Repository: UIHistories Project: War Publications - WWI Compilation 1923 - Article 46 [PAGE 26]

EXTRACTED TEXT FROM PAGE:

i >ETER MI .VATION OF Tl IE I )EFLECTION. Accurate Solution : measurement termination of d iKpends on finding the offsets P and T. In APBG the angle at B can always be measured, since by assumplengtf tion both P and G are visible from />. may also be assumed known, we find P from

* J0** *

#

1

1

r

T*%

F*

#

i

l

l

t

*~m -

sin P ~GB~

sin PEG GP

In &GBT the angle at i? can be measured, and the sides GT and GB may be assumed known. Hence

air

sin T

sin 77?(V GT

)

from which we find 7". (The three angles: ^f, 77? £, PBG, are not independent of each other, so that it would really be sufficient to measure A and one of the other angles. (See problems of p. 28). In Field Artillery Service, this method is not employed. Instead, there are several methods of approximation in use which are closely related to each other and which are based on the use of parallaxes.

We turn to a brief disrnssinn nf nnp nf th^c^ mpthnrlc

I

.

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