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
The first purpose-built radio telescope was a 9-meter parabolic dish constructed by radio amateur Grote Reber in his back yard in Wheaton, Illinois in 1937. The sky survey he did with it is often considered the beginning of the field of radio astronomy.