Mathematical and Physical Science, 345 



Greenwich 29*87. A glance at the table, however, shewed 

 how very small the extreme range of the instrument was on 

 the Nile. 



The average weight of a cubic foot of air at Greenwich was 

 549 grains, in Egypt 527 grains. 



Rain fell in various districts of England on averages 

 from 31 to 61 days, while in Egypt it only fell on 5 days, 

 and on three of these a shower was of but a few minutes' 

 duration. On two days rain fell heavily at Cairo for several 

 hours. 



The mean daily range of the temperature of the air at 

 Greenwich was 11*37, in Egypt 10-31 ; but while the mean 

 extreme range in Egypt was 38, at Greenwich it was but 29 ; 

 the mean extreme range in the cabin being only 7 degrees 

 below that on the grass at Greenwich in the open air. 



Fog was occasionally but rarely observed. It was general 

 in the Delta in the early morning ; but above Cairo was only 

 observed on three occasions. 



" On the Causes of the Rise of the Isothermal Lines in 

 the Winters of the Northern Hemisphere," by Mr T. Hop- 

 kins. — Mr Hopkins examined some of the isothermal lines 

 exhibited in the maps recently constructed by Professor Dove, 

 and objected to the theory which is put forward to account 

 for the irregular rise of the winter isothermals in the 

 Northern Pacific, Atlantic, and Arctic Oceans, through the 

 warming influence of the water of those oceans. 



" On the Daily Formation of Clouds at Makerstoun," by 

 Mr T. Hopkins. — The author went into an examination of 

 the meteorological registers kept at Makerstoun, for the 

 year 1844, to prove that the facts registered were in har- 

 mony with and tended to establish the theory he had ad- 

 vanced, that the horary fluctuations of the barometer were 

 attributable to the daily vaporization of water by the sun, 

 and the daily condensation of a portion of that vapour into 

 cloud. The great difficulty being to account for the fall of 

 the barometer from ten in the morning till four in the after- 

 noon. At Makerstoun, the state of the atmosphere as to 

 cloud was registered by noting an overcast sky by 10, and a 

 cloudless sky by 0, and intermediate states by intermediate 

 numbers. The state of the wet and dry bulb thermometers 



