Of all these specimens of carpentry, the Slide of Alpnach was the most considerable, from its great length, and from the almost inaccessible position from which it descended. The following account of it is taken from Gilbert"s Annalen, 1819, which is translated in the second volume of Brewster"s Journal:
For many centuries, the rugged flanks and the deep gorges of Mount Pilatus were covered with impenetrable forests; which were permitted to grow and to perish, without being of the least utility to man, till a foreigner, who had been conducted into their wild recesses in the pursuit of the chamois, directed the attention of several Swiss gentlemen to the extent and superiority of the timber. The most skilful individuals, however, considered it quite impracticable to avail themselves of such inaccessible stores. It was not till the end of 1816, that M.
Rupp, and three Swiss gentlemen, entertaining more sanguine hopes, purchased a certain extent of the forests, and began the construction of the slide, which was completed in the spring of 1818.
The Slide of Alpnach is formed entirely of about 25,000 large pine trees, deprived of their bark, and united together in a very ingenious manner, without the aid of iron. It occupied about 160 workmen during eighteen months, and cost nearly 100,000 francs, or L4,250. It is about three leagues, or 44,000 English feet long, and terminates in the Lake of Lucerne. It has the form of a trough, about six feet broad, and from three to six feet deep.
Its bottom is formed of three trees, the middle one of which has a groove cut out in the direction of its length, for receiving small rills of water, which are conducted into it from various places, for the purpose of diminishing the friction. The whole of the slide is sustained by about 2,000 supports; and in many places it is attached, in a very ingenious manner, to the rugged precipices of granite.
The direction of the slide is sometimes straight, and sometimes zig-zag, with an inclination of from 10 degrees to 18 degrees. It is often carried along the sides of hills and the flanks of precipitous rocks, and sometimes pa.s.ses over their summits. Occasionally it goes under ground, and at other times it is conducted over the deep gorges by scaffoldings 120 feet in height.
The boldness which characterizes this work, the sagacity and skill displayed in all its arrangements, have excited the wonder of every person who has seen it. Before any step could be taken in its erection, it was necessary to cut several thousand trees to obtain a pa.s.sage through the impenetrable thickets. All these difficulties, however, were surmounted, and the engineer had at last the satisfaction of seeing the trees descend from the mountain with the rapidity of lightning. The larger pines, which were about a hundred feet long, and ten inches thick at their smaller extremity, ran through the s.p.a.ce of three leagues, or nearly nine miles, in two minutes and a half, and during their descent, they appeared to be only a few feet in length.
The arrangements for this part of the operation were extremely simple. From the lower end of the slide to the upper end, where the trees were introduced, workmen were posted at regular distances, and as soon as everything was ready, the workman at the lower end of the slide cried out to the one above him, "Lachez" (let go). The cry was repeated from one to another.
and reached the top of the slide in three minutes. The workmen at the top of the slide then cried out to the one below him, "Il vient" (it comes), and the tree was instantly launched down the slide, preceded by the cry which was repeated from post to post.
As soon as the tree had reached thebottom, and plunged into the lake, the cry of lachez was repeated as before, and a new tree was launched in a similar manner. By these means a tree descended every five or six minutes, provided no accident happened to the slide, which sometimes took place, but which was instantly repaired when it did.
In order to shew the enormous force which the trees acquired from the great velocity of their descent, M. Rupp made arrangements for causing some of the trees to spring from the slide. They penetrated by their thickest extremities no less than from eighteen to twenty-four feet into the earth; and one of the trees having by accident struck against another, it instantly cleft it through its whole length, as if it had been struck by lightning.
After the trees had descended the slide, they were collected into rafts upon the lake, and conducted to Lucerne. From thence they descended the Reuss, then the Aar to near Brugg, afterwards to Waldshut by the Rhine, then to Basle, and even to the sea when it was necessary.
