Page:Passages from the Life of a Philosopher.djvu/341

Rh If the concussion had occurred, the probability is, that Brunel's engine would have been knocked off the rail by the superior momentum of my train, and that my experimental carriage would have been buried under the iron contained in the waggons behind.

These rates of travelling were then unusual, but have now become common. The greatest speed which I have personally witnessed, occurred on the return of a train from Bristol, on the occasion of the floating of the "Great Britain." I was in a compartment, in conversation with three eminent engineers, when one of them remarked the unusual speed of the train: my neighbour on my left took out his watch, and noted the time of passage of the distance posts, whence it appeared that we were then travelling at the rate of seventy-eight miles an hour. The train was evidently on an incline, and we did not long sustain that dangerous velocity.

One very cold day I found Dr. Lardner making experiments on the Great Western Railway. He was drawing a series of trucks with an engine travelling at known velocities. At certain intervals, a truck was detached from his train. The time occupied by this truck before it came to rest was the object to be noted. As Dr. Lardner was short of assistants, I and my son offered to get into one of his trucks and note for him the time of coming to rest.

Our truck having been detached, it came to rest, and I had noted the time. After waiting a few minutes, I thought I perceived a slight motion, which continued, though slowly. It then occurred to me that this must arise from the effect of the wind, which was blowing strongly. On my way to the station, feeling very cold, I had purchased three yards of coarse blue woollen cloth, which I wound round my person. This I now unwound; we held it up as a sail, and gradually acquiring