THE ROYAL ARTILLERY INSTITUTION. 
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10 yards only, there is not much, to complain of on this score, but 
then elasticity in the base is not sufficiently acquired; if the 
tables are made out for each yard complication ensues. 
The majority of these instruments only measure one angle; this 
is again open to the objection of rigidity, ground not always admitting 
of a right angle being observed easily. To be able to use any 
chance base that may arise is, I consider, an essential feature of an 
instrument for measuring distances, and this can only be practically 
effected by the use of a mechanical calculator. This is one of 
the leading features of my range-finder. A decimal notation for the 
scale I also consider very useful, though not essential for success. It 
must be remembered that this class of instruments is to be con¬ 
sidered in a totally different light from the two former classes, 
as, while the latter fail because they cannot be depended on to give 
the true range, there is no doubt that .any one of the 3rd Class 
can be depended upon to ascertain the distance, provided the base 
used is sufficiently large, and if other circumstances are favourable. 
This 3rd Class may be sub-divided into two sub-classes. 
1st. Those which require stands. 
2nd. Those which can be used without stands, and which are 
reflecting instruments. 
As to the first sub-class, it seems impossible that any of these 
could, if fixed on guns, compete with the range-finder. 
1st.—Because all lack the mechanical calculator, which ‘enables 
my instruments to work with any base. 
2nd.—Because the decimal notation gives the range-finder a 
superiority in point of simplicity. 
3rd—Because all these instruments lack the I /’s, and the consequent 
rotary motion round the line of sight which my instruments enjoy. 
It has been said that the range-finders should be supplied with stands, 
so as to make them independent of the guns. I have always disliked 
countenancing a step which might tend to divorce the instruments from 
the guns; still, perhaps it might be advisable to adapt some existing 
article of equipment—say the camp kettles, to act as stands on very 
occasional emergencies, the gun always being looked on as the main 
stand. 
The second sub-class are the reflecting instruments, notably the 
sextant; of these, I believe that far the best is my infantry range-finder, 
which consists of a pair of sextants, carried either separately or in the 
butts of two rifles ; the advantages enjoyed by these over other reflecting 
instruments are:—1st, that they are provided with a mechanical 
calculator, carried also in the butt of the rifle ; and 2nd, that the notation 
is decimal; they are of course neither more nor less accurate than other 
sextants of similar size, but the decimal notation makes them simple, 
and the calculator imparts the necessary elasticity. 
These, and all other sextant arrangements are, however, unsuited to 
the exigencies of field artillery. 
lstly—The sextants cannot, at 2000 or 3000 yds., work with small 
bases. In skilled hands, on some days, they will give good results with 
