APPENDIX. 193 



a direct line), and nearly east from Ooroomiah, there is daily a strong wind from 

 the Caspian Sea, which is about one hundred and fifty miles north-east of that city. 

 This wind is very invigorating." 



N. 



. Extract from a letter from the same, accompanying observations from Tehran, 

 Persia : — 



" Properly to understand these phenomena, it may be well that you have in 

 mind the local situation of Tehran. I will copy a reference to its situation, penned 

 on the spot when I visited it several years ago. ' The local situation of Tehran 

 renders its situation extremely warm, and hemmed in as it is on the north and 

 east by naked mountains, which tower some 6000 or 6000 feet above it in the rear, 

 and the vast extent of arid land in the two opposite directions, reflecting the heat in 

 summer like a burning desert, the city cannot be otherwise than like a great oven 

 during the warm months of the year, not taking into account at all its relative 

 elevation, which is much less than that of Tabreez, and other cities of Azerbijon.' 



" I may add to this notice that the Caspian Sea, lying some seventy or eighty 

 miles north of Tehran, though separated from it by a lofty range of mountains, 

 doubtless affects the character and direction of its winds, and still more probably, 

 the immense salt desert that skirts the plain of Tehran, some fifty miles south- 

 east of the town." 



0. 



When these sheets were first sent to the Smithsonian Institution for publication, 

 the observations from Tehran and Tabreez had not been received, and those pre- 

 viously received from Ooroomiah, gave the mean direction a good deal more south- 

 erly. This addition of three new stations, at which the direction of the wind is 

 westerly, may lead us to question whether the southern limit of the zone of west- 

 erly winds should not be altered so as to include this region of country. 



The reception of Lieutenant Maury's Charts of the North Pacific Ocean, after 

 the entire completion, as was supposed, of the foregoing manuscript, and the kind 

 aid of Mr. Solon Albee, a fellow college officer, in discussing them, and making the 

 necessary computations, has enabled me to add, as an appendix to Series C, Section 

 IV, the following list of resultants, deduced from an aggregate of more than one 

 hundred and sixty-five years' observations. Owing to the probable monsoon cha- 

 racter of the winds near the coast, or say within six hundred miles of it, the re- 

 sultants for each of the several months were computed separately, and from them 

 the mean for the year; but, in mid-ocean, where there was no reason to apprehend 

 any influence of that kind, such precaution was deemed unnecessary, and the 

 resultants were obtained by simply resolving the traverse of all the winds re- 

 ported, without reference to the time of the year in which they were taken. 



The almost entire want of observations during the colder months of the year, 

 north of latitude 40°, necessarily renders the results near the coast doubtful, and 



