Soil Heater
17 of 20

Top: The Ball, or Illinois hot water, soil heating device.

Insets: Location of steam and water intakes, steam gauge, and thermometer.

Bottom: A man operating the outfit in a greenhouse.

One negative, Panchromatic, ray filter not used. 1939.

Image: W. Fisher. Copyright © Dept. of Plant Pathology, Cornell University
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