108 J^'ew Method of determining the Longitude. 



shameful manner in which the Enghsh Nautical Almanac 

 has been conducted. 



The determination of the longitude by the culmination 

 of the moon and stars, which is the subject of Mr. Baily's 

 paper, cannot be employed at sea, because it requires a 

 transit instrument fixed in the meridian. This gentleman 

 does not pretend to be the inventor of this method, since it 

 has been known nearly two centuries : But he proposes a 

 more advantageous mode of making the observation, and a 

 new formula for deducing therefrom the longitude. And 

 in its present improved form, he regards this method as 

 more likely than any yet proposed, to lead to accurate and 

 satisfactory results : and after an examination of the sub- 

 ject, we are inclined to the same opinion. But we will let 

 him speak for himself. 



" The meridional transits of the moon, agreeably to the 

 method about to be described in this paper, are free from 

 all these objections : the observations are made with the 

 greatest facility; the opportunities are of frequent occur- 

 rence ; the absolute time is of no material consequence ; 

 the computations are by no means intricate or troublesome ; 

 and the results are (1 believe) more to be relied on than 

 by any of the preceding methods ;" (by chronometers, 

 eclipses of Jupiter's satellites, of the sun, and of the moon, 

 and occultations, of which the author had been treating.) 



'* The nezvly proposed method consists in merely observ- 

 ing, with a transit instrument, the differences of right as- 

 cension between the border of the moon, and certain fixed 

 stars previously agreed on ; restricting the observations to 

 such stars as differ very little from the moon in declination. 

 It is evident that this method is quite independent of the er- 

 rors of the lunar tables, except so far as the horary motion 

 of the moon (in right ascension) is concerned, and which 

 in the present case, may be depended on with sufficient 

 confidence : that it does not involve any question as to the 

 compression of the earth : that a knowledge of the correct 

 position of the star is not at all required : and finally, that 

 an error of several seconds, in the state of the clock, is of 

 no consequence. Consequently a vast mass of trouble- 

 some and unsatisfactory computation is avoided. More- 

 over, it is the only method that is universal, or that may be^ 



