy of labour.



51. In some countries, where wood is scarce, the evaporation

of salt water is carried on by a large collection of ropes which

are stretched perpendicularly. In passing down the ropes, the

water deposits the sulphate of lime which it held in solution,

and gradually incrusts them, so that in the course of twenty

years, when they are nearly rotten, they are still sustained by

the surrounding incrustation, thus presenting the appearance of a

vast collection of small columns.



52. Amongst natural operations perpetually altering the

surface of our globe, there are some which it would be

advantageous to accelerate. The wearing down of the rocks which

impede the rapids of navigable rivers, is one of this class. A

very beautiful process for accomplishing this object has been

employed in America. A boat is placed at the bottom of the rapid,

and kept in its position by a long rope which is firmly fixed on

the bank of the river near the top. An axis, having a wheel

similar to the paddle-wheel of a steamboat fixed at each end of

it, is placed across the boat; so that the two wheels and their

connecting axis shall revolve rapidly, being driven by the force

of the passing current. Let us now imagine several beams of wood

shod with pointed iron fixed at the ends of strong levers,

projecting beyond the bow of the boat, as in the annexed

representation.



If these levers are at liberty to move up and down, and if

one or more projecting pieces, called cams, are fixed on the axis

opposite to the end of each lever, the action of the stream upon

the wheels will keep up a perpetual succession of blows. The

sharp-pointed shoe striking upon the rock at the bottom, will

continually detach small pieces, which the stream will

immediately carry off. Thus, by the mere action of the river

itself, a constant and most effectual system of pounding the rock

at its bottom is established. A single workman may, by the aid of

a rudder, direct the boat to any required part of the stream; and

when it is necessary to move up the rapid, as the channel is cut,

he can easily cause the boat to advance by means of a capstan.



53. When the object of the machinery just described has been

accomplished, and the channel is sufficiently deep, a slight

alteration converts the apparatus to another purpose almost

equally advantageous. The stampers and the projecting pieces on

the axis are removed, and a barrel of wood or metal, surrounding

part of the axis, and capable, at pleasure, of being connected

with, or disconnected from the axis itself, is substituted. The

rope which hitherto fastened the boat, is now fixed to this

barrel; and if the barrel is loose upon the axis, the

paddle-wheel makes the axis only revolve, and the boat remains in

its place: but the moment the axis is attached to its surrounding

barrel, this begins to turn, and winding up the rope, the boat is

gradually drawn up against the stream; and may be employed as a

kind of tug-boat for vessels which have occasion to ascend the

rapid. When the tug-boat reaches the summit the barrel is

released from the axis, and friction being applied to moderate

its velocity, the boat is allowed to descend.



54. Clocks occupy a very high place amongst instruments by

means of which human time is economized: and their multiplication

in conspicuous places in large towns is attended with many

advantages. Their position, nevertheless, in London, is often

very ill chosen; and the usual place, halfway up on a high

steeple, in the midst of narrow streets, in a crowded city, is

very unfavourable, unless the church happen to stand out from the

houses which form the street. The most eligible situation for a

clock is, that it should project considerably into the street at

some elevation, with a dial-plate on each side, like that which

belonged to the old church of St Dunstan, in Fleet Street, so

that passengers in both directions would have their attention

directed to the hour.



55. A similar remark applies, with much greater force, to the

present defective mode of informing the public of the position of

the receiving houses for the twopenny and general post. In the

lowest corner of the window of some attractive shop is found a

small slit, with a brass plate indicating its important office so

obscurely that it seems to be an object rather to prevent its

being conspicuous. No striking sign assists the anxious enquirer,

who, as the moments rapidly pass which precede the hour of

closing, torments the passenger with his enquiries for the

nearest post-office. He reaches it, perhaps, just as it is

closed; and must then either hasten to a distant part of the town

in order to procure the admission of his letters or give up the

idea of forwarding them by that post; and thus, if they are

foreign letters, he may lose, perhaps, a week or a fortnight by

waiting for the next packet.



The inconvenience in this and in some other cases, is of

perpetual and everyday occurrence; and though, in the greater

part of the individual cases, it may be of trifling moment, the

sum of all these produces an amount, which it is always worthy of

the government of a large and active population to attend to. The

remedy is simple and obvious: it would only be necessary, at each

letter-box, to have a light frame of iron projecting from the

house over the pavement, and carrying the letters G. P., or T.

P., or any other distinctive sign. All private signs are at

present very properly prohibited from projecting into the street:

the passenger, therefore, would at once know where to direct his

attention, in order to discover a post-office; and those

letter-boxes which occurred in the great thoroughfares could not

fail to be generally known.





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