162 Steam Power and Tlirashing Machines. 
machines usually cost from 16Z. to 18/. per liorse-power. The 
difference, therefore, in purchasing a fixed or moveable engine, 
say of 6 or 8 horse power, would stand about thus : — 
Fixed Engine and Machine. Portahle Engine, &c. 
6 horse-power engine, at 25Z. £150 Engine, 6 horse-power, at 33?. £198 
Ditto macliine, at SI. 48 Machine, at 16? 96 
£198 I 294r 
Deduct cost of fixed engine, &c 198 
Extra cost of portable engine, &c. .. ... .. £96 
Thus, in round numbers, there is a difference of lOOZ. when the 
moveable engine, &c., is of 6 horse-power ; and the same relative 
cost holds good for any higher power ; although the price per 
horse-power is less as the size and power are increased. For sim- 
plicity of calculation, I shall take the above statement of a 6 horse- 
power engine for estimating the cost of maintenance. Two years 
ago I put up a fixed engine on this farm, the working of which, 
&c., I shall by and by describe. After thrashing out two crops 
of about 120 acres each, the engine seems as good as new, and 
has cost nothing whatever for repairs of any kind. I allude to 
this meiely to show that estimates on the cost of maintenance of 
engines generally cannot be fairly based on personal experience 
alone. My calculations will, therefore, refer to a number of en- 
gines, both fixed and portable, which have been working in various 
parts of the country for from ten to twenty years. Some of the 
fixed engines have worked for twenty years, and the portable 
engines from eight to twelve years. Fixed engines generally 
require a new boiler every ten or fifteen years, with a small outlay 
for very moderate repairs and new brasses. The average cost of 
maintenance for several fixed engines, which have worked about 
six months in the year, has been about 10 per cent. Portable 
engines are, however, well known to be extremely costly articles 
for repairs, and those who have worked them six years and 
upwards tell me that the cost of maintenance is fully 20 per cent. 
This seems a high allowance, certainly ; but then it is necessary 
to remember that engines which travel about the country and are 
in nearly constant work, with rough usage, must suffer more than 
would be the case with an engine confined to one farm, worked 
less, and taken more care of. With portable engines there is 
seldom much cost for repairs for a few years ; but, as the saying 
is, " when once they begin to go, there is no end to their wants." 
From their construction, however much care be taken of them, 
they are sure to require more repairs than fixtures. The fire-box, 
tubes, brasses, &c., wear out sooner, besides being more costly for 
repairs than the more solid parts of a fixed engine. The estimate 
