22 THE YOUNG 
streams into which the meshes divide the 
air, unite and again form large bubbles. 
The true way is to allow the air to escape 
along the bottom of the tank from a series 
of fine holes bored in the pipe at a con- 
siderable distance from each other. 
When the water in an aquarium needs 
aerating, and there is no contrivance pro- 
vided of the kind we have just described, 
the best plan is to dip out some of the 
water and pour it back in a very fine 
stream. This is, however, rather tedious, 
and the temptation becomes very strong 
to allow the stream to get large and 
strong. Such a stream not only fails to 
accomplish the object in view, but it pro- 
duces in the tank a commotion, which is 
very apt to do damage. Experience hav- 
ing taught us the objections to the ordin- 
ary plan, and all ordinary aquaria requir- 
ing a little occasional mechanical aeration, 
we devised the following method which 
we have found in practice to answer ad- 
mirably. Make a bundle of straight, 
sound and clean straws about 12 to 18 
inches long and two inches or more in 
diameter. Tie them firmly but not tightl*^ 
together, and hold them slightly sloping, 
and with the lower end dipping in the 
water of the tank. Pour the water on the 
bundle of straw as near the top as possi- 
ble, and allow it to flow down the bundle 
into the tank. Each straw and each space 
between the straws, acts as a Sprengel 
pump, or the blast of a Catalan forge ; and 
not only is the water that is poured in 
thoroughly saturated with air, but a series 
of very minute bubbles are carried far 
down into the tank, serving to oxygenate 
the entire body of water. Two or three 
pitchers full poured into the tank in this 
way will make the w^ater sparkling and 
pleasant. 
Cheap and Useful. 
WE find that we have on hand a few 
copies of the first edition of the 
"Amateur's Handbook of Practical Infor- 
mation for the Laboratory and the Work- 
shop." It contains quite a large number 
of useful recipes and directions for 
mechanical processes. In order to close 
out the remainder of this edition, we will 
send a copy to any address, on receipt of 
seven cents in postage stamps, ' 
SCIENTIST. 
Make Shifts for Young Microscopists. 
ONE of our most common proverbs is 
that ''accidents will happen," and 
unfortunately its truth is too frequently 
proved. Some time ago a young friend of 
mine broke the mirror of his microscope, 
and, of course, sent it some distance to an 
optician to have it replaced. While it was 
gone his microscope was laid aside as use- 
less, although he was very anxious to ex- 
amine some new slides and some fresh 
collections that he had made. Now came 
the time for a make shift. 
I took a thin piece of fine grained wood 
(less than a quarter of an inch thick) and 
on it described a circle of the same 
diameter as the brass frame in which the 
mirror was mounted. This wood was then 
cut away so as to leave a thin circular 
disc which could be easily placed in the 
mirror-holder and could be adjusted to any 
angle. To one side of the disc I fastened 
a bit of looking glass, and the other side 
I covered with the whitest, clearest, pafper 
I could find. Common paste answered 
very well to fasten both, and the micro- 
scope was again in good condition. 
When examining a large object with a 
low power we used the white paper and 
this answered better than any mirror, as 
it gave a softer and more even illumin- 
ation. For ordinary objects the bit of 
looking glass answered very well either 
by daylight or lamplight, but when a 
stronger light was needed in the evening, 
by lamplight, it was an easy matter to con- 
centrate the light of the lamp by means of 
the bull's eye condenser, and this gave 
all the effect of a concave mirror. 
And, by the way, let me here advise those 
readers of the Young Scientist who have 
microscopes with condensing lenses 
attached, to at once provide a separate 
stand for the lens. It is easily done by 
means of a common upright letter file and 
a bit of wood or even a cork, somewhat 
after the manner dercribed in the Young 
Scientist, vol. 1, page 70. A lens thus 
mounted is not only more easily applied 
to the illumination of opaque objects, but 
it can be used for other important pur- 
poses for which it cannot be employed 
i when it is a fixture. . o. w. 
