No. 158. Cambridge, Mass., July 7, 1906.

Will you please inform me whether is is feasible to use a small balloon for elevating the aerial wire for wireless telegraphy, and if so, give description for making one. H. J. C.

Balloons have been used to elevate the aerial wire for wireless telegraphy, but such use has besn almost entirely confined to military work. A balloon of considerable size is required to give sufficient capacity to lift itself and the weight of an aerial wire of say, 10 pounds. If illuminating gas is used for inflating, a balloon of 1000 cubic feet capacity would lift only 32 to 37 pounds, according to the kind of gas and humidity of the atmosphere. The diameter of such a balloon would be nearly 13 feet, and the expense of inflating it would be considerable, as well as requiring considerable time unless a large supply pipe was available. The lifting capacity of hydrogen gas is about double that of illuminating gas, consequently the balloon would need to be only half the size for the same capacity, but a generating plant would be necessary. As amateurs make use of wireless telegraphy inter-mitently, it is decidedly the best plan to put the money required for a balloon outfit into other parts of the apparatus and make up through increased efficiency in these parts what is lost in a lower aerial.