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chap. iii.

THE CENTRE RAIL.

49

with two pairs of horizontal driving-wheels as well as with the ordinary coupled vertical ones, and the power of the machine is thus enormously increased; the horizontal wheels gripping the centre rail with great tenacity by being brought together, and being almost incapable of slipping, like the ordinary wheels when on even a
THE CENTRE RAIL ON A CURVE.moderate gradient.[1]

The third rail is the ordinary double-headed rail, and is laid horizontally; it is bolted down to wrought iron chairs, three feet apart, which are fixed by common coach-screws to a longitudinal sleeper, laid upon the usual transverse ones: the sleepers are attached to each other by fang-bolts. The dimensions of the different parts will be seen by reference to the annexed cross section:—

SCALE OF FEET

Let us now take a run on the railway, starting from St. Michel. For some distance from that place the gradients are not of an ex-[2]

  1. ↑ These engines are described in the reports by Captain Tyler to the Board of Trade.
  2. ↑ tions of the line, and round all except the mildest curves. Thirty miles, in all, of the road have the centre rail.
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