209 
RANGE-FINDERS. 
BY 
LIEUT. E. Gr. EDWARDS, R.A. 
The introduction of tlie above subject by Major J. B. Richardson 
in the “Proceedings" of December, 1879, induces me to offer the 
following description of a system of range-finding somewhat resem¬ 
bling that described by Major Richardson. 
The principle up to a certain point is the same—namely, an isosceles 
triangle, of which the angles are constant, the object whose range is 
required being at the apex of the triangle, and two observers at the 
extremities of the base, which bears a constant proportion to the sides 
of the triangle, or the range. 
So far the two systems are identical, except that in Major Weldon's 
the constant proportion between range and base is as 20 to 1, while in 
the other it is as 18*973666 to 1, or roughly 19 to 1. 
Major Weldon obtains the range by measuring the base and mul¬ 
tiplying by 20. Both of these operations are open to objection, 
especially the former, if the base is long and the ground broken; while 
calculation of the simplest kind should be avoided, if possible, in the 
field. 
These difficulties may be overcome by employing a short auxiliary 
base, bearing the same proportion to the main base that the main base 
bears to the range. 
Fig. l. 
o 
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