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ON MAGNETICAL AND METEOROLOGICAL OBSERVATIONS. 39 
most welcome, and indeed indispensable, to be possessed of such a stock of 
exact facts relating to several parts of the earth as have been furnished by 
the English magnetical and meteorological observatories. In the first place, 
as regards the laws of periodical changes, the probable error of each particular 
observation has been exceedingly reduced by the exemplary and successful 
care your observers bestowed on the examination of the instruments employed. 
If therefore the phenomena under investigation were strictly periodical, | am 
inclined to think that a set of five years’ observations would suffice for deter- 
mining exactly the constants of the series that must represent them. But in 
reality this is not the case. In almost every one of the phenomena examined, 
the particular values for a given day varied so much from the average peri- 
odical range, and the discovery of the law of these variations relative to many 
of these phenomena is of so much importance, that the prolongation of the 
activity of the English observatories beyond the period of five years is ren- 
dered particularly desirable by this same circumstance. Let me quote only 
one example of this fact, out of the great number that actually exist. The 
English observations have first demonstrated that the instantaneous changes 
of terrestrial magnetism do not take place at so strictly contemporaneous mo- 
ments in America and in Europe as we were led to surmise by the European 
observations only. The proofs of this important fact however have not been 
obtained for every day of the period of observations, but only during the so- 
called term days, in which the English operations corresponded with those of 
the German Magnetic Association (Verein). How desirable would it be, 
notwithstanding, to discover on which of the stations a given perturbation 
has first occurred, and in what degree and rate of proceeding it has extended 
to the other points of observation! It is only by this course that we may 
hope to fathom the true law of these momentary variations of magnetic 
power ; or, in other words, the real position of their active cause and the pro- 
pagation of its effects. It will certainly be of material service to a future in- 
quirer on this subject to be provided with simultaneous observations of all the 
principal meteorological phenomena; but nevertheless it may be confidently 
predicted that he will be highly gratified to be furnished with the results of a 
longer series of observations than those given by a period of five years. Any 
one who has been engaged in similar investigations will recollect the pleasure 
he has often felt if, after having had a limited number of observations as the 
basis of his work, he has been able to strengthen it by the addition of some 
new ones. It seems to me, therefore, that the English Government will give 
a new proof of the zeal so worthy of a free and happy nation which they have 
displayed in the patronage and promotion of science, by granting a prolonga- 
tion of their magnetical and meteorological observations, in exactly the same 
manner as they have been proceeding hitherto, even after the expiration of the 
year 1845. A sufficient encouragement for the continuation of this institu- 
tion is afforded indeed by the brilliant results already obtained, which would 
immortalize it, even if its visible existence should be prematurely discontinued. 
I allude particularly to the exactitude of the mean annual values obtained at 
the different stations for every particular phenomenon. Toronto, for instance, 
affords in meteorological respects a highly interesting comparison with the 
opposite (western) coast of America. In an article on the climate of Ross 
in California, which I take the liberty of inclosing, I fixed the isothermal line of 
Yy°-267 R.= the mean temperature at the level of the sea, in 38° 34! lat., 233° 41! 
long. east of Paris. A further investigation proved that there is scarcely a 
point on our globe where in an equal latitude the mean temperature is as low 
as under this meridian, although in higher latitudes it is distinguished by re- 
