D.—l.

Bepairs and Wages and Fuel. Stores. General. Total, d. d. d. d. Operating cost, standing ... ... 075 0-15 4-2 5-1 running ... ... 8-00 1-50 7-4 16-9 The capacity of the plant will be based on eighty train-miles per day in the tunnels for 312 days per annum, or 24,960 miles per annum. In round figures, 25,000 miles per annum is near enough. The estimated cost of construction and installation of the ventilating plant is as follows :— £ Cost of blowers, connections, &c. ... ... ... ... ... 500 „ boilers and engines ... ... ... ... ... 1,000 „ outside wall of nozzle ... ... ... ... ... 500 „ inside „ .. ... ... ... ... 100 buildings ... ... ... ... ... ... 300 Total ... ... ... ... ... ... ... 2,400 Interest at 3-| per cent on cost of construction, £84 per annum. With this data the total annual charges for tunnel-ventilation of Table 10 are obtained. Additional Cost op Maintenance of Way in Tunnels. All the data available indicate that the cost of maintenance of way in tunnels is about twice the cost outside for the same length of track. This was referred to in the first supplementary report, but was not taken into account in the calculations. The additional information which I now have on this subject justifies the addition of an extra item for the maintenance of way in tunnels. The total length of tunnels for the several lines considered with the train-mileage and extra cost of maintenance of way at 22-15d. per train-mile is given in Table 11. Summary of Ebsults. Adding together the cost of motive power from Table 9, the cost of maintenance of way and carriages and wagons from Tables 12 and 14 of my first supplementary report, and the cost of tunnel-ventilation and extra cost of maintenance of way in tunnels from Tables 10 and 11 above, the total of the variable items in the annual cost of working, Otira to Bealey, is the result, and is given in Table 12. Adding interest on cost of construction at 3-J- per cent, to the working-costs of Table 12, the total annual charges, which form the true basis for the economic comparisons of these lines, is the final result given in Table 13. The Shay Locomotive. I submitted the profiles of lines C, E, and F to the Lima Locomotive and Machine Company, of Lima, Ohio, builders of the Shay locomotive, and received their reply dated the 14th August, 1902. After making some calculations on the data given in their letter, and finding the assumed fuel-consumption per indicated horse-power hour was rather low, I wrote them for some additional data, and in reply received their letter of the 9th February, which did not contain the desired data, but which did contain an error in calculating the coal-consumption per horse-power hour. I called their attention to these, and their letter of the 16th February confirms my calculations on the coal-consumption per indicated horse-power hour, and also gives the ratio of effective to indicated horse-power at 85 per cent., and the evaporation at 6 lb. of water per pound of coal " to place the estimate on a safer basis." These revised figures can be depended upon to work out well in practice. The letters of the Lima Locomotive and Machine Company are attached hereto. The Shay locomotive proposed for the Arthur's Pass lines will develop a maximum tractive power of 33,764 lb. and a speed of six miles per hour on the maximum grades, as stated by the builders. From this data the effective horse-power developed is found to be 540. Then, taking 85 per cent, for the ratio of effective to indicated horse-power, the latter is found to be 635. + . On this basis the water-consumption stated by the builders is 271b. per horse-power hour. This is correct for the water-consumption calculated from diagrams, and on that basis 6 lb. of water to 1 lb. of coal is a safe estimate. (See Wellington, p. 463.) With this data, and coal at 13s. per ton, the cost of fuel per engine-mile running up hill is found to be 31d. Eunning down hill it will be taken at one-tenth that amount, as before, or, say, 3d. per engine-mile. The average cost of fuel per engine-mile for the round trip will then be 17d. The average speed of the east-bound trains, obtained by dividing the length of the respective lines in miles by the time required as given by the builders, will be seven miles per hour, within a fraction of 1 per cent, for any of the lines considered. The speed returning from Bealey to the Summit is given in the Shay letter of the 9th February at seven miles per hour. From the Summit to Otira it would be twelve miles per hour. This makes the average west-bound speed from Bealey to Otira 106 miles per hour, and the average for the round trip about 8-8 miles per hour. These are the average speeds for all three lines, but are sufficiently exact since the variation is only one- or two-tenths of a mile per hour. This average speed of B'B miles per hour will be used in taking from the diagram the cost of wages and general expenses per enginemile. The running-time west-bound will be : For line C—Bealey to Summit, 22 minutes ; Summit level, 2 minutes; Summit to Otira, 39 minutes: for line E—Bealey to Summit. 25 minutes ; Summit level, 2 minutes; Summit to Otira, 38 minutes : for line F—Bealey to Summit, 28 minutes, Summit level, 2 minutes ; Summit to Otira, 36 minutes.

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