ASTRONOMY AXD METEOROLOGY. 391 



prevailed. 'In referring to periodic changes of the atmosphere, we 

 should not be guided, in this country, by observations made in Europe, 

 where very different conditions of the atmosphere prevailed. 



Mr. W. C. Redfield remarked that nothing could be more unfounded 

 than the traditional notion of an immediate or special connection be- 

 tween the equinox and the storms of that period. The meteorological 

 records which he had examined afford no ground for this very preva- 

 lent opinion, as will equally appear whether we view the fall of rain 

 above as constituting the storm, or consider the rain as but a common 

 though not essential feature of a storm or gale. 



ALTERNATION OF COLD AND WARM SEASONS. 



THE idea of a cycle of good and bad seasons has often been mooted 

 by meteorologists, and has frequently recurred to my thoughts when 

 endeavoring to find a reason for the ease with which, at some periods 

 of arctic discovery, navigators were able to penetrate early in the sum- 

 mer 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 presented 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 shown, 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 

 probable 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 mean 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 curves are not likely to be coincident with, 

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

 pherical currents from the south, which, for a period, raise the annual 

 temperature of England, must be counterbalanced by currents from the 

 north or other meridians. The annual heat has been diminishing 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 favorable condition of diminution, 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 favorable years 

 of the cycle, the ice, produced in the unfavorable ones which followed, 

 has shut him in, and been found insurmountable. Sir J, Richardson's 

 Arctic Expedition. 



