For measuring thermal conductivities of poor conductors.
The apparatus is capable of a high degree of accuracy and
consists of three cylindrical blocks of aluminium 50 mm diameter
x 12.5 mm thick, drilled radially to take thermometers. Between
the first and second block is inserted a small 4 to 6V electric
heater, sandwiched between the mica sheets, of known resistance.
The test specimen, in the form of a thin disc is inserted
between the second and third blocks, and the whole is clamped
together by an insulating clamp. The assembly is supported
upon a sheet metal stand 118 x 70 x 90 mm high is notched
to locate the clamp rods.
The theory of the method can be found in most advanced textbooks
on hear, but a detailed instruction sheet is enclosed with
The apparatus is supplied with stand but without thermometers.