in connection wittt tlie Aurora of Oct. 14, 1870. 81 



photographs, taken at several stations differing greatly in longi- 

 tude. This shows the absolute necessity of several such stations ; 

 and that ftiture research in this direction cannot rely alone on 

 the work of the Kew Observatory. Also, the prevalence of 

 cloudy weather in England, especially during- the lall and 

 winter months, will add force to the above opinion. 



Kapid changes in spot-area are well known to nl! students of 

 the solar surface. A good example occurred in the lar.uvst spot 

 in the S.W. quadrant of the sun dunni:- the tnne ot tlie 

 memorable eclipse of Aug. 7, 1869. ]\[easnreiueuts on two 

 photographs, taken at intervals of about two Inmis uaye a 

 closing up of the umbra of 2360 miles in a X.E. :uul S.W. 

 direction. (See my report on the eclipse in Get. No. oi the 

 Jour, of the Franklin Inst). The astronomer Wallaston says : 

 — " Once I saw, with a 12-inch reflector, a spot Inu-st m pieces 

 while I was looking at it. I could not expect such an event, 

 and therefore cannot be certain of the exact particulars ; but 

 the appearance, as it struck me at the time, was lik(> that ol a 

 piece of ice when dashed on a frozen pond, which breaks in 

 pieces, and slides on the surface in varicnis dira'tH.ns. I was 

 then a very young astronomer, but I think I may be sure ot 

 the fact." 



Carrington, Hodgson and Brodie have oljserved brilliant 

 clouds appear in the neighborhood of spe>ts. and i)roL;ress with 

 a velocity of over 6,000" miles per minute: whih- Prot: C. A. 

 Young has recently made a most remarkable spectrosco]»ic 

 observation of two such brilliant clouds— together over 130,000 

 miles in breadth— which in ten minutes had contracted their 

 dmiensions to an enormous extent ; this however, judgmg from 

 analogy, was probably due to vertical motion. 



The question now naturally presents itself :— In case this 

 phvsical connection between the disturbed solar area and the 

 terrestrial magnetic condition exist, in what does it consist. 

 What is the nature of this connection ? Is it owmg to an induc- 

 tive action of the sun? if so, the magnetic intensity of a body 

 depending greatly upon the condition of its surface, that induc- 

 tive action will vary with the character of its surface, li this 

 be the case then we should take into consideration the probable 

 condition of the hidden solar hemisphere, deduced from preced- 

 ing obsei-vations on it where it was visible combined with subse- 

 quent ones when it again appeared. But can we apply such 

 reasoning to a body covered with tumultuous gases heated to 

 an enormous temperature ? Does not the connection consist m 

 the action of the solar vibrations sent forth from the chiel 

 source of all energy ? The experiments of Mornchim, Mrs. 

 Somerville, Zantedeschi and others were once viewed as con- 

 clusively showing effects produced by these vibrations sufhcient, 

 not only to increase the magnetic intensity of natural and arti- 



