380 Miscellanies. 
tioning, that when a jet of water is discharged under mercury the 
results are the same, under a given force, as when it takes place in 
water or air, the quantity discharged being in all cases the same in 
the same time. Hence, it appears that the force with which a mov- 
ing or spouting fluid recoils, is not affected by the surrounding medi- 
um, however rare or dense it may be; and thus we may understand 
why the attempts, which have been made to propel vessels, by forcing 
water through them against water, have not proved advantageous. 
The well known fact that large rivers penetrate in.a direct course, far 
into the ocean, notwithstanding its agitation by tides and currents, is 
somewhat analogous; and were it not for this remarkable degree of 
mobility in water, the sediment which is now mostly deposited at a 
considerable distance in the sea, would accumulate near the mouths 
of rivers and divert them from their courses. Whilst making my ex- ~ 
periments on the jet of water, I noticed that where sand was dropped 
into the water near the orifice from which the jet issued, it was drawn 
laterally toward the hole, till it distinctly appeared to enter it, but it 
was in fact only an optical deception, the grains of sand being carried 
away by the jet, as soon as they come into contact with it, with suc 
great velocity as to be perfectly invisible —Jdem. 
4. On the discharge of a jet of water in water.—It has been pr oved 
by Rob. W. and Alfred Fox, Esqs., of Falmouth, that a jet of water 
discharges the same quantity in water as in air, in a given time, with- 
out reférence to the depth or motion of the water, at least within cer- 
tain limits. When the head of water was six feet, the quantities dis- 
charged were equal in air, in still watet, and in a rapid stream, and 
when the jet was turned with the current or against it; and when by 
lengthening the tube, the aperture was submerged to the depth of 
fifteen feet, the effect was the same as at the surface, under the press 
ure of an equal column above it.—Phil. Mag. and Annals. 
5. Clement’s experiment.—An easy mode of performing this eX- 
periment is this.—Holding the open hand horizontally, with the palo 
downwards and the fingers close together, apply the lips to the inter 
val between the second and third finger, nearest the roots; and then 
blowing with force, a strong jet of air will, of course, jgsue from the 
aperture at the’under side of the hand. Now put a piece of paper 
or card three or four inches square against that aperture, and mre 
blow; the paper will not be blown away, nor fall by its own : 