It is to be regretted that this magnificent structure no longer exists, and that scarcely a trace of it is to be seen upon the flanks of Mount Pilatus. Political circ.u.mstances having taken away the princ.i.p.al source of demand for the timber, and no other market having been found, the operation of cutting and transporting the trees necessarily ceased.(4*)
Professor Playfair, who visited this singular work, states, that six minutes was the usual time occupied in the descent of a tree; but that in wet weather, it reached the lake in three minutes.
NOTES:
1. The author of these pages, with one of his friends, was recently induced to visit this most interesting establishment, after midnight, during the progress of a very important debate.
The place was illuminated with gas, and was light as the day: there was neither noise nor bustle; and the visitors were received with such calm and polite attention, that they did not, until afterwards, become sensible of the inconvenience which such intruders, at a moment of the greatest pressure, must occasion, nor reflect tha the tranquility which they admired, was the result of intense and regulated occupation. But the effect of such checks in the current of business will appear on recollecting that, as four thousand newspapers are printed off on one side within the hour, every minute is attended with a loss of sixty-six impressions. The quarter of an hour, therefore, which the stranger may think it not unreasonable to claim for the gratification of his curiosity (and to him this time is but a moment), may cause a failure in the delivery of a thousand copies, and disappoint a proportionate number of expectant readers, in some of our distant towns, to which the morning papers are dispatched by the earliest and most rapid conveyances of each day.
This note is inserted with the further and more general purpose of calling the attention of those, especially foreigners, who are desirous of inspecting our larger manufactories, to the chief cause of the difficulty which frequently attends their introduction. When the establishment is very extensive, and its departments skilfully arranged, the exclusion of visitors arises, not from any illiberal jealousy, nor, generally, from any desire of concealment, which would, in most cases, be absurd, but from the substantial inconvenience and loss of time, throughout an entire series of well-combined operations, which must be occasioned even by short and causual interruptions.
2. It is true that the transport of letters is not the only object which this apparatus answers; but the transport of pa.s.sengers, which is a secondary object, does in fact put a limit to the velocity of that of the letters, which is the primary one.
3. A proposal for such a vessel, and description of its construction, by the author of this volume, may be found in the Encyclopaedia Metropolitana, Art. Diving Bell.
4. The mines of Bolanos in Mexico are supplied with timber from the adjacent mountains by a slide similar to that of Alpnach. It was constructed by M. Floresi, a gentleman well acquainted with Switzerland.
Chapter 29
On the Duration of Machinery
340. The time during which a machine will continue to perform its work effectually, will depend chiefly upon the perfection with which it was originally constructed upon the care taken to keep it in proper repair, particularly to correct every shake or looseness in the axes--and upon the smallness of the ma.s.s and of the velocity of its moving parts. Everything approaching to a blow, all sudden change of direction, is injurious. Engines for producing power, such as windmills, water-mills, and steam-engines, usually last a long time.(1*)
341. Many of the improvements which have taken place in steamengines, have arisen from an improved construction of the boiler or the fireplace. The following table of the work done by steam-engines in Cornwall, whilst it proves the importance of constantly measuring the effects of machinery, shows also the gradual advance which has been made in the art of constructing and managing those engines.
