262 Mr. Ivory's Remarks on a late Article 



one into the other, by the addition or subtraction of a con- 

 stant logarithm, or by increasing or diminishing the numbers 

 in a given proportion. The remainder of my table is more 

 uncertain, as I was not in possession of a sufficient number 

 of exact observations for determining the measure of its accu- 

 racy; and of this circumstance I have sufficiently apprised 

 the reader at the end of the table. I should therefore have 

 been highly gratified if any astronomer had undertaken to 

 show its defects by comparing it with good observations at 

 low altitudes. But what has appeared in the Journal of 

 Science I can consider in no other light than as a mockery, 

 the more remarkable that, although quite uncalled for, to say 

 no more, it professes to be undertaken in the discharge of an 

 official duty. 



The article referred to, pretends to compare my table with 

 observations. But it is plainly a comparison of it with the 

 table in the Nautical Almanack ; if indeed that can be called 

 comparing two things, which takes one of them as it is, and 

 the other as it is not. Both the tables are computed for the 

 same mean temperature and barometric pressure ; and, in ap- 

 plying them to practice, nothing more is necessary than to 

 know the heights of the thermometer and barometer at the 

 several observations. Astronomers are divided in opinion 

 about estimating the temperature. Some reckon by the ther- 

 mometer within the observatory ; while others think that the 

 one without is more accurate. There seems to be some ground 

 in experience for this difference of practice ; for the errors of 

 some observers are found to be less with the interior, and 

 those of others with the exterior, thermometer. Mr. Groom- 

 bridge has always found an advantage in using the exterior 

 thermometer ; and his judgement in this respect has been con- 

 firmed by Delambre, who compared the results obtained from 

 both thermometers. There can be no doubt therefore that, 

 with regard to the stars in my paper, p. 490, Phil. Trans. 1823, 

 the exterior thermometer is to be preferred. But in comparing 

 the two tables, the calculations should be made in the same 

 manner from both. It can produce no other effect than to 

 warp the judgement to a wrong decision, if one table be al- 

 tered by empirical corrections made expressly to lessen the 

 errors, while the other table remains unchanged. And if 

 both tables be so altered, the tendency to a false estimate of 

 their comparative merits will only be increased. If there 

 must be a trial, the litigants should come into court upon 

 equal terms. Why should one appear tricked out in all sorts 

 of disguises for the purpose of ensnaring unwary judges into 

 a favourable sentence, while the other stands at the bar with- 

 out 



