220 



calibration to pressures at which the elongation is no longer propor- 

 tional to tlie |)ressnre (supposing the rotation in any case to be 

 infinitel}' small) the a|)|)aratus can be made into a pressure-indicator 

 i'or that range, instead of an absolute nianon)eter. 



For the purpose of the calibration the manometer was connected 

 with a system of pipettes according to Knudskn^), for the description 

 of which vve refer to a subsequent paper '■'). The results are contained 

 in the following table: 



The first column gives the pressures calculated according lo the 

 indications of the absolute manometer by the forniula 



') Martin Knudsen, 1. c. 



-) S. Weber. Vapour-pressures etc, II. The vapour-pressures of carbon dioxide 

 between — 140° G. and — 160° G. Gomm. N". 137c. The same pipettes have 

 also been used for Ihe calibration of a hot-wire manometer for the purpose of 

 thermomelric measurements, which will be discussed in future communications 

 about experiments willi liquid helium. 



