PHILOSOPHICAL SOCIETY OF WASHINGTON. 35 



country between the Ural Mountains and Lake Baikal. It will 

 be extremely important in giving us a correct knowledge of the 

 elevation of a great part of the Asiatic Continent. Barometric 

 observations are entirely inadequate for this, as we do not know 

 the normal pressure which must prevail there. 



The expedition is again to be conduoled by Col. Tillo. Besides 

 the help afforded by the Geographical Society, there are 7000 

 roubles of private contributions to the expenses of this work, and 

 more money is expected. 



Dr. WoEiKOPP also gave an account of 



METEOROLOGICAL OBSERVATIONS IN PERU, AND OP SOME OF THE 

 METEOROLOGICAL CONDITIONS IN THAT COUNTRY, 



and stated, in reply to inquiries, that Lake Titicaca is more than 

 12,000 feet above the sea-level ; that the changes there of mean 

 diurnal temperature were very small, but there was often a dif- 

 ference of 40° between the day and night temperatures ; and 

 therefore its vicinity was not suitable for an astronomical observa- 

 tory. 



Mr. Gill remarked that in Lakes Bacal and Titicaca are seve- 

 ral species of fish of peculiar types not found elsewhere, 



Mr. Joseph Henry made a communication on 



THE glacial theory, 



remarking that in all theories on the subject, attempts were made 

 to explain the abnormal cold ; but the enormous accumulation 

 of snow also required explanation. He presented an hypothesis, 

 which he had adopted many years ago, of extensive outbursts of 

 submarine volcanoes in the equatorial regions, sending out im- 

 mense volumes of steam, which, carried to a high elevation and 

 flowing northward, would be precipitated as snow of an abnor- 

 mally low temperature. More of this snow falling in winter than 

 was melted in summer, the accumulation in many successive years 

 would be sufficient to satisfy the demands of the glacial theory ; 

 while the power sufficient to move boulders would be produced 

 by the changes in this accumulation from cracks and fissures, and 

 their filling up with water subsequently freezing. 



The earth in that period, as a whole, may have had a higher 

 temperature than that which it has at the present time. This 

 theory rests on a single hypothesis — that of the existence at the 



