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up a plane ascending 134 inches in 1164 feet,and also the convoy-carriage, weighing 1^tons, the wheels not slipping. Rails quitedry. Edge-rail 24 inches broad at the top.
Then, weigh! of the engine 1680012 carriages — 9408 X 12 ~ 112896
3360 134
Convoy-carriages x ^ = 1277 lbs. gravity
Friction of 12 carriages, at 43 lbs. each - =: 316
Friction of convoy-carriage - — 17
1810 lbs. the to-tal resistance overcome by the engine, (exclusive of thepower required to propel itself forward); and, consequently,the adhesion of the wheels upon the rails, when the surfaceof the rails are dry.
EXPERIMENT XXVIII.
Same engine, with 29 empty carriages, eachweighing 3472lbs., up an ascent of 1 in 324;rails slightly covered with mud, and in theworst state; wheels slipped a little, but theengine proceeded at the rate of about 4 milesan hour.
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Then, as before, 16800 + 3360 + 3472 x 29 = 96128 X 324 =296 lbs. the gravity of the engine and carriages. Friction ofcarriages 29 X 16 = 464 + 17 = 481 lbs.; which, added to thegravity, gives 481+296 = 787 lbs., the adhesion in the worstweather.
This latter should, of course, be taken asthat resistance with which the engine should
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