\ 



Qitenes relative to Schumachei^s Tables. 24-9 



plain to what period of time the first line of his table is meant 

 to correspond, I shall feel much obliged. Perhaps he will 

 also condescend to give an example of the use of M. Schu- 

 macher's tables. I am induced to hope this, from his having 

 himself acknowledged the utility of it. In the work above 

 alluded to, he observes, " that it would be desirable that ma- 

 thematicians should agree among themselves, never to recom- 

 mend or adopt any table that is not accompanied with an ex- 

 planation of the method of using it." The force of this very 

 Just observation applies, in this instance, only to M. Schu- 

 macher, But as Mr. Baily has already had the goodness to 

 supply one defect of the tables, by continuing the supple- 

 mental one, I am not without hope that he may also be in- 

 duced to supply the odier; without which I am afraid they 

 must still remain useless to many persons who might wish to 

 avail themselves of their assistance, as well as to 



Your obedient servant, 

 Oxford, April 1-2, 1823. T. M. 



hV. On the late Opposition of the Planet Vesta. By 

 S. Geoomeeibge, Es(i. F.B.S. S^c. Sfc 



To the Editors of the Philosophical Magazine andjournal. 



VOUR Correspondent W. M. M. in the article No. 34, of 

 -■■ the Journal of last month, having stated some discre- 

 jiancies in the computation of the ephemerides of the planet 

 V^esta, for the opposition in June 1822, I will explain that 

 part which arises from the elements which I had used; and 

 which now appear from observation to be rather in excess of 

 the true place of the planet. I had assumed for the mean 

 longitude on 1st of January 1822, 216° 55' 6". The Tables of 

 M. Daussy for the same epoch, give 216° 37' 4'", a difference 

 of 18', to which I alluded when observing these had fallen 

 into arrear; and not recollecting at that time they were com- 

 puted for the preceding midnight, which would add 8' 8''*89 

 to the epoch for the twelve hours, and reduce the difference 

 to ten minutes. 



Tlie object in the computation of an ephemeris is to point 

 out nearly the situation of a planet for observation, from which 

 to deduce the elements ; and each succeeding opposition will 

 introduce corrections that continually approximate to the true 

 place of the planet. It is not therefore necessary for that 

 piupose to go through the labour of computing die varioiis 

 {)erturbutions of Uie elliptical orbit; but having found the 

 equation of the centre for each sixth dav at noon ; and takiiig 

 Vql. 61. No. 300. April 1823. ' I i out 



