nia(lj^ at the Fafl of the Stauhl^mh- 
but I made it with much care, and was a considerable time be- 
fore I satisfied myself of the adjustments of the two levels. Mr 
Herschel w’as in the mean time taking the temperature of the 
wf^ter, v/hich he found to be the same as that of the air ; whilst 
at the point where it quits the summit, it was between two 
and three degrees of lieaumur colder. I now held my band- 
kerchkf to protect the instrument from the wind and mist pro- 
duced by the fall, whilst my friend made an observation, Thi^ 
is No. S. Einding it so very different from mine, I again made 
one with considerable care. No. S. and then Mr IJerschel made 
No. 4. Amongst some hundred observations, I have not met 
with instances of our differences amounting to half or even a 
quarter of that which occurs here; and from the eare with which 
the ob^rvations were made, I conclude some cause of irregu- 
larity operated, of which we were not aware. There are twor 
circurnstances which seem to have some influence on these re-! 
suits : one is the state of the atmosphere at the foot of the falh 
and as high as a thousand feet above it, being in a state of satu- 
ration with regard to moisture ; the other is the violence of 
the wind which is formed by the descending torrent, and which 
eddies about with rapidity in all directions. Notwithstanding 
the differences in the observations, I am inclined to believe the 
mean to be extremely near the truth. At the bottom of a mea-; 
dow immediately below the inn, there is a small stream, and a 
fish-box at its junction with the river which waters the valley of 
Lauterbrunnen. The ground-floor of the inn is 114.6 feet above 
this spot. I remain, my Dear Sir, truly yours, 
C. Babbage. 
Devonshire Street, j 
Portland Place, v 
Dec. 7. 1821. j 
Art. V.— Ofi the Ihtermiimtion of certain Secondary Faces in 
Crystalsy whkh require neither Measurement nor Calculation. 
By A. Levy, M. A. of the University of Paris. Communi- 
cated by the Author. 
Xhe observation of the several polyhedrons, or crystals pre- 
sented by the same crystallised substance, naturally leads us to in- 
