The Apparent Effect of the Observer's Temperature on Talcott's Level Readings
Shigeru Yumi · Publications of the Astronomical Society of Japan · 1952
Abstract It has long been known that the Talcott’s levels for the latitude observation have a peculiar systematic shift of bubbles during an observation. But the cause bas not yet been explained thoroughly. The writer experimentally proved that the systematic shift was mostly apparent and was independent of the actual tiltation of the telescope tube, and that the body temperature of the observer caused the apparent bubble shift, because the bubbles were found to move always towards the observer, while there was not any tiltation of the telescope, to which the levels were fixed during an observation. Lastly he estimated the effect of the apparent bubble shift on the results of the actual observations.