196 
Scimtijic Intelligence. 
Height of water in the 
Force exerted on the 
Force exerted on the 
reservoir. 
plain disc. 
disc with a raised 
edge. 
6 feet. 
5 lb. 
11 lb. 
8 
7 
15 
10 
9 
20 
M. Morosi applied rims 2 inches high with great success to 
the vertical float-boards of a horizontal wheel, leaving an aper- 
ture below, to allow the water to escape after it had expended 
its force on the float-boards. This construction may be consi- 
dered as an extension of the piinciple of concave Jtoat-boards^ 
which have been long used in horizontal wheels, and which the 
Chevalier Borda found to give in practice a greater efiect than 
plain ones in the ratio of 3 to 2. A fuller account of Morosfs 
experiments will be found in the Bibliotheque Universelle^ vol. 
xii. p. 217, 
11. Compressibility of Water.—Mx Perkins, the ingenious 
inventor of the siderographic process of engraving described in 
p. 141., appears to have ascertained that water is compressible in 
a much greater degree than it appeared to be from the experi- 
ments of Canton and Zimmerman. “ Having filled a cylinder, 
three feet long and four inches diameter, with water, into which 
a rod or piston was passed through a stuffing box, and having a 
sliding ring upon the rod, the whole was lowered 500 fathoms 
into the sea, when it appeared, by the situation of the sliding ring, 
that the column of water which pressed upon the ipiston, had 
sunk it so as to have compressed the water one hundredth part of 
its bulk. The same apparatus was placed in a cannon filled with 
water, and secured very tight, when a pressure equal to 500 fa- 
thoms, was forced in by means of the hydraulic press, and the 
same results as in the experiment in the ocean took place.” Lon- 
don Journal of Arts, No. II. p. 140. 
MAGNETISM. 
12. Daily Variation of the Needle at Spitzhergen. — Mr 
Fisher, who accompanied the expedition under Captain Buchan 
to the Spitzbergen seas, made a series of observations on the 
daily variation of the needle, upon a small island on the N. W. 
coast of Spitzbergen, in latitude 79'’ 40' 20''.63 and longitude 11“‘ 
