ON MAGNETICAL AND METEOROLOGICAL OBSERVATIONS. 53 
laws to which I have alluded above (if they are not, I can hardly conceive 
that any number of years would be found sufficient). And if they are suffi- 
cient, then I see that very great mischief is done by continuing them. At pre- 
sent, by the greatest efforts which it is possible to make, the Prague observa- 
tions are published in a roughly reduced form, only as far as 1843 ; those of 
Toronto and Greenwich as far as 1842, and no other so far. While the ob- 
servations continue, with the existing establishment of computers, there is no 
possibility of hastening this reduction and publication. Now we want leisure 
to complete the publication (to the same extent to which it has already gone). 
We want leisure further to discuss with reference to more scientific principles 
the observations at each station. We want leisure calmly to compare the 
results obtained at different stations. And above all, we want leisure to unite 
all by some such comprehensive theory as that by which Gauss united the 
then accessible observations of declination, dip, and intensity, all over the 
earth. As long as the observations shall be continued, so long a¢ leasé will 
those discussions be delayed, and so long aé /east will the real intellectual pro- 
gress of the science be put off. 
I am therefore clearly of opinion that it is desirable to terminate the pre- 
sent system of observations at the end of the present year. 
In thus terminating the existing system of observations, I do not consider 
that the attention to the subject is at all suspended. I consider that the at- 
tention is diverted to a more favourable direction ; and I look to the resump- 
tion of the observations at some future time as a probable consequence of it. 
Such observations would probably be undertaken under very different cir- 
cumstances from those of the present series. | New points of theory would. 
have been suggested, new stations selected, new instruments adopted ; and the 
object of the new series of observations would be, to make out the new laws to 
which I have alluded above. 
In all that I have said thus far, I have alluded only to the interests of sci- 
ence as involved in the decision as'to the time of terminating the observations. 
But I think that I should be wrong if I omitted to call attention to the ex- 
pense of the. observations. The annual expense of the Greenwich Magnetical 
and Meteorological Observatory, including printing, is almost £1200. This 
expense, while the observations and reductions are printed in the same detail, 
can scarcely be diminished. 
I request that you will use your discretion as to printing the whole or any 
part of this letter. i 
I am, my dear Sir, 
Very truly yours, 
G. B. Arry. 
XV.—Lieut.-Colonel Sabine to Sir John Herschel, Bart. 
Woolwich, April 21, 1845. 
My pear Srr,—It has been intimated to me that the consideration of the 
questions now before the Committee may be materially aided by such a brief 
notice as I may be able to take in the compass of a letter, of what the colonial 
observatories will have accomplished at the close of 1845, towards the fulfil- 
ment of the objects originally proposed; and of what further they may be 
expected to accomplish if their continuance is prolonged for another period. 
I propose to comply with this suggestion, and at the same time to state the 
opinions to which my own judgement at present inclines. 
I. Magnetical Observations.—We shall have determined the absolute values 
of the different magnetic elements at the several stations with as much, or 
