486 Mr. Ivory on the astronomical refractions. 
The error is here very small, as it ought to be in a mean of 
so many good observations. Half a degree subtracted from 
the thermometer would bring out an exact result ; and some 
small difference may be fairly ascribed to the uncertainty 
arising from the different temperatures of the interior and 
exterior thermometers. 
But it will be satisfactory to exhibit the errors of every 
particular observation. In the Irish Transactions for 1815, 
Dr. Brinkley has given 44 sub- polar observations of a Lyras 
with the observed refractions ; and these are contained in 
the following Table, extracted from the Connaissance des Terns 
for 1819, p. 418, the column of the errors of the new Table 
being added. 
