312 



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METEOROLOGY, 



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[Sect, IX. 



Le made in dry soil, and 7i7ider 

 tvind. In winch should be buried 



/ 



at depths of three, six, 

 and nine feet, thermometers well wrapped in woollen cloth, 

 or in pots of pounded charcoal or even of dry sand, 

 enclc^od in strong vessels to defend them from damage, 

 and to prevent the possibility of change of temperature 

 in extracting and reading them. The zero points of the 

 thermometers should be most scrupulously ascertained, 

 and their errors at the temperatures registered made a 

 subject of special inquiry- The readings should be exact 

 to tenths of degrees. Observations thus made under the 



in various longitudes with scientific precision^ 

 might furnish data of the utmost value towards deter- 

 mining tlie constancy or variability of the sun's radiation 

 from year to year. If the thermometers cannot be spared, 

 bottles of water similarly defended may be buried (or of 

 brandy, if in frozen soil), and the temperature of the 

 liquid taken immediately on raising them. In case of 

 prolonged Bojourn this should be repc^vLoJ monthly. 



Some localities are remarkable for enormous tails of 

 rain. Tlius it is stated on the authority of Captain 



that between the 1st and 24th of February, 

 1820, there fell ticelvefeet seven inches of rain in the Isle 

 of Cayenne.* In all such localities great attention should 

 be paid to the rain gauge, and pains taken to procure 



from perfectly authentic registers containing 



instances of the kind^ and information respecting their 

 attendant circumstances. In some geographical localities 

 it is said never to cease raininar — in others* that rain never 



* Ed, Phil. Joura.j viii. 186, from Silllman's American Journal of 



Science^ iy. p. 375. 



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