Chase.] 432 [October. 



all localities in North America, where the laws of the disturbances 

 have been investigated. But ... at Nertschinsk and Pekin . . . 

 the conical form and single maximum characterize the icesterly de- 

 flections, whilst the easterly have the double maximum. . . . At the 

 two Asiatic stations, the aggregate values of the vie&terly deflections 

 decidedly predominate, whilst in America the easterly deflections 

 are no less decidedly predominant; and at Kew, . . . the amount of 

 deflection in the two directions may be said to be balanced;" p. 282. 



10. The diff'erences of the weekly from the annual means of 

 declination, indicate " with a very high degree of probability, an an- 

 nual variation, whereby the north end of the magnet points more 

 towards the east when the sun is north, and towards the west when 

 the sun is south of the equator;" p. 291. 



11. The residual errors in the monthly determinations of the Hori- 

 zontal Force and of the Dip, "are thoroughly confirmatory of a semi- 

 annual inequality, having its epochs coincident, or nearly so, with 

 the sun's passage of the equator;" p. 303. 



12. There appears to be "an increase of the Dip and of the Total 

 Force, and a deflection of the north end of the Declination magnet 

 towards the West, in both hemispheres, in the months from October 



to March, as compared with those from April to September 



The greater proximity of the earth to the sun in the December com- 

 pared with the June Solstice most naturally presents itself as a not 

 improbable cause ; but we are as yet too little acquainted with the 

 mode of the sun's action on the magnetism of the earth, to enter 

 more deeply into the question at present;" p. 307. 



I have neither the leisure nor the ability to undertake an exhaus- 

 tive analysis of the results thus brought together ; but I present them 

 as well worthy of a profound mathematical investigation, as con- 

 firmatory in very striking and minute particulars of my mechanical 

 hypotheses, and as furnishing new and strong presumptive evi- 

 dence of that marvellous simplicity of force to which many indepen- 

 dent branches of modern physical research so strongly point. This 

 evidence is strengthened by the existence, as I have shown elsewhere, 

 of the tidal law of sines in the solar-diurnal variation of the magnetic 

 needle, by the magnetic effect of the daily barometric rotation-tide, 

 as exhibited in the convergence of lines of equal barometric disturb- 

 ance towards the hours of high barometer and their divergence from 

 the hours of low barometer, by many points of resemblance between 

 the daily and yearly variation-curves, both of temperature and of 

 magnetism, and by certain considerations confirmatory of the reason- 



