CLUANTITY OF HORIZONTAL REFRACTION. 51; 



TABLE. 



At 8, A. M. 



Air. 



Water. 



Diffe- 



Refrac- 



Cold by 



Hygro- 





57 





rence. 



tion. 



evaporation. 



meter. 



1800. Sept. 23 



60P 



3p 



4' 







72" 



Oa. 17 



461 



49| 



3 



3 







72 



22 



38 



49i 



uf 



3 







67 



Nov. ] 



41 



45i 



4 



8 



z 



76 



4 



431 



46| 



3 



3 - 



H 



72 



5 



37 



45 



8 



8 + 



1 



69 



12 



441 



48 1- 



4 



1 + 



3| 



73 



13 



40 



44t 



41 



5 





76 



1801. June 13 



50 



63 



13 



9 + 



5 



65 



22 



55 



61 



6 



6 + 



6 



65 



25 



55 



62 



7 



6 



4f 



65 



24t 



55 



61 



6 



5 



3 



67 



Sept. 8 



60 



64 



4 



7 



2 



78 



9 



64 



64| 



i. 

 4- 



5 



3 



74 



10 



58 



64 



6 



7 



2 



70 



12 o'clock, 10 



63 



64 



1 



2 







From a review of the preceding Table it will be found, upon The dip of the 

 the whole, that when the water is wander than the air, fome"^'.'?^)^ horizon 



r cj n- ruL- u -iju will be increafea 



mcreale of deprellion ot the horizon may be expected ; but by the water 

 that its quanlity will be greatly influenced, and in peneral^^^^S'^^'^mtt 

 J. • -n J 1 1 r r fi / r 1 ^"^^n the air,- 



dimmilhed, by drynels or the atmolphere. and diminiflied 



It appears, however, that no obfervable regularity is dedu-Cmo^e confider- 



cible from the meafures above given ; but that the quantity, ^^ H^ a^r.'^^"^ ' 



on fome occafions, is far different from what the Ifates of the The meafures 



thermometer and hygrometer would indicate. On the 9th of '"'^'"'^ *'."'^ °^ 

 r. 1 r ■ n i , • r^ r • i any prattical 



September, tor mltance, the difference or temperature is only jaw, 



1°, and the evaporation, to countera6l this flight excef; of 

 warmlh, produced as much as 3® of cold; neverthelds, the 

 refradion vifible was full 5'. In this obfervation I think that 

 I could not be miffaken, as the water was at the time perfectly 

 Calm, the air uncommonly clear, and I had leifure to pay par- 

 ticular attention to fo unforefeen an occurrenct. 



This one inflance appears conformable to the opinion enter- Solution of 

 tained by Mr. Huddart, and by M. Monge, that, under fome '"^'^"^^ "^'^'^f 

 circumftances, the folution of water in theatmofpherecaufesa^ni^augn^,,* 

 decreafe in its refradlive power; but, on no other occafi on 

 have I been induced to draw a fimilar inference. 



E2 Tlie 



