Holt spoke favorably of
the single-crank engine, and stated his belief that the compound system
would ere long be abandoned for the simple engine. He is endeavoring to
feel his way to using the steam in one cylinder only, and so far the
results have been encouraging, and he is now fitting a 2,200-ton vessel
on that system. He is also endeavoring to do without a crank shaft, the
forward end of the screw shaft carrying an ordinary crank with overhung
pin. This experiment also promises satisfactorily. In his opinion the
great improvement of the immediate future is to increase the steam
production of our boilers. A ton weight of a locomotive boiler produces
as much steam as six tons of an ordinary steamboat boiler.
Mr. Holt speaks of the coal account as one of the minor disbursements
of a steamer. He does not give the ratio which coals bear to the total
disbursements, but from other reliable sources Mr. Marshall found that,
according to the direction of the voyage, it varies from 16 to
20 percent.--or, say, an average of 18 per cent.--of the total
disbursements, in a vessel carrying a cargo of 2,500 tons. This will
represent to-day about L3,000 per annum, and in 1872, at equal prices,
the cost would have been L3,750--showing a saving of L750, equal to a
dividend of, say, 3 per cent.
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