486 
Covered Cattle Yards. 
will show the outlay for renewals, repairs, and interest for other 
forty years, and also how the balance stands at the end of eighty 
years : — 
£ S. d. £ s. d. 
Debit balance, slate roof, as above . . 294 13 5 
Add interest, at 4 per cent, per annum, on 
first cost for a second 40 years . . 176 5 0 
Kepairs for 40 years, at 1^ per cent, per 
annum on first cost, llOi. 3s. 5d. . 55 1 8 
Total cost of slate roof for 80 years . . . 526 0 1 
Debit balance, board roof, as above . . 188 5 1 
Add interest on first cost, 51Z. 16*. id., at 4 
per cent, per annum on second 40 years 82 17 8 
Add interest on first renewal of boards, 
251. Is., at 4 per cent, per annum for 
40 years 40 0 10 
Cost of second renewal of boards . . 25 1 0 
Interest on second renewal of boards, 251. Is., 
at 4 per cent, per annum for 40 years . 40 0 10 
Cost of third renewal of boards and first 
renewal of purlins, at 60 years . . 34 13 0 
Interest on third renewal, 34Z. 13s., at 4 per 
cent, per annum for 20 years . . 27 14 2 
Total cost of board roof at end of 
80 years . . . . . . 438 12 7 
£87 7 6 
We have thus at the end of eighty years a surplus balance in 
favour of boards of 871. 7s. 6d. ; but in all probability an entirely 
new roof would by this time be required, which would absorb 
about two-thirds of it. If the condition of the slate roof at this 
time could with any certainty be determined, the relative 
economies of each might be apportioned, at least approximately ; 
but as this cannot be done we can only come to this conclusion 
— that, although the first cost of the board roof is less than half 
that of the slate, the cost of the frequent renewals renders it 
doubtful whether, in the end, there is any great saving effected. 
The chief utility of the invention I consider to be that it 
enables two yards to be covered at a cost at which one only 
could be covered by the ordinary mode of cover. This at the 
present day is a matter of the first importance, and enables a 
landlord to give the benefit of a covered yard to a much larger 
number of his tenants than he perhaps otherwise could have 
done. 
Tiled Roof. 
The tiled roof comes next for consideration, and compares a 
little more favourably with board than slate does; but it must 
be borne in mind that the cost is estimated on the basis of flic 
