38 REPORT—1845. 
rather as consequent on the published results of the observatories, than as 
coincident with their labours, that we may expect to see private exertion 
stimulated and directed, and science advanced by these means. Individual 
efforts may be useful at the beginning to indicate, and finally to complete the 
application of great natural laws, but in such branches cf knowledge as mag- 
netism, the great body of facts must embrace areas of surface, duration of 
time, and frequency of observation, which remove all but special problems 
from the domain of private exertion. Nor can these special problems be 
properly defined or prosecuted by good methods until the more general re- 
sults to which they are supplementary are further advanced. 
If indeed self-registering instruments can be found for magnetism, it may 
become popular, as meteorology undoubtedly is popular, however little ad- 
vanced by the circumstance. 
3. In respect of magnetical phenomena, the systematic, simultaneous and 
extraordinary observations appear to include all that is essential. To the 
meteorological registration something may be added. 
To complete the data for studying the relations of heat and moisture, it is 
desirable to have observations of the thermometer and wet-bulb hygrometer 
at more than one height above the ground. If at three or four levels, say 
3, 6, 12, 24 feet above the surface, these instruments were frequently ob- 
served, information would be gained concerning the distribution of heat and 
moisture, in the part of the atmosphere where these conditions are the most 
variable, which could not fail to be important. 
There would probably be little difficulty in adding to the observations a 
register of long thermometers, sunk 3, 6, 12, and 24 feet below the surface, so 
as to extend the basis of the laws of distribution of daily and annual heats at 
small depths, which have been developed by Quetelet and Forbes. 
The rate of evaporation of water appears worthy of record, in connection 
with so complete a system of two-hourly (better hourly) temperature and 
hygrometry, especially as this observation may be found hereafter a valuable 
check upon the mechanical indications of the anemometers, which taken alone 
are liable to some objection. 
Very truly yours, 
To Col. Sabine, R.A., Woolwich. JOHN PHILLIPS. 
XI. Dr. Adolphe Erman, of Berlin, to Sir John Herschel and the Com- 
mittee of the British Association for the Advancement of Science. 
Berlin, March 11, 1845. 
GENTLEMEN,—I had the pleasure, a few days since, of receiving the volume 
entitled ‘ Observations at the Toronto Observatory, 1840 to 1842,’ and take 
the earliest opportunity of expressing my thanks to the British Government, 
through your kind intervention, for this most important present. Magnetical 
and meteorological observations made so uninterruptedly, and with such per- 
fect regard of all important circumstances as those contained in this volume, 
are of immeasurable value for the physical knowledge of our globe. The 
true object of meteorology appears more and more to be twofold, viz.— 
1. The representation of the periodical changes of every pheenomenon by 
function of sines ; and 
2. The representation of the mean values of the various phenomena by the 
V functions of Laplace, which must be applied to the values of atmospheric 
pressure, temperature, &c. observed in different points of the globe, as they 
have been by Gauss to the phenomena of terrestrial magnetism. 
Which part soever of these two we may employ ourselyes with, it is always 
