343 
the Slide of Aljmach, 
immediately, and the remaining part came to rest soon after. 
This is a valuable fact : it appears from it that the friction is 
not in proportion to the weight, but becomes relatively less as 
the weight increases, contrary to the opinion that is generally 
received 
In viewing the descent of the trees, my nephew and I 
stood quite close to the edge of the trough, not being more in- 
terested about any thing than to experience the impression which 
the near view of so singular an object must make on a specta- 
tor. The noise, the rapidity of the motion, the magnitude of 
the moving body, and the force with which it seemed to shake 
the trough as it passed, were altogether very formidable, and 
conveyed an idea of danger much greater than the reality. 
Our guide refused to partake of our amusement ; he retreated 
behind a tree at some distance, where he had the consolation to 
be assured by Mr Rupp, that he was no safer than we were, 
as a tree, when it happened to bolt from the trough, would of- 
ten cut the standing trees clear over. During the whole time 
the slide has existed, there have been three or four fatal acci- 
dents, and one instance was the consequence of excessive teme- 
rity. 
I have mentioned that a provision was made for keeping 
the bottom of the trough wet ; this is a very useful precaution ; 
the friction is greatly diminished, and the swiftness 'is greatly 
increased by that means. In rainy weather the trees move 
much faster than in dry. We were assured that when the 
trough was every where in its most perfect condition, the wea- 
ther wet, and the trees very large, the descent was sometimes 
made in as short a time as three minutes. 
The trees thus brought down into the Lake of Lucerne 
are formed into rafts, and floated down the very rapid stream of 
the Reuss, by which the lake discharges its waters first into the 
* This fact has been long known from the launching of vessels. “ Shipbuild- 
ers,” says M. Bossut, “ give only a slope of ten or twelve lines per foot to the 
planes on which vessels are launched.” “ This declivity, which is sufficient to put 
large masses in motion, in spite of the resistance of friction, is too small for 
weights of moderate magnitude. If we wish, therefore, to suppose that the fric- 
tion of two bodies are proportioned to their weight, it is necessary that the diffe- 
rence between their weights should not be very great.”— Ed. 
