VI. VELOCITY. 81 



414. Edelmann's Anemometer with galvanic register. 



M. Th. Edelmann, Munich. 



416. Anemometer for determining the velocity of the air, 

 and other gaseous currents in pipes and canals. 



Moritz Gerstenhofer, Freiberg. 



C. CHRONOGRAPHS. 



4O1. Apparatus for measuring the velocity of projectiles, 

 and capable of recording several measures or lengths on one and 

 the same trajectory and of the same projectile. 



Antoine Joseph Gerard, Liege. 



403. Ballistic Apparatus Chronoscope, with two pendu- 

 lums, for ascertaining the speed of a projectile at any point of its 

 trajectory, by measuring the time of direction of a portion of the 

 trajectory ; also for measuring portions of time between one tenth 

 of a second and 25 seconds. Lieutenant- General Leurs, Brussels. 



404. Electric Chronograph, for measuring the initial velo- 

 city of projectiles (space required, 0.50 square centimetres on the 

 ground). Le Bouletige, Liege. 



405. Electric Clepsydra, for measuring the period of time 

 of the trajectory of projectiles (space required, 0.50 square centi- 

 metres on a table). Le Boulenge, Liege. 



4O5a. Electro-Ballistic Apparatus, for determining the 

 velocity of a projectile, with description of experiments and addi- 

 tional apparatus. M. JVavez, Paris. 



406. Electric Chronograph for the measurement, of minute 

 portions of time, &c. &c. Lieut. H. Watkin, R.A. 



This instrument consists of two upright cylinders resting on a base of wood ; 

 between them, suspended by an electro-magnet, is a weight with projecting 

 arms. The cylinder being connected with the secondary circuit of an induc- 

 tion coil, the circuit is complete with the exception of the small spaces on 

 either side of the weight. When taking velocities of shot, the primary 

 circuit is led through screens, constructed so that the current is broken and 

 immediately made again during the passage of the shot. The gun being 

 fired, the weights begin to descend ; the shot in passing the first screen causes 

 a spark to flash from one cylinder to the other through the weight ; then 

 having been previously smoked register of a white spot the position of the 

 weight at that instant. As the weight continues to descend the same result 

 is obtained at the next screen, &c. &c. Adjacent to the cylinder is a time 

 scale divided into thousandths of a second, subdivided by a novel vernier into 

 hundred thousandths of a second, by which the absolute time taken by the 

 shot between the screens is easily read off. 



407. The Clock-Chronograph, contrived for the purpose 

 of measuring the time occupied by projectiles in passing over a 



39508. F 



