Two views of the latest automobile engine. At the top can be seen the sliding sleeves, the inlets and outlets which do away with valves.
A PORTABLE ARMY WIRELESS OUTFIT
The Signal Service is rapidly increasing its wireless equipment for use on land.
THE WIRELESS IN THE NAVY
Practically all of Uncle Sam's warships and Navy Yards now are equipped with wireless, and a regular navy wireless operators' school is maintained at the Brooklyn Navy Yard.
From the use of concrete it was only a short step to reinforced concrete, or, concrete braced on the inside with iron or steel rods. It is sometimes called concrete steel, ferro-concrete, and armoured concrete. If we asked an engineer the idea in using reinforced concrete he might say to us that the steel when imbedded, united so closely with the concrete as to form one single mass of very great strength. Steel rods add to the tensile strength of concrete which alone has a tremendous strength under compression. In other words, steel does not break nor stretch easily; that is, it has great tensile strength. Concrete has great strength under compression; that is, it will hold up an enormous weight without crushing. Thus, a concrete beam alone might crack on the bottom, because it has not as great tensile strength as steel. But, if we put steel rods into a concrete mould, an inch or so from the bottom, turn out a reinforced concrete beam, for instance, and place it in the building, with the reinforcement at the bottom, we use a beam in which the strength of the concrete and iron is combined. Thus, when a great weight is placed on the top of the beam the concrete resists the compression of the weight, and the reinforcement at the bottom, by its tensile strength, prevents the beam from cracking where the strain of the weight is greatest.