xxxii GENERAL SUMMARY OF SCIENTIFIC AND 



and non-existence of such connection. On tlie other liand, 

 it being apparent that the inHuence of solar spots, if it exist- 

 ed at all, should be most apparent in the temperature of the 

 atmosphere, Koppen has undertaken to investigate this point 

 in a more tllorou^h manner than had hitherto been done. Al- 

 though numerous and able men had for the past twenty-five 

 years studied the subject, and generally arrived at positive 

 conclusions as to the actual existence of such connection, yet 

 it seemed to Koppen that the study should be based upon a 

 broader field of observations, and he accordingly, instead of 

 confining himself to the observations of any one country, has 

 endeavored to sfct rid of all local climatic influences, by em- 

 bracing in his computations every accessible observation 

 of the temperature made during the past one hundred and 

 fifty years in the northern hemisphere. This immense mass 

 of material has been handled by him with the most con- 

 summate skill ; and his conclusions, which will be found in 

 detail in the subsequent part of this work, must be consider- 

 ed as proving in the most irrefragable manner the actual ex- 

 istence of a slight period in the temperature of the earth, fol- 

 lowing the changes in the solar spots at an interval of from 

 one to three years. 



Miihry has contributed an important chapter to our knowl- 

 edge of clouds and cloud formations, by calling attention to 

 an almost forgotten observation made by Meissner in the 

 course of his researches on ozone, from which it would seem 

 that in an atmosphere having no oxygen there can be form- 

 ed no true clouds, since only in the jM'esence of oxygen are 

 the true vapor vesicles observed. And, again, he has con- 

 tributed a most important theory as to the origin of atmos- 

 pheric electricity, in that he finds it to be in some sort a con- 

 version of the heat radiated from the sun into electricity, 

 which exists in greatest intensity at the surface of the earth, 

 and acts inductively upon the atmosphere above. The sug- 

 gestion lies not far off* that in this electricity we find the prin- 

 cipal disturbing agent acting upon the magnetic needle. 



Among the most memorable storms of the past year, the 

 so-called Nova Scotia cyclone takes precedence. According 

 to the short preliminary memoir of Abbe, this storm was first 

 lieard of at a ])oint east or northeast of the West India isl- 

 ands on the 13th of August, passing thence Avest and north- 



