Abstract. This recorder was developed for the purpose of recording temperatures of experimental tanks, also for hydrographic survey, etc. The record is obtained by casting the shadow of a flat section mercury column of a thermometer on to bromide paper or film, by a feeble source of light.

The recorder is actuated by a constant clock with an intermediate mercury in glass type of switch, operating a relay which drives the drums carrying the paper. The thermometer is graduated in half degrees, and a tenth of a degree is easily estimated. This recorder requires very little attention.

Print publication: Issue 6 (June 1940)
Received 19 February 1940