SHORT MEMOIRS ON METEOROLOGICAL SUBJECTS. 379 



meteorological elements for four days at the altitude of 2,310 meters 

 (Sardar-Bonlagh), for ten days at 3,31G meters, and through nearly five 

 days on the summit of the Greater Ararat, 5,125 meters. During the 

 entire time, observations were regularly maintained at Erivau, Alexan- 

 dropol, Tiliis, Eedoute Kale, and Lenkoran. From these observations, 

 1 have deduced the corresponding averages. 



leneriffe. — Observations by Piazzi Smyth at Villa Orotava (374 me- 

 ters), Guajara (2,715 meters), and Alta Vista (3,264 meters), in July, 

 August, and September, 185G, and simultaneously at Santa Cruz. 



The AJi^s. — Observations at the Tbeodul Pass, August, 18G5and 1866, 

 in connection with the Swiss system of observations; also the obser- 

 vatious of Kamtz on the Rigi and the Faulhorn, referred to Ziirich. 

 (Kiimtz particularly remarks, in his Vorlesungen, that in the dry year 

 1832 the ratio of the vapor-tensions at Faulhorn and Ziirich was 0.43, 

 almost exactly the same as the ratio 0.46 for the damp, cold year 1833.) 



Balloon Voyages. — [a) Observations by Welsh, computed and commu- 

 nicated by Strachey; (b) observations by Glaisher during five trips in 

 summer time; (c) three voyages in late summer and fall of 1863; {d) 

 three voyages in the winters 1864 and 1865. On the ascension of 1864, 

 January 12, the temperature and humidity at first increased with the 

 elevation, and at a higher altitude first began to regularly diminish. 



After a consideration of the figures in the above table, one must con- 

 fess that the attempt to represent these by any formula is quite as rea- 

 sonable as the establishment of any ratio for the diminution of temper- 

 ature with altitude. The agreement between observations on mountains 

 and in the free atmosphere in balloons is much better for the humidity 

 than for the temperature. Only the Himalaya observations show for 

 small altitudes a materially greater quantity of vapor on the mountains 

 than in the free atmosphere ; at great altitudes, there is scarcely any 

 difference. Had the vapor atmosphere of the earth attained to a con- 

 dition of equilibrium, and subject to its own pressure only, we could in 

 a simj)le manner compute the pressure corresponding to a given altitude, 

 since for every such gaseous atmosphere the equation 



_ h 



must obtain. Here p audpo represent the pressures at the altitude h 

 and at the earth's surface, measured by the height of the mercurial column 

 supported by these pressures; e is the base of the natural logarithms; C 

 is a constant, and equal to the product of 0.760 into the ratio between 

 the density of mercury and that of the gas under a normal pressure of 

 0.76 meter at a temperature of 0° C. and with the intensity of gravity as 

 at the sea-level at 45° latitude. This constant corresponds to the alti- 

 tude of a column of gas of uniform density and at the uniform temper- 

 ature of 0° C, which exerts the same pressure as a mercurial column of 

 0.76 altitude. For another temperature of the gaseous column, and for 

 another value of the force of gravity, and one diminishing with the 



