112 Observations on Inclined Planes. 
' Experiment 27th.—Boulton and Watt’s low pressure condensing 
engine, with two thirty inch cylinders, steam 44 lbs. per square inch — 
above the pressure of the atmosphere, weight of rope 6967 lbs., 
sheaves 10278 lbs., rope-roll 8960 Ibs., length of plane 2646 feet, 
height 1544 feet. Fue of drawing up seven loaded carriages, each 
weighing 9408 Ibs., six hundred and twenty seconds, the engine 
making three hundred and seventy four single strokes, five feet each.” 
Here we have f=294, and F=,';(k-+-m+p)=655, or more accu- 
rately, by a previous experiment on a plane precisely similar, we 
have F=686 lbs. Hence by (M) the resistance overcome by the 
engine is R=1288960 lbs., the power of the engine is 4988738 lbs. 
whence we have the ects power of the engine upon the load, 
compared with the pressure of the steam upon the — equal to 
Ab 8 per cent., nie the same as obtained by the a 
1 uppose an inclined plane, one —. yards in 
=~ height sixty feet, up which a train of eight loaded carriages, 
each weighing 9408 Ibs., is required to be drawn by an engine on 
the summit, in three hundred seconds, with a rope weighing 4065 
Ibs., sheaves 6000 lbs., rope-roll 4500 Ibs., while at the same time 
the same number of empty carriages, each weighing 3472 Ibs, are 
descending ; required the power of the engine.” Here we have 
f=515, and by (K) F=315 lbs., hence by (S) we have P=324 
horses’ power. Mr. Wood gives in this case P=334 for the power 
of the engine, the two results differing by £ of a horse power. 
It will be seen from the above examples, that the results of the 
equations given, do not differ greatly from those derived from the 
equations of Mr. Wood ; and the facility of using them is much great- 
er. Strict accuracy is ‘unadiainable 3 in questions of the above kind. 
- The friction of the moveable parts of the apparatus on an inclined 
plane, and other circumstances may so vary, that it would be impos 
sible to give equations that would meet with accuracy every ease that 
may be presented in practice. 
The reduction of friction is of the greatest importance in rail read 
improvements. We have had no accurate experiments for ascertaill- 
ing the amount of friction on curved rail ways. In order to reduce 
this kind of friction, various plans have been proposed and tried. 
The exterior wheel has been enlarged by causing it to run on ils 
flange while passing a curve ; sometimes the conical wheel has bee? 
adopted to answer the same purpose ; and it has been sed, in 
order to avoid the inconvenience of the conical wheel, to suffer 00° 
of a pair of wheels to turn freely on its axle. That the first method 
