242 H. L. Smith on a new Growing Slide for the Microscope. 
as is employed for the small cheap looking glasses, and easily 
obtained. 
The upper plate has a small hole, 
a, drilled through it. This is ef- 
fected by means of the ordinary 
writing diamond, and the sharp 
edge of a broken steel brooch or 
small rat-tail file. A hole can be 
drilled through glass of this thick- 
ess in a few minutes. One cor- 
ner of the upper glass is removed, 
as at 6, and a small strip of glass 
cemented at c serves to prevent the thin glass cover placed over 
the object from sliding. Another strip of glass is cemented om 
the lower side of the cell at d, but not extending as far as the 
removed part at b. The object of this is to prevent the water 
in the cell from being removed by capillary attraction, In case 
the slide in the neighborhood of 6 should be a little wetted. 
This strip is not, however, absolutely necessary. 
of thin glass, e, at the same time covering the hole 4. 
ide can now be placed upright, or in any position no water 
ean escape. It is, in fact, only a new application of the old 
principle of the bird-fountain. As the water evaporates from 
under the cover more is supplied through the hole a, and from 
time to time an air bubble enters at }; thus, a constant circula- 
tion is maintained. A cell of the size named will need replen- 
ishing only about once in three days, and this is readily effect 
without disturbing the object. I have been enabled to make 
observations by means of this slide, which it would have been 
abe 6 Rar hs if not impossible, to have made without it. 
ar ange 
some other microscopic a) n : 
vestigations upon the growth of the Diatoms, in order to pa lish 
ode ¢ 
ry ; re 2 between Mr. 
_--* The address is W. Wales & Co, Fort Lee, Bergen Co, New Jersey. 
