614 
MODE OF APPLYING A HORSE POWER. 
hour when unloaded. Hence, we have 
Durations, 1 23 45 6 7 8 &10 
Velocities, 14i 13 Hi 10^ 9 71 6i 5f 4| 4. 
Tredgold’s formula gives the following 
rule for the same purpose : — Divide l4.7 by 
the square root of the duration in hours, 
and the quotient ivill he the maximum 
velocity in miles per hour, ivhen unloaded. 
Hence, we have 
Durations, 1 234 5678 910 
Velocities, 14f 10§ 8f 7i 6f 6 5§ 5|^ 5 4^ 
These results nearly agree with the 
former in the extreme cases, but differ 
considerably in the intermediate cases. 
Tredgold’s formula foi* the power of a horse’s 
traction, expressed in words, is as follows: 
— Divide the difference between the maxi- 
mum velocity, when unloaded, and the given 
velocity, when loaded, at the given dura 
tion of labour per day, by the said maximum 
velocity, and multiply the quotient by 250 ; 
the result will be the horse’s povjer of 
traction in lbs. Taking the hours of 
labour at 6 per day, the utmost that he 
would recommend, the maximum of useful 
effect will be 125 lbs., moving at the rate of 
3 miles an hour ; considering the expense of 
carriage at this rate as unity, the comparative 
moving force, and proportional expense at 
different velocities, will be as follows : — 
Velocities, 2 3 3f 4 5 5§ 
Forces, 166 125 104 83 62^ 41| 36^ 
Expense, U 1 UHi li U 2 
Thus it appears that the expense, which 
is inversely proportional to the effect, that 
is, the product of the force and the velocity, 
is doubled when the speed is increased from 
3 to 5|- miles per hour. 
14. According to the preceding rules of 
Tredgold, the greatest useful effect of the 
horse is 125 X 3 X 6 = 2250 lbs. raised 1 
mile per day. In comparing this with fact 
Mr. Bevan who made many experiments 
on a horse’s power in dragging boats on the 
Grand Junction canal, found the force of 
traction to be 80 lbs. and and the space 
travelled in a day 26 miles ; this gives the 
greatest useful effect equal to 80 X 26^ 
2080 lbs. raised 1 mile per day, the rate”of 
travelling being barely 2§ miles per hour. 
15. The most useful mode of applying a 
horse’s power is in draught, and the worst 
is in carrying a load. This is owing to the 
structure of the animal. It has been found 
that 3 men carrying each 100 lbs. will as- 
cend a hill with greater rapidity than 1 
horse carrying 300 lbs. When a horse has 
a large draught in a waggon, however, it is 
found useful to load his back to a certain 
extent ; this prevents him from inclining so 
much forward as he would otherwise do, 
and consequently frees him from the fatigue 
of great muscular action. 
16. The best disposition of the traces 
in draught is when they are perpendicular 
to the collar ; when the horse stands at 
ease, the traces are then inclined to the 
horizon, at an angle of about 15® ; but when 
he leans forward to draw, the traces should 
then become nearly parallel to the road. 
The most proper inclination, however, is 
determined from the relation which subsists 
between the friction and the pressure, in 
every particular case. When a horse is 
employed in a gin, or in moving a machine 
by travelling in a circular path, the diameter 
of his path should not be less than 25 or 
30 feet, and in most cases 40 feet should be 
preferred ; at all events it should not be less 
than 18 feet. 
17. The following is a useful table from 
Tredgold, showing the maximum quantity 
of labour which a horse of average strength 
is capable of performing at different velo- 
cities, on canals, railways, and turnpike 
roads. 
Velocities 
per Hour. 
Day’s Work. 
Force of 
Traction. 
Useful effect per day for a distance 
of 1 mile on a 
Canal. 
Level Rail- 
way. 
Level Road. 
Miles. 
Hours. 
Lbs. 
Tons. 
Tons. 
Tons. 
2^ 
IH 
83i 
520 
115 
14 
3 
8 
do. 
243 
92 
12 
5,9-lOths 
do. 
153 
82 
10 
4 
4|- 
do. 
102 
72 
9 
5 
2,9-lOths 
do. 
52 
57 
7-2 
6 
2 
do. 
30 
48 
6-0 
7 
n 
do. 
19 
41 
5.1 
8 
do. 
12-8 
36 
4.5 
9 
9-lOths 
do. 
9-0 
32 
4-0 
10 
3 
do. 
6-6 
28-8 
3.6 
