846 Capt. J. H. Lefroy o« a great Magnetic 



-<^^-x\x\x^^x\xlx^^ 



-(p„=a;2^X + ^I-^I^i + 



— <^^=-X^X^X^-\-X^Xi^^ + 



-(^^-x\x\x^ + x\x\x^ + 



(pg — c*^./.5X_^-t-</:.^.X3<*g-^ 



By adding these six equations, the sum of the second mem- 

 bers will be a symmetrical function of iPj, &c., and we easily 

 find — 2(fi)=S(.2;'Ja;2), a given quantity. Thus the coefficient 

 of the second term of the equation of the sixth degree, of which 

 the roots are fj, (^5, &c., is known, and the other coefficients 

 may be found by means of it. It does not appear that there 

 is any other relation between (pj, f^? &c. ; and therefore it 

 would seem that the equation of the sixth degree is not redu- 

 cible. But if any one thinks that there may exist such a rela- 

 tion as * 



fl=/(^2)» 



y* denoting a rational function, he may, from what precedes, 

 make the trial. Success however seems so hopeless, that it is 

 pity that time and talent should be wasted upon it. 



Gunthwaite Hall, near Barnsley, 

 October 2, 1847. 



LV. Letter from Capt. J. H. Lefroy, B.A.^ Director of 

 the Magnetic Observatory of Toronto in Canada, to Lieut.- 

 Colonel Sabine, R.A., on a great Magnetic Disturbance on 

 the 2Uh of September 1847. 



Observatory, Toronto, 

 My dear Colonel, September 24, 1847. 



THIS day has been distinguished by a greater disturbance 

 than any we have had yet. The observed range of De- 

 clination was 4° 2' ; and I have little doubt that the actual 

 range was greater, as the non-commissioned officer on duty, 

 when he found that the movement was beyond the scale of 

 the Observatory declinometer, lost time in sending for me, 

 instead of at once lighting the lamp of the transportable one, 

 and following it up on that. The observed range of horizontal 

 force was over 600 divisions, or 0*052 of the horizontal force ! 

 The day has been raw and cloudy, with occasional rain, so that 

 if an aurora existed, it could not have been seen. The disturb- 

 ance seems to have begun between 2liiand 22'' Gottingen time 

 on the 23rd, as the observation at 22^ was decidedly unusual; 

 but extra observations did not commence until 23^ 20°*. The 

 extreme disturbance began about 0'' 35°* on the 24th, when 

 both thelargedeclinometer and large bifilar went off" their scales. 



