On Refraction. 453 



with the navy ; whilst it is well known, that at this mo- 

 ment a few of our best mathematicians are groaning tinder 

 insults, degradations, and injuries, as severe as they are un- 

 provoked and undeserved. Had France the tenth part of our 

 naval power, with her present number of scientific men, the 

 whole world must soon be subjected to her dominion : and 

 where so much is at stake, it behoves us, by giving all the 

 encouragement in our power, to place -our navy as much 

 above that of other nations in scientific knowledge, as it is 

 in all other high and great qualifications. 



The gradual decrease of the study of mathematics in this 

 country has already been publicly noticed*; but its cause?, 

 although very evident, have not yet been mentioned. Per- 

 haps, at some future period, this may form the subject of 

 another communication. I have been led into this digres- 

 sion by considering the still more deplorable state if possi- 

 ble of astronomy, which at this moment is scarcely culti- 

 vated by half a dozen persons throughout the whole king- 

 dom. But to return. 



It has been doubted, notwithstanding what is stated by 

 La Caille, \vhether the mean refraction of France be the 

 same as that of England,. What gave rise to this was the 

 use of Bradley's Table in the determination lately made 

 there of the obliquity of the ecliptic, wherein a difference 

 of some seconds was found, between the result obtained 

 from observations made in t the winter solstice, and that 

 from others made in the summer. This doubt has not yet 

 been satisfactorily removed : but the very accurate astrono- 

 mic circles lately made by our English artists, who are un- 

 doubtedly the best in the world, will, it is presumed, with 

 good assistance from theory, not onlv soon decide this 

 question, but furnish us with such observations as will de- 

 termine the refraction to a second, till we approach near the 

 horizon. 



A very material step has lately been made towards this, 

 by the publication of Mr. Groombridae's valuable paper on 

 Refraction f, wherein he has determined, by a great number 

 of very accurate observations, both the quantity of mean 

 refraction at 45°, and the coefficients for correcting it on 

 account of the state of the atmosphere. The former of 

 these he makes 58"*] 192 by a mean of a great number of 

 observations, when the barometer is at 29*6 inches > and the 



* Edinburgh Review of La Place's Mecanique Celeste. 

 f Philosophical Transactions for 1810. 



2 F 3 mother- 



