INSPECTION, MAINTENANCE AND RECHARGING FIRE. EXTINGUISHERS. The provisions of this bulletin apply to the selection, installation, inspection, maintenance and testing of portable extinguishing equipment. This guide is prepared for. the use of persons charged with selecting, purchasing, installing, and maintaining. portable fire extinguishers. The following requirements are excerpts from the National.
On 27 August 1920, regular wireless broadcasts for entertainment began in Argentina, pioneered by the group around Enrique Telemaco TelÃ©maco, susini and spark gap telegraphy. Stopped on 31 august 1920 the first known radio news program was broadcast by STATION, 8mk the unlicensed predecessor OF (WWJ) am In, Detroit. michigan
In 1914 the American Radio Relay League was founded by Hiram Percy Maxim, who found that messages could be sent more reliably over long distances if relay stations were organized. Transatlantic transmitting and receiving tests began in 1921 and by July 1960 the first two-way contact via the Moon took place on 1296 MHz.