Intelligence and Miscellaneous Articles, 389 



three Almanacs, to show how very slightly they differ from each 

 other. I accordingly addressed the following to the Editor of the 

 Literary Gazette; viz. 



« Sir, Bristol, Sept. 18, 1830. 



" The charges alleged against the accuracy of the Nautical Al- 

 manac, by your correspondents C. H. Adams of Edmonton, and 

 J. T. B. of Deptford, are of so serious a nature, as would be suffi- 

 cient, if properly substantiated, to destroy all future confidence in 

 the calculations of that work. 



" From the observations of both these gentlemen on the late 

 eclipse of the moon, it would seem that the actual commencement 

 of total darkness was at least half an hour later than the Almanac 

 had predicted ; and the close agreement between the calculations 

 of our Greenwich astronomers, and those at Paris and Berlin, must 

 indicate either that a typographical error had crept into all the 

 copies of the astronomical tables employed at those three Obser- 

 vatories, or that the science of astronomy itself, even in its pre- 

 sent advanced state, does not enable us to foretel the time of a con- 

 junction or opposition of the sun and moon to within half an hour 

 of the truth. 



" The first of these suppositions is easily refuted, by comparing 

 together, for a few days before and after the eclipse, the moon's 

 longitudes, as given in the Nautical Almanac, which being 

 computed for every noon and midnight, afford a check on each 

 other, by forming a series of terms wherein an error, either 

 in the tables or the calculations, amounting to a few seconds 

 only, may be immediately detected, by the interruption occasioned 

 in the series, when examined by first, second, &c. differences. I 

 have in this way compared the computations of the moon's longi- 

 tude for a day or two before and after the '2nd of September, and 

 find them perfectly consistent with each other. The times of the 

 opposition also, and of the duration of total darkness, I find to be 

 correctly deduced from the series of the daily longitudes, &c. of the 

 sun and moon. 



"If, therefore, the assertions of these observers are to be depended 

 upon, we are reduced to the humiliating alternative of pronouncing 

 our best astronomical tables, with all their boasted accuracy, insuffi- 

 cient to determine the moon's place within a quarter of a degree : 

 so that, had a ship's captain attempted to determine his longitude 

 at sea by the Almanac and lunar distances on either the 1st, 2nd, 

 or 3rd of September, he must have been thrown out in his reckon- 

 ing at least four hundred geographical miles ! 



" Happily, however, for the credit of astronomy, and the conso- 

 lation of sea-faring men, I am able to contradict the whole of these 

 statements by my own observations, made during the eclipse; pro- 

 bably under a more propitious state of the atmosphere than these 

 gentlemen were favoured with at Deptford and Edmonton. In 

 order to verify the computations of our almanac-makers, I pro- 

 cured an excellent compensated watch, and set it a few hours be- 

 fore commencing my observations, by my friend Mr, Jones's astro- 

 nomical 



