52 REPORT—1845. 
XIV.—G. B. Airy, Esq., Astronomer Royal, to Sir John Herschel. 
Royal Observatory, Greenwich, April 7, 1845. 
My pear S1r,—I have to acknowledge the receipt of the circular letter 
issued by you on the part of a Committee of the British Association, dated 5th 
December 1844, and proposing certain queries regarding the propriety of 
continuing the existing magnetic and meteorological observatories beyond the 
termination of the present year, to which answers are invited. 
In the answers which I subjoin, I beg leave to refer to the numbers at- 
tached to the questions in your letter. : 
In reply to question 1. 
Several important points have already been made out from the observa- 
tions; and undoubtedly, by continuing the observations, these same points 
would be established with an accuracy somewhat (but not much) greater 
than at present. I do not expect to obtain anything new; but it is scarcely 
possible yet to tell, for want of reduction and digestion of the observations as 
far as they are made. It seems not improbable that a great part of what 
future theory may suggest can be made out by simultaneous observations 
conducted at a comparatively trifling expense: at the same time it is certain 
that great light has been cast upon the interpretation of the simultaneous ob- 
servations by using them in conjunction with the hourly and two-hourly 
observations. All things considered, I do not see sufficient ground for con- 
tinuing the systematic two-hourly observations. 
In reply to question 2. 
If by “private research” is meant “research by persons not officially con- 
nected with the various Magnetical, &c. Observatories,” I do not believe that 
private research has been stimulated in the smallest degree. The research of 
persons connected with the observatories, in subjects nearly related to but 
not exactly included in the routine of the observatories, has naturally been 
much stimulated. 
In reply to question 3. 
I am totally unable, from want of discussion of the observations already 
made, to suggest anything. I perceive that strict simultaneity of observations 
and precisely similar construction of instruments are desirable; and I urge the 
latter point the more strongly, because there has been a sensible change in 
the construction of the instruments adopted for many observatories, and be- 
cause it is far more difficult to carry out any general regulation regarding 
the instruments than anything which depends on mere personal arrange- 
ments. 
I now advert generally to the general question, as requested in the last 
paragraph of the circular letter. 
First, it must be remarked that the object of these observatories is totally 
different from that of astronomical observatories. It is not intended to attach 
very great importance to the accurate determination of the present state of 
certain elements, or of their secular changes (as in astronomical determina- 
tions), not because they are unimportant, but because they can be determined 
in a very much less expensive way. It is scarcely an object to ascertain the 
co-efficients or argument-epochs of inequalities following known laws (as in 
astronomy), because the present state of the science does not admit of it. 
The object is, to make out such laws as we can, to use our discoveries for the 
suggestion of other observations, and from these to make out other laws, &e. 
Now it is to be remarked that we shall have at most of the observatories full 
five years of continuous and simultaneous observations. I certainly do 
think that these are sufficient to give us, with reasonable accuracy, the first 
