He kept daily records of the weather and the tides, made regular magnetic observations, determined gravity from pendulum observations, studied astronomical refraction
, measured the height of Table Mountain, and so on.
Now that we know the latitude accurately, we can re-analyze these observations, taking into account computer-calculated declinations, astronomical refraction, and horizon dip.
No corrections were made for astronomical refraction and horizon dip.
Corrections for astronomical refraction, including its dependence on temperature and atmospheric pressure, were taken from today's Nautical Almanac.
The sun's altitude was measured with an astrolabe as 37[degrees], for which the astronomical refraction is 1'.
Beke has tried to find an explanation for both feats in a possible anomaly in the astronomical refraction of light: "Owing to the particular condition of the atmosphere, there existed an extraordinary refraction, not merely on the 25th of January, but continuously during fourteen days afterwards, at first amounting to nearly four degrees, but gradually decreasing to about one degree and a half." But he admits immediately: "The problem is a curious, and, with our still insufficient knowledge of the laws of atmospheric refraction in high latitudes, a difficult one" (Beke, 1876:clv).
The correction for astronomical refraction applies to normal atmospheric conditions, i.e., assuming that the density of the air and therewith the index of refraction, n, decrease monotonously with elevation.