I'RESlDli.NTIAL AUDRKSS — SKc TloN A. 7_^ 



Duration of Tests: In testing internal cunilnistiun engines 

 it is generally recognised that a test lasting i honr is suftieient to 

 obtain reliable data owing to the uniformity df tlie conditions 

 and the rapidity with which these are reached. ( )nly in tlie case 

 of a gas-engine producer i)lant is it regarded as desirable to 

 run 6 hours. In the recent important tests carried out by the 

 United States Government un \K'ivn\ and alcoholic fuels the 

 duration of each test was from 15 to 30 minutes. It was, how- 

 ever, decided to nm each c^f the lirst two tests for a period of 

 6 hours, partly as a test of reliability under a continuous heavy 

 load, and partly with the object of examining the pistons, cylin- 

 ders, plugs and valves for deposit, etc., after the test. The 

 remaining tests lasted two liours each. 



Load on Brake: The engine was found to be capable of 

 exerting with petrol a maximum brake horse-power of about 15 

 for short periods. To leave a slight margin over a 6 hours' 

 run it was decided to run it at a load correspf)ndiiig to about 

 12^-2 b.h.p. at 1,300 revolutions per minute, the load being 

 maintained constant, and the speed of the engine regulated by 

 hand control. 



Carburettors: The engine on receipt was fitted with a 

 Claudel-Hobson carburettor, so this type was retained. No 

 structural alterations of an\- kind was made to the carburettor 

 during the whole of the tests, but various sizes of jets were 

 used both for petrol and the alcohol fuel. The use of a variable 

 jet would have been advantageous with regard to mixture 

 adjustment, but it was considered desirable to adhere to the 

 standard jets, selecting the one for use which ga\'e the best 

 running results. This "■ tuning u]) " was left entirely in the 

 hands of the motor experts, and the test was not proceeded 

 with until they were satisfied from their practical experience 

 that the best was being got out of the engine. 



Startiiuj: Starting from cold with ordinary denatured 

 alcohol has always been a difiicult problem, and one of the objec- 

 tions to its use. involving starting on ])etrol or running on a mix- 

 ture of alcohol and benzol. In the tests under consideration 

 no trouble was experienced on any occasion in starting up with 

 the alcohol fuel, with the engine either hot or cold, due. no 

 doubt, to the presence in the fuel of sulphuric ether as a car- 

 burant. When cold, as is usual in practically all motor-car 

 engines using petrol, it was necessary to partly reduce the air 

 supply. 



Tests Conducted: The following are the particulars, ob- 

 served and calculated, of llu- wirious tests conducted. Sec Table 

 XVI.) 



Test No. I. — The duration of this test was 6 hours, with 

 petrol fuel and a 95 jet in the carburettor. A temperature of 



