A great deal of engineering skill has been displayed in the erection of the giant elevators now in operation in various parts of the country, and our readers will probably be interested in some items respecting the Niagara elevator at Buffalo, which we cull from a letter of one of the correspondents of the New York Tribune. ” This, although the largest, is only one of 25 others which line the river upon both sides for a mile from the harbor's mouth. Buffalo has often been called “the world's granary a view of these elevators at work proves it. But a few years ago all the grain was handled in the bushel measure; many will be glad to learn how it is handled now. I propose to give as minute a description ot one of the great elevators by which this is accomplished as my memory will enable me. The produce of the great West is so enormous that it requires enormous steam power to handle the millions of bushels of grain which are passing through this port. ” After several destructive fires, whieh consumed vast amounts of grain, a party of gentlemen determined to build an elevator that should be fire proof; the Niagara was the result. It is almost wholly composed of stone, brick, and iron, inside and out. The tall structure upon all elevators known as the “tower” is extremely liable to take fire, on account of the accumulation of dust, which is dry and highly inflammable. This tower has eight iron floors, reached by an iron, spiral stairway. The side walls are without openings. The foundations are stone and brick; the superstructure iron. The main building is 125 by 130 feet, the walls resting upon piles driven to the solid rock. The bins, which contain an enormous weight when full, rest upon independent foundations. There are 132 solid cut stone piers, each upon nine piles. Upon each pier are three solid oak timbers, braced together, which support the floor of the bins 20 feet above the pavement. This gives room for spouting the grain from any one of the 144 bins, upon endless-belt grain-carriers, to the bottom of elevators, which raise it to the top of the building, whence it flows by its own gravity into boats or cars or other bins. Grain keeps best in wood, so the bins are made of planks six to ten inches wide, laid up like a blockhouse, flat-wise. The center bins are 73 feet deep, and those under the lowest part of the roof, 52 feet. An iron ladder is built into one corner of each to enable a man to examine the grain or sweep out the dust when empty, or for any other purpose. The valves for discharging the grain are plainly marked by registered numbers, and are opened or shut in the lower story, information being conveyed by speaking tubes throughout the building to those in charge of the various departments. The boiler and engine which set in motion the ponderous machinery are in a separate, fire-proof building, away from any danger from sparks. Some of the grain is shamefully dirty—a disgrace to the growers. Sometimes the owners of such grain contract to have it run through the cleaner, with which every perfect elevator is furnished. In this one the dirt is driven by a powerful blast through a sheet iron pipe, two feet in diameter, and discharged into the river. Tuns of a good manurial substance and some grain are thus wasted, though many weed seeds are got rid of. There should be a law requiring all grain passed through a public elevator to be passed through the cleaner, if not already clean, before being offered for sale. ” Now let us suppose that a vessel full of grain has arrived. The steamer upon which I am now sailing up Lake Erie, the Dean Richmond, is capable of carrying 38,000 bushels of wheat. Imagine, if you can, the labor of transferring such a cargo, by the old process, with pails, tubs, half bushel measures, bags, hands, slioulders, carts, and horses. Now, as Boon as the hatches are off a signal is given to the engineer, and directly the machinery of the tower begins to rumble, and a ponderous iron case rises, until high enough to swing its foot out over the hatchway. Another signal, and down it drops into the pile of grain. This is the “ leg,” and contains a belt of iron buckets which scoop up the grain and carry it into the first story of the tower. Thero it is poured into the hopper of a weighing machine, gaged exactly for 100 bushels. The moment the scale turns a man in charge stops the supply and opens a valve at the bottom, which lets out the grain while he is making his score; it sho uld be seli-register- ing—perhaps it is. Then he closes the lower valve, and opens the upper, repeating the operation so often that 7,000 bushels an hour are thus weighed. As fast as it falls from the scale ho pper it is taken up by another elevating belt, and emptied into a receiver at the top of the tower, whence it r uns to any part of the building. If it has to be eleaned it is re- weigheCi and loss charged, as well as a small charge for cleaning. The quantity, quality, and owner's name of the wheat iri each bin is registered, the elevator proprietors being responsible for the contents. The grain is sOd by sample, but can be readily inspected and quantity ascertained by visiting the bins. If the grain heats it is immediately transferred to other bins, the operation giving it a thorough airing. As the floor of the bins is 20 feet above the ground, it will readily be seen how easily canal boats or cars can be loaded, while the unloadin r and elevating go on simultaneously. "Suppose a cargo of wet grain arrives at this elevator. The same machinery is applied to its discliarge, but instead of being stowed in the bins or shifted about to dry it in the air, it is sent into a spout which conducts it into another building owned by the same company, and built for a model malt house, with all the modern improvements. Here upon drying kilns, each 50 feet square, 15,000 bushels of wet grain can be dried daily. At the time of my visit the kilns were all in full blast with a cargo of oats from a sunken canal boat, and I wondered whether his damaged grain, when dry, would be put upon the market as s un<1. On being ' kiln dried,' will the oats be ground for human food Or, having their vitality thus destroyed, if sold cheap, will they be, like other trash, mixed with 'Norway oats' and sold as pure improved seed 'I This malt house is 212 feet long and 5<1 feet wide, of solid blue limestone, with slate roof, iron .gutters, and fire-proof floors, where the barley is sprouted, after having been steeped, 500 bushels at a charge. The kilns are heated by anthracite fires in the basement, and the flues are conducted up to and form the bottom of the kilns, which are of perforated iron, so that all the air or gas of the furnace may pass out through the grain. The finished malt or dried grain can be delivered directly from the store rooms of the malt house to the cars which run between the building and the elevator." «5R> % Tbe Woolwich Backyard Abandoned. This celebrated dockyard, nine miles southeast of London, which has been in operation as government works for over three hundred years, has been c losed, and will either be sold or leased to private shipbuilders. This dockyard, at the lowest estimate is worth $5.000,000, and if leased at 2J per cent on this valuation, would yield a rent of $125,000. The town of Woorwich has a population of over 40,000 souls, and owes its prosperity to the government establishments. In addition to the dockyard, which is one . mile in length, separating the town from the Thames, it is the site of th e largest arsenal in Great Brit am, which covers more than 100 acres, and contains 24,000 pieces of ordnance and a vast amount of warlike material. Woolwich is also the headquarters of the Royal Horse and Foot Artillery and Corps ot Sappers and Miners, for the accommodation of which extensive barracks have been built and parade grounds prepared. It is also the seat of a Government Military Academy for engineering and artillery. In consequence of the increasing shallowness of the Thames, the Woolwich d ockyard has been used for the construction of steamers and the lighter class of vessels, and for the above reason the establishment is now c1os8d. When in full operation, the dockyards employed two thousand workmen, and great apprehensions of distress and inconvenience were entertained in case this large number of men should be discharged at once. However, the force was gradually reduced, and when the works were finally closed, only two hundred men were at work, The removal has caused,) many dwelling houses in the town to Hfccome empty, and th i business of the tradesmen has been seriously affected, © 1869 SCIENTIFIC AMERICAN, INC.