THE ROYAL ARTILLERY INSTITUTION. 
9 
EXTRACTS FROM REPORT 
ON 
BALLISTIC EXPERIMENTS CARRIED ON DURING THE YEARS 1861-2, UNDER 
THE DIRECTION OF THE O. S. COMMITTEE. 
BY CAPTAIN W. H. NOBLE, M.A., R.A. 
ASSOCIATE MEMBER, ORDNANCE SELECT COMMITTEE. 
1. The determination of the velocity of projectiles is indispensable to 
the necessary calculations which belong to the theory of gunnery. 
The most primitive method of estimating this velocity was by measuring 
the ranges of the projectiles on a horizontal plane. This method was 
employed by Lombard in 1797. It is unnecessary to enumerate the 
difficulties with which it is surrounded. 
The case to which it was most applicable was the determination of the 
velocity of mortar shells. 
The estimation of velocities, by observing the total duration of a 
projectile's flight in the air, that is to say, the time of its ascent and descent 
combined, is subject to less causes of error, but the difficulty of noting the 
time with sufficient minuteness is a great obstacle. Subsequent to the 
invention of the Ballistic Pendulum of Robins, several methods were 
adopted for measuring the velocity by the time a projectile occupied in 
passing from one point to another in the trajectory. One of the first of 
these is due to Mattei, about 1767.* 
INSTRUMENTS FOR MEASURING TIME* 
Mattel's Machine of Rotation. Fig. 1. 
Mattel's machine consisted of a vertical cylinder of paper ot thirl 
cardboard fixed to a wooden frame, to which a certain velocity of rotation 
was given, and musket balls were fired against it in a direction perpendicular 
to the axis of the cylinder. The difference between the deviation of the 
holes that the ball had really made and of those it would have produced if 
the cylinder had been at rest gives the time of flight comparatively to the 
time of an entire revolution of the cylinder; as, moreover, by means of 
* Lieut, de Butet, of the Italian service, seems to have been before Mattfei. Vide fiat. 6, j). 13. 
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