286 Petroleum and other O1tls as Fuel. 
the results have been obtained. Good wine needs no bush, 
and such results as the patentee, aided by the dockyard 
authorities, has obtained, need no comment. When it is 
known to every practical engineer that 74 lb. of water per 
I lb. of the best steam coal is the maximum quantity in 
ordinary practice; that not more than 34 lb. to 4 lb. of 
water are done by common coals, and 64 lb. is the usual 
rate for railway locomotives, what need could there be to 
add one word of remark to a table of practical experiments 
showing 13 lb. for American rock oils, 15 lb. to 17 lb. for 
Burslem, and above 18 lb. for the Torbane hill oil ? 
Taking the average evaporation effected by coal as 6 lb. 
we may fairly urge that the best mineral -oil, being three 
times as strong as coal in the quantity of heat it generates, 
and evaporating three times the quantity of water in the 
same space of time, is just as cheap as coal if it cost three 
three times as much to distil it from the shale as it does 
to get the coal out of the earth, and convey to our furnaces. 
It is quite a mistake to say that, however valuable shale 
may be for the production of paraffine, it can never be a 
satisfactory substitute for coal. No one ever dreams of 
carting shale about with its great percentage of earthy base, 
any more than bones and coprolites are expected by far- 
mers to be carted over their lands, while chemists can 
supply them with superphosphate of lime. What men have 
been trying to do is to burn shale-oil; to get the oil away 
from the mineral base, and to have as little useless matter 
to carry about as possible. What has been done at Wool- 
wich has been to burn such oil in a boiler-furnace practi- 
cally, and to beat coal with it. It is no use any longer to 
question results. The mineral oil has been burnt for days 
together, just as it might be burnt for months together, and 
it has raised steam effectively, efficiently, quickly, steadily, 
and continuously. It is now only a question of time how 
s_on the world will accept the fact, and engineers begin to 
employ it. Already oil-works are dotting with numerous 
manufactories considerable regions in England, Wales, and 
Scotland, and our shales and bituminous rocks are being 
fast brought into commercial use. Evident it is, that great 
will be the future supply when oil is admitted as the best 
steam fuel—a fuel that our factories will burn day and 
night with only a flickering glimmer of hot air from their 
chimney tops. Ships will carry the oil in tanks, and stow 
it in the bilge-ways under the lower decks, and in other- 
wise useless spaces, pumping it as wanted; all the labour 
