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Vintage Bendix Psychron ML-450A/UM US Navy Psychrometer Case & Original PapersVintage Bendix Psychron electric psychrometer, model ML-450A/UM, manufactured for the Department of the Navy, Bureau of Aeronautics, by Bendix Aviation Corporation, Friez Instrument Division, Baltimore, Maryland.This Cold War era military weather instrument includes its original Navy marked carrying case and original military paperwork, including an instruction booklet dated June 1957.WHAT IT WAS USED FORNavy weather personnel used psychrometers like this aboard ships and at shore weather stations to measure air temperature and wet bulb temperature. Those readings were compared with reference tables to determine relative humidity and dew point, supporting weather observations and forecasting for naval and aviation operations.The instrument uses two thermometers and a battery powered fan. One thermometer measures ambient air temperature. The other has a dampened wick around its bulb, which cools through evaporation as air moves across it. The difference between the readings is used to determine atmospheric moisture.IDENTIFICATIONManufacturer: Bendix Aviation Corporation
Division: Friez Instrument Division
Product name: Psychron
Military model: ML-450A/UM
Serial number: 481
Marked power requirement: 4.5V DC
Manufactured for: Department of the Navy, Bureau of Aeronautics
Carrying case designation: CY-1238A/UM
Contract number: N383-46988-AINCLUDEDBendix Psychron ML-450A/UM instrument with two mounted thermometers.Original Navy marked metal carrying case with handle, latch, and green felt interior.Original military paperwork, including the June 1957 instruction booklet, dew point and relative humidity tables, and additional operation and service instructions shown in the photographs.CONDITIONThe instrument appears to have seen little use and may be unused, but its service history is unknown. It is being offered as a vintage, untested instrument.There is visible age and storage wear, including discoloration, scratches, and chipped or broken areas on the cream colored thermometer housing. The carrying case has finish wear, scratches, and corrosion on portions of the hardware. The original paperwork shows age toning, spotting, and handling wear.Fan operation, illumination, thermometer accuracy, and calibration have not been tested. Completeness of the original equipment kit has not been verified.The instruction booklet is dated June 1957. The exact manufacturing date of the instrument has not been established.An interesting piece for collectors of U.S. Navy equipment, military meteorology instruments, vintage scientific instruments, and Cold War history.Please review all photographs carefully for condition and included contents. Only the items shown are included.
