15 JUNE 1918, Page 16

The Year Book of Wireless Telegraphy and Telephony (Wireless Press,

Os. net) is a bulky volume which by its very size testifies to the high importance that wireless has so rapidly acquired. The list of land and ship stations alone fills nearly three hundred pages, closely printed, and is illustrated in a large wireless map of the world which is of great interest. The editors necessarily preserve silence concerning new developments effected for naval and military purposes during the war, in which many wireless operators have displayed great heroism. We are interested to learn that the signal " S.O.S." has no special signification, such as "Save our souls," as some ingenious people have suggested, but was" adopted simply on account of its easy radiation and its unmistakable character" to replace the original " C.Q.D.," a modification of the signal " C.Q." (" all stations ") used by all land telegraphists.