172 THE POPULAR SCIENCE MONTHLY. 



it probably nowhere exceeds five thousand ; that in depths of about 

 two thousand fathoms there is the globigerina ooze, a substance resem- 

 bling chalk, formed of the shells of living organizations that existed 

 on the surface of the sea, and sunk to the bottom on the death of the 

 animal. This ooze occupies considerable portions of the bed of the At- 

 lantic, Pacific, and Southern Oceans. In depths below three thousand 

 feet an extremely reddish clay is found, which is apparently the decom- 

 position of submarine volcanoes and of decomposed organisms. What 

 is at present forming a great depth does not correspond, either in 

 structure or chemical composition, with any known geological forma- 

 tion, and warrants the belief that none of the older formations of the 

 globe were laid down at such great depths. Sir Wyville Thomson 

 adopts the opinion of Professor Dana, of Yale College, that the erup- 

 tions which originated the mountain-chains that form the skeleton of 

 our present continents, and the depressions occupied by our present 

 seas, arose from the cooling and contraction of the crust of the earth 

 at a period more remote than the deposition of the earliest fossiliferous 

 rocks. 



Dr. Kroll, of Gottingen, has also been engaged in investigating the 

 depth of the ocean, and estimates the mean depth at 1,877 fathoms, an 

 estimate not very much below that of Sir Wyville Thomson. 



In meteorology the most notable phenomena have been the very 

 marked changes of the ordinary temperature in different parts of the 

 world, particularly in western Europe, in certain parts of Asia, and 

 in the eastern portion of the United States. It has been marked in 

 Europe by winters of increased severity and an undue prevalence of 

 moisture in the spring and summer, attended by very disastrous con- 

 sequences to agriculture in Great Britain, France, and some other 

 countries. The last winter on the European Continent, as well as in 

 Great Britain, has been one of the severest upon record. In France 

 the thermometer has never been so low since 1795, with the exception 

 of one year, 1871, when the cold, however, was but of short duration. 

 In Switzerland and southern Germany, especially in the mountainous 

 parts, the severity of the winter has been exceedingly disastrous ; while 

 in this country the winters especially the present winter have been 

 of unusual mildness in all the States east of the Mississippi. 



In Asia the changes in the ordinary temperature have been equally 

 remarkable. In the mountains of Cashmere there was a snowfall last 

 winter extraordinary even in that mountainous region. In certain 

 places it snowed uninterruptedly and heavily for ten continuous days, 

 the snow upon the level plains being from thirty to forty feet deep, 

 and in some of the mountain-passes it was piled up to a height of one 

 hundred and fifty feet, and in others to two hundred and fifty feet. 



Various conjectures have been advanced as to the cause of this 

 unusual change of temperature. A writer in the " New York Herald " 

 attributes the fact that the spring and summer in Europe was exces- 



