MEMOIR OF DAXIEL TREADWELL. 511 



T. To obtain from the experiments licrcin related tlie cfFect of the sparker, I take from them tlie 

 following facts : — 



1st. Wood and water reqnired in going to and retnrning from Framingham, 41 miles. 



Sparkei! on. Spaukeu off. 

 MEnCURY. 



■"'""'I- Water. Wood. Wiiter. 



Out, 83 cubic feet. 53.4 cubic feet. G7.0 cubic feet. .52.6 cubic feet. 



Return, 60 " " 42.5 " " 48.7 " " 40.0 



143 " " 95.9 " " II0.7 " " '9372 " " 



Meteok. 



Out, 61 cubic feet. 37.50 cubic feet. 42.0 cubic feet. 39.42 culiic feet. 



Retarn,_40 " " 31.55 " " 20.5 " " 20.13 •• 



101 " " 69.05 " " Q±l .. .. 50.55 " « 



Lion. 



Out, 67 cubic feet. 53.42 cubic feet. 82.91 cubic feet. 58.84 cubic feet. 



Return, _44 " '• 43.35 " " 33 " '• 89.50 " 



111 " " 96.77 " " 11.5.91 " •' 98.34 " " 



Total 355 cubic feet. 261.72 cubic feet. 291.11 cubic feet. 251.09 cubic feet. 



2d. Time required in going to and returning from Framingham, 41 miles, with the mean draft as 

 shown bj- the dynamometer. 



Sparker on. Sjarker off. 



Mercury. 



">• 8. m. 8. 



91 15 out. 75 55 out. 



69 45 return. 64 15 return. 



Time 161 50 i\Iean draft, 414.3 lb. Time 139 10 Mean draft, 467 lb. 



Meteor. 



™- s. ni. s. 



106 45 out. 89 40 out. 



83 25 return. 63 return. 



Time 190 10 Mean draft, 232.4 lb. Time 152 40 Mean draft, 340.4 lb. 



Lion. 



ni. 8. ni. 9. 



89 45 out. 92 40 out. 



72 45 return. 70 40 return. 



T; me 162 30 Mean draft, 5.36 lb. Time 163 20 Mean draft, .591 1 lb. 



Time required in rnnning the 123 miles with the sparker on, and the same distance without the 

 sparker, with the mean draft in both cases. 



Sparker on. Sparker off. 



m- 9. m. 8. 



Time 513 40 Time 455 10 



Mean draft 427.6 lb. Mean draft 466.2 lb. 



By the above it appears that, although the loads in the paralltd experiments with and withont the 

 sparker were almost identical, the draft or traction when the sparker was not used was nine per cent 

 greater than when it was used. I attribute this (lilforence to some slight and accidental dilferenco in the 

 state of the road, or to the condition of the oil upon the journals (or gudgeons), or to both these com- 

 bined. Adding to this nine per cent for the wood and water used when the sparker was on the engine, 

 we find required Uj produce equal elfeets, taking the mean of the i)arallel experiments, about thirt}- per 



