150 
THE YOUNG SCIENTIST. 
that they are the best tools for turning, planing 
or boring glass where much work is to be done. 
With a good diamond a skilful worker can turn 
a lens out of a piece of flat glass in a few sec- 
onds, so that it will be very near the right 
shape. — Amateur's Handbook. 
Looking Through a Brick. 
A very common exhibition by street show- 
men, and one which never fails to excite sur- 
prise, is the apparatus by which a person is 
apparently enabled to look through a brick. 
Mounted on a simple-looking stand are a 
couple of tubes which look like a telescope cut 
in two in the middle. Looking through this 
telescope, we are not surprised, of course, 
when we see clearly the people, buildings, 
trees, etc., beyond it, but this natural expecta- 
glass. The telescope should be mounted on a 
common box, the better to disguise the ar- 
rangement. The lid of the box supports the 
upright tubes, and may form the upper side of 
the concealed tube. Indeed there is no reason 
why an apparatus of this kind that would work 
well, might not be made out of a few old en- 
velope boxes, some bits of looking glass, and a 
little paper and paste, and if once made it will 
be a source of constant amusement. 
Imitation Terra Cotta. 
The following recipe from the Magazin Pit- 
toresque will enable our readers to convert plas- 
ter casts into excellent imitations of terra 
cotta ware : The colors required are brick red, 
lampblack, zinc white, and yellow ochre, all in 
powder. The object to be treated is first care- 
LOOKENG THBOTJGH A BBICK. 
tion is turned into the most startled surprise 
when it is found that the view of these objects 
is not cut off by placing a common brick be- 
tween the two parts of the telescope and 
directly in the apparent line of vision. 
In truth, however, the observer looks round 
the brick instead of through it, and this he is 
enabled to do by means of four mirrors ingeni- 
ously arranged, as shown in the engraving. 
As the mirrors and the lower connecting tube 
are concealed, and the upright tubes support- 
ing the pretended telescope, though hollow, 
appear to be solid, it is not very easy for those 
who are not in the secret to discover the trick. 
Any ingenious boy can easily make this appar- 
atus. The tubes may be made of pasteboard, 
and the mirrors of pieces of common looking- 
fally rubbed with "00" sandpaper, so as to 
remove all roughness of the surface or ridges 
indicating where the parts of the mold have 
been joined. The mixed color consists of yel- 
low ochre two parts, brick red two parts, and 
black one part. These are well rubbed to- 
gether. Then three parts of zinc white are 
separately mixed with a little milk to paste. 
All the ingredients are then combined in a 
mortar with eight or ten parts of milk, and the 
resulting mixture is passed through a fine 
sieve to remove any particles of the white. A 
soft brush is then used to spread the stain over 
the object, care being taken to lay it on evenly. 
After 24 hours' drying, a second coat is applied. 
When the article is completely dry, rubbing 
with the fingers will eliminate the brush marks. 
