Pufther Errors in the Nautical Almanac. 305 



these engines in Cornwall, the Editors describe them as those in 

 which oil or melted tallow is interposed to prevent the possi- 

 bility of steam escaping past the piston, and which have been 

 described in our xlvith volume. The Cornish engines are not of 

 this construction, but conformable to Mr. Woolf's first patent ; 

 and are worked by steam expanded by temperature^ as described 

 in our xixth volume. 



FURTHER ERRORS IN THE NAUTICAL ALMANAC. 



To Mr. Tilloch. 



Sir, — In the explanation inserted at the end of every Nautical 

 Almanac it is stated that " the conjunctions of the moon with 

 the planets, or stars not less than the fourth magnitude, which 

 may prove occultations in some inhabited parts of the globe, are 

 evidently designed to instruct mariners or travellers to look out 

 frequent li/ for such observations : which, if they happen to prove 

 occultations, and are carefully observed, will afford a certain 

 means of determining the longitude of the place of observation." 

 Yet, notwithstanding the declared utility of this method, and the 

 obvious intention of the publication of the Nautical Almanac, it 

 is much to be regretted that the Astronomer Royal (under whose 

 directions this work is formed) should have neglected, of late years, 

 to insert the several conjunctions of the moon with the fixed 

 stars ; whereby many persons are prevented from looking out 

 for such conjunctions as may prove to be occultations at the places 

 where they are stationed. 



It is true that a feia of these conjunctions are inserted ; but, 

 many others, which have even proved occultations in this coun- 

 try, are not so much as noticed. For instance, the only con- 

 junction inserted in the list of phsenomena for the last month 

 (March) was j3 Scorpionis ; the time of which, by the by, was 

 set down at least an hour too late. There were, however, no 

 less than two occultations in the course of the same month j viz. 

 of y Virginis on the 4th, and of rj Leonis on the 29th ; both 

 of which were seen in London. In the Connaissance des Terns 

 these conjunctions are carefully noted ; and the editors of that 

 work justly observe, that " Les occultations d'ctoiles par la lune 

 ^tant les phenom^nes les plus utiles pour determiner avec preci- 

 sion les longitudes gcographiques, les voyageurs we doivent pas 

 negliger de les observer: les conjonctions, qu'on indique ici, 

 serviront a les guider pour'prevoir les occultations qui pourront 

 avoir lieu dans les pays oil ils se trouveront." Agreeably to, these 

 principles, a long list of conjunctions and other phaenomena, 

 occupying no less than six pages, is given in every volume of thai 

 work. 



Vol.49. No.228.^prj7 1617. U But 



