76 PKESlDEiNTIAL ADDRESS — SKCTION A. 



130° F. in the jackets was aimed at, the mean for the test being 

 130.5° F. The brake horse-power developed was I-.235, the 

 petrol consumption .13 gallon, per b.h.p. per hour, and the 

 l)rake thermal efficiency 14.36 per cent. It i> to be noted that 

 in all the tests the Ijrake thermal efficiency is based on the 

 lower calorific value ; that is, the total caloritic value, minus the 

 latent heat carried away by steam formed from the hydrogen in 

 the fuel, the result l)eing the heat available fur conversion into 

 work. 



Test Ah). 2. — This test was carried out with alcohol fuel 

 under the same conditions as test No. i, the only change being 

 the substitution of a 125 jet for the 95 jet used with petrol. 

 The brake horse-j^ower was 12.478, the consumption .187 gal- 

 lons per b.h.p. hour, and the brake thermal efficienc}- 15.29 

 per cent., the caliM-jfic value (lower) being 10,975 B.Th.U., as 

 compared with i8,ij85 I'.Tli.U. for i)etro]. as shewn in Table 

 XVL The valves at the ends of the test were remarkably clean, 

 and required practically no regrinding for the next test. 



Tests Nos. 3 and 4. — As compared with the jjublished per- 

 formances of petrol motors, the consumption in Test No. i 

 ai)peared to l)e high, so tests Nos. 3 and 4 were made specially to 

 endeavour, by improved conditions, to reduce the petrol con- 

 sumption. In test No. 3 a too jet was u>(h1, and all the air 

 sui)ply possible given, the regulating plug being ^vith(l^awn. The 

 percentage of CO in the gas analysis shows tliat the air supply 

 w^as inadefiuate, resulting in increased ])ctrol consum])tion and 

 reduced thermal efficiency. Test No. 4 was run tmder the >ame 

 conditions as test No. 3. but with a 90 jet. This ensured a 

 greater excess of air than in te.^t Xo. 1, Init the percentage of 

 CO2 showed a diminution, as com])ared witli test No. 1. and tlie 

 C( ) remained high, althougb over 2 ' ^ per cent, of oxygen \\as 

 found in the exhaust gases. It \\as conse(|iiently decided, in 

 any further test with petrol, to use a <j5 pet lor the gi\en load. 



In any comparison these tests shotdd be eliminated. ])ut they 

 are ^jiven to show how, if the nn'xture is not correct, the fuel 

 consum])tion ma\' be greatly increased, and the thermal efficiency 

 reduced, although the power developed is greater, and the run- 

 ning of the engine [perfectly satisfactorily from a mechanical 

 point of view. 



Tests Nus. 5 and C) were run under, as nearly as possible, 

 local conditions as regard tem])erature of water in the jackets. 

 Tests were made, by ex])erimental runs, with \arious types of 

 motor-cars, British and Anu'ric-an. and ii was ascertained tint 

 the average tem]XM-atiu\' in ilie jacket-^, allowing 22'' V . difference 

 between summer and winli-r mean almiis]ilu'ric lemperatures, 

 averaged 171° V. Tlii-^ u-niiiei-aturc \\a> aimed ;it. but owing to 

 the varialioi) of ]>resstn"c in town mains, it wa-^ difficult to main- 

 tain the jackets exactly at this temperatm-e. The results sliow 



