Radio broadcast .. (1922-30)

254 Radio Broadcast The evolution of the Audion patent claims marks, in a general way, the evolution of the Audion — first it was a gas effect in the open air, then in an enclosed vessel, then in an exhausted vessel, exhausted like an incandescent lamp — then to higher and higher degrees of vacuua (as early as 1912 I employed an X-ray vacuum) But always it was a relay. Always the "B" battery was employed. The control electrode idea even preceded the enclosed vessel. And never was the Audion " the Fleming valve with merely a grid added." Professor Morecroft continues: "The thing which he (De Forest) actually did, namely, the insertion of the third electrode into a Fleming valve, was a most wonderful contribution to the radio art." It was not. Remember that a mere valve with three electrodes is still only a valve — with one electrode too many. Unfortunately, prior to the year 1917, very little, indeed scarcely anything at all, appeared in radio history concerning the Audion art, although nearly a decade had elapsed since my first patents were granted on the Audion. It was in this period of bitter commercial rivalry that certain British radio interests first saw fit to attempt to discredit an American invention and put forth the suggestion, altogether at variance with the truth, that an American had simply put another electrode in the twoelectrode tube. There is no excuse, however, why, at this late day, such an untruth should persist in American radio history, above all, when the whole world is making use of the Audion in radio communication as well as in long distance wire telephony and the successors of these same English commercial rivals are now operating under the original De Forest Audion patent licenses. In fact, their entire radio system, outside of the generators and aerials, is built around the three-electrodeanode-voltage vacuum tube. Very truly yours, Practical Pointers on Cabinet Wood Finishing By W. S. STANDIFORD ELECTRICAL experimenters can make neat-looking cabinets, but often fall down in their finishing work. 1 1 is too bad to get so far along with the construction of a set and then omit those finishing touches that make it a pleasure to look at and to operate. As crudely finished apparatus is generally the result of a lack of knowledge of the processes and materials needed rather than to lack of interest or carelessness, a few practical pointers may prove helpful. At the outset, it cannot be emphasized too ^strongly that a clean, smooth exterior is necessary in order to get a first-class finish, whether the wood is to be painted, enameled, oil-finished in natural-colored woods, or varnished. The first thing to do is to decide what kind of wood the box is to be made of, whether it is open or close-grained, and also whether it contains any sap, as such conditions will make necessary different methods of working. Open-grained woods include: Oak, ash, chestnut, walnut, mahogany, and butternut. These require fillers. Close-grained woods include: Pine, cherry, maple, birch,, cypress, whitewood, poplar, sycamore, beech, and redwood. These and others like them do not need fillers, but can be finished in natural colors or stained, as preferred. Five operations in wood finishing are needed: sandpapering, staining, filling, varnishing, and polishing. First, plane the wood as smooth as possible. Then tack a piece of No. oo sandpaper on a level block of wood and rub with the grain, using moderate -pressure and taking care when working near the edges, not to round them. Wipe all dust from the surface with a cloth; if any remains, rough spots in the finished product will result. Staining comes next, if pine or poplar are used to imitate the appearance of more costly woods. By using pine or poplar, radio cabinets can be made which will