A vintage, Model 204, Du Mont oscillograph used for examining electrical pulses, particularly those from radiation detectors. The artifact, which measures 23 cm in width by 36 cm tall by 48 cm deep, was one of the first commercially available oscilloscopes. The screen measures 12.7 cm (nominal 5 inch) in diameter. Records on the internet indicate that versions of this model were on the market as early as 1940. This artifact was located stored by the donor alongside a number of newer (surplus) oscilloscopes which bore identification tying them to the Chalk River laboratory. Although no identification tag could be located on this unit, it is believed to have been used either at the Montreal Lab and/or during the very early days of the Chalk River site and that it was replaced by newer units before the NRX-XXX inventory scheme was instituted at the site.