# Page:Popular Science Monthly Volume 3.djvu/158

148
THE POPULAR SCIENCE MONTHLY.

not been obtained? There must be something wrong somewhere. As Artemus Ward says, "Why is this thus, and what is the reason of this thusness?"

Speed is the delinquent, and the cause of the loss of the great primary advantages: the vehicles on railways are propelled very fast; hence they involve great strength in their construction, and enormous weight in proportion to the paying load carried.

An old stage-coach, according to Nicholas Wood, weighed only 16 to 18 cwts., and would carry upward of 2 tons of paying passengers with their luggage, or about 410 of a hundred-weight of dead load to every hundred-weight of paying load. Now, a third-class carriage with four compartments would represent 2.8 cwts. of dead weight to every 1 cwt. of paying load. Therefore, the stage-coach has the advantage over the third-class railway-carriage of 6½ to 1.

It becomes impossible to institute any absolute comparison between roads and railways at speeds above 10 miles an hour, because such speeds are impossible on the former for any considerable distance. Again, the question of a gradient has to be noticed, for in the preceding remarks a level road and a level railway have only been considered.

As has been explained, where steep gradients occur, the resistance due to gravity so much outweighs that due to friction that rails afford a comparatively insignificant advantage, and one which is entirely lost if the stock has to be increased in weight 6½ times.

It may easily be shown that, on a gradient of 1 in 10, for instance, taking the foregoing figures, the advantages of a steam-worked railway over a horse-worked road would be little more than one-fourth, if the stock on the former be only 6½ times heavier in proportion than the latter would require. Hence it follows that no railway having gradients of 1 in 10 could be worth making (assuming such to be possible) unless the stock upon it were assimilated to that of the ordinary omnibus or stage-coach type.

In former times calculations were made by Nicholas Wood of the comparative costs of conveyance on ordinary roads by horses; he showed that on an average a stage-wagon could carry at the rate of 2½ miles an hour profitably at 8d. a ton per mile; that a light van or cart at 4 miles an hour could take for 1s. a mile a ton of goods. Passengers in stage-coaches were charged 3d. a mile each, or 3s. 6d. a ton, at 9 miles an hour. Now, let us consider what railways actually do. At the present moment coals are conveyed at ⅝d. per ton per mile, at an average speed of 20 miles an hour; and this low rate actually leaves a profit. Excursion-trains take passengers at less than ½d. each per mile, at twenty miles an hour, or at 7d. a ton a mile.

Now, bearing in mind the relative proportions of paying and non-paying loads involved in carrying passengers and coals, a simple calculation will show that a ton of passengers could be carried for