THE YOUNG SCIENTIST. 
9 
spot of light upon any opaque object that 
we wish to look at under the microscope. 
With the cheaper forms of the microscope 
HOME-MADE CONDENSING LENS. 
an opaque object which is illuminated 
only by ordinary daylight or lamplight, 
is hardly visible, but if we throw a beam 
of light on it by means of a condenser, it 
at once becomes visible, and such objects 
as seeds, shells, butterfly's scales, etc., 
seen in this way, are not only interesting, 
but really very beautiful. A short time 
ago, being on a visit to a friend's house, I 
found a young boy working with a cheap 
microscope, and trying to examine some 
portulacca seeds, which he had heard 
were very beautiful. Unfortunately, how- 
ever, their beauties remained hidden, be- 
cause they were literally kept in the dark. 
Eummaging amongst some odds and ends 
I found a small flask about an inch and a 
half in diameter. This I filled with gly- 
cerine, and then taking two corks and a 
darning needle I arranged the whole on 
an old paper file, as shown in the en- 
garving. This little contrivance gave 
splendid results, and enabled me to bring 
out the beauties of quite a number of 
opaque objects, such as seeds, scales, | 
feathers, etc. i 
In filling such a globe, I always use! 
glycerine where I can get it. I do so be- 
cause glycerine makes a stronger con- 
denser, and also because in cold weather 
it does not freeze and burst the flask, o. w. 
Cutting, Grinding and Engraving 
Glass— I. 
TO ordinary persons, glass is a synonym 
for brittieness, and very few^ people 
ever think of it as an article that can be 
cut and worked like other materials. But 
those who have had a little experience 
find that glass is very easily shaped and 
finished, and as it is susceptible of taking 
a very high polish, its transparency and 
refractive powers give it a peculiar beauty 
which specially adapts it to the finer kinds 
of ornamental work. In former numbers 
w^e have told our readers how to cut it 
with a diamond or hot iron, and how to 
bore it with a steel drill, with emery, and 
with a diamond. We now propose to 
point out one or two other methods by 
which it may be worked up by the amateur 
for special purposes. 
As a lid for an ornamental box, or a 
panel for a fancy cabinet, glass has 
peculiar fitness. In some cases it is bes 
when left perfectly transparent, so as to 
show the contents, as for example, where 
boxes are used for holding specimens of 
natural history. In this case good ordin- 
ary window glass may be used, and it is 
easy to cut the glass to fit the lid of the 
box and then fasten it in, after cutting out 
the material which it is to replace. A stout 
paste-board box with a plate of glass for a 
top, is exceedingly useful and convenient. 
But where the box is intended for orna- 
ment as well as for use, as for example, 
glove boxes and collar boxes, work boxes, 
etc., the glass may be beautifully orna- 
mented by engraving it by means of the 
sand-blast, as will be explained in a suc- 
ceeding article. Those who have had no 
experience in such work will be astonished 
how easily the most beautiful figures may 
be worked on glass by the sand-blast pro- 
cess, and the apparatus required is of the 
simplest kind, such as may be made by 
any one. Where glass panels are fitted 
to the doors of cabinets, such for example, 
as those used for holding microscopic ob- 
jects, it is best to use heavy plate glass and 
