Page:Passages from the Life of a Philosopher.djvu/348
832 TRACTIVE POWER REGISTERED.
smile on his eountenance, 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 dijBTerently-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 im- perative on the engine-driver to mark upon the paper a dot upon passing each of certain prescribed points upon the rail- way. This latter is not absolutely necessary, but may occa- sionally 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 j>ov)erful spring to measure the force exerted hy 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