The Measurement of Projectile Velocities

The paper discusses the requirements imposed by proving ground practise upon a chronograph which is intended for general ammunition testing. Instruments of the standard pre-wvar pattern were entirely inadequate in number for testing the immense quantities of ammunition contracted for by the Government during the war. The development work undertaken to cope with the whole problem of velocity testing was first directed towards devising methods for speeding up measurements with the existing instruments. Conditions made it necessary to lay aside this work and concentrate upon the devel. pment of a totally new device for obtaining the results both speedily and accurately. The instrument wbich was developed, and adopted as a standard ordnance chronograph, is designated ``Aberdeen chronograph.'' An account of its development is given. It is an assembly of many standard parts, with a few necessary special ones. Rapid production of the instruments was thereby made possible. The Aberdeen chronograph, and the procedure in determining velocities by this means, are described in detail. For the sake of comparison, the Boulengé chronograph is briefly described. Comparative results as to speed and accuracy of measurement are given.