My visitors always wound up with the same question, “How do you drive your air-pump?” And in my innocence I uniformly replied, “The engine is a non-condensing engine; it has no air-pump”; all unconscious that every time I said that I was consigning the engine to the rubbish heap. This reply was taken necessarily as a frank admission that the high-speed engine was not adapted for condensing. Of course, then, it had no interest for them. No doubt many wondered why I should have troubled myself to show it there at all. If I had thought more deeply I must have been struck by the unvarying form of this question, always assuming the air-pump to be a part of the engine, but which, of course, could not be used there, and only inquiring how I worked it; and also by the fact that after getting my answer the questioner soon departed, and I scarcely ever saw the same visitor again. But I did not think deeply. Perhaps the conditions of excitement were not favorable to reflection. All I thought was that this same everlasting question, which at home I would never have heard, was getting awfully monotonous. After a while this annoying question came to be asked less and less frequently, and also the engine attracted less and less attention. The engine had failed in a vital respect, and I did not know it. That the fact of the engine being non-condensing should have been an objection to it never once entered my mind. But I doubt if I could have bettered the matter, however alive to this difficulty I might have been. I showed all I had yet accomplished. In the minds of my visitors it no doubt appeared impossible to run an air-pump successfully at such a speed; the water and air would be churned into foam, and the valves would not close in time. This objection I was not prepared to meet, for I had not thought on the subject at all. Moreover, it could not have been met in any way except by a practical demonstration. For that demonstration I had yet to wait five years. There were many things connected with this season which were well worth remembering. One of these was the visit of the jury. It was the only time I ever met Professor Rankine. There were two or three Frenchmen on the jury, and they engaged in an animated discussion of the question whether the steam could follow the piston at so great a speed. I well remember the sharp exclamation with which Professor Rankine put an end to this nonsense, when he had got tired of it. “There is no limit to the speed at which steam will follow a piston.” One day I had a call from Mr. John Penn, Mr. William Fairbairn, and Mr. Robert Napier, who came together on a visit of ceremony, and presented me their cards. In return I presented to them the cards of the engine. But their visit, like most others, closed with the same inevitable question.