force-holders, or energy-preservers; that one of these set the waggon in motion, whilst the others were to be delivered either at private houses for domestic purposes of hoisting, raising, or carrying; or to blacksmiths, turners, and other artisans, who wanted motive powers not so extensive as regular. Large manufactories used similar energeiathecs, only of greater power and dimensions. Some of these (in mountainous districts) collected the power of falling water; others (situated in the lower districts) utilised the wind. With regard to the construction, etc., of those cylinders, I could do nothing more than to form a faint idea. Thus I thought of compressed air, or some other gas, which, by some strong pressure or other might have been turned into a liquid or hard substance retaining the capability of rendering again its deposit of force on subsequent explosion. But I merely give this hypothesis for what it is worth. While Bacon had thus been endeavouring to enlighten me on a subject which after all I did not profess to understand, we had reached the aluminium railings of an elegant and lofty edifice, bearing the inscription, National Library. Naturally enough, I evinced a strong desire to enter, but Bacon remarked that a visit to such a place would take up a good deal of valuable time, that might be turned to a much more pleasurable and profitable account; to which Miss Phantasia added that if the gentlemen chose to enter that labyrinth of learning, she, for her part, preferred a walk in the square; the latter, crossed in all directions by parks and avenues and flower-beds, was moreover crowded with the most exquisite works of ancient and modern sculptors, living illustrations of her former assertion that genuine works of art had not quite died out. As soon as we had arrived at the opposite side of the square, I fully understood the wisdom of Bacon's remarks. So far as my eyes reached, I could see a dense cluster of buildings, more resembling a moderately sized town than a depository of literature. "You see, my friend," Bacon said, "it is imperative here to make up your mind what to see, or else our lady friend will be tired of waiting. Which branch of human knowledge do you give the preference to?" I answered that I was especially interested in works of natural science. "Impossible to think of visiting the buildings in which all these are deposited. You will have to restrict yourself considerably." "Well, then, let us confine ourselves to zoology." "Too much even for the most cursory glance. It would take us hours to have a mere walk through. Select a sub-section of zoology." "Shall we say the literature of entomology?" "That won't do either; you must keep to one single order of insects." "Well, then, be good enough to select for yourself," said I; "I'll follow you."