161

17. Thus the gradient at which the line could be
    constructed from the top seam of coal in Coalbrook
    Dale until the saddle is crossed, is of the greatest
    consideration, as the utmost power of the locomotives
    would be required on this length, because it determines
    the weight of the trains to be passed over other lengths
    of line, where the full powers of a locomotive are not
    required, and, in fact, could not be used.

18. The level of the top seam of coal now exposed
    to view in Coalbrook Dale is 1342 feet above the sea.
    Other seams lower down the valley, which it would be
    desirable to touch with the line of railway, have
    levels of 1890, 1803 and 1810; so that a falling
    gradient for loaded trains can be got which would
    strike all the best seams of coal in the valley. The
    bottom of the Gorge of Waimangaroa is 1000 feet
    high; the top of the precipice, which is the edge of
    the plateau, is 1900 feet. The plateau has various
    levels, but the highest, which may be called the
    saddle is 2129 feet. A passing point on the saddle
    adjoining the gorge may be taken at about 1970 feet,
    and as the last best seam of coal down Coalbrook
    Dale is at a level of 1810 feet, the height of about
    160 feet has to be overcome in a distance of 8000
    feet, which gives a rising gradient of 1 in 50 to get
    over the saddle. Detailed surveys and levels can
    alone show, if it would be justifiable at an increased
    cost, to seek an easier gradient than this, as being of
    more consequence than any other gradient upon the
    line, but sufficient data do not exist to give more
    than a very general opinion; there cannot, however,
    be any doubt but that it is of importance to get the
    easiest gradient that is practicable at a moderate
    cost, as upon this length the powers of a locomotive
    would be taxed to the utmost. After passing the
    saddle, with this rising gradient, a falling one of
    about 1 in 30 may be laid out along the slope of the
    mountain until the table land behind Westport is
    reached, from whence to Westport the gradient
    would be more moderate.

19. On plan No. 2, I have shown, by a brown line,
    the direction and probable length of the line I pro-
    pose, the total length of which would be about 19¾
    miles, being as compared with that proposed by Mr.
    Burnett, 7 miles longer. As may be observed on the
    plan, the course of the line is very tortuous, and the
    curves numerous and severe; but the use of locomo-
    tives, on Farlie's principle, will secure perfect safety
    in working the line.

20. From Coalbrook Dale until the plateau is
    crossed, the whole surface is a barren waste, covered
    chiefly with loose blocks of grit of various sizes and
    thickness, and any cutting necessary will be in this
    material, which, however, is easily got; but, in des-
    cending from the plateau down the breast of the
    mountain, the slopes are so severe that it would not
    be safe, as a rule, to have any side-cutting, as there
    would be much risk of causing heavy slips, both at
    the time of execution and after the works were com-
    pleted. I propose, therefore, that the whole breadth
    of way shall be embanked and constructed after the
    manner shown in cross section by the sketch attached
    hereto. Materials for the purpose can be got from
    adjoining surfaces, and from favorable places along
    the line.

21. Being purely a mineral line, a gauge of 3 feet
    6 inches will suffice. A breadth of formation equal
    to 12 feet will be necessary, and with gradients so
    sharp as 1 in 30, and severe curves, the rails should
    not be less weight than 54lbs per yard.

22. The chief works for the locomotives running
    from Westport to the mines, would be to take back
    empty waggons, up a long gradient of about 1 in 30,
    as nothing but provisions for the mines and prop
    timber would be required as back carriage.

23. The cost of constructing the line will vary very
    much in different lengths. It is probable that about
    one-third of the entire length will have to be con-
    structed after the manner shown in the sketch at-
    tached, the approximate estimate for one mile of
    which is as follows:—

24. The estimate for one mile on about two-thirds
    of length of line would probably be nearly as
    follows:—

25. The average cost per mile would therefore be
    about £5034.

26. The total cost of works of all kinds that would
    be necessary to be incurred by a company, before
    coal could be sold would be about as follows:—

27. The rolling plant I have allowed in the above
    estimate would enable 144,000 tons of coal to be
    delivered in Westport per annum.