Temperature of the air minus 45.5 degrees.
By comparing this altitude, corrected by the mean refraction and parallax with that deduced from the latitude which was observed in autumn, the increase of refraction is found to be 6 minutes 50 seconds, the whole refraction therefore for the altitude 2 degrees 52 minutes 51 seconds is 21 minutes 49 seconds.

Admitting that the refraction increases in the same ratio as that of the atmosphere at a mean state of temperature the horizontal refraction will be 47 degrees 22 seconds.

But the diameter of the sun, measured immediately after the observation, was only 27 minutes 7 seconds, which shows an increase of refraction at the lower limb of 3 minutes 29 seconds.

The horizontal refraction calculated with this difference and the above-mentioned ratio is 56 minutes 3 seconds at the temperature minus 45.5 degrees.

So that in the parallel 68 degrees 42 minutes where, if there is no refraction, the sun would be invisible for thirty-four days, his upper limb with the refraction 56 minutes 3 seconds is in fact above the horizon at every noon.
The wind was from the westward a moderate breeze and the air perfectly clear.