The discussion then commenced: it was continued with considerable energy, but with great temper; and after a long and instructive debate the assembled multitude separated. Some few who attended in expectation of a scene were sorely disappointed. As I was passing out, one of my acquaintance remarked, “You have saved that —— —— Lardner:” to which I replied, “I have saved the British Association from a scandal.”
Before I terminate this Chapter on Railways, it will perhaps be expected by some of my readers that I should point out such measures as occur to me for rendering this universal system more safe. Since the long series of experiments I {329} made in 1839, I have had no experience either official or professional upon the subject. My opinions, therefore, must be taken only at what they are worth, and will probably be regarded as the dreams of an amateur. I have indeed formed very decided opinions upon certain measures relative to railroads; but my hesitation to make them public arises from the circumstance, that by publishing them I may possibly delay their adoption. It may happen, as is now happening to my system of distinguishing lighthouses from each other, and of night telegraphic communication between ships at sea—that although officially communicated to all the great maritime governments, and even publicly exhibited for months during the Exhibition of 1851, it will be allowed to go to sleep for years, until some official person, casually hearing of it, or perhaps re-inventing it, shall have interest with the higher powers to get it quietly adopted as his own invention. I have given, in a former page, a list of the self-registering apparatus I employed in my own experiments.
〈MEANS OF SAFETY FOR TRAINS.〉
In studying the evidence given upon the inquiries into the various lamentable accidents which have occurred upon railways, I have been much struck by the discordance of that evidence as to the speed with which the engines were travelling when they took place.
Even the best and most unbiassed judgment ought not to be trusted when mechanical evidence can be produced. The first rule I propose is, that—
Every engine should have mechanical self-registering means of recording its own velocity at every instant during the whole course of its journey.
〈SELF-RECORDING MEANS.〉
In my own experiments this was the first point I attended to. I took a powerful spring clock, with a chronometer movement, which every half second lifted a peculiar pen, and left {330} a small dot of ink upon the paper, which was moving over a table with the velocity given to it by the wheels of the carriage.
Thus the comparative frequency of these dots indicated the rate of travelling at the time. But the instrument was susceptible of giving different scales of measurement. Thus it might be that only three inches of paper passed under the pen in every mile, or any greater length of paper, up to sixty feet per mile, might be ordered to pass under the paper during an equal space. Again, the number of dots per second could, if required, be altered.
The clock was broken four or five times during the earliest experiments. This arose from its being fixed upon the platform carrying the axles of the wheels. I then contrived a kind of parallel motion, by which I was enabled to support the clock upon the carriage-springs, and yet allow it to impress its dots upon the paper, which did not require that advantage. After this, the clock was never injured.