ON THE MONTHLY ISOTHERMAL LINES OF THE GLOBE. 85 
Remarks by Professor Dove on his recently constructed Maps of the 
Monthly Isothermal Lines of the Globe, and on some of the principal 
Conclusions in regard to Climatology deducible from them: with an 
introductory Notice by Lieut.-Col. Epwarp Sasine, Gen. Sec. 
[Tue report of the British Association for 1847 contained a communication 
from Professor Dove of the mean temperature in Fahrenheit’s scale of every 
' month of the year at above 800 stations-on the globe, to which he has since 
added in the volume for 1848 a supplemental list of 84 stations. [rom the 
materials thus collected and combined Professor Dove has constructed maps 
of the isothermal lines over the whole surface of the globe for every month of 
the year, which maps have been partly engraved and partly lithographed at 
_ the expense of the Royal Academy of Sciences at Berlin. ‘The Association 
has received from Professor Dove the very liberal offer of a supply of any 
number of copies of these maps that may be desired, at no other cost than 
that of the paper and of taking off the impressions. This offer having been 
received since the meeting of the Association at Swansea, the Council, who 
in the intervals between the meetings act on behalf of the General Committee, 
have directed that 500 copies of the plates,—which it is understood will be 
three in number, one containing the isothermals for January and July con- 
trasted, as being the months of greatest dissimilarity, and the other two 
- containing the isothermals of each of the twelve months separately repre- 
sented,—should be asked for, for the purpose of being offered to the mem- 
bers of the Association at a price which should merely cover their cost. It 
is expected that these copies will be received in England and be ready for 
distribution by the time of the Birmingham Meeting. 
- In part fulfilment of Professor Dove’s promise to lay before the British 
Association a notice of some of the more interesting conclusions in regard to 
climatology, to which he has been led by this extensive generalisation, he 
has communicated the following paper (written in German and translated by 
Mrs. Sabine), which the Council have directed to be inserted in the annual 
volume, as a supplemental report to the one printed in the volume for 1847; 
and they have also directed that a sufficient number of additional impressions 
should be struck off to furnish copies to accompany the maps. 
Epwarp SABINE, 
General Secretary. | 
Professor Dover's Supplemental Report. 
Tue preliminary works on which these maps are based, are printed in the 
Transactions of the Berlin Academy.. They treat of the elimination of the 
non-periodic and periodic variations of the temperature. 
The temperature of any particular month varies very much in different 
‘years ; its true value can therefore only be concluded from observations 
during a long series of years, and we possess such for so few places, that if 
we were to limit ourselves exclusively to them, the points through which the 
isothermals are drawn would be too few in number. It was therefore 
hecessary to find some means of correcting observations which extend over 
only a few years, so that they might be in some degree equivalent to con- 
‘clusions drawn from a longer period. This would be impossible if the va- 
_ Miations in different years were local in a very restricted sense, and an inquiry 
_ into this point was therefore the first thing required. The thermic march of 
_ the weather during an interval of 115 years, from 1729 to 1843 inclusive, was 
‘sought to be determined in four memoirs on the non-periodic variations of tem- 
_ perature on the earth’s surface ; this was done by forming tables of contempo- 
— series of observations for a considerable number of years, and dedu- 
x 
