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 LXVI. Intelligence and Miscellaneous Articles. 



NEW TABLES OF PRECESSION, ABERRATION AND NUTA- 

 TION. 



THE Astronomical Society of London have undertaken the 

 formation of an extensive work, which will prove highly 

 useful and convenient to every practical astronomer. It is 

 1 the computation of Tables for determining the Precession, 

 Aberration and Nutation of nearly 3000 of the principal fixed 

 stars, for every day in the year ; with their mean places for 

 the beginning of the year 1830. This list will contain all the 

 stars, not less than the 5th magnitude, which are inserted in 

 Piazzi's catalogue ; and also all the stars above the 7th mag- 

 nitude, situated within 30° of the equator. The tables will be 

 constructed on the principles detailed in our Number for 

 October 1822; and which has been partly acted upon on the 

 continent by M. Schumacher. This mode of arranging tables 

 of this kind is by far the most convenient of any that has been 

 hitherto adopted ; as by the help of A> logarithms added to 

 4 other logarithms (all of which will be found in the book) 

 the correct quantities are determined without reference to any 

 other work than a small table of logarithms to 5 places of 

 figures. The whole will be calculated by two computers, in 

 order to guard as much as possible against errors. 



NAUTICAL MAGNETIC PREMIUM. 



The Board of Longitude have conferred the Parliamentary 

 premium of 500/. on Mr. Peter Barlow, of the Royal Military 

 Academy, for his method of correcting the local magnetic at- 

 traction of ships. The great quantities of iron employed at 

 this time in the construction and equipment of ships of war, 

 produce so much deviation in the compass (varying according 

 to the direction of the ship's head) as to render it almost an 

 useless instrument in certain situations, particularly in high 

 northern and southern latitudes. It appears by Lieutenant 

 Foster's report of experiments made in His Majesty's ship 

 Conway, under the superintendence of Captain Basil Hall, to 

 lat. 61 degrees S., and under that of Captain Clavering, in the 

 recent voyage of the Griper, to lat. 80 degrees north, that the 

 difference in the bearing of an object with the ship's head at 

 east and west, amounted to 28 degrees before the latter vessel 

 left the Nore: this difference afterwards amounted to 50 de- 

 grees at the North Cape, and to 75 degrees at Spitzbergen. 

 Great, however, as this effect was, the method recommended 

 by Mr. Barlow was completely successful in counteracting 



it, 



