1922.] Jenkinson.—Development of the Locomotive. 299 
for locomotives and 2 per cent, for plant. The cost of electrical equip¬ 
ment of the permanent-way is a very difficult item to estimate at the 
present time, and enormous variations exist in the cost of the various 
lines electrified to date. For instance, the ten miles of single track 
electrified at Otira cost as much as the 114 miles dealt with on the Butte, 
Anaconda, and Pacific in 1910. 
It will be instructive to consider the electrification of two sections that 
are representative of the two types of line on which electricity is considered 
to offer the most advantages—a short suburban line and a line of heavy 
gradients ; and the Wellington-Lower Hutt line and the Bimutaka Incline 
suggest themselves naturally. 
The Wellington-Lower Hutt section will entail eighteen miles of single 
track, and with a couple of stations for the conversion of alternating to 
direct current this would have cost at least £54,000 in 1914. Assuming 
50 per cent, increase in the number of suburban trains would give forty 
trains each way per day, and seven steam or six electrical locomotives 
would be required to deal with this traffic, each locomotive being of 
1,200 h.p. and 70 tons weight. The seven steam-locomotives would be 
capable of doing other useful work at odd times, as the train-mileage of 
each engine for the year would be low, extra power being required to 
allow for washout days and liability to failure. In fact, four locomotives 
of either class could do each day’s work. The fuel burnt per brake- 
horsepower-hour would not exceed 3f lb., which is equivalent to 5 lb. of 
coal per kilowatt-hour, or l^d. per electrical unit. The cost of electrical 
energy will be taken at Jd. per unit at the substation, although this does 
not allow 50 per cent, increase on the pre-war cost. It must be remembered 
that a 50-per-cent, increase would apply both to first cost and interest 
charges, so that the cost of an item when the charges are mainly interest 
and depreciation would be doubled where a new system is installed, and 
increased by 50 per cent, in the case of an existing plant where loans are 
falling due for renewal, as in the case of Lake Coleridge. However, to 
avoid argument I will assume that electrical energy can be delivered at 
Jd. per unit, which is impossible at the low load-factors involved. Taking 
75 per cent, efficiency from the input to the locomotive-wheels, this will 
give us Id. per electrical unit of useful work ; or, in other words, electrical 
energy will cost one-seventeenth less than coal for the same work, under 
the very generous assumptions I have made as to the cost of electrical 
energy. I will also assume that the cost of repairs, which includes the 
maintenance of locomotives, overhead work, and substations, is 50 per 
cent, less with electrical working than for the steam-locomotives alone. 
This again is an absurdly flattering estimate to electrification. 
The Bimutaka Incline is treated in the same way, taking ten trains, 
each way per day, each hauled by two engines, each of 60 tons weight 
and 1,200 h.p. The steam-locomotives would be specially-designed tank 
engines with small water and coal space, and the electrical locomotive 
could be lighter for the same power than the Lower Hutt one, as it works 
for only half an hour at a time. The fuel burnt would be 4J lb. per 
brake-horsepower-hour, or 6 1b. per kilowatt-hour, or'l^d. per electrical 
unit, or g 9 ¥ more than electricity for the same work, still assuming 
the low rate of Jd. per unit. Table III gives the full comparison, and 
shows that electrical working is much dearer than steam for either of 
these two sections, even on the absurdly generous estimates allowed for 
electricity. 
