328 }Fear and Tear of Ar/riciiliiiral Steam-Eiigines. 
It remains for us to put n value on such an engine when thirty 
YC'irs old, and jjractically such valuations are of rare occurrence, 
il we estimate that an outlay of 40/. will again be required for a 
general repair, and put a value of 50Z. on the engine as it stands, 
we arrive at the total sum of 90/., or less than half price for an 
engine nearly as good as new. We have known a fiftj-horse- 
power condensing engine working at fifty years old, and said to 
be " as good as new." 
Interest and Depreciation. 
We must now attempt to arrive at a specific ciiarge for the 
•depreciation of a portable engine, however open to correction, 
wherewith to debit the account for threshing. 
As to the value of a portable engine ten years old and out of 
repair any one Avho has had such a one to sell must have found it 
a most unmarketable article. Let us suppose it to be Avorth 40/. 
The original cost of an eight-horse-power engine having been 
230/., the depreciation of capital so invested (reckoned at 5 per 
cent.) is 26/. 135. per annum ; namely, 21. per annum, the interest 
of the 40/. which the engine will be worth at the end of the 
period, and 24/. 13s., the value of an annuity (calculated at 5 
per cent.) which could be bought for ten years for the I'JO/., the 
sum supposed to be sunk.* 
But besides these charges there are certain other contingent 
expenses to be taken into account, such as buildings and shafts, 
straps and covers, which we shall include in the account of the 
Threshing Machines. 
An eight-horse portable engine requires a house 12 feet wide 
by 20 feet long by 10 feet high up to the plate ; the roof should 
be of galvanized iron ; total cost, including large folding-doors, 
eaves' trough, paving, and tank, 30/., which at 7^ per cent, per 
annum comes to 21. 5s. 
The building for a fixed engine should be of a somewhat more 
substantial character, costing about 40/., and to this we add the 
cost of building the chimney-shaft (40 to 45 feet high, and made 
square for the sake of economy), setting the boiler, foundation 
i'or engine, &c , bringing the total cost to 120/. This estimate 
applies to the Eastern Counties ; in the North it would be lower, 
and in the South rather greater. The rent for this building at 7^ 
per cent would be 9/. 
In this calculation both interest and depreciation are included. — P. H. F. 
