S42 
Professor V\ei^f3i\v\ Description 
ed horizontally, or rather parallel to the surface of the ground, 
it is invisible from both. When the tree is launched from the 
top, a signal is made, by turning the board upright ; the same 
is followed by the rest, and thus the information is conveyed, 
almost instantaneously, all along the slide, that a tree is now on 
its way. By and bye, to any one that is stationed on the side, 
even to those at a great distance, the same is announced by the 
roaring of the tree itself, which becomes always louder and 
louder ; the tree comes in sight when it is perhaps half a mile 
distant, and in an instant after shoots past, with the noise of 
thunder and the rapidity of lightning. As soon as it has reach- 
ed the bottom, the lowest telegraph is turned down, the signal 
passes along all the stations, and the workmen at the top are 
informed that the tree has arrived in safety. Another is set 
off as expeditiously as possible ; the moment is announced, as 
before, and the same process is repeated, till all the trees that 
have been got in readiness for that day have been sent down 
into the lake. 
When a tree sticks by accident, or when it flies out, a sig- 
nal is made from the nearest station, by half depressing the 
board, and the workmen from above and below come to assist 
in getting out the tree that has stuck, or correcting any thing 
that is wrong in the slide, from the springing of a beam in the 
slide ; and thus the interruption to the work is rendered as 
short as possible. 
We saw five trees come down; the place where we stood 
was near the lower end, and the declivity was inconsiderable, 
(the bottom of the slide nearly resting on the surface,) yet the 
trees passed with astonishing rapidity. The greatest of them 
was a spruce fir a hundred feet long, four feet in diameter at 
the lower end, and one foot at the upper. The greatest trees 
are those that descend with the greatest rapidity ; and the velo- 
city as well as the roaring of this one was evidently greater 
than of the rest. A tree must be very large, to descend at all 
in this manner ; a tree, Mr Rupp informed us, that was only 
half the dimensions of the preceding, and therefore only an 
eighth part of its weight, would not be able to make its wa,y 
from the top to the bottom. One of the trees that we saw 
, broke by some accident into two ; the lighter part stopped almost 
