ON RAIL-ROADS.

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force than the standard I have assigned them;and by moving slower, until they traverse theascent, they can again resume their usualspeed, after they have surmounted it. Wehave already seen an increase of effect from33 to 70 per cent, by a diminution of speed,which shews that there is a sufficiency ofinherent power in the engines, to enablethem to traverse occasional undulations thatmay present a transient increase of resist-ance : and this may render the use of atable, which could only shew the performance,at a determinate and unvarying angle of in-clination, unnecessary; still it will, in general,be found most advantageous to preserve asstrictly as possible, a uniform inclination ofroad, suitable for the nature of the traffic, andthe relative weight of goods to be conveyedin both directions.

In the use of loco-motive, as with everyother kind of engines, where steam is themoving power, we need never diminish thequantity of work to be performed, as we canalways effect the performance, by an augmen-tation in the power of the engine. In the useof horses we are restricted—they can only bemade to produce a certain effect; and theiraction must, therefore, be limited: we haveseen them superseded in every other species of