Measurement of a Bafe on Ho u n flo w-He nth. 4 jfij 
level) were brought to the proper height, the platform was 
laid upon them ; and on that the {land itfelf being placed, its 
pofition was ultimately corrected by the fpirit level laid on 
the top of the table. Each of the beech pickets had a hole 
bored through its top, fit to receive a piece of ftrong tent- 
line, by which, and the help of one of the camp mallets, the 
pickets were eafily pulled up again, when the platform was to 
be removed to a new fituation. 
Boning Telefcope and Rods. Tab. XVI If. 
In order to trace the line of 200 yards or 600 feet through 
the air, from one fixed hand to the other, it was ufual, in the 
iirfi; place, to id retch a cord extremely tight along the ground, 
and to divide the fpace into rod lengths, by fmall wooden pins 
placed clofe by the cord, which remained there, and accordingly 
marked, very nearly, the points over which the centers of the 
Intermediate hand's were to come. A piece of wood, about 
fourteen inches in length, and one and a half in breadth, 
painted white, with a narrow black line along the middle of 
it, being prepared for the purpofe, was laid on the furface of 
the farther hand. The boning telefcope, fourteen inches long 
and one and a half in diameter, with a fmall magnifying 
power, and moveable objedhglafs, fo as to fit it for very fhort 
cbftances, was then laid on the furface of the nearefl hand *• 
which, by means of wedges placed under the legs, had that 
fide towards the farther hand fo elevated or depreffed, as to 
bring the crofs wires to coincide with the black line on the 
painted board. Twenty- four boning rods had been originally 
provided; but it rarely happened, that more than eight or ten 
of 
