As we left the exhibition building, I saw a huge waggon without any horses, but simply governed by one man, in spite of which it seemed to roll on as easily as possible, and to pull up at pleasure. The waggon was loaded with all sizes of black-coloured cylinders, resembling casks or barrels. I was perfectly aware of the numerous successful experiments made long ago in England and elsewhere with the construction of steam-engines destined to run, not along iron rails, but along the ordinary roads. I could not, however, help noticing that this waggon differed totally from those old locomobiles, inasmuch as there were no signs of steam about the novelty. Once more I turned to my amiable guide for an explanation; but although he immediately prepared to comply with my request, still I am obliged to confess that not everything was quite clear to me. I imagine this was partly owing to Bacon's making use of the names of engines and materials with which I was unfamiliar; but this is about what I understood him to say: "So long as we had abundance of coal, the use of steam was found to be amply sufficient for the locomotion of all kinds of engines, waggons, or carriages; but about the beginning of this century the quantity of coal in the different countries of Europe had decreased to such an extent that the price of the article became by far too high for daily and ordinary use. True, the supply of North America was far from being exhausted; but, of course, the exportation from thence could not but influence the cost. The same inconvenience further presented itself with such engines where the locomotive power was produced by continually recurring explosions of a mixture of light-gas and common atmospheric air, since the cost of light-gas naturally increased with the decrease of coal, from which it was principally made. Under these circumstances, recourse was had to the electro-magnetic machines, which could not be used to advantage so long as coals were inexpensive; now, however, these were not only able to compete with the different kinds of steam-engines, but they had this advantage over the latter, that they were entirely free from the danger of explosive boilers. "Nevertheless the electro-magnetic power, with all its improvements, was, and remained, a more expensive one than that formerly produced through coal, and the consequence of this was a decrease in the produce of a great many things which had not only grown into matters of daily necessity, but even into a sine quâ non of a progressive and lasting civilization. Then it was, since necessity is the mother of invention, that every one contrived to devise a new means of locomotion, until, after innumerable unsuccessful experiments, a power was finally arrived at in every way practical and satisfactory, whilst inexhaustible in its sources. It was, namely, this.