1907.] on Flame in Gas and Petrol Motors. 503 



100 lb. weight only compresses the Diixture to something like 10 lb. 

 on the square inch. On pressing tiie igniting key, however, you 

 observe that the explosion is much more powerful, and the weight is 

 thrown about 18 inches, instead of 10 inches. This shows quite 

 clearly that for the same weight of gas and air charge introduced 

 into the same cylinder, a compressed charge gives more power than 

 the same charge without compression. It is obvious, therefore, that 

 this method supplies a means of obtaining greater power for a given 

 volume and weight of gas and air. In making this experiment it is 

 necessary to be cautious not to bring too much pressure to bear upon 

 the mixture. Otherwise the 100 lb. weight would get too much 

 energy, and probably damage the apparatus. 



These two last methods are commonly known as the non-com- 

 pression method and the compression method of operation in gas 

 and petrol engines. 



I:. A cylinder is supplied with gas and air under pressure ; but 

 the mixture is ignited at a grating or gauze as it enters the cylinder, 

 and so the pressure in the cylinder never rises above the pressure at 

 which it is supplied. The power here is obtained without any 

 increase in pressure, and is due to the fact that a small volume of 

 cool mixture, when inflamed, increases in volume ; so that although 

 a pump may be used to compress mixture, the expansion in the motor 

 side is greater, although at the same pressure as the pressure in the 

 pump. I have here an apparatus to illustrate this action. Fig. 4. It 

 consists of a glass cylinder A having in it a piston B, which you see. 

 At the low^er end of this glass cylinder are arranged two perforated 

 brass discs C, and between these discs is placed wire gauze. An 

 electric igniting plug D is placed immediately above the discs, the 

 spark is passed continuously, and a pump E, w'hich you see connected 

 up to the glass cylinder, supplies mixture of gas and air through the 

 grating, igniting at the electric spark, and expanding to force up the 

 piston in the glass cylinder. You will observe that upon passing the 

 spark and forcing down the pump piston, a flame appears in the glass 

 cylinder, which pushes the piston through its range, a small move- 

 ment of the pump piston resulting in a large movement of the motor 

 piston. In this apparatus power is obtained without explosion. The 

 flame serves the purpose of increasing the volume of the fluid supplied 

 under pressure. Here the volume is increased, and not the pressure. 



These four modes of action, and combinations or modifications 

 of them, include all the fundamental methods used in obtaining 

 motive power from flame, which have been attempted by mankind 

 for the last hundred years. In the early part of last century, the 

 vacuum methods were naturally the favourite methods of attempted 

 operation. In the year 1820 the Rev. W. Cecil, M.A., of Cambridge, 

 read a paper at the Canibridge Philosophical Society with the fol- 

 lowing title, " On the Apphcation of Hydrogen Gas to Produce a 

 Moving Power in Machinery, with a Description of an Engine which 



