424 
Steam Culture. 
of horse-labour, but with that which it bears at the busy seasons. 
Now if in consequence of the exigencies of these six months, 
three horses were kept where two would otherwise suffice, and if 
these extra horses were utterly useless during the remaining half 
of the year, the work done by them (for w hich steam is proposed 
as a substitute) would cost double the usual rate. But since 
steam does not offer thoroughly to provide for extra work (viz., 
during harvest), and the horse can be turned to some account at 
other times, I propose only to charge for the busy months half 
as much again as for the slack months, viz., Qd. and 4ff. per 
hour respectively, maintaining the average of 5d. per hour on 
the whole year. This amount of difference will not, I think, 
appear excessive, if it be borne in mind that the actual amount 
of work done will differ with the season, as well as the urgency 
of that work. For instance, when roads are bad three horses 
will not be more efficient in carting than two in dry weather. 
If it should appear that in halving the year, to simplify our 
calculations, the busy season is too much restricted, on the other 
hand it may be thought by some that the cost of the horse is here 
set rather low, so that a few more days' work, charged at a higher 
rate, will admit of the cost of keep being slightly augmented. 
It would seem then that horse-labour, as contrasted with that of 
steam, may be fairly charged at not less than 6d. per hour. 
Let us now apply this conclusion to one special case. 
It has been estimated that a Fowler with a 12-horse engine 
will, on the average, plough 5 acres of very stiff clay in ten 
hours, at a so much greater depth than four horses could attain 
to, that in theory it may be looked on as 5-horse work. 
Four horses would go over f of an acre per day ; on this 
all are agreed. How much time would they spend over it? 
With a 9-inch furrow the distance traversed would be f of 
11 miles, or miles. If we allow 2h hours for about sixty 
turnings and incidental delays, we shall have 5 hours left for 
travelling 8 J miles, requiring less than the rate of 1| miles per 
hour.* The horses, therefore, may just as well accomplish their 
task in 7i hours, as waste more time about it. 
The cost of the four horses working 7^ hours, at 6d. apiece 
per hour, would be 15s. for ^ of an acre, or 11. per acre. 
The ploughing as done by steam being equal to 5-horse work, 
would cost, if practicable for horses, 'lbs. The steam-plough, 
therefore, costing only 12s. per acre, or ^ of 6O5., shows again over 
horses of 13s. an acre, or more than half; and even if, to keep 
on the safe side, we reduce the steam-power's day's work to 4^ 
acres, the cost will still be under 13s. 6d. 
* The size of the field is assumed to be adapted for steam culture. 
