it could be subject, the gunner to measure the resistance to the motion of the shell, to plot its trajectory, determine its time of flight for various ranges, set his fuse, and design his sights so that his shooting may be accurate. But the long range gunnery of our modern ships, the high angle fire required for anti-aircraft work, have each introduced new difficulties, and in solving these Cambridge men such as Littlewood, Hill, Richmond, Herman, Gallop and Fowler have been well to the fore, while for anti-aircraft work the Bennett heightfinder in one of its many forms is in general use in the Allied Armies.
One striking feature has been the development of methods of accurate workmanship. With some few exceptions all the gauges for munitions pass through the National Physical Laboratory. About 400,000 have been dealt with in the last eighteen or twenty months.
