112 EEPOET — 1878. 



result being obtained with about 1 cubic foot per bour, and the highest 

 ■with 5 cubic feet. This last result, i.e., 26 candles for 5 cubic feet of gas 

 per hour, burned in a union jet at - 5 inch pressure, is taken as the 

 standard of comparison in all the experiments in cannel-gas. The ratio 

 of illuminating power to quantity is nearly the same at higher pressures, 

 and there is no difficulty in deducing the general law that the value in 

 illuminating effect per cubic foot of gas increases with the mass of the 

 flame. • 



The effects of pressure are not less striking, and might have been 

 more so had the gas been tested at lower pressures than - 5 inch and higher 

 than 1-5 inch. The results obtained with a jet consuming 5 cubic feet 

 per hour gave 26 candle3 at the low pressure and only 166 at 1*5 inch, 

 showing a loss'of lighting power amounting to about 36 per cent, ; 3 feet 

 per hour, calculated to 5 feet, gave at the low pressure 21 candles, at the 

 high pressure 123 candles; the burner being a No. 4 in the one case and 

 a No. 2 in the other. The medium pressure gave results intermediate 

 between these. At the higher pressures some of the larger-sized burners 

 became useless, as already explained. 



As in practice it is found impossible to distribute gas at a pressure of 

 less than 12 or 15 tenths of an inch of water, various contrivances for 

 breaking the force of the gas have been invented. Among union jets of 

 this kind, the simplest, perhaps, is that of Leoni, consisting of a brass and 

 an iron tube which fit into one another, and between which a thin film of 

 cotton wool is placed. This is a very good burner, but it cannot be 

 depended upon for delivering exact quantities of gas. Bray has con- 

 structed a very good burner similar to those already mentioned, but 

 having a double ply of cotton cloth stretched across a metal ring placed 

 in the tube, in order to reduce the pressure. The same manufacturer has 

 more recently invented another burner in which the reduction of pressure 

 is attained by passing the gas through an orifice in a porcelain plate 

 cemented into the lower part of the burner. He calls these special 

 burners, and they are of two kinds — one intended for general use and the 

 other for street lamps, in which the orifices are somewhat smaller, and 

 in which, consequently, the pressure is further reduced. Morley's patent 

 burner is of brass and vase-shaped, with a porcelain top, and at the bottom 

 one or two small orifices in the metal for admitting the gas. Williamson's- 

 jet is similar in principle, but more complicated in construction. Da 

 Costa's burner consists of a hollow vase stuffed with iron turnings, into 

 which an ordinary iron union jet is screwed. There are others, but all 

 have the same object in view ; and the simpler and cheaper burners, such 

 as Bray's, accomplish it as successfully as those of more complicated con- 

 struction, and these have, therefore, been selected for a series of com- 

 parative trials, all being made with 26 candle gas. Some of the burners 

 referred to are called regulators, but this is a mere name, for it is obvious 

 that they merely obstruct the flow of the gas, the quantity delivered rising 

 as the pressure is increased. In Bray's special burners the two holes 

 forming the " union " jet are placed at an angle of about 120°. 



