22 
THE YOUNG SCIENTIST. 
Place by the eye on tlie upper left hand cor- 
ner of your paper, two dots, say two inches 
apart (thus learn to judge measurement) ; and 
be careful that they are at equal distances 
from the upper edge of the paper. Then as a 
straight line is that which lies evenly between 
two points, join thtm from left to right by 
broken motiouo f^rst, as you will find this 
easier than in one continuous line. The per- 
pendicular lines are to be treated in the same 
manner, tl^ey are to be drawn from the top 
downwards. The union of these two will give 
us a right angle. 
By joining these two by an oblique line, we 
have a triangle ABC, and by carrying another 
line from A parallel to B C, of the same length 
to D, and then joining D C, we have a square ; 
Join D C and we have the diagonals of the 
square. This must be fully mastered, and 
work out these exercises that they can do more 
than they imagine they can. For 
*' By slow degrees to noble Art we rise, 
But lo ! how grand to gain the glorious prize." 
"CI 
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you must be careful to test and try your work 
not only with the eye, but by measurements, 
as an error in this stage of a drawing would 
throw the whole drawing out of proportion. 
This you will see, is the key to any number 
of designs which may be contained in the 
square. 
Again, by using the dotted lines as in the 
next example, the circle can be constructed in 
easy sections, and within the circle, all the pos- 
sibilities of design which it may contain. We 
close this introductory lesson with an earnest 
appeal to our young readers to make them- 
selves masters of these important exercises, 
not by merely drawing them once or twice, 
but making them part of themselves. In our 
next lesson we will show those who faithfully 
How to Make a Good Pantagraph. 
BY WALTER W^. SCOTT. 
A MONG the instruments for reducing or en- 
^ larging drawings, the pantagraph, when 
accurately made, certainly takes the first place. 
Since the value of the pantagraph depends 
upon its accuracy and the absence of all lost 
motion at the joints, it is necessarily a costly 
instrument and seldom finds its way into the 
hands of the young, except in a very crude 
form. Now I will show how a very good in- 
strument of this kind can be manufactured by 
any boy of intelligence, who has a little prac- 
tice in the handling of carpen- 
ters' tools. By reference to the 
accompanying illustration it 
will be seen that the instru- 
ment consists of four parts, re- 
sembling rulers jointed togeth- 
er at their extremities, and two 
sliding carriages, having pro- 
vision on their under sides for 
holding a pencil, while they are 
provided with clamping screws 
to hold them in their place. 
The piec^ AB and AC are 
each two feet four inches long, 
from the centre of the screw at 
A, to the extreme end, one inch 
wide and one-quarter inch 
thick. The distances center to 
center AD, AE, FD, FE, are 
equal, being twelve and a half inches. All the 
joints of the instrument are made with one inch 
screws, and small blocks of hard wood, one 
inch by one inch, by half-inch thick, are glued 
under each joint to form a good hold for the 
points of the screws. 
The fulcrum B is a leaden weight four inches 
diameter, and about one inch thick, having a 
wooden stem in it, so that it measures two and 
a quarter inches from the under side of the lead 
to the top of the wooden stem. A stout needle 
or short piece of wire, is driven into the top of 
the stem for the instrument to turn on. The 
holes in the piece AB at B, are about half an 
inch apart, and of such a size as to slip over the 
wire on the fulcrum easily. 
The pencil used must be rather hard, say an 
