From Glossary of Meteorology


An apparatus, used in studying soil temperatures, for measuring the total supply of heat during a given period.

It consists of a long nickel coil forming a 100-ohm resistance thermometer and a 6-volt battery, the current used being recorded on a galvanometer. The coil is attached to a rod for insertion. A mercury thermometer can be used. The instrument can also measure the heat balance in a plant cover.