This is a reconstructed Leeds & Northrup Model G strip chart recorder representative of those used in the discovery of the background microwave radiation in 1965. While calibrating a very large microwave horn antenna at Holmdell, N.J., used for satellite communication, and trying to account for all sources of radiation, known and unknown, Bell Laboratories scientists Arno Penzias and Robert Wilson detected what seemed to be persistent background noise that they could not account for. After ruling out all other possible sources, and advised by physicists from Princeton who had been looking for just this phenomenon, they identified this radiation due to a cosmic microwave background remnant predicted to exist by the Big Bang theory; essentially diluted and red shifted radiation from the extremely hot and violent origin of the universe. They were awarded the Nobel Prize in recognition of their discovery of this first confirmatory evidence of that theory. The outer case of this recorder has been refurbished to simulate the appearance of a working instrument. It was fabricated and donated to NASM by the Leeds+Northrup Division of Honeywell.