OF THE MAGNETIC DECLINATION AT POINT BAEEOW. 
507 
value ; especially those of the second year, when the situation of the ships was probably 
intermediate between the meridians of Toronto and Point Barrow. In the Royal Society 
at least the hope is still cherished that the recovery of these records, amongst the other 
journals and papers of the ‘Erebus’ and ‘Terror,’ may yet recompense the devotion and 
perseverance with which the research has been pursued. By the aid of the Royal Society, 
the distinguished officer who has recently quitted our shores for the Polar Sea in com- 
mand of the Fox Yacht, has been supplied from the Kew Observatory with the necessary 
instruments for observations of both the magnetic direction and force, to be used at the 
station where the ship wiU remain whilst the sledge parties are absent. All that the 
most zealous and earnest purposes can accomplish may be confidently expected from 
Captain IVPClintock and his associates in this honourable enterprise ; but the number 
of persons who can be considered as competent to take part in scientific observations is 
unfortunately but barely sufficient for the conduct of the travelling parties for the primary 
object for which the enterprise was undertaken. Such opportunities of special scientific 
research are of rare occui’rence ; and it is greatly to be regretted that Mr. Geay, Mate 
in the Royal Na\"y, who having served under Captain Maguiee in the ‘ Plover’ had been 
well trained in magnetic observations, and was most desirous to have accompanied 
Captain M'^Clixtock, was unable to procure from the Admiralty leave of absence from 
his employment on the Coast Guard Serwce. 
But, to return to the Point Barrow observations: — It is well known that apparent 
anomahes have been found in the diurnal variation of the declination in the high magnetic 
latitudes of the northern hemisphere, when compared with the regular and consistent 
diurnal march of the phenomena in other parts of the hemisphere. It is usually a prmcipal 
featui’e in these anomalies, that the westerly extreme of the diurnal range, which most 
commonly elsewhere occurs between I and 2 p.m,, is found to take place later in the after- 
noon, and even in some cases nearly as late as midnight. A leading step towards the 
explanation of these apparent anomalies was made, when it was shown that the diurnal 
variation derived Rom a mean of all the observations must in all instances be regarded 
as the joint effect of two distinct variations superimposed upon each other, proceeding 
from different causes and having different laws, viz. the occasional disturbances, and the 
regular solar variation. Hence it was natural to imagine that in passing from the parts 
of the hemisphere where the regular solar variation predominated, by reason of its 
greater amount, to other parts where the disturb ance-variation should predominate, 
differences, of the nature of the so-called anomalies, would present themselves in the 
results which should comprehend their joint effects. Still, however, in attempting, with 
the very hmited knowledge that was then possessed of the differences that might be sup- 
posed to take place in the disturbance-variation in different localities, to apply this mode 
of explanation to particular cases, doubts have been entertained of its sufficiency to meet 
the phenomena in all cases. The fact which has now been established by the compa- 
rison of the disturbances at Point Barrow and Toronto, that the prevailing disturbance- 
3u2 