A table of the duty performed by steam-engines in Cornwall, shewing the average of the whole for each year, and also the average duty of the best engine in each monthly report
Years; Approximate number of engines reported; Average duty of the whole; Average duty of the best engines
1813; 24; 19,456,000; 26,400,000 1814; 29; 20.534,232; 32,000,000 1815; 35; 20.526,160; 28,700,000 1816; 32; 22,907,110; 32,400,000 1817; 31; 26,502,259; 41,600,000 1818; 32; 25,433,783; 39,300,000 1819; 37; 26,252,620; 40,000,000 1820; 37; 28,736,398; 41,300,000 1821; 39; 28,223,382; 42,800,000 1822; 45; 28,887,216; 42,500.000 1823; 45; 28,156,162; 42,122,000 1824; 45; 28,326,140; 43,500,000 1825; 50; 32,000,741; 45,400,000 1826; 48; 30,486,630; 45,200,000 1827; 47; 32,100,000; 59,700,000 1828; 54; 37,100,000; 76,763,000 1829; 52; 41,220,000; 76,234,307 1830; 55; 43,350,000; 75,885,519 1831; 55(2*); 44,700,000; 74,911,365 1832; 60; 44,400,000; 79,294,114 1833; 58; 46,000,000; 83,306,092
342. The advantage arising from registering the duty done by steamengines in Cornwall has been so great that the proprietors of one of the largest mines, on which there are several engines, find it good economy to employ a man to measure the duty they perform every day. This daily report is fixed up at a particular hour, and the enginemen are always in waiting, anxious to know the state of their engines. As the general reports are made monthly, if accident should cause a partial stoppage in the flue of any of the boilers, it might without this daily check continue two or three weeks before it could be discovered by a falling off of the duty of the engine. In several of the mines a certain amount of duty is a.s.signed to each engine; and if it does more, the proprietors give a premium to the engineers according to its amount. This is called million money, and is a great stimulus to economy in working the engine.
343. Machinery for producing any commodity in great demand, seldom actually wears out; new improvements, by which the same operations can be executed either more quickly or better, generally superseding it long before that period arrives: indeed, to make such an improved machine profitable, it is usually reckoned that in five years it ought to have paid itself, and in ten to be superseded by a better.
"A cotton manufacturer," says one of the witnesses before a Committee of the House of Commons, "who left Manchester seven years ago, would be driven out of the market by the men who are now living in it, provided his knowledge had not kept pace with those who have been, during that time, constantly profiting by the progressive improvements that have taken place in that period."
344. The effect of improvements in machinery, seems incidentally to increase production, through a cause which may be thus explained. A manufacturer making the usual profit upon his capital, invested in looms or other machines in perfect condition, the market price of making each of which is a hundred pounds, invents some improvement. But this is of such a nature, that it cannot be adapted to his present engines. He finds upon calculation, that at the rate at which he can dispose of his manufactured produce, each new engine would repay the cost of its making, together with the ordinary profit of capital, in three years: he also concludes from his experience of the trade, that the improvement he is about to make, will not be generally adopted by other manufacturers before that time. On these considerations, it is clearly his interest to sell his present engines, even at half-price, and construct new ones on the improved principle. But the purchaser who gives only fifty pounds for the old engines, has not so large a fixed capital invested in his factory, as the person from whom he purchased them; and as he produces the same quant.i.ty of the manufactured article, his profits will be larger. Hence, the price of the commodity will fall, not only in consequence of the cheaper production by the new machines, but also by the more profitable working of the old, thus purchased at a reduced price. This change, however, can be only transient; for a time will arrive when the old machinery, although in good repair, must become worthless. The improvement which took place not long ago in frames for making patent-net was so great, that a machine, in good repair, which had cost L1200, sold a few years after for L60. During the great speculations in that trade, the improvements succeeded each other so rapidly, that machines which had never been finished were abandoned in the hands of their makers, because new improvements had superseded their utility.
345. The durability of watches, when well made, is very remarkable. One was produced, in going order, before a committee of the House of Commons to enquire into the watch trade, which was made in the year 1660; and there are many of ancient date, in the possession of the Clockmaker"s Company, which are still actually kept going. The number of watches manufactured for home consumption was, in the year 1798, about 50,000 annually. If this supply was for Great Britain only, it was consumed by about ten and a half millions of persons.
