Figure 3. Thermometer comparison block.

A. Stainless steel tube to support thermometer comparison block.

B. Manganin leads for thermometers and copper leads for block heater.

C. Platinum leads of resistance thermometer.

D. Stainless steel well for thermometer block.

E. Heater distributed along well “D”.

F. Copper thermometer block with wells for six thermometers.

G. Heater for thermometer block.

H. Platinum resistance thermometer.

I. Copper sleeve (attached to central supporting tube) with longitudinal grooves to serve as thermal tie-downs for manganin leads and thermocouples.

J. Brass plug to seal end of central support tube.

K. Location of grooves in sleeve “I”.

L. Reference junctions for thermocouples on shield (at “W” in fig. 2) and thermometer block well ring heater (at “R” in fig. 2).

M. Closely fitted reentrant copper “thumb” (with a groove for venting gas).

N. Copper plug with longitudinal grooves to serve as thermal tie-downs for thermocouples.

O. Vent.

P. Thermocouple leads to shield and thermometer block well ring heater.