THE ADTAKCEMENT OF SCIEKCE. 67 



being and needs of mankind. Magnetism has been studied with two aims : the one, to 

 note the numerical relations of its actirity to time and space, both in respect of its 

 direction and intensity ; the other, to penetrate the mystery of the nature of the mag- 

 netic force. In reference to the first aim, ray estimable predecessor adverted, last 

 year, to the fact, that it was in the committee-rooms of the British Association that 

 the first step was taken towards that great magnetic organization ■which has since 

 borne so much fruit. Thereby it has been determined that there are periodical changes 

 of the magnetic elements depending on the hour of the day, the season of the year, 

 and, what seemed strange, intervals of about eleven years. Also, that besides these 

 regular changes there were others of a more abrupt and seemingly irregular charac- 

 ter — Humboldt's "magnetic storms," — which occur simultaneously at distant parts 

 of the earth's surface. Major-Geueral Sabine, than whom no individual has done 

 more in this field of research since Halley first attempted " to explain the change 

 in the variation of the magnetic needle," has proved that the magnetic storms ob- 

 served diurnal, annual, and undecennial periods. But with what phase or pheno- 

 menon of earthly and heavenly bodies, it may be asked, has the magnetic period of 

 eleven years to do 1 The coincidence which points to, if it does not give, the 

 answer, is one of the most remarkable, unexpected, and encouraging to patient ob- 

 servers. For thirty years a German astronomer, Sehwabe, had set himself the task 

 of daily observing and recording the appearance of the sun's disc, in which time he 

 found the spots passed through periodic phases of increase and decrease, the length 

 of the period being about eleven years. A comparison of the independent evidence 

 of the astronomer and magnetic observer has shown that the undecennial magnetic 

 period coincides both in its duration and in its epochs of maximum and minimum 

 with the same period observed in the solar spots. 



A few Aveeks ago, during a visit of inspection to our establishment at Kew, I 

 observed the succesful operation of the photo-heliographic apparatus in depicting 

 the solar spots as they then appeared. The continued regular record of the ma- 

 cular state of the sun's surface, with the concurrent magnetic observations now 

 established over many distant points of the earth's surface, will ere long establish 

 the full significance and value of the remarkable, and, in reference of the observers, 

 undesigned, coincidence above mentioned. Not to trespass on your patience by 

 tracing the progress of Magnetism from Gilbert to Oersted, I cannot but advert to 

 the time, 1807, when the latter tried to discover whether electricity in its most 

 latent state had any effect on the magnet, and to his great result, in 1820, that the 

 conducting wire of a voltaic circuit acts upon a magnetic needle, so that the latter 

 tends to place itself at right angles to the wire. Ampere, moreover, succeeded, by 

 means of a delicate apparatus, in demonstrating that the voltaic wire was affected 

 by the action of the earth itself as a magnet. In short, the generalization was es- 

 tablished, and with a rapidity unexampled, regard being had to its greatness, that 

 magnetism and electricity are but different effects of one common cause. This has 

 proved the first step to still grander abstractions, — to that which conceives the 

 reduction of all species of imponderable fluids of the chemistry of our student 

 days, together with gravitation, chemicity, andneuricity, to interchangeable modes 

 of action of one and the same all-pervading life-essence. Galvani arranged the 

 parts of a recently-mutilated frog so as to bring a nerve in contact with the exter- 



