But if instead of fifty miles an hour
seventy is required, an entirely different state of things obtains. Taking
a train of 100 tons, with engine and tender weighing 75 tons, or 175 tons
gross, the first question to determine will be the train resistance, and
with reference to this we much want careful experiments on the subject,
like those which Sir Daniel Gooch made in 1848, on the Bristol and Exeter
Railway, which are even now the standard authority; the general use of oil
axle-boxes and long bogie coaches, irrespective of other improvements,
would render this course desirable. With regard to the former, they appear
to run with less friction, but are heavier to start, oil boxes in some
experiments made on the South-Western Railway giving a resistance of 2.5
lb. per ton, while grease boxes ranged from 6 lb. to 9 lb. per ton. Again,
the long and heavy bogie Pullman and other coaches have the reputation
among drivers, rightly or wrongly, of being hard to pull. The resistance
of an express train on the Great Western Railway at seventy-five miles an
hour was 42 lb. per ton, and taking 40 lb. per ton for seventy miles an
hour would give a total resistance on the level of 7,000 lb.
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