1902.] on Auto-Cars. 115 



was possible to bring gas and air together in small quantities, and 

 instead of having enormous destructive genii to deal with, to have 

 a number of bottle imps which you could let out one after another 

 and make each do serviceable duty. The gas engine was a device 

 for letting a small quantity of gas and a small quantity of air meet 

 together and explode in a confined space, so that by a succession of 

 small explosions suflScient power was developed to drive an engine. 

 I will explain to you how the gas engine works. Tt somewhat 

 resembles a steam engine in general appearance, but the action is 

 quite different. I have prepared this model with a cylinder of trans- 

 parent glass for the purpose of demonstrating it. The first thing we 

 have to do is to get our cylinder filled with a mixture of gas and air, 

 whether coal gas or vapour of petrol or alcohol. In order to make it 

 clear to you, I attach a piece of blue paper to the piston, which, when 

 drawn up and showing through the glass cylinder, symbolises the 

 mixture of gas and air. When the piston is drawn up and you have 

 sucked into the cylinder a mixture of gas and air, the next thing you 

 have got to do is to force the piston down again to squeeze and press 

 that mixture close together ; then it is ignited, by means which will 

 be afterwards described, and the piston again ascends, but this time 

 it is driven up by the explosion, while the cylinder is filled by the 

 products of the combustion, which now I represent by a brown 

 paper. These products of combustion have, by a fourth motion of 

 the piston, to be excluded and driven out again. You suck the mix- 

 ture of gas and air in ; you then press it ; it is then expanded and the 

 piston driven up by force of explosion ; and then the piston descends 

 again, pushes out the exhausted gas, and it is ready to begin its work 

 of sucking up gas and air again ; and so it goes on in a succession of 

 strokes. 



Now you will, I think, ask me three questions, which will occur 

 to everyone. First, how do you get your first two strokes when you 

 have nothing to do it with, as the explosion does not take place until 

 the third time the piston moves ? Next you will ask when the piston 

 is driven up why does not it stay there ? When driven up by a 

 strong explosion it would be expected to stop there or knock the top 

 of the cylinder off. The third question is, if gas is being admitted 

 into this space, how is it that when the explosion takes place, the fire 

 is not communicated to all the fuel carried, so burning it up at once, 

 and causing a conflagration. 



I will explain these things to you very shortly. In the first place, 

 one of the difficulties of the gas engine is that it has to be started by 

 some other power before it can do its work. To start a steam engine, 

 steam is let in first at one end of the cylinder and then at the other, 

 and so pushes the piston from one end to the other alternately. But 

 in this spirit engine something has to be done first, mechanically, in 

 order to give the gas the opportunity of being sucked in along with 

 the air and compressed so as to make an effective explosion. I dare- 

 say some of you have seen people on the road, whose engines have 

 stopped, busy with a sort of barrel-organ handle turning it round 



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