New Books. 313 



ine former being, in our judgement, too small by this 

 quantity. 



The comet has been continually approaching the earth 

 for many weeks. From September 15th till October 14th, 

 its decrease of distance amounted to 25 millions of miles, 

 yet its brilliancy and the magnitude of its tail have gone on 

 diminishing, as Burckhardl" properly remarked. Persons 

 ignorant of astronomy would naturally inter from this di- 

 minution the recedure of the comet from us, as, from its 

 increase they conjectured its approach. Astronomers 

 laugh at such idle dreams when applied to a demonstrative 

 science, in which conjecture has found no place since the 

 days of Newton. Its first principles leach, that these phae- 

 nomena arise from the comet's varying distance from the 

 sun. At the period of the perihelion passage these bodies 

 are known uniformly to attain their maximum of size and 

 brightness. 



If Glasgow has been justly ridiculed on the present occa- 

 sion for the dexterous appropriation of every floating error 

 about the comet, I trust this conmiunication will, in some 

 measure, redeem its former scientific character. It is to 

 be hoped that some of our eminent philosophers will take 

 the trouble of comparing Burckhardt's elements with our 

 observations, and that they will speeddy give the result of 

 their comparisons to the public. Nothing could have in- 

 duccd us to enter the lists against so able a competitor, but 

 the conviction of the justice and importance of the cause 

 which public duty assigned. I am your obedient servant, 



Andrew Ure 



Mr. T. Levbourn, of the Royal Military College, editor 

 of the Mathematical Repository, intends to publish, by sub- 

 scription, A Collection of all the Mathematical Question? 

 and their Answers, which have appeared in the Almanack 

 called T/ie Ladies' Diary, from its commencement in 1704 

 to the present time, the editor of the Diary (Dr. Charles 

 Hutton) published a similar v\oik in 1773, but compre- 

 hending both its mathematical and poetical parts down to 

 that period. Mr. Levbourn's publication will cotnprehend 

 only the Mathematical Part ; and, with Dr. Hutton's per- 

 mission, will contain all the vaKial)le Additions given in his 

 Edition, as far as it extends. He also hopes to be able to 

 give other Additions by the assistance of some of the in- 

 genious Mathematicians who have for a number of years 

 past contributed to the Mathematical Repository. 



The work will be printed in 8vo, and will be published 



