118 The Bight Hon. Sir John Macdonald [April 18, 



pression of the air when you shut them. It is exactly the same 

 thing with a petrol engine, except that we assist the valve to close 

 by providing it with a spring to make it move more quickly. 



The next thing is the means by which we keep this engine cool. 

 The engine is running as high as 700, 800 or even 1200 or more 

 revolutions every minute, and these constant explosions which are 

 taking place every second time the piston moves, necessarily cause an 

 enormous amount of heat. In the case of very small motors we can 

 have working along with the machine a small fanner to keep it cool, 

 but with large motors this is quite inefficient. We have to use a 

 series of pipes with gills upon them : water is kept circulating in 

 these pipes either by means of a pump or other means, so that the 

 heat taken up from the cylinder is drawn off, and the water returns 

 and again draws off the heat. 



The next thing is how we apply speed to get our running, because, 

 as your engine is going round and round at 700 or 800 or more 

 revolutions a minute, the speed must be brought down, so as to apply 

 the power effectively to the wheels at a much slower rate, and to vary 

 the speed as required. [Illustrations on screen of methods regu- 

 lating speed by various sizes of pulleys, gear wheels, chains and 

 sprockets, etc.] 



Then we come to the tyres which we put upon our wheels. In 

 the days of the " Enterprise " coach there were no rubber tyres. It 

 was rough work, and required very powerfully-built carriages. Here 

 is a specimen of the latest tyre for the motor car, if you want very 

 comfortable running and are prepared to risk puncture every now 

 and again. There are other specimens here, which can be examined 

 afterwards, of the different modes in which the pneumatic tyre is 

 made up. Here are specimens of the solid tyre, one of them being 

 composed of hard rubber outside, and softer material for the inner 

 part. [Specimens of tyre exhibited.] 



There is a necessity for having very powerful brakes upon these 

 carriages. Here is one which closes round a drum upon the axle. 

 These carriages can, in fact, be pulled up in an extraordinarily short 

 distance ; if people are willing to sacrifice a tyre upon some occa- 

 sions, they can be stopped almost instantly. [Specimens of brakes 

 exhibited.] 



That is a description generally of what I call a spirit engine. 

 I have used illustrations more particularly of Herr Daimler's 

 engine. He is dead, but he was the great pioneer in this direction. 

 I have no wish in this lecture to praise any person's particular 

 work, or any individuals; but everyone can, without partiality, 

 give a tribute to the memory of Daimler as one of the great in- 

 ventors and manufacturers of our time. It was he who practically 

 adapted the gas engine to the use of petrol vapour, which at present 

 is nearly universally found suitable for the smaller machines, 

 such as tricycles and bicycles. We very often see, indeed, an 

 engine supported between two wheels, and there is one which has 



