Observations on Inclined Planes. Ill 



^'Experiment 2d, on friction. — Length of plane 1164 feet; per- 

 fectly straight, with a uniform and regular descent of 1 yard in 104.24 j 

 edge rail of Losh and Stevenson's patent, 2J inches broad at top. 

 The carriages were allowed to descend freely by their gravitating 

 force, and the space they passed over ascertained by a stop watch. 

 Four loaded carriages, each weighing 9408 lbs. descended the plane 

 in 120 seconds." The value of x in equation A, from these data, 

 is .15, and /=42.79 lbs. for the resistance of friction of each car- 

 riage, being nearly the 220th part of the weight. By Mr. Wood's 

 formula, we have, in this case, /^— 39.35 lbs. The difference in re- 

 sults may be caused by the resistance of inertia not being included 

 in the latter value o( f. 



^'Experiment 19th. — Upon the KiUingworth rail road: self-acting 

 plane, with a rope-roll, round which the rope winds, one end of 

 which is attached to the descending, the other to the ascending car- 

 riages; length of plane 715 yards, descent 57^- feet. Six loaded 

 carriages, each weighing 8764 lbs. descended by their gravitating 

 force, and drew up seven empty carriages, each weighing 2800 lbs. 

 on a mean of several times, in 180 seconds; weight of the rope 3884 

 lbs. ; weight of the sheaves 3297 lbs. ; weight of the rope-roll 4636 

 lbs. The descent of this plane is not regular, being greater at the 

 top than at the bottom, the line of the road perfectly straight." Ta- 

 king, in this case, /= the 200th part of the weight, we find F, from 

 equation D, equal to 212 lbs. Mr. Wood gives, in this instance, 

 F=204 lbs. 



'^ Example. — Suppose a descending plane, the length of which is 



1800 yards, down which it is intended to pass 9 loaded carriages at 



fl time, each weighing 4 tons, which drag up 9 empty carriages, each 



weighing 24 cwt. ; required the height of the plane, or inclination, 



tliat will cause the descent in 400 seconds. Weight of rope 5562 



lbs. ; weight of the sheaves 5400 lbs. ; rope-roll 454 lbs." In this 



case, taking /= the 200th part of the weight of the carriages, and 



^ /, 2r-h/c\ 1099 



t =^\\k-{-m-\-p-\- 1=228-] 5 we have, by substitution 



1099 d 2as 

 m equation D, 228-}- =-— — ^ — /, which gives ?i=51f ; that 



is, the plane rises 1 in 51|. The formula of Mr. Wood gives 1 in 

 50, -for the elevation of the plane. It should be observed, that t has 

 been taken equal to ^^ of 400, a correction adopted by Mr. Wood, 

 in order to cause the descent within the required time, in all states 

 of the weather. 



