118 REPORT— 1878. 



Manchester and other towns in England, and which is an excellent burner 

 for gas not exceeding 20 candle power, but gives a somewhat smoky 

 flame with gas of high quality. 



The only other batwing that requires further to be noticed is the 

 patent regulating batwing used in the United States of America, where 

 it was introduced in 1871, and which is practically the only flat flame 

 burner capable of burning advantageously the "air-gas" made by saturat- 

 ing air with the vapour of petroleum spirit. It consists of a very much 

 elongated iron batwing with an exceedingly narrow slit, surrounded by a 

 brass tube at the distance of about 2 millimetres ; into the space between 

 the two, gas is admitted by a wide orifice (the amount being regulated 

 by a screw) , and this gas ascends entirely without pressure, while the 

 force of the gas issuing from the narrow slit spreads it out into a fine 

 soft flame. This burner gives excellent results with gas of all qualities, 

 but its shape is not adapted to the gas fittings in use in this country, and 

 it has not been used here except for air-gas made for private houses. 



Argand burners are exclusively used in the photometric testing of 

 common gas, and they are also employed rather extensively for lighting 

 shops and public buildings, but to a limited extent for private houses. 

 They give a higher photometric effect with common gas than any flat- 

 flame bui'ner known ; and even with cannel-gas, the best descriptions, 

 especially those of Sugg and Silber, give results which approach very near 

 to those obtained when the gas is tested at a comparatively low pressure 

 by large-sized fishtail or batwing burners. 



The original form of Argand was a brass double cylinder with, above, 

 an iron ring perforated with small holes, and below, a " crutch " or forked 

 tube, by which the gas was introduced at opposite sides. A wide and 

 short glass chimney was used, but this was afterwards modified in a variety 

 of ways with a view to making the current of air impinge more directly 

 upon the flame and so increase the intensity of combustion. The holes 

 being small, the gas escaped at a comparatively high pressure ; and the 

 character of the flame both as to volume, shape, and luminosity, depended 

 partly upon the initial velocity with which the gas escaped from the 

 burner, and partly upon the shape and dimensions of the funnel. The 

 enlargement of the holes enabling the gas to escape at a moderate pressure 

 was proposed by the late Dr. Letheby, who was afterwards associated with 

 Mr. Sugg, by whom many improvements in Argand burners have been 

 introduced. The Letheby burner raised the apparent quality of London 

 gas from 12 to 14 candles, and a further increase of 2 candles was obtained 

 by Sugg's London Argand now generally accepted as the standard burner 

 for testing gas made from common coal. In this burner the principle is 

 recognised of permitting the gas to escape practically without pressure, 

 the shape and volume of the flame being determined by the narrow funnel 

 and a " cone " of thin metal which serves to throw the current of air into 

 close contact with the outside of the flame. The upper portion of the 

 burner is of steatite, and instead of the ordinary " crutch " below, the gas 

 is introduced by three very narrow tubes. A number of sizes of this 

 burner are made of which details are given below, but the following are 

 the various dimensions of the standard burner used in photometry : — 

 Diameter of steatite top, external, '84 inch ; internal, - 47 inch ; number of 

 holes, 24 ; diameter of holes '04 inch, chimney 6 x If inches, for gas of 14 

 candles, and 6x2 for gas of 16 candles. The narrow funnel and the 

 cone restrict the quantity of air to very little more than is required to 



