OF KAIL-ROADS.

51

and the rails fastened neatly together, theywill, with the exception of the joinings, atintervals of every three or four feet, accord*ing to the length of the rails, which will,if the road be laid down with tolerableaccuracy, and the ends of the rails squared,be scarcely visible, form a continued uniformline. The carriage-wheels, in rolling alongsuch, can meet with little obstruction, andthe friction or resistance upon such a road iscomparatively trifling.

The base of the stone should be formedquite parallel with the bed of the chair, andconsequently square with the line of the rails:the chair should also be placed exactly inthe centre of the stone. The surface of theground, wherever the stone rests, should bemade firm aiul hard, to secure the parallelism ofthe base of the stone with the line of the rails ;otherwise, when the weight comes upon them,the parallelism of the rails will be soon destroyed.

I have before stated, that the rails are fas-tened to the chair, and also kept at the properdistance from each other, by two pins passingthrough the chair, and through holes near theends of the rail. In the chairs these holesare situated in a line or parallel with thebase of the chair on which the rail rests. Inthe rails they are at equal distances from

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