Karl then reserved a room and equipment for Theremin's experiments. Abram Fedorovich suggested Theremin also look at methods of creating gas fluorescence under different conditions and of examining the resulting light's spectra. However, during these investigations Theremin was called up for World War I military service. Although only in his second academic year, the deanery of the Faculty of Physics and Astronomy recommended that Theremin go to the Nikolayevska Military Engineering School in Petrograd (previously Saint Petersburg), which usually only accepted students in their fourth year. Theremin recalled that Ioffe reassured him that the war would not last long and that military experience would be useful for scientific applications. Beginning his military service in 1916, Theremin finished the Military Engineering School in six months, progressed through the Graduate Electronic School for Officers, and attained the military radio-engineer diploma in the same year. In the course of the next three and a half years he oversaw the construction of a radio station in Saratov to connect the Volga area with Moscow, graduated from Petrograd University, became deputy leader of the new Military Radiotechnical Laboratory in Moscow, and finished as the broadcast supervisor of the radio transmitter at "Tsarskoye Selo" near Petrograd (then renamed "Detskoye Selo"). During the Russian civil war, in October 1919 White Army commander Nikolai Nikolayevich Yudenich advanced on Petrograd from the side of "Detskoye Selo", apparently intending to capture the radio station to announce a victory over the Bolsheviks. Theremin and others evacuated the station, sending equipment east on rail cars. Theremin then detonated explosives to destroy the 120-meter-high antennae mast before traveling to Petrograd to set up an international listening station. There he also trained radio specialists but reported difficulties obtaining food and working with foreign experts whom he described as narrow-minded pessimists. Theremin recalled that on an evening when his hopes of overcoming these obstructing experts reached a low ebb, Abram Fedorovich Ioffe telephoned him. Ioffe asked Theremin to come to his newly founded Physical Technical Institute in Petrograd, and the next day he invited him to start work at developing measuring methods for high-frequency electrical oscillations. The day after Ioffe's invitation, Theremin started at the institute. He worked in diverse fields: applying the Laue effect to the new field of X-ray analysis of crystals; using hypnosis to improve measurement-reading accuracy; working with Ivan Pavlov's laboratory; and using gas-filled lamps as measuring devices.