232
MOTIVE POWER EMPLOYED
generally traversed that distance eight times aday, being in all about nineteen miles.—Therewere four horses regularly employed, but itwas found necessary to keep a spare horse, togive the others alternately a day’s rest; so that,in fact, five horses were kept to perform theconstant work of four horses effectively.
TABLE IV.
Table of the performance of horses upon the BackworthColliery Edge-rail-road, where a horse takes six loadedcarriages, each weighing 9,0101bs. down the plane, andreturns with six empty carriages up the plane, each weighing3,0801bs.
Friction of loaded carriages 421bs. and of empty 151bs.
Length of planein feet.
1Descent of plane
in inches.
Gravity of sixloaded carriagesdown the planein lbs.
Total resistancein lbs. being thedifference be*tween the fric-tion and gravity.
Gravity ot sixempty carriagesdown the planein lbs.
Total resistancein lbs. being thegravity and fric-tion together.
330
15.
204
48
70
160
330
14.5
197
55
67
157
330
7.
95
157
32
132
330
14.5
204
48
67
157
330
5.
68
184
23
113
330
5.5
75
177
Q6
116
330
18.
245
7
84
174
330
12.5
170
82
58
148
330
16.5
225
27
77
167
330
18.
245
7
84
174
330
31.
423
144
134
330
24.5
334
114
204
330
38.5
525
179
269
330
26.
354
121
211
330
20.
273
93
183
330
31.
423
144
234
330
48.
655
224
314
330
40.
546
186
276
411
41.5
454
193
283