Addition to the Chapter on Railroads + 

One of the most important facts which the engine-driver ought to know is the exact time since the preceding train has passed the point of railroad on which his own engine is. + 

This may be done by placing signals, about to be described, by the side of or across the road at all places where such knowledge is most important. + 

The principle to be employed is, that at the passage of those places the engine itself should, in its transit, wind up a weight or spring. That this weight should act upon an arm standing perpendicularly, which would immediately commence moving slowly to the horizontal position. This it should attain by an equable motion at the end of three, five, or any desirable number of minutes. + 

The means of raising the weight may be derived either from a projection below the engine or by one above it. The latter, which seems preferable, might be attached to a light beam traversing the road to which the apparatus should be fixed. + 