130 COSMOS. 



Singapore lies a little to the north of the geographical 

 equator, between the latter and the magnetic equator, which, 

 according to Elliot, coincides almost exactly with the curve 

 of lowest intensity. According to the observations which 

 were made at Singapore every two hours during the years 

 1841 and 1842, Sabine again finds the St. Helena types in 

 the motion of the needle from May to August and from 

 November to February ; the same occurs at the Cape of 

 Good Hope, which is 34 distant from the geographical and 

 still more remote from the magnetic equator, and where 

 the inclination is 53 south and the sun never reaches the 

 zenith. 66 We possess the published borary observations made 



1847, pt. i, pp. 51 56, pi. iii. The regularity of this opposition in the 

 two divisions of the year, the first occurring between May and Sep- 

 tember (type of the middle latitudes in the northern hemisphere), 

 and the next between October and February (type of the middle lati- 

 tudes in the southern hemisphere), is graphically and strikingly mani- 

 fested when we separately compare the form and inflections of the 

 curve of horary variation in the portions of the day intervening be- 

 tween 2 P.M. and 10 A.M., between 10 A.M. and 4 P.M., and between 

 d P.M. and 2 A.M. Every curve above the line which indicates the mean 

 declination has an almost similar one corresponding to it below it 

 (vol. i, pi. iv, the curves A A and BB). This opposition is perceptible 

 even in the nocturnal periods, and it is still more remarkable, that 

 while the type of St. Helena and of the Cape of Good Hope is found to 

 be that belonging to the northern hemisphere, the same earlier occur- 

 rence of the turning hours which is observed in Canada (Toronto) is 

 noticed in the same months at these two southern points. Sabine, 

 Olserv. at Hobarton, vol. i, p. xxxvi. 



66 Phil. Transact, for 1847, pt. i, pp. 52, 57, and Sabine, Observations 

 made at the Magn. and Meteor. Observatory at the Cape of Good Hope, 

 1841 1846, vol. i, p. xii xxiii, pi. iii. See also Faraday's ingenious 

 views regarding the causes of those phenomena, which depend upon 

 the alternations of the seasons, in his Experiments on Atmospheric 

 Magnetism, 3027 3068, and on the analogies with St. Petersburg, 

 3017. It would appear that the singular type of magnetic declina- 

 tion, varying with the seasons, which prevails at the Cape of Good 

 Hope, St. Helena, and Singapore, has been noticed on the southern 

 shores of the Red Sea by the careful observer, d'Abbadie (Airy, On the 

 Present State of the Science o/ Terrestrial Magnetism, 1850, p. 2). " It 

 results from the present position of the four points of maximum of 

 intensity at the surface of the earth," observes Sabine, "that the im- 

 portant curve of the relatively, but not absolutely, weakest intensity in 

 the Southern Atlantic Ocean should incline away from the vicinity of 

 St. Helena, in the direction of thj southern extremity of Africa. The 

 astronomico-geographical position of this southern extremity, where the 

 eun remains throughout the whole year north of the zenith, affords a 



