364 
THE WELDON RANGE-FINDER. 
that a base 69 yds. long would be shown on the tape, and read as 138 
divisions. No multiplication was then necessary, as the range was 
read off at once by annexing 0, and was given as 1380 yds. 
The first practical difficulty I encountered with this method was, that 
if the range should be as much as 4000 yds., the base must be 200 yds. 
long, and to find a position for a base of such length was often 
impossible in enclosed countries ; or, if the base could be obtained, the 
distant object—the range of which was required—could not be seen 
from both ends of the base. 
In order to have a choice of positions I usually carried the instrument 
showing 88° 34', and when a base of 200 yds. for a 4000 yds. range was 
not obtainable, I used a base of half the length, and the angle 88° 34', 
when the range = base x 40. 
Owing to obstacles, the nature of the ground, &c., I found that a 
fixed base of -jq, ~io, or the range was most inconvenient in rough 
country, and so I gave up this method in favour of that requiring a 
variable angle and any convenient base, the optical square being used 
as before to set off the right angle, and the pocket sextant being used 
to measure the angle KAO. A table being used to read off the range. 
After many years practice in all countries I have found this method 
the best and most convenient. The errors, with competent observers, 
vary from 1 to 3 per cent., and the time occupied varies from 1 to 3 
minutes. 
Captain Everett, 33rd Regt., who was my assistant at the Royal 
Military Academy, could with me find a range in less than 40 seconds, 
and with an error rarely more than one per cent., and such results were 
obtained before a Committee at Shoeburyness. 
In all these methods, however, it is necessary, from the principle of 
the instruments used, that the base should be horizontal or nearly so. 
In hilly country this is almost impracticable, and great errors will 
result. 
In order to obtain the full benefit of any range-finder, thoroughly 
competent observers must be employed. To hope that any method of 
range-finding can be used by men who are unskilled, is a delusion. So 
that it really seems desirable that there should be attached to each 
Battery men trained as range-finders, receiving some small increase of 
pay when thus qualified. 
We do not expect that every gunner should, after an hour's instruc¬ 
tion, be competent to shoe a horse, and the value of knowing one's 
range so as not to waste ammunition is certainly of sufficient importance 
to demand training and attention. 
The method of using the fixed angles and variable base, such as 
88 ° 34, 87° 8', and 84° 17', I taught at Hythe to the School of 
Musketry, also at Aldershot, and at Woolwich about ten years ago. 
Also, the more useful method of any angle and any base, in order to 
overcome the defects*of the fixed angle. 
It will be seen from these facts that the Weldon range-finder is not 
quite a novelty, and from the supposed perfection of the instrument 
and the method, it appears that its practical difficulties have not yet 
been discovered. 
