This is a polymeter made by Wilhelm Lambrecht of Germany.  I believe it was made in the early 1900s, though polymeters with this form were made by Lambrecht from 1893 until at least the 1980s.  A Lambrecht polymeter with this dial face (in English) is shown in the 1913 Eimer & Amend catalog, though the temperature scale there is in Celcius.  It has a mercury thermometer and beveled glass.  Newer polymeters have a silvered dial face, this face looks much older.  It is in excellent condition.

The lower instrument is a hair hygrometer that shows the relative humidity and also the depression of the dew point in degrees F. The upper thermometer shows the air temperature in degrees F and the saturation vapor pressure in mm Hg.  The dew point temperature can be determined by subtracting the dew point depression from the air temperature.  

Go to Lambrecht catalog page.

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