To record the signal, he installed a very fast oscilloscope, provided as a prototype by DuMont Laboratories, in an underground bunker several hundred feet from the Gadget, where it was photographed. To bring the signal to the oscilloscope, he devised an oversized coaxial transmission line, whose inner conductor was made smaller as it went from chamber to oscilloscope. Because this configuration enhanced the signal reaching the oscilloscope, there was no need for amplification. To confirm this surprising behaviour, Rossi consulted with Harvard professor Edward Purcell.