506 MAJOErGENEEAL SABINE ON THE EESULTS OP HOUELT OBSEETATIONS 
on the earth’s surface where the periodical laws of the occasional disturbances have 
hitherto been examined, are too few to furnish a basis for prudent generalization. The 
'primary dependence of the disturbances upon the sun seems to be established by the 
universality with which, wherever they have been examined, their mean effects have 
exhibited a variation regulated by the hom’s of solar time ; as well as by the evidence 
which has been uniformly furnished, wherever the investigation has been made, of their 
participation in the same solar period which appears to govern the increase and decrease 
in the frequency and amount of the solar spots. Perhaps the next most important ques- 
tions which present themselves for solution concern the mode of operation of the pri- 
mary or exciting cause ; whether, for instance, the phenomena which we obsen e are the 
results of the sun’s influence, acting independently of the magnetism of the earth, — or of 
a reaction, in which the specialities of the latter will require to be taken into the account ; 
or whether, as may possibly be the case, the action of the primary cause is modified in 
different localities by physical considerations of other kinds, such as particular condi- 
tions of the earth or of its atmosphere. It may be possible that a further knowledge of 
the phenomena at a very few additional stations, supposing them to be judiciously distri- 
buted, might be sufficient for the solution of these or similar questions ; particularly if the 
observations were to include variations of the magnetic /br’ce as well as of the magnetic 
direction. The instrumental means and the processes of observation are sufiiciently 
simple. Instruments similar to those which have been so usefully, and so honoiu-ably 
to themselves, employed by Captain Maguike and his officers, have been sent vith 
nearly all the expeditions which, in the last twelve years, have wintered within the Ai-ctic 
circle ; but the maintenance of a routine of hourly observation during several morrths 
of compulsory deteirtion, in the absence of authoritative direction or professional 
errcouragement, requires perhaps a greater amourrt of private zeal arrd devotion than 
carr be expected, unless in such exceptiorral cases as the orre which has srrpplied the 
materials for this commuirication. In one of these expeditions in particular (the only 
oire that unhappily has not returned in safety), the well-krroum zeal of its commarrder 
Sir John Franklin in the cause of scierrce, and the anxiety of his officers to cooperate 
with him irr every useful and honourable work, gave reasoir for hopes of the highest 
promise. In the letters written by the commanders of the ‘ Erebus’ and ‘ Terror’ after 
their arrival at Baffin’s Bay, the full purpose of establishing their magnetic observatories 
on shore or on the ice, wherever the ships should be detained during a tvinter, is promi- 
nently dwelt upon. They were provided with instruments for the variation of the force 
as well as of the direction, prepared at W oolmch imder the superintendence of my then 
assistant. Captain Biddell. That observations icere made with these instruments at the 
first winter station, in 1845-1846, no reasonable doubt can be entertained; or that the 
observations were repeated at one at least of the subsequent occasions of similar detention 
in a new locality. The records of these obseiTations, too voluminous to have been brought 
away by parties setting forth with the prospect of hating to make their way across the 
continent to the Hudson’s Bay Stations, could scarcely fail to possess a high scientific 