346. Machines are, in some trades, let out to hire, and a certain sum is paid for their use; in the manner of rent. This is the case amongst the framework knitters: and Mr Henson, in speaking of the rate of payment for the use of their frames, states, that the proprietor receives such a rent that, besides paying the full interest for his capital, he clears the value of his frame in nine years. When the rapidity with which improvements succeed each other is considered, this rent does not appear exorbitant. Some of these frames have been worked for thirteen years with little or no repair. But circ.u.mstances occasionally arise which throw them out of employment, either temporarily or permanently. Some years since, an article was introduced called cut-up work, by which the price of stocking-frames was greatly deteriorated. From the evidence of Mr J. Rawson, it appears that, in consequence of this change in the nature of the work, each frame could do the work of two, and many stocking frames were thrown out of employment, and their value reduced full threefourths.(3*)
This information is of great importance, if the numbers here given are nearly correct, and if no other causes intervened to diminish the price of frames; for it shews the numerical connection between the increased production of those machines and their diminished value.
347. The great importance of simplifying all transactions between masters and workmen, and of dispa.s.sionately discussing with the latter the influence of any proposed regulations connected with their trade, is well examplified by a mistake into which both parties unintentionally fell, and which was productive of very great misery in the lace trade. Its history is so well told by William Allen, a framework knitter, who was a party to it, that an extract from his evidence, as given before the Framework Knitters" Committee of 1812, will best explain it.
"I beg to say a few words respecting the frame rent; the rent paid for lace frames, until the year 1805, was 1s. 6d. a frame per week; there then was not any very great inducement for persons to buy frames and let them out by the hire, who did not belong to the trade; at that time an attempt was made, by one or two houses, to reduce the prices paid to the workmen, in consequence of a dispute between these two houses and another great house: some little difference being paid in the price amongst the respective houses, I was one chosen by the workmen to try if we could not remedy the impending evil: we consulted the respective parties, and found them inflexible; these two houses that were about to reduce the prices, said that they would either immediately reduce the price of making net, or they would increase the frame rent: the difference to the workmen was considerable, between the one and the other; they would suffer less, in the immediate operation of the thing, by having the rent advanced, than the price of making net reduced. They chose at that time, as they thought, the lesser evil, but it has turned out to be otherwise; for, immediately as the rent was raised upon the percentage laid out in frames, it induced almost every person, who had got a little money, to lay it out in the purchase of frames; these frames were placed in the hands of men who could get work for them at the warehouses; they were generally constrained to pay an enormous rent, and then they were compelled, most likely, to buy of the persons that let them the frames, their butcher"s meat, their grocery, or their clothing: the enc.u.mbrance of these frames became entailed upon them: if any deadness took place in the work they must take it at a very reduced price, for fear of the consequences that would fall upon them from the person who bought the frame: thus the evil has been daily increasing, till, in conjunction with the other evils crept into the trade, they have almost crushed it to atoms."
348. The evil of not a.s.signing fairly to each tool, or each article produced, its proportionate value, or even of not having a perfectly distinct, simple, and definite agreement between a master and his workmen, is very considerable. Workmen find it difficult in such cases to know the probable produce of their labour; and both parties are often led to adopt arrangements, which, had they been well examined, would have been rejected as equally at variance in the results with the true interests of both.
349. At Birmingham, stamps and dies, and presses for a great variety of articles, are let out: they are generally made by men possessing small capital, and are rented by workmen. Power also is rented at the same place. Steam-engines are erected in large buildings containing a variety of rooms, in which each person may hire one, two, or any other amount of horsepower, as his occupation may require. If any mode could be discovered of transmitting power, without much loss from friction, to considerable distances, and at the same time of registering the quant.i.ty made use of at any particular point, a considerable change would probably take place in many departments of the present system of manufacturing. A few central engines to produce power, might then be erected in our great towns, and each workman, hiring a quant.i.ty of power sufficient for his purpose, might have it conveyed into his own house; and thus a transition might in some instances be effected, if it should be found more profitable, back again from the system of great factories to that of domestic manufacture.
