Identifier: sponsdictionaryo05spon (find matches)
Title: Spons' dictionary of engineering, civil, mechanical, military, and naval; with technical terms in French, German, Italian, and Spanish
Year: 1871 (1870s)
Authors: Spon, Edward Byrne, Oliver Spon, Ernest
Subjects: Engineering
Publisher: London, New York : E. & F.N. Spon
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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fall ,• then on B C we write the spaces described in thesuccessive seconds, and on B A the velocity acquired ; the two bars will therefore be graduatedthus :— Time 1 2 3 4 5 6 7 8 9 10, &c. BO.. .. 16-2 64-4 144 254-4 395 565-2 764-4 992 1247-4 1530, &c. AB.. .. 31-8 64-1 95-1 125-6 155-5 184-8 213-5 241-6 269-1 296, &c. 3. These three bars thus graduated enable us to show the right-angled triangle formed by thesimultaneous ascent and descent of any ball fired obliquely upwards ; and we proceed to show howthe trajectory is drawn. 4. For this purpose a set of metal rods, tinned or plated iron wire, are prepared, one for eachsecond of time, as shown in our paragraph 2, where we show the space described by a falling body. GUNNERY. 1771 These are hung on the points of graduation of the oblique ascent, in an inverted order of succes-sion, that is to say, the shortest rod lowest down ; then a line drawn through the lower extremitiesof all these rods is the trajectory. 3376.
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Example.—To draw the trajectory of a ball fired at an elevation of 11° 58 56-25, with initialvelocity 736 ft. a second, we set the bar A B in the ring of the collar at A, and clamp it to showvelocity 736 ft., and we beard A B down to the desired angle, clamping its vertical bar B C at adistance of 58775 ft. from A, and proceed to hang the metal rods for 1, 2, 3, 4, 5, 6, 7, 8, and 9seconds on the oblique ascent ; the last of these meets the range exactly, and we see the trajectorymarked by ten given points ; our Table showing the fall by gravity will enable us to give thiscurve for the tenth parts of seconds if required. This instrument was offered to the service in 1864, when the model of which the above is adrawing was lodged in the United Service Institution. Fig. 3377 is of an Electro-Chronoscope, invented by Major-General Anstruther, C.B. Theobject of the electro-chronoscope is to measure exactly the time of flight of a projectile betweentwo given points. Various modes of taki

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