However, the problem of deflection settings — 'aim-off' — required knowing the rate of change in the target's position. Both France and UK introduced tachymetric devices to track targets and produce vertical and horizontal deflection angles. The French Brocq system was electrical, the operator entered the target range and had displays at guns; it was used with their 75 mm. The British Wilson-Dalby gun director used a pair of trackers and mechanical tachymetry; the operator entered the fuse length, and deflection angles were read from the instruments. COUNT 5
QSN1 What did the tachymetric devices do? ANS1 track targets and produce vertical and horizontal deflection angles QSN2 Which system had electrical tracking? ANS2 French Brocq QSN3 What gun was the French Brocq system used with? ANS3 75 mm QSN4 Which system used a pair of trackers? ANS4 British Wilson-Dalby gun director QSN5 Deflection settings were also called what? ANS5 aim-off