The turrets and eagles of galvanized sheet iron, not being intended to support anything but jokes, need not be criticized as part of the construction. The tiled pavements of the vestibules, designed to sustain, besides criticism of the he-who-walks-may-read order, the impact of the feet of all nations, are more important. Their pattern is very fair--their solidity will doubtless stand the test. The turf and shrubbery meant to brighten the _entourage_, especially at the carriage concourse on the east front, we can hardly hope will fare so well. The defence of their native soil, to prevent its being rent from them by the heedless tread of millions and scattered abroad in the shape of dust, will demand the most untiring struggles of the guardian patriots in the Centennial police service. Shall we step northward from the middle of this building to Memorial Hall, or thread the great nave to the western portal and enter the twin tabernacle sacred to Vulcan? The answer readily suggests itself: substantials before dessert--Mulciber before the Muses. Let us get the film of coal-smoke, the dissonance of clanking iron and the unloveliness of cog-wheels from off our senses before offering them to the beautiful, pure and simple. We come from the domain of finished products, complete to the last polish, silently self-asserting and wooing the almighty dollar with all their simpers. We pass to their noisy hatching- and training-ground, where all the processes of their creation from embryo to maturity are to be rehearsed for our edification. We shall here become learned in the biography of everything a machine can create, from an iron-clad to a penknife or a pocket-handkerchief. In the centre of the immense hall, fourteen hundred and two by three hundred and sixty feet and covering fourteen acres, the demiurges of this nest of Titans, an engine--which if really of fourteen hundred horse-power must be the largest hitherto known--is getting together its bones of cast and thews of wrought iron, and seems already like the first lion "pawing to be free." Its first throb one would fancy inevitably fatal to the shell of timber and glass that surrounds it. [Illustration: AGRICULTURAL BUILDING.]