Page:Popular Mechanics 1928 01.pdf/111

 

Building blocks of compressed packing excelsior, impregnated with a mineral cement which makes them practically fireproof, are being used successfully in a new form of home construction. The blocks, four by eight by sixteen inches, are each equivalent to eight ordinary bricks in volume, but, weighing only three pounds, are less than one clay brick in weight. Each block is pierced by two four-inch holes, and when they are laid in overlapping row, as are bricks, the holes match. After three rows or courses are piled up, steel reinforcing clips are inserted, and the holes filled with concrete. The clips are equal to four courses, and each pouring ends one below the top, so that a continuous bond is obtained. The finished wall is a series of four-inch reinforced concrete columns, spaced four inches apart, and surrounded by the compressed-excelsior blocks. At the floor levels a four by eight-inch reinforced-concrete beam is worked in, and the next wall started on top of it. Laboratory tests show the material is equal to four inches of cork in insulating value; that it is a sound deadener and that a reinforced wall built of it will carry a load of 16,000 pounds per running foot. No skilled labor is required in laying the walls, as the blocks are simply piled on top of each other, the steel reinforcing dropped into the holes, and the concrete poured from an ordinary coal scuttle. No lath is required on the inside, plaster being applied direct to the blocks, the fibers of which furnish a good bond, and stucco is applied in the same way on the outside. Owing to the mineral cement with which the blocks are impregnated, they will not support combustion.



 



That the fly is a spreader of dirt and disease has long been known, but the microscope reveals a particular reason why the insect should be killed. Its footprints are scarcely visible to the unaided eye. even when materials make the marks plainer, but examination of the tracks a few hours after they have been formed, explains the hazard of allowing the fly to walk across articles that should be kept clean. The microscope shows how tiny disease germs in substances carried by the fly's feet, have developed. A few hours after the photograph was taken, some of the germs had developed tiny balls of spores which were carried away in the air to seek lodgment and possible growth. Where flies have been eradicated, a marked decrease in disease has been observed.

