Radio broadcast .. (1922-30)

Latin-American Activities SLOWLY but surely our Latin-American neighbors are getting more and more interested in radio communication and radio broadcasting. It is announced that the Radio Corporation of America has secured orders for the erection of five stations, each of which will have a sending radius of more than 2,000 miles. Three will be in Central America— in Honduras, Nicaragua, and Panama, respectively— and the other two in the United States. There is news, also, to the effect that certain South American republics are formulating new radio laws to take care of early broadcasting activities. Uruguay, for instance, has just made public its new laws. Private stations will be permitted anywhere except at points where State stations exist, provided that (i) they are not within 31 miles of the sea coast or of the Argentine and Brazilian frontiers, and (2) they are not installed in important cities or towns. Without being too inquisitive, it occurs to us that 31 miles in from the sea and from the two frontiers leaves very little room in which to operate, remembering that Uruguay is the smallest of the South American countries. Again, important cities and towns are barred to radio workers. We trust there is still a section of territory left for the followers of radio; they might go there and establish a colony! Then there is good news from Cuba. Radio broadcasting has just been introduced in that -Republic, and Cubans can now receive an allCuban programme instead of depending on the greatly attenuated programmes from the States. The demand for radio apparatus in Cuba is said to be enormous. Radio Communication in Mines EXPERIMENTS designed to demonstrate the possibility of radio communication between th: shaft head and the lowest workings of a mme have been recently carried out in England by a party of Birmingham radio amateurs. The colliery used for the tests was chosen because its main shaft is one of the deepest in that country, nearly 700 yards. The receiving set employed in the experiments was of the three-tube type, and a temporary antenna was made by suspending a length of insulated copper wire between the top of the steel hoisting gear above the shaft, and an adjacent railway bridge. The ground connection was made by clamping a wire to one of the rails of the permanent way. From this makeshift arrangement, messages were heard from the station at Bordeaux. The portable transmitting set was fir?t installed in the steel cage of the shaft, the aerial being insulated wire suspended in a lattice pattern across the roof of the cage, the ground being a connection to the steel floor. It was expected there would be much "screening" on account of the steel framework of the cage, and by the structural steel work built inside the shaft for a depth of more than 100 feet. This did affect the first transmissions, which were begun from the cage at the top. As it slowly descended, however, signals became much stronger. When the cage wes at a point 300 yards or so down, the maximum signal strength was attained, i-nd this remained undiminished until the cage reached the bottom. When the bottom was reached — and here there was more steel work — the signals became inaudible. The transmitting set was therefore taken from the cage and a new aerial made by suspending the wire between pit props. The ground was improved by attaching the wire to a length of cable laid along the ground. The new arrangement resulted in faint signals being received above. A distance of nearly threequarters of a mile was spanned by the radio set, working through solid earth. Radio telephony was tried and worked quite well. Radio Outfits for Mexican Lighthouses THE installation of small radio outfits in all lighthouses of the Mexican Department of Communications is reported in the Mexican press. Two sets of the apparatus are being installed on trial, after which, if they prove satisfactory, all lighthouses will be similarly equipped. Nauen's Latest Improvements GOOD progress is being made with the extension of the radio station at Nauen. in Germany, according to The Engineer. It is expected that by the beginning of next year it will be possible to establish