130 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Bezold, who is led to the condusion that the phenomena of 

 thunder-storms show, in general, during the summer months 

 in the northern hemisphere, two maxima. These maxima ap- 

 proach each other in proportion as we go away from tropical 

 regions. They are scarcely distinguishable in Germany, but 

 are recognized by taking advantage of the observations in 

 Barnaul and St. Petersburg. Of all the stations examined, 

 only one, Katherineburg, shows a single maximum, and the 

 climate of this station is certainly, on many accounts, to be 

 considered as influenced less by the meteorological conditions 

 of the tropical zones than almost any other point in Europe. 

 It is considered therefore that we shall not go far wrong 

 if in the two maxima of electric phenomena, which is so 

 plainly seen in Europe, we recognize an echo of the two sum- 

 mers, or the two maxima of temperature experienced in the 

 tropical zones. Sitzb. K.-B. Akad. der Wissens.^ Munich^ 

 1875,220. 



CONSTITUTION OF THE ATMOSPHERE OVER THE LIBYAN 



DESERT. 



Pettenkofer has examined the air brought back from the 

 Libyan Desert by Dr. Zittel, the companion of Dr. Rohlfs, 

 with respect to the quantity of carbonic-acid gas contained 

 therein. He finds that the atmosphere in the desert has pre- 

 cisely the same chemical constitution as in Germany, where 

 the quantity of carbonic-acid gas varies between two and a 

 half and five ten-thousandths. He has also examined the air 

 contained in the water of springs, and finds the same agree- 

 ment. Sitzh. K.-B. Akad. der Wissens.^ Munich^ 1874, IV., 

 339. 



EFFECT OF TIDES ON THE ROTATION OF THE EARTH. 



Mr. Tylor, in some remarks on a new theory of tides and 

 waves, advocates the view that the level of the ocean is 

 nearly represented by high-water mark on coasts and bays 

 where there is free access of the tide, or in a channel without 

 a constant flow. He states that he entirely disbelieves in 

 tidal action having the smallest efl*ect on the rotation of the 

 earth, and that the assumption of a great heap of water trav- 

 eling: in one direction is a grross error. He also suoro-ests that 

 some geological difticulties, such as the evidence that tides 



