NOTES. XXV11 



jections which Necker and Forbes have raised as to the result, see vol. xiv. of 

 the Transactions of the Eoyal Society of Edinburgh, 1840, p. 23 25. [All the 

 elevations given in this and the preceding note are, as in the original, in French 

 feet; it did not appear necessary to encumber the page by stating them in Eng- 

 lish feet likewise. Ed.] 



( 113 ) p. 104. Compare Laugier and Mauvais, in the Comptes rendus,t. xvi. 

 1843, p. 1175, and Bravais, Observ. de I'lntensite* du Magne'tisme terrestre en 

 France, en Suisse et en Savoie, in the Annales de Chimie et de Phys. 3 9 se'rie, 

 t. xviii. 1846, p. 214; Kreil, Einfluss der Alpen auf die Intensitat, in the 

 Denkschriften der Wiener Akad. der Wiss., mathem. naturwiss. Cl. Bd. i. 1850, 

 S. 265, 279, and 290. It is the more remarkable that a very exact observer, 

 Que'telet, should have found, in 1830, the horizontal intensity at Geneva 1*080, 

 at the Col de Balme 1-091, and at the Hospice on the Grand St. Bernard 1*096, 

 being an increase with increasing elevation. Comp. Sir David Brewster, Treatise 

 on Magnetism, p. 275. 



( 1H ) p. 104. Annales de Chimie, t. lii. (1805) pp. 86 and 87. 



( 115 ) p. 104. Arago, in the Annuaire du Bureau des Longitudes pour 1836, 

 p. 287. Forbes, in the Edinb. Trans, vol. xiv. (1840) p. 22. 



( 116 ) p. 105. Faraday, Exper. Researches in Electricity, 1851, p. 53 and 

 77, 2881 and 2961. 



( m ) p. 106. Christie, in the Phil. Trans, for 1825, p. 49. 



( 118 ) p. 106. Sabine, On the periodical Laws of the larger magnetic Disturb- 

 ances, in the Phil. Trans, for 1851, Pt. I. p. 126; and the same, On the annual 

 Variation of the magn. Declin., in the Phil. Trans, for 1851, Pt. II. p. 636. 



( 119 ) p. 107. Observ. made at the Magn. and Meteor. Observatory at Toronto, 

 vol. i. (18401842) p. Ixii. 



( 12 ) p. 107. Sabine, in Magn. and Meteor. Observations at Hobarton, vol.i. 

 p. Ixix. " There is also a correspondence in the range and turning hours of the 

 diurnal variation of the total force at Hobarton and at Toronto, although the 

 progression is a double one at Toronto, and a single one at Hobarton." The time 

 of the maximum force is, at Hobarton, between 5 and 6 P.M., and that of the 

 principal maximum at Toronto 6 P.M. ; the time of the minimum at Hobarton is 

 between 8 and 9 A.M., and that of the secondary minimum at Toronto at 10 A.M. 

 Therefore, according to local time, the increase and decrease of the force follow 

 the same hours in the two hemispheres; not the opposite ones, as in the case of 

 the inclination and declination. On the causes of this phenomenon see p. Ixix. 

 of the above-cited work. (Compare also Faraday, On Atmospheric Magnetism, 

 30273034.) 



( m ) p. 107. Phil. Trans, for 1850, Pt. I. p. 215 to 217; Magnetical Ob- 



