340 Astronomical and Nautical Collections. 



True Distance. Mr. Thomson. 



50 26 28 50 26 28 



41 18 54 41 18 56 



86 16 45 86 16 44 



33 56 49 33 56 49 



55 32 42 55 32 42 



60 14 44 60 14 43 



107 17 13 107 17 14 



30 11 29 30 11 26 



When it is considered that these tables of Mr. Thomson occupy 

 less than ninety octavo pages, and that the work of Mendoza is 

 nearly out of print, it cannot be doubted that many navigators, who 

 wish to spare their labour, yi'iW become purchasers of this volume. 



ii. Comparison of the Astronomical Tables of Carlini and of 

 CoiMBRA with those o/Delambre and Burckhardt. 



In a little work entitled Esposizione di un nuovo metodo di cos- 

 iruire le tavole astronomiche, applicafo alle tavole del sole, di Fran- 

 cesco Carlini; S.Milan, 1810, published also with the Efemeridi 

 di Milano, the author has introduced a very valuable simplification 

 of the process of taking out the respective arguments of the 

 equations of his tables, by making a mean solar day the unit of 

 each ; so that the epoch and arguments being found for the year 

 only, the time is only to be added to each in days and parts 

 of a day, without the necessity of taking out separate " move- 

 ments" for each separate argument, as is usual in all the more 

 common tables. The comparative facility afforded by this arrange- 

 ment will be best illustrated by an example taken from Delambre's 

 tables, sheet h, which is the same that Carlini has exhibited. 



The diligent astronomers of Coimhra have given, in a very neat 

 and compact form, a collection of tables for the sun, moon, and 

 principal planets, arranged in general so as to require single 

 entries only, which lengthen in a slight degree the apparent length 

 of the process, though they render it simpler and more conve- 

 nient. But for the moon they have given also a method consi- 

 derably more compendious, in which double entries are employed 

 for shortening the computation. The same example of a place of 

 the sun is here subjoined, as determined by these tables also. 



