IX. MISCELLANEOUS. 215 



978a. Apparatus for measuring the magnitude of Gas 

 Jets at a distance. Invented by Mr. C. Wolfberger. 



Geneva Association for Constructing Scientific Instru- 

 ments. 



This apparatus, invented by the civil engineer Wolfberger, is intended for 

 the surveying, from the street level, of gas lamps. 



Founded on the principle of the sextant, it is composed of two mirrors : 

 the one fixed, the other movable parallel to the first along a graduated scale. 



In order to measure the magnitude of the gas jet, the operator holding 

 the instrument by its handle on a level with the visual ray, and looking 

 through the diaphragm, sights simultaneously in a direct line the jet to be 

 measured, above the fixed mirror, and indirectly the reproduction of the same 

 jet by double reflection. The swivel placed below the handle is then turned, 

 until the right edge of the jet, seen in a direct line, coincides with the left 

 edge of the jet, seen by reflection. The magnitude of the jet, or flame, ascer- 

 tained, is then fhown on the metallic scale which is reckoned hi millimetres. 



978b. Patent Illuminating Power Meter, for showing the 

 illuminating power of gases in the terms of the Parliamentary 

 sperm candles and the standard quantity of five cubic feet of gas 

 per hour by the observation of one minute. William Sugg. 



979; Trepiscope. An optical machine made by the late 

 Richard Roberts, of Manchester, and first shown at the meeting 

 of the British Association at Dublin in 1835. 



The Committee, Royal Museum, Peel Park, Salford. 



The machine being turned by hand or by power will cause the card on the 

 disc to revolve from 6,000 to 40,000 times a minute ; on viewing the re- 

 volving disc through the eye-hole, the printing on the card can be read with 

 ease and distinctness. 



The time given for one view of the card does not exceed the 150,000th of 

 a second when the disc is revolving at the highest speed. 



97 9a. Phosphoroscope, by Becqucrel. 



M. J. Duboscq, Paris. 



980. Radiograph. 



The Committee, Royal Museum, Peel Park, Salford. 



A small machine to show that the spokes may be counted whilst the wheels 

 revolve at a very high velocity, probably the highest attainable. Invented 

 by the late Richard Roberts, C.E., of Manchester. 



981. Newtonian Disc, for rotating movement transmitted by 

 caoutchouc bands. Luizard, Paris. 



981a. Newton's Apparatus. M. Lutz, Paris, 



982. Clock for producing Eclipses in groups, on Sir Wm. 

 Thomson's plan in azimuthal condensing lights, by periodically 

 dropping a screen over the flame. 



Chance Brothers $ Co., Birmingham. 



