The new method of building dwellings of small cost, recently announced by Mr. Thomas A. Edi son, opens tremendous additional possibilities for the use of concrete. Instead of the old box-like concrete structures with which we are all famil iar, it will be possible to have attractive houses at a much lower cost than was possible in the first-mentioned type. When asked in what particulars his idea was novel, Mr. Edison said: "There is nothing par ticularly novel about my plan ; it amounts to the same thing as making a very complicated casting in iron, except that the medium is not so fluid. Some one was bound to do it, and I thought that I might as well be the man, that's all." The method consists in the use of molds, cost ing $25,000 the set, made of %-inch cast iron, planed, nickel-plated, and polished. The different pieces vary in size, some of the interior parts being but two feet square. When in position, the units are held in place by trusses and dowel pins. Into the top of these molds concrete is pumped continuously by compressed air, using two cylinders. The concrete itself acts as a pis ton, and the two cylinders are alternately filled and emptied. The delivery of the mixture must be continuous, for wherever it is stopped a line appears. To secure this rapid and continuous flow, at the rate of 175 cubic yards per day, a very efficient mixer is required. It has not yet been decided whether a Ransome or a specially designed machine will be used. No rubbing up is necessary, although a few flaws may be pres ent, owing to the difficulty of expelling all air. The escape of air is permitted by the special design of the house, or, when necessary, by a temporary pipe, which may be removed later. The concrete used is mixed according to the ordinary proportions of one part of cement high in lime, three parts of sand, and five parts of crushed stone. The cement is so finely ground that it readily takes up the requisite quantity of water to make it flow. Another result of the fine grinding, to which the possibility of repro ducing minute details is due, is the absolute water-tightness of this material, since there are none of the intergranular openings that are pres ent when coarse ingredients are used. Great strength is assured at the points of stress by wire reinforcements set in the body of the material. Bath-tubs and similar fixtures will be cast in place. Pipes for the steam heat, conduits for the electric wir ing, and the iron tubing through which the lead pipes for the plumbing are to be afterward drawn, are all set in the molds before the cement is run in. The only wood present will be the doors, window sashes, and perhaps a few strips to which to attach carpets. Although any type of architecture can be fol lowed in making the origi nal molds, the first house of this kind to be built will be in the style of Francis I., richly deco rated with designs that would be prohibitive be cause of their cost were they in stone. It will have a cellar and three stories, with nine rooms. The walls are to be 12, 10, and 6 inches thick in the various parts. The inte rior will be handsomely ornamented, making no further decoration work necessary after the molds are removed. If it is de-Sired to heighten the in side effect, tinting can be resorted to. In addition to the enrichments, all of these dwellings will have elaborate chimney pieces. The roof imitates tiling and can be painted to suit the owner's taste. Owing to the perfect in sulation secured, both to the steam pipes, and to the rooms themselves from the outside cold, but on -quarter the coal ordinarily required is needed to heat these dwellings. By keep ing the doors and win dows closed, they can be kept correspondingly cool in summer. This manner of building is not economical for putting up single houses, owing to the cost of the initial outlay, although this outlay is in the nature of a permanent invest ment, as the plant is practically indestructible. On the other hand, for constructing, say a thousand houses, in proximity to each other, it is very suitable. For instance, suppose that it is desired to lay out an in dustrial village. After the posi tions of the vari ous buildings are staked out. a large gang of la borers digs the cellars, and the mold for a house is set up, the operation taking about twelve hours. The run ning in of the concrete requires twelve hours more, and after seven days the molds are re moved, and the next house is erected. According to Mr. Edison, the actual cost of a dwelling made according to this method would be one thousand dollars. The wear and tear on the molds and the interest on the outlay, he fig ures at about fifty dollars a house. This makes the total cost f1,050 for a house that in the quarter-size model in Mr. Edison's laboratory bears every mark of refinement and comfort. The architects who have designed the house for Mr. Edison are Messrs. Manning and Macneille, to whom we are indebted for the accompanying detail view.