ON MAGNETICAL AND METEOROLOGICAL OBSERVATIONS. 57 
The object of this publication being to present in their most salient point 
of view the irregular movements of the needle and variations of the magnetic 
force, it is necessary in the first instance to ascertain and subduct from the 
observed changes everything of a regular periodical nature which the actual 
amount of our present knowledge has enabled us to ascertain. This has been 
accordingly done, so far as Toronto and Van Diemen’s Land are concerned, 
both for the diurnal, monthly, and annual fluctuations of the magnetic ele- 
ments as far as it has been practicable yet to deduce them, and the results 
have afforded room for preliminary conclusions of no small interest, which 
have been stated by Colonel Sabine in his preface, and of which the follow- 
ing is a brief outline. 
At Toronto the regular diurnal movement in declination does not consist 
in a simple uninterrupted progress and regress of the needle. Commencing 
from 2" p.m. its movement is continuous to the eastward till 10 P.., it then 
returns westward (through a comparatively small angle) until 2? a.m., when 
its eastward movement is resumed and continued till 85 a.m., after which its 
return is continuous to the west until 2" p.a. This second eastward pro- 
gression is more decided in summer than in winter, and the total range 
of diurnal fluctuation is also more considerable. 
At Van Diemen’s Land (a station it is to be borne in mind almost 
antipodal to Toronto), the course of the diurnal oscillation corresponds with 
that above stated in all but one essential feature, viz. that the hours (in 
mean time at the station) of easterly movement of the north end of the bar 
at the one station are those of its westerly movement at the other, that the 
diurnal range being nearly the same in both, with a similar inequality in its 
summer and winter amount; a similar alternate progression and recess also 
prevails, and at the same hours. 
These are certainly very remarkable features, showing a regular connexion 
between two stations so remote, carried out into what may be regarded 
as minute particulars. Falling in however with the generally received im- 
pression of the universality of the causes (whatever they may be) which pro- 
duce the periodical fluctuations of the magnetic elements, they can only be 
regarded as contributions to our knowledge of details. It is otherwise with 
the results deduced by a comparison with each other of the observations 
recorded in this volume, not only at these two stations but also at St. Helena, 
and with those made by M. Kreil at Prague, as respects cases of unusual 
magnetic disturbance which occur (so far as we can yet perceive) casually, 
or at least non-periodically. Such comparison has enabled us at length, 
unequivocally, to state it as a general proposition, that the whole magnetic 
system of our globe is affected in the majority of cases of great disturbance. 
- For it is found that if a list of days of great disturbance, independently noticed 
as such, and marked by extra observations on each station, be made out, 
these lists will be found to coincide in at least a majority of days, and more 
especially on those days when the recorded disturbances have been greatest. 
Of twenty-nine principal disturbances recorded in Colonel Sabine’s Synoptic 
Table, some confined to a single day, others running through two or three 
‘successive days, and comprehending altogether forty-nine days, by far the 
greater part are shown to have manifested themselves at Toronto, Van Diemen’s 
Land, and Prague, and fifteen are marked by extra observations at St. Helena. 
_ But though it is thus rendered certain that the whole globe is affected in 
many and great “magnetic storms,” it is equally shown that the minute iden- 
tity of particular shocks, which seemed to result from the earlier observations 
of this nature in Europe, cannot be maintained (as a general proposition) as 
traceable on anything like so extensive a scale. 
