506 Mr. Dtujald Clerk [Feb. 22, 



that is, the charge of inflammable mixture is compressed before 

 ignition. 



Many attempts to construct engines operating on the compression 

 principle were made before success was obtained. In such attempts 

 England had a full share. One of the very earliest feasible com- 

 pression gas engines was that described by William Barnett, an 

 Englishman, in the year 1888. This engine liad many of the features 

 of successful engines of to-day. Later proposals VTere made for 

 similar engines, both in France and Germany ; but the iirst inventor 

 to succeed in overcoming difficulties to a sufficient extent to produce 

 a commercial engine was the late Dr. Otto, of Deutz. To Dr. Otto 

 belongs the honour of producing the first successful compression gas 

 engine. The great majority of modern gas and petrol engines 

 operate on what is now known as the Otto cycle. The combustion of 

 a compressed charge in a motor cylinder in a safe, quiet, and econo- 

 mical manner, is a much more difficult problem than appears at first 

 sight. Those of us upon w^hom fell the brunt of working out this 

 problem about thirty years ago, appreciate fully the ability and 

 knowledge displayed by the late Dr. Otto in producing his famous 

 engine. In the Otto engine the characteristic feature is found in the 

 alternate use of the same piston and cylinder for the purpose of 

 pump and motor. In one complete revolution the cylincler is used 

 as a pump, and another complete revolution as a motor. The cycle 

 is very simple. It is so well known that I need hardly sUite it. On 

 one outstroke a charge of gas and air is taken into the cylinder. On 

 the next instroke the charge is compressed into a space at the end of 

 the cylinder ; on the second outstroke explosion and expansion 

 occur ; and on the second instroke the exhaust gases are discharged. 

 One piston and cylinder thus serves to alternately supply compressed 

 mixture, and use that compressed mixture for the purpose of motive 

 power. It takes, however, four strokes, or two revolutions of the 

 engine, to complete its cycle. I have here a section showing the 

 operation of the original Otto engine. The engine has been greatly 

 improved in recent years, and the Otto cycle was applied by Daimler, 

 one of Otto's former managers, to the purpose of the petrol engine. 

 The modern petrol engine has been developed from the original 

 Daimler invention. I have here a Lanchester petrol engine in 

 section, and can show you the operation of the piston and valves 

 performing its cycle. 



The Otto cycle has many great advantages. The charging and 

 discharging of the gases is accomplished easily. The heat-flow 

 through the sides of the cylinder is not too continuous, and conse- 

 (juently the cycle can be operated at very high speeds indeed. Many 

 attempts, however, have been made to obviate the main disadvanttige 

 of the (Jtto cycle, that is, the necessity for two complete revolutions 

 for every power impulse, and I have devoted nuich time and experi- 

 ment with this end in view. In 1881, twenty-six years ago, I 



