The probability that the production of beetroot-sugar would before many years attain a position among the industries of this country gave interest in the eyes of American visitors to the display of European machinery employed so successfully in that business. Labor-saving machinery we have not generally been in the habit of borrowing. Neither, on the other hand, has Europe been accustomed to draw from us crude material for the finest manufactures; and the balance was set even by the admirable quality of the glass made from American sand and the porcelain moulded in American kaolin. The latter substance, a silicate of alumina, is not found in England, and at but few points on the Continent. We have it in abundance and of the finest quality. [Illustration: GRAND VESTIBULE OF THE PARIS EXPOSITION BUILDING, 1867.] The extraordinary steps made within five years in the arts of destruction were illustrated by the twelve-inch Armstrong rifles of England and the Essen gun, throwing a 1212-pound shot. In 1862 the heaviest projectile shown did not exceed one hundred pounds. For field-service the limit of practice in weight seems long ago to have been reached: for forts and ships it cannot be far off. Armor and projectiles must soon bring each other to a standstill; as when, in the Italian wars of the fifteenth century, offence and defence reached the _reductio ad absurdum_ of the incapacity of men-at-arms to inflict serious injury upon each other, or even to pick themselves up when the weight of their armor, with some aid from the clumsy blows of an antagonist, had overthrown them. Assailant and assailed were _in equilibrio_, and personal equilibrium could not be restored. Some such inane result may be witnessed when a pair of hostile iron-clads, out of sight of their nursing convoys, shall meet alone upon the deep; with the disagreeable difference that they will, if they go down, have a great deal farther to fall than the cuirassiers of the land. [Illustration: VIENNA EXPOSITION BUILDING AND GROUNDS, 1873.] Since 1851 a new commercial cement had come into operation in the adoption by neighboring powers of the French metrical system. England and America still hold out against the mètre and the gramme; and the press of both occasionally levels at it the old jokes of making the spheres weigh a pound of butter and the polar axis measure a yard of calico. With the innovation, however, our merchants have become perforce familiar, a large share of their imported commodities being invoiced in accordance with it. Its immense superiority to our complicated and arbitrary weights and measures, in the tables whereof the same word often has half a dozen meanings, is beyond argument. In the United States it has earned a quasi-official adoption, but the force of habit among the people has yet to be overcome.