10 
THE YOUNG SCIENTIST. 
to bevel the edges. This is easily done if 
the proper tools are at hand. At first 
sight one would think that a good grind- 
stone would be the best tool for grinding 
down the bevels of such a panel, but we 
have never found one that would answer 
even tolerably. Working glass on a 
grindstone is tedious, disagreeable work, 
and those who give much attention to 
glass-grinding will find it to their advan- 
tage to provide a suitable plate of cast 
iron or other metal. The plate should be 
round, and it should be mounted like a 
potter's wheel. In other words it should 
be fixed to the top of an upright spindle 
so that it may revolve horizontally, the 
glass being held against its upper surface. 
For such a purpose a cast iron plate is 
best and cheapest. It should be turned 
perfectly true, and the "skin" or hard 
outer scale of the casting should be en- 
tirely removed. When such a plate is fed 
with good sharp sand or emery, and is 
made to revolve rapidly, it cuts glass very 
fast. It takes but a few minutes to grind 
off the edge of a common tumbler so that 
it will be quite true, after which it may be 
used as a receiver for an air-pump. We 
have several glass vessels which were 
ground in this way, and which have proved 
very serviceable in experiments on gases, 
as they may be closed air-tight by means 
of a piece of plate glass and a little lard. 
It is equally easy to grind off the edge 
of a thick glass ])late so as to form a bevel 
on it, and since the great beauty of such a 
plate consists in its high polish and 
freedom from scratches, special care 
ought to be taken to prevent the sand or 
emery from acting upon the polished 
parts. This is best effected by pasting a 
piece of tough paper over the entire sur- 
face to be protected. 
The grinding material consists of sand 
or emery and water, of which several 
grades of fineness should be provided. 
And as the muddy mixture flies off the 
plate as soon as the latter is set in motion, 
a hoop of paste-board, tin or zinc should 
be placed round the wheel or plate to 
catch it. The great objection to the oper- 
ation is the dirt that it makes, but this is 
easily remedied by the use of an old apron 
or even a few newspapers, and any spots 
that may get on our clothes are easily 
brushed off when dry. 
( To Ite continued.) 
Taming Fishes. 
pROCUEE a large bell-glass— twenty 
inches in diameter— if you can get it. 
Such bell-glasses usually have a knob 
which prevents them from standing 
mouth up. Provide a block of wood with 
a large hole in it, or better still a stand 
like that shown in the figure ; set it on a 
BELL-GLASS FOE AQUAKIUM. 
stand in a north window ; lay down a bed 
of pebbles ; plant a few tufts of water- weed 
(Anacharis), and fill with river water. 
After it has stood a few days, procure 
three small Prussian carp and six min- 
nows. Have no gold-fish, no molluscs, 
and no rockwork. Allow the conferva to 
grow^ on the glass, except on the side next 
the room, which keep clean. 
Every morning and evening feed the 
fishes with very small earthworms, 
gentles, or small caterpillars, and be care- 
ful to drop them in only one or two at a 
time, so that none be left to foul the 
water. Frequently sit beside the vessel, 
and watch the gambols of your pets ; now 
and then tap on the front of the glass with 
your finger-nail, and so accustom them 
to your presence. By degrees they will 
get bold and playful ; be sure to tap with 
your finger-nail before you feed them, and 
instead of dropping the food in for them 
to take it in their own way, hold a worm 
between your fingers at the surface, and 
one of the boldest of the minnows will 
snatch it away playfully. Persevere, and 
you may call them together by tapping 
on the "glass, and have them feed from 
your fingers, and even submit to be tickled 
on the back in quiet enjoyment of your 
friendship and familiarity. H. 
