56 Proceedings of Philosophical Societies. [July, 



tricity. Without making use of the eccentric anomaly, he 

 explained the invaluable formula given by Laplace, in his "Theory 

 du Mouvement et de la Figure Elliptique des Planetes." This 

 did not merely serve as a confirmation of the solution ofSchubert, 

 as the author found the numeral coefficients discovered by the 

 latter to be quite right ; but he also detected, by means of the 

 observations made during the process, a very simple and sym- 

 metrical law for the explanation of the true anomaly, in conse- 

 quence of which we may continue the same as far as we 

 please; as also fix every term, independently of the other 

 terms found out before. To these discoveries, the author added 

 several explanations and applications useful in theoretical 

 astronomy. 



It is certain that the magnetical needle does not every where 

 stand due north and south. In most places it declines con- 

 siderably either towards the east or the west. This deviation, 

 known at first only to seamen who made use of the magnetic 

 needle to direct their course at sea, was afterwards found 

 to lead to a knowledge of the spreading and diffusion of the 

 magnetic powers over the globe, and may, perhaps, hereafter 

 render the compass a still more perfect means of direction to 

 the mariner than ever it could, had it every where, without 

 variation, pointed to the same parts of the heavens. But if 

 we desire, in this respect, to make the wished-for progress, the 

 science must be continually enriched with observations respect- 

 ing the deviations of the needle, which is perpetually changing 

 in every place. 



For London and Paris they have been so fortunate, with respect 

 to the variations of the magnetic needle, as to have observations 

 that extend further back than two and a half centuries, but the 

 oldest of these cannot be considered as very exact. 



With us the two Louises, father and son, have, through most 

 part of the last century, made nice inquiries about the direction 

 of the magnetic needle. Our present director of navigation, 

 Mr. Wleugel, Commander and Knight, has, through a series of 

 years, occupied himself with inquiries about magnetism, and has 

 applied to this subject the additional knowledge and more per- 

 fect instruments with which he is favoured by the progress of 

 the age. 



In the remotest times, from which we have records of the 

 magnetic needle, it had a declination towards the east, which 

 gradually diminished, till about the middle of the 17th century it 

 < eased in most parts of Europe ; so that the needle stood regu- 

 larly north and south, which soon was followed by a declination 

 towards the west, that since that time has increased till very lately, 

 when this westward declination again seems to be diminishing. 

 But it is a matter of greater difficulty than it appears to be at first 

 sight to determine whether this alteration has taken place or not. 

 The declination of the magnetic needle is subject to incessant 

 variations ; every day is to it a period in which it increases and 



