38 LYDD EXPERIMENTS, 1890. 
rection of fire with the aid of balloons, as compared with the theodolite 
system. 
In a series of 190 rounds recorded by the Experimental Officer, the 
mean error with the theodolite system was 6*25 yards in range, and 
3*2 feet in line. 103 or 54 per cent, of the errors in range were 
under five yards, and 149 or 78 per cent, were under 10 yards. In 
160 or 84 per cent, of the observations, the error as regards line was 
under five feet. 
It was evident that the system of observation by means of a pair of 
theodolites is more accurate than the system of observation from a 
balloon. This was, indeed, to be expected, since in the latter case the 
observer, though well situated as regards his field of view, has only 
his own estimate of distance to guide him in his report, whereas the 
theodolite measures instrumentally the position of the burst of the 
shell. 
Again, the balloon can be used only in still weather. It is, more¬ 
over, probable that on service a balloon would be compelled to remain 
at a greater distance from the enemy than was the case at Lydd. 
It is advisable, however, that the observation of fire from a balloon 
should still form a part of the programme for the practice at Lydd, 
since the introduction of smokeless powder will render impossible the 
system at present adopted, of deciding as to the position of the enemy 
by taking the bearings of the smoke of his guns ! Such a proceeding 
would even now be fallacious in the case when the enemy fired with 
howitzers from hollow ground, especially if the smoke drifted to one 
or the other flank. 
Series (M.)— A comparative trial of French’s and Scott’s sights for 
laying back, after four comparative trials of these sights made during 
service practice, it was found that the use of Frenches sights, with a 
clinometer, gave the best results. 
A further trial with R.M.L. howitzers (Series G.) showed that the 
rectangle of the howitzer with which Scott’s sight was used, was worse 
by 10 yards than that of the other, which was laid with French’s 
sights and a clinometer. 
Additional trials with the 4-in. B.L. gun and with the 7-in. and 8-in. 
B.L. howitzers showed that Scott’s sight was much effected by mirage, 
while the small amount of deflection which can be given on it renders 
it unsuitable for use with howitzers. This defect might, however, be 
remedied in a later pattern. 
Other objections to Scott’s sight are urged, for example 
1. Its peculiarities render it unsuited to any but exceptional layers. 
2. The laying back mark, when it is used, must be at some little 
distance from the gun ; while French’s sights with the clinometer are 
independent of any such consideration. 
3. As designed it is better adapted to laying forward than to laying 
back (for which purpose it has to be reversed), while laying back is 
universal with siege howitzers and frequent with siege guns. It is, 
moreover, doubtful whether, taking the short radius of Scott’s sight 
into consideration, that instrument is as accurate as French’s sights in 
