No. 8.] PENDULUM OBSERVATIONS. 7 
The above observations thus give the following values for the tempera- 
ture, (the reduction for Tonnelot to the hydrogen-thermometer being — 0°.095 
at this temperature): 
according to Tonnelot 4519 Pendulum therm. 20 Pendulum therm. 23 
15°.852 C. 15°.916 C. 16°.113 C. 
Thus, with Von Sterneck’s formule, both the pendulum thermometers give 
somewhat too high a temperature, indicating that the zero has risen. 
I have examined thermometer 20 repeatedly. The year after | received 
the pendulum apparatus, in the summer and winter of 1893, some compari- 
sons were made in the air with a thermometer Baudin 8967, of which the 
corrections to the hydrogen-thermometer were determined by the aid of a 
thermometer Tonnelot 4506, which had been examined at the “Bureau Inter- 
national des Poids et Mesures’. I have since made several series of compa- 
risons, some with Baudin 8967, some with Tonnelot 4519, with the two ther- 
mometers hung up side by side in water. It appears that thermometer 20 
has not changed more than a couple of hundredths of a degree since the 
summer of 1893, and that the zero has risen about 0°.09. My temperature 
comparisons give the following formula: 
t° C. = 1°863 (reading — 3°46). 
It is the same with the other thermometer, 17, belonging to the pendulum 
apparatus for the “Gradmaalings Kommission”. Its zero has risen 0°.12 C, 
I assume therefore, that it may be taken for granted that the rise of the 
zero in the case of thermometer 23 had already taken place before the ob- 
servations made during the expedition were begun on July 30th, 1893. 
According to the above observation, I have assumed a rise of 0°.25 in the 
following calculations, and in so doing will remark that a more exact agree- 
ment between the indications of the pendulum thermometers than within a 
few hundredths of a degree cannot be expected, as one division on them 
answers to 0°.2, and the thermometers are not calibrated. The second ther- 
mometer of the expedition, 24, shows a zero-rise of 0°.375. 
The following are the observations made, in Vienna, in Christiania, and 
during the expedition. For the calculation of the time of coincidence, ¢, we 
have, by the method of least squares, 
