THE YOUNG SCIENTIST. 
129 
tance there shown would indicate. A 
sharp puff of breath applied as shown in 
the engraving, will cause the egg to leap 
from one glass to the other. 
The rationale of this striking experi- 
ment is very simple. An egg presents 
considerable surface, and the glass serves 
to concentrate and confine the force of 
the current of air to this surface. We 
have, therefore, a strong current passing 
down the very narrow space between the 
Home-made Telescopes and Micro- 
scopes— XI. 
NEW FORMULA FOR A MICROSCOPE OBJECT- 
GLASS BY MR. WENHAM. (Continued). 
i T the commencement of the year 1873, 
the author caused a few object-glasses 
to be made, with a middle of the form of 
Fig. 18, the performance of which was very 
satisfactory. In this the extreme rays 
pass at more favorable incidences, and 
LIFTING AN EGG BY THE BKEA.TH. 
glass and the egg, and then exerting its : within the angle of total reflection. The 
force on a broad surface to raise the ' upper lens is of dense flint, 
egg. When the experiments on the single 
It is evident that Ave must send the cur- 1 front were concluded, and the remarkable 
rent between the glass and the egg ; it will ! corrective power of the triple back in con- 
not do to blow directly on the egg. The ac- j junction therewith had been proved, the 
tion is then something like that of the ; next attempt was to make the middle also 
hydraulic press, and the experiment never a single lens, leaving the entire color cor- 
fails after the operator has had a little rection to be performed by the one bi- 
practice. This was one of Faraday's concave flint in the back. After numer- 
favorite lecture experiments, and we our- ous trials it was found that though some- 
selves have often performed it to the ' thing like over-correction or negative ab- 
astonishment of large audiences. erration could be obtained with the back, 
