ON COMPARING AND REDUCING MAGNETIC OBSERVATIONS. 85 
any station, but whether they would be the same at other stations has 
not, as far as I know, been ascertained. Lloyd,as you know, worked out 
the consequences of adopting every possible value of disturbance test. 
Sabine has given two or three values, all purely empirical. If my plan 
of areas were practically feasible, it does seem to me free from that ob- 
jection. Dr. Wild appears to disregard magnitude, and to refer all the 
observed data to his normal values, and I think nothing less comprehen- 
sive will be found satisfactory inthelong run. It is gratifying, however, 
to find that his results are not widely different from those obtained by 
Sabine’s method. As Dr. Wild quotes Toronto, I suppose that some 
limited circulation and occasional comparison does go on, but Carpmael 
has no staff to keep it up regularly. We all want more hands, which 
means more money. 
Believe me faithfully yours, 
J. H. Lerroy. 
XII. Observations, §c. By Cuartes Cuaupers, F.R.S. 
Superintendent, Colaba Observatory, Bombay. 
There can be little doubt that the activity displayed during the last 
quarter of a century in the record of the phenomena of terrestrial mag- 
netism was induced mainly by the interesting results to which Sabine 
was led in his discussions of the observations of the British, colonial, and 
other observatories ; that it was in the hope of extending and completing 
such results by wider observation, that men of science in all parts of the 
civilised world urged upon their respective Governments the advisability 
of establishing magnetical observatories. ew who have studied Sabine’s 
Memoirs—displaying, amongst other remarkable generalisations, the out- 
lines of a system of the globe in respect of the regular solar diurnal: 
variations and the variations of these with the season of the year, and 
connecting with the sun-spot period variations of the range of the regular 
diurnal variation of declination and of the aggregate amounts of dis- 
turbance—will doubt the wisdom of the influence thus brought to bear 
on the guardians of the public purse, nor, whatever else may be done, of 
the propriety of carrying the work to the legitimate conclusion of extend- 
ing and completing Sabine’s results. To act otherwise, in the absence of 
a physical theory to which there is as yet no clue, would be to admit a 
change of judgment which there is nothing in the circumstances of the 
present day, any more than there was at the time when the work of auto- 
matic registration was initiated, to justify, and would, moreover, be to 
discourage the statesmen who, by the provision of funds, have aided in 
the production of records of the crude phenomena, from making farther 
Sacrifices in that direction: these dignitaries would, in their capacity of 
trustees for society, rightly complain that they had been led to expect 
systematised knowledge, but had been given instead piles of records of 
unused facts, and that the responsibility and expense of preserving these 
4s scarcely a substitute for the reward they had been dazzled with the 
promise of, 
2. In my opinion the scientific authorities, on whose advice much 
- money has been spent in procuring many years’ continuous records, are 
bound in honour to see that the representations which induced the various 
- Governments to provide funds are justified by at least a full carrying out 
