Page:Passages from the Life of a Philosopher.djvu/348

332 smile on his countenance, that he also perceived our sitaation on the line. I had scarcely glanced back at the growing curves upon the paper, to confirm my interpretation, when each of my three assistants at the same instant called out "Thames Junction."

At the period I speak of the double line of a small railway, called the Thames Junction, crossed the Great Western line on a level at between two and three miles from its terminus. The interruption caused certain jerks in several of our curves, which, having once noticed, it was impossible to mistake.

I would suggest that every engine should carry a spring clock, marking small equal intervals of time by means of a needle-point impinging upon paper, the speed of whose transit should be regulated by the speed of the engine. It might, perhaps, be desirable to have a differently-formed mark to indicate each five minutes. Also, two or more studs on the driving-wheel should mark upon the same paper the number of its revolutions. Besides this, it might be imperative on the engine-driver to mark upon the paper a dot upon passing each of certain prescribed points upon the railway. This latter is not absolutely necessary, but may occasionally supply very valuable information.

The second point which I consider of importance is, that—

Between every engine and its train there should be interposed a dynamometer, that is, a powerful spring to measure the force exerted by the engine.

It may, perhaps, be objected that this would require a certain amount of movement between the engine and its train. A very small quantity would be sufficient, say half an inch, or less. The forces in action are so very large, that even a still smaller amount of motion than this might be sufficiently magnified. Its indications should be marked by