370 JOSEPH LOVERING. 



management of the primitive astronomical observatory first located 

 at Cambridge in the dwelling-house still remaining on the corner of 

 Quincy and Harvard Streets, and there took part in that concerted on- 

 set on the problem of the earth's magnetism instituted by Humboldt 

 and Gauss, and continued throughout the British Empire for several 

 years under the direction of the Royal Society of London. An appeal 

 was made to various academies and men of science in this country to 

 co-operate in the work, and the appeal was responded to by the Mag- 

 netic Observatory at Philadelphia under the care of the late Professor 

 Bache, and by the Americau Academy of Arts and Sciences in Boston, 

 who supplied the Cambridge Observatory with the requisite instru- 

 ments. The plan of the Royal Society involved, besides frequent reg- 

 ular daily observations, an almost continuous watch on the magnetic 

 needle during one day of each mouth. On these days, called term 

 days, observations were made every five minutes on three different 

 instruments, day and night. The chief burden of all this work fidl 

 on Professor Lovering, although he was greatly assisted, not only 

 in the observations themselves, but also in their reduction and in 

 the mathematical discussion of the results, by Professors Bond and 

 Peirce and a few competent undergraduates. Of these last, the late 

 Thomas Hill, afterward President of Harvard College, and Benja- 

 min A. Gould, the present distinguished astronomer, deserve special 

 mention. 



Professor Lovering's experience in this famous magnetic campaign 

 must have familiarized him with the magnetic disturbances accompany- 

 ing the auroral discharge, and thus led him to discuss the mooted ques- 

 tion of the periodicity of the aurora. His study of this problem was 

 the most considerable work of his life. It involved the collating and 

 discussing of an immense number of more or less indefinite observa- 

 tions, and the mere presentation of the result of this long and laborious 

 investigation occupies over 350 pages of the quarto Memoirs of this 

 Academy, New Series, Vol. X. Part I. In this memoir, Professor 

 Lovering clearly defined the secular periods of the aurora, and also 

 showed that no apparent connection could be traced between the 

 secular periodicity of the aurora and the secular changes of the earth's 

 magnetism, the periods of sun-spots, fire-balls, or earthquakes, or any 

 other secular changes with which the aurora had been associated 

 by various physicists. As he writes in this memoir, " A lesson of 

 caution against hasty conclusions on subjects of such complexity may 

 be drawn from the fact, that whereas Bone favored the conclusion 

 that the aurora goes hand in hand with the earthquake, and whereas 



