226 Proceedings of the British Association. 



reference to the daily as annual variation. This leads us to a more 

 precise definition of continental and sea climate ; the former is one in 

 which the diminution of pressure caused by the expansion of air 

 by heat is greater than the increase of pressure produced by the 

 evaporation of water ; the latter in which the contrary takes place. 

 The separating line, being that in which the compensation is exact, 

 passes between St. Petersburgh and Moscow. The true phenomena 

 of a continental climate are not met with in America, because there in 

 the summer months the quantity of vapour is so great as to produce 

 an over-compensation. — Sir J. Herschel spoke of the fact stated 

 by Sir James Ross of the low mean state of the barometer in the 

 southern seas, and concurred in the opinion, that the special attention 

 of meteorologists should be directed to it. 



* On M. Kreil's Self-Registering Meteorological Instruments,' by 

 Baron von Senftenberg. — The self-registering instruments of M. Kreil 

 register at intervals of 5' continually the state of the barometer, 

 of the thermometer, and of the hygrometer. The instruments are 

 placed at Prague and at Senftenberg, which is nearly due east of 

 Prague, about 100 English miles distant. It is situated on the Adler, 

 1281 Paris feet above the level of the sea, in latitude 50° 8' 8", and 

 longitude east of Greenwich 1 h. 5' 46" *98 ; situated on lias and mica 

 slate, and near higher grounds of granite, gneiss and old red 

 sandstone, and considerable forests. Prague is in a more level coun- 

 try, with the river Moldau flowing through it in a breadth of about 

 200 fathoms : it is only 524 feet above the level of the sea, without 

 much wood-land in its neighbourhood ; the surrounding hills being 

 lias, sandstone, and argillaceous schist. The Baron then exhibited 

 the dotted curves produced by the instruments, and the curves 

 and mean curves and tables deduced from them ; and showed their 

 use, by comparing the curves of Senftenberg with those of Prague, in 

 informing us at which the changes began to occur first ; this was 

 readily inferred from the coincidences of the curves after having 

 arrived at maxima and minima; — and concluded by pointing out, 

 as an exemplification of their utility, the curious relations at each 

 place during some remarkable thunder-storms. 



Sir J. Herschel next laid before the Section the Report of the 

 Magnetical and Meteorological Committee. As this Report was 

 printed and circulated among the members before the commencement 



