THE VALUE OF A HIGH SITE FOR COAST ARTILLERY. 
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In the first column are three sets of ranges, each set consisting of 
two ranges, differing by 100 yards; in the next three columns, in each 
case, are the quadrant elevations due to these ranges, when the height 
of site is O', 100' and 200' respectively. The next three columns give 
the amount of alteration in elevation, due to a change in range of 
100 yards, for each of the sites. The next two columns contain the 
values of m 100 and m 200 . The value of m 100 is given in any case, by the 
ratio of the change in elevation due to 100 yards, on the level site, to 
the change in elevation, due to 100 yards, on the site 100' high; 
m 20 o is a similar quantity concerning the site 200' high, when compared 
with the level site. 
Thus with the 9" R.M.L., 10' elevation on the level will alter the 
range from 1000 to 1100, whereas if the gun is 100' high, it requires 
20'5 
20*5' to effect the same result; hence m 100 = -qqp or 2‘05. The other 
values of m 100 and m 200 are found on the same principle. The various 
angles of arrival and their cotangents are given in the remaining 
columns. 
From an inspection of the table, it is apparent that the same 
mistake in elevation will cause a greater longitudinal error, in the case 
of a low site, than in the case of a high site; that this effect will be 
more apparent at a short range, than a,t a long range, and in the case 
of a new type gun than in that of an old : and further, that in .the 
case of the high site and the old type gun, the angles of arrival are 
steeper. 
If the mistake then is such as would cause an ‘under/ the high 
site has the advantage, which increases the shorter the range and the 
flatter the trajectory of the gun. (See fig. 4.) 
If the mistake is such as would cause an ‘ over/ the compensating 
effect of the ratio of cot co to cot 8 must be taken into consideration. 
The following method will give a criterion, sufficiently accurate for 
the estimation of the net result of the two conflicting causes. 
Let e, e be the ‘overs’ which would just cause an objective ABGD, 
to be missed from the level and the high site, respectively. 
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