368 Slide from Mount Pilatus to the Lake of Lucerne. 
that has been observed in North America and probably one 
of the most interesting in the world. A specimen now lies 
before us more than six inches square, on which are depos- 
ited between three and four hundred distinct cubes and par- 
allelopipeds some of which are an inch in diameter, and 
others so minute as to be almost microscopic; they are of a 
deep violet and purple colour, and the whole group paid 
that it has not quite the freshness of specimens which hav 
been recently taken from the cavities of mines) is moe 
inferior to the finest pieces of Derbyshire and France. 
Il. FOREIGN LITERARURE AND SCIENCE. 
cabs Slide from Mount Pilatus to the Lake of Lucerne.* 
Communicated by Professor posts 
A slide waserected in 1812, by Mr. Rupp, for the pupae 
of bringing down to the lake of Lucerne the fine pine trees 
which grow upon, Mount Pilatus. The wood was purchas- 
ed by a company for 3,000/ and 9,000/ were expended in 
forming the slide. The length of the slide is about 44,000 
English feet, or about 8} miles, and the difference of level of 
its two extremities is about 2,600 feet 
It is a wooden trough about five feet broad and four deep, 
the bottom of which consists of three trees, the middle one 
vans a little hollowed, and small rills of water are conduc- 
inish friction. _ 
tits commencement is about 221°, and it 
sy I r Playfair thata heavy body, not 
bln io feiction, would describe the whole length of the 
trough in 66”. 
The large pines with their - branches and bows cut off, 
are placed in the slide, and descendin by their own gravity 
they acquire ne an impetus by ee descent through 
efiret part o 
f the slide, thas they perform their journey ‘ a 
tho facts have been slready published in our newspapers we 
in; Se present them in a nope pwnmicge rmanent form. Indeed it often 
at articles of scientific a 
