347 
LETTER 
ON THE 
WELDON EANGE-FINDER, 
EROM 
MAJOR J. B. RICHARDSON, R.A. 
St. Thomas Mount, Madras, 
October 4, 1880. 
My Dear Sir— 
I forward to-day, by parcel post, as a present to tbe Institution, 
a complete set of Weldon's Range-Finders, consisting of two angle¬ 
finding and one auxiliary base-finding instrument. 
These instruments have been made up, out here, at a cost of Rs. 10 
per instrument, or under £3 for the three. I mention this to give an 
idea of what their probable cost will be. I fancy that in England they 
will be much cheaper if made in any quantity, but Major Weldon has 
patented his inventions, and I have great difficulty in obtaining a 
supply of instruments from him, though, since I wrote a paper on the 
subject (No. 1, Yol. XI.) in the “ Proceedings," many officers have 
written to me to try and get them a set of instruments. 
As the instruments leave here they are in perfect adjustment, but 
should the journey derange them, I shall be glad if you will let me 
know. I have, purposely, not taken any great care in packing. 
Two of the instruments read the same angle. The other (that with 
the long glasses) is the t( Auxiliary Base Glass.” I have painted 
“ base glass” on its under side in white. 
The paper I have above quoted will give a rough idea of the use 
of the instruments, but it was written before I had the experience of 
its use which I now possess. In my battery, for a year-and-a-half, no 
other range-finder has been in use, and I have generally instructed all 
my range-finding N.-C.-O's. myself, so that it seems to me a few 
further notes on its use may be interesting to any officers who may 
take an interest in improved range-finding, and who may make a trial 
of the instruments I send. Perhaps you would let any such see this 
letter. 
To work with the instruments, some further articles are required. 
They are such as any battery artificers can make. 
1st. A reel* capable of holding at least 150 yds. of fine twine. I 
