1907.] Flame in Gas and Petrol Motors. 501 



observe that the engine at once rotates. The power obtained, it is 

 true, is small for the gas consumption ; but here jou have an actual 

 example of an engine operating with flame as its working fluid at 

 atmospheric pressure. This modification may be called the flame 

 vacuum method. 



'1. Bj admitting a charge of atmospheric air and inflannnable gas 

 or vapour at atmospheric pressure to a cylinder containing a piston, 

 catting off access to the atmosphere and the gas supply, and igniting 

 the mixed charge, a mild explosion occurs ; the pressure rises in the 

 cylinder, and the piston is driven forward to the end of its stroke. 

 I have here an apparatus to illustrate this effect. This apparatus, 

 shown in Fig. :3, consists of a petrol engine cylinder A fitted with a 

 piston B in the usual way. This piston, however, carries a piston 

 rod C, having at its upper end a long key D operating in a slot in 

 a tubular pillar E mounted over the open end of the cylinder, and 

 held firmly by flanges and bolts. The upward movement of the 

 piston is buffered by rubljer rings F placed within it. The down- 

 ward movement of the key is buffered by rubber rings G covered by 

 a metal plate surrounding the tubular pillar. A circular cast-iron 

 weight H of about 100 lb., slides upon the tubular pillar, and rests 

 upon the key in the piston rod. The weight can be hoisted up out 

 of the way, as you see, by means of a small block and tackle. The 

 inlet valve of the petrol engine is used to admit a mixture of air and 

 gas. The gas is carefully measured in under the valve by means 

 of a separate measuring pump, and electric igniting gear is arranged 

 as in the usual petrol engine. 



I have here a stop, wliich permits the piston to be raised through 

 half its stroke. Raising it then through half its stroke, and talking 

 in a charge of air and gas in measured proportions, I then place a stop 

 K underneath the key, and lower the weight on the top of it. The 

 mixture within the cylinder is then at atmospheric pressure, and the 

 weight is not allowed to move the piston to compress the contents 

 of the cylinder. On pressing down the igniter key, you observe that 

 the 100 lb. w^eight is thrown up along the tubular pilhr, and it 

 rises about 10 inches, and then falls again. This lo-inch rise gives 

 a measure of the energy of the explosion and the expansion during 

 the half stroke of the piston. It is obvious that power can be 

 obtained from an inflammable mixture treated in this way. 



:>. By supplying to a cylinder containing a piston a mixture of 

 inflammable gas and air in a compressed state, and then igniting that 

 mixture, motive power can l)e obtained. Using the same apparatus 

 as I have described under the second method (Fig. ;-)), T charge the 

 cylinder with exactly the same charge of gas and air. Instead, however, 

 of supporting the piston by means of the stop used in the last experi- 

 ment, I remove this stop and allow the 100 lb. weight to rest upon the 

 piston rod, thus compressing the charge within the cylinder. This 

 particular cylinder is :-»f uiches in diameter, so that the addition of 



