north polar distances of the principal fixed stars. 55 
however, as has been mentioned, has done otherwise, and 
applied Bradley's refractions to my Catalogue.* 
I particularly regret this circumstance, because it has oc- 
casioned my Catalogue to appear to differ more from that of 
Mr. Bessel, than it really does. The differences that actually 
exist are sufficiently difficult to account for. Indeed had 
Mr. Pond also reduced the Catalogue of Mr. Bessel by the 
same refraction, the differences would have appeared much 
better. But this mode of proceeding would not have been 
less objectionable. From the differences between his own 
Catalogue and my Catalogue reduced, Mr. Pond infers that 
my telescope is subject to flexure by the quantity of the dif- 
ference at each zenith distance. Now it must appear a very 
extraordinary law, and not easily reconcilable to any me- 
chanical principle, that the flexure should be nearly as the 
tangent of the zenith distance. This it must necessarily be 
according to his method of changing my North Polar dis- 
tances. 
It is evident, by comparing the two Catalogues, that there 
is no difference between them but what might arise from un- 
avoidable errors. Had each star been exact to the tenth of 
a second, still Mr. Pond's reasoning would have led him to 
do the same. He would have reduced them by Bradley's 
* It may be said, that in a Paper in the Transactions of the Royal Irish Academy, 
about eight or nine years ago, I changed my own North Polar distances for the pur- 
pose of comparison. But the circumstances are entirely dissimilar. I have always 
referred to, and always used, the North Polar distances computed by my own re- 
fractions. 
Mr. Bessel, in his comparison of my polar distances with his own, does not 
change mine to adopt his own refractions. He knew I had determined my own 
with my own instruments. 
