Foot-Candle Light Meter, specifically a Model 8DW40Y2 series. Introduced around 1935, this device was designed to measure "illuminance" (the amount of light falling on a surface) in units called foot-candles. Unlike photography-specific "exposure meters" that tell you what camera settings to use, this tool was primarily intended for architects, lighting engineers, and workplace safety inspectors to ensure adequate lighting for specific tasks like drafting, sewing, or assembly.