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

Amongst the forests which flank many

of the lofty mountains of Switzerland, some of the finest timber

is found in positions almost inaccessible. The expense of roads,

even if it were possible to make them in such situations, would

prevent the inhabitants from deriving any advantages from these

almost inexhaustible supplies. Placed by nature at a considerable

elevation above the spot at which they can be made use of, they

are precisely in fit circumstances for the application of

machinery to their removal; and the inhabitants avail themselves

of the force of gravity to relieve them from some portion of this

labour. The inclined planes which they have established in

various forests, by which the timber has been sent down to the

water courses, have excited the admiration of every traveller;

and in addition to the merit of simplicity, the construction

these slides requires scarcely anything beyond the material which

grows upon the spot.

 

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 passes 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 passage 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 space 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 circumstances having taken

away the principal 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

passengers, 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.