141 
place it on C, so that the pins, b, b, enter into the holes a ; 
next turn down B and D, which are of such lengths that 
their ends will exactly meet, and the pins at 10, 11, lie in 
the notches at d. D, when set up, has its middle nearly 
level with A. H shows the instrument folded up. The one 
from which this drawing is taken measures then one inch 
in thickness, an inch and a half in breadth, and thirteen 
inches and a half in length, made of mahogany. 
I do not know of any thing contrived for a similar pur¬ 
pose, so portable and simple in its construction. Gentle¬ 
men inclined to amuse themselves with landscape drawing, 
will find it an agreeable and not cumbersome companion. 
The method of using it is this : 
Set up the instrument as in the drawing ; then, with a 
gimlet of a suitable size, make a hole on the head of a post 
or stout stake, driven into the ground, or any other proper 
firm supporter, and passing the screw through the hole in 
the middle of C, into the hole on the supporter, screw the 
instrument firmly to it in a horizontal position. The paper 
on which the drawing is to be taken, must be ruled with 
pencil lines into a proper number of squares, and the ranges 
numbered from left to right, and from top to bottom, in nu¬ 
merical order: then, looking through the sight hole mark¬ 
ed 1,2, draw the objects seen through the squares of A, on 
the corresponding squares of the two uppermost ranges on 
the paper; next, looking through the sight hole 2, 3, draw, 
on the third range, the objects seen through the corres¬ 
ponding squares on the lower range of A, connecting them 
with what was before drawn on the second range ; and so 
on, shifting the eye successively to all the sight holes, till 
the outlines of the picture are completed, when it is to be 
finished in the usual way. 
It is here proper to observe, that the shifting of the eye 
from one sight hole to another will have an effect on the 
drawing that will make it somewhat different from a per¬ 
spective perfectly accurate. This difference, however, will 
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