1 823 .] On the Declination of the principal fixed Stars. 247 



and more resemblances might, I suspect, be traced by any one 

 who had the inchnation and opportunities to exaniine the earUer 

 forgeries termed alchemical, those especially which are extaat, 

 or were oiigiually written, in the Greek language, 



(.To be continued,) 



Article II. 



On the Changes which have taken place in the Declination of 

 some of the principal fixed Stars. By John Pond, Esq. Astro- 

 nomer Royal, FRS. Read April 18, 1822 * 



The mural circle having in September last been put into 

 complete repair, and declared by Mr. Troughton to be in as per- 

 fect a state as when first erected, I resumed my examination of 

 the principal fixed stars which form the Greenwich Catalogue, 

 In the course of a very short time, I found that several anoma- 

 lies, which had previously given me much perplexity, still sub- 

 sisted: some of these were of such a nature as to lead to a sus- 

 picion that a change might possibly have taken place in the 

 figure of the instrument; on the other hand, there were circum- 

 stances, that strongly militated against such a supposition. 



Several of the stars in which the supposed discordance 

 appeared the greatest, passed over almost the same divisions 

 with others, in which no such discordance could be perceived. 

 Moreover, in examining these discordances in different points of 

 view (that is, both with respect to their right ascensions and 

 polar distances) I fancied I perceived something like a general 

 law, that was quite incompatible with any possible hypothesis 

 of error in the instrument. 



On a point of this importance, I clearly saw the necessity of 

 devising some new method of observation which might decide 

 with certainty, that which otherwise would become an endless 

 subject of doubt and conjecture. 



1 had often attempted to observe the altitudes of stai's by 

 means of an artificial horizon of quicksilver, or other fluid, but 

 had abandoned the attempt from the difficulty of protecting it 

 from the wind, and from the number of observations I lost in 

 fruitless experiments. To this method I had again recourse ; 

 and by means of wooden boxes of different sizes and figures, 

 according to the different altitudes of the stars, I have sufficiently 

 accomphshed my purpose. A very few observations were suffi- 

 cient to convince me that the instrument was in every respeqt 



• From the Philosophical Transactioni for 1823, Part T, 



