trace their destruction; but to the utter and entire disregard of all theessential quantities, circumstances, and considerations, on which suc-cess was dependent.

The ruling fact, which ought to control every movement and everyplan, is the number of tons to be conveyed one mile. This quantityis made up of the absolute tonnage and the length of the line. If alocomotive engine of 50 horses power be capable of conveying thetlaily trade on a road 50 miles long, it follows that an engine of fivehorses power will be adequate to the conveyance of the same tonnageon a road five miles long. And if an engine of 50, or any other num-ber of horses power is able to accomplish the whole labour requiredon the first road, the same engine will be occupied but one hour outof ten in doing the work of the second road. The shorter road, there-fore, requires less power—engines of less weight—rails consequentlyof less strength—and admits, as we have seen, of steeper grades.

In short, the number of tons to be carried, and the distance whichit is to be carried, control the grades, establish the location, and de-termine the power; the power required fixes the weight of the enginewhich supplies it; the weight of the engine rules the strength of therail by which it is supported, and the strength of the rail limitsthe iveight qf the car and its load.

There are certain obvious relations between the duty to be perform-ed by the road and the capacity of the improvement, and the powerof the machinery to be applied on it; and if these relations be not re-spected, both in the general design, and in all the detail, it can onlybe by sheer accident that the enterprise is successful.

On the Value of Time.

In estimating the cost of transportation on railroads I have takenno account, in the preceding numbers, of an item which is generallyconsidered of great consequence in determining the result; viz. thevalue of time. Speed is the peculiar advantage of railroads, and onewhich is certainly sometimes deserving of much consideration in theadministration of the work. I propose to estimate its real value, asnearly as it can be done, in the transportation of passengers and mer-chandize.

First, then, what are we to regard as the measure of the value oftime on any article of merchandize? Is it not the interest on the capi-tal invested in the commodity, at the rate at which the proprietor es-timates his profits for the time, added to the rate at which his goodsdepreciate in value in consequence of detention on the route?

If this be true—and I cannot well perceive what other value thanthis the time lost in their conveyance can possess—let us endeavour

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