These low degrees are indicated by a H thermometer, or if too low for that, by a "Thermo-electric couple" of copper and German silver.
"An Introduction to Chemical Science"
R.P. Williams
Here are the colossal Thermo-electric batteries which work throughout the year by there being stored up in immense solid blocks of aluminium the heat of summer and the cold of winter.
"The Dominion in 1983"
Ralph Centennius
I wasn't kidding about dropping those Thermo-nucs, either.
"This Crowded Earth"
Robert Bloch