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SCIENTIFIC INTELLIGENCE. 



METEOROLOGY. 



1. The Climatology of Arctic America in reference to the fate of 

 Sir John Franklin. — " The idea of a cycle of good and bad seasons 

 has often been mooted by meteorologists, and has frequently re- 

 curred to my thoughts when endeavouring to JSnd a reason for the 

 ease with which at some periods of Arctic discovery navigators were 

 able to penetrate early in the summer into sounds which subsequent 

 adventurers could not approach, and to connect such facts with the 

 fate of the discovery ships. But neither the periods assigned, nor 

 the facts adduced to prove them by different writers, have been pre- 

 sented in such a shape as to carry conviction with them, until very 

 recently. Mr Glaisher, in a paper published in the Philosophical 

 Transactions for 1850, has shewn, from eighty years' observations 

 in London and at Greenwich, that groups of warm years alternate 

 with groups of cold ones, in such a way as to render it most pro- 

 bable that the mean annual temperatures rise and fall in a series of 

 elliptical curves, which correspond to periods of about fourteen years, 

 though local or casual disturbing forces cause the means of particular 

 years to rise above the curve or fall below it. The same laws 

 doubtless operate in North America, producing a similar gradual 

 increase, and subsequent decrease of mean heat, in a series of years, 

 though the summits of the curve are not likely to be coincident with, 

 and are very probably opposed to those of Europe, since the atmo- 

 spherical currents from the south, which in a period raise the annual 

 temperature of England, must be counterbalanced by currents from 

 the north or other meridians. The annual heat has been diminish- 

 ing in London ever since 1844, according to Mr Glaisher' s diagram, 

 and will reach its minimum in 1851. It can be stated only as a 

 conjecture, though by no means an improbable one, that Sir John 

 Franklin entered Lancaster Sound at the close of a group of warm 

 years, when the ice was in the most favourable condition of diminu- 

 tion, and that since then the annual heat has attained its minimum, 

 probably in 1847 or 1848, and may now be increasing again. At 

 all events, it is conceivable that, having pushed on boldly in one of 

 the last of the favourable years of the cycle, the ice, produced in the 

 unfavourable ones which followed, has shut him in, and been found 

 insurmountable ; but there remains the hope that if this be the 

 period of the rise of the mean heat in that quarter, the zealous and 

 enterprising officers now on his track will not encounter obstructions 

 equal to those which prevented their skilful and no less enterprising 

 and zealous predecessor in the search from carrying his ships be- 

 yond Cape Leopold." — Sir John Richardson. 



2. Atmofipheric distribution of Iodine. — M. Chatin, the disco- 



