1919 Tyco's Hygro-Autometer

Functional "Hygro-Autometer" by Tyco's Instrument Company, dated 1919. Water from the glass container is wicked up which allows the Wet-Bulb thermometer to be read. The left Dry-Bulb shows temperature unrelated to systems' humidity. Using the difference of both temperatures, scroll to corresponding data index. Once aligned, the Dry-Bulb temperature can be found in the first column of numbers on data plate. The second number shows overall humidity in percentage, with the third number indicating the system's exact dew point. Original paper instructions on back discern this as a T3673 3-20 500 model. 

 Directions for Use: "To find the relative humidity, turn the roll until the number at the head of the column corresponds to the difference of the readings of the Wet- and Dry-Bulb Thermometers, then follow down the first row to the number corresponding to the reading of the dry bulb. The figures on the same line in the second row will indicate the relative humidity."

Source: 1919 Tyco's Industrial Equipment Catalog (page 77) 

Scrolling Data Index marked:

"1709 3-21-300" "HRYGO-AUTOMETER HUMIDITY AND DEW POINT TABLE" 

'Copyright 1919 by Tyco's Instrument Companies, Rochester, N.Y.'

Glass Bulb marked: "TAYLOR INSTRUMENT COMPANY" 

Dimensions: 8.00" x 3.25" x 10.00"

Weight: 2 lbs. 14 oz.