350. The transmission of water through a series of pipes, might be employed for the distribution of power, but the friction would consume a considerable portion. Another method has been employed in some instances, and is practised at the Mint. It consists in exhausting the air from a large vessel by means of a steam-engine. This vessel is connected by pipes, with a small piston which drives each coining press; and, on opening a valve, the pressure of the external air forces in the piston. This air is then admitted to the general reservoir, and pumped out by the engine. The condensation of air might be employed for the same purpose; but there are some unexplained facts relating to elastic fluids, which require further observations and experiment before they can be used for the conveyance of power to any considerable distance. It has been found, for instance, in attempting to blow a furnace by means of a powerful water-wheel driving air through a cast-iron pipe of above a mile in length, that scarcely any sensible effect was produced at the opposite extremity. In one instance, some accidental obstruction being suspected, a cat put in at one end found its way out without injury at the other, thus proving that the phenomenon did not depend on interruption within the pipe.
351. The most portable form in which power can be condensed is, perhaps, by the liquefaction of the gases. It is known that, under considerable pressure, several of these become liquid at ordinary temperatures; carbonic acid, for example, is reduced to a liquid state by a pressure of sixty atmospheres. One of the advantages attending the use of these fluids, would be that the pressure exerted by them would remain constant until the last drop of liquid had a.s.sumed the form of gas. If either of the elements of common air should be found to be capable of reduction to a liquid state before it unites into a corrosive fluid with the other ingredient, then we shall possess a ready means of conveying power in any quant.i.ty and to any distance. Hydrogen probably will require the strongest compressing force to render it liquid, and may, therefore, possibly be applied where still greater condensation of power is wanted. In all these cases the condensed gases may be looked upon as springs of enormous force, which have been wound up by the exertion of power, and which will deliver the whole of it back again when required. These springs of nature differ in some respects from the steel springs formed by our art; for in the compression of the natural springs a vast quant.i.ty of latent heat is forced out, and in their return to the state of gas an equal quant.i.ty is absorbed. May not this very property be employed with advantage in their application?
Part of the mechanical difficulty to be overcome in constructing apparatus connected with liquefied gases, will consist in the structure of the valves and packing necessary to retain the fluids under the great pressure to which they must be submitted. The effect of heat on these gases has not yet been sufficiently tried, to lead us to any very precise notions of the additional power which its application to them will supply.
The elasticity of air is sometimes employed as a spring, instead of steel: in one of the large printing-machines in London the momentum of a considerable ma.s.s of matter is destroyed by making it condense the air included in a cylinder, by means of a piston against which it impinges.
352. The effect of compet.i.tion in cheapening articles of manufacture sometimes operates in rendering them less durable.
When such articles are conveyed to a distance for consumption, if they are broken, it often happens, from the price of labour being higher where they are used than where they were made, that it is more expensive to mend the old article, than to purchase a new.
Such is usually the case, in great cities, with some of the commoner locks, with hinges, and with a variety of articles of hardware.
NOTES:
1. The amount of obstructions arising from the casual fixing of trees in the bottom of the river, may be estimated from the proportion of steamboats destroyed by running upon them, The subjoined statement is taken from the American Almanack for 1832:
"Between the years 1811 and 1831, three hundred and forty-eight steamboats were built on the Mississippi and its tributary streams During that period a hundred and fifty were lost or worn out, "Of this hundred and fifty: worn out 63 lost by snags 36 burnt 14 lost by collision 3 by accidents not ascertained 34 Thirty-six, or nearly one fourth, being destroyed by accidental obstructions.
Snag is the name given in America to trees which stand nearly upright in the stream, with their roots fixed at the bottom.
It is usual to divide off at the bow of the steamboats a watertight chamber, in order that when a hole is made in it by running against the snags, the water may not enter the rest of the vessel and sink it instantly.
2. This pa.s.sage is not printed in italics in the original, but it has been thus marked in the above extract, from its importance, and from the conviction that the most extended discussion will afford additional evidence of its truth.