suitable for the Atmosphere of Hot-houses. 



507 



Table of the Dew Point when the Temperature of the Air, in the Shade, is 

 between 55° and 100° Fahrenheit. 



6.3 



Difference between the dry and moistened Thermometers in Degrees of Fahr. 



1° 



2° 



3° 



4° 



5° 



6° 1 7° 



8° 



9° 



10°|ll° 



12° 



27 



13° 

 25 



14° 



22 



15° 



20 



55° 



53 



50 



48 



46 



43 



41 



39 



36 



34 



32 



29 



56 



54 



51 



49 



47 



44 



42 



40 



37 



35 



33 



30 



28 



26 



23 



21 



57 



55 



52 



50 



48 



45 



43 



41 



38 



36 



34 



31 



29 



27 



24 



22 



58 



56 



53 



51 



49 



46 



44 



42 



39 



37 



35 



32 



30 



28 



25 



23 



59 



57 



54 



52 



50 



47 



45 



43 



40 



38 



36 



33 



31 



29 



26 



24 



60 



58 



55 



53 



51 



48 



46 



44 



41 



39 



37 



34 



32 



30 



27 



25 



61 



59 



56 



54 



52 



49 



47 



45 



42 



40 



38 



35 



33 



31 



28 



26 



62 



60 



57 



55 



53 



50 



48 



46 



43 



41 



39 



36 



34 



32 



29 



27 



63 



61 



58 



56 



54 



51 



49 



47 



44 



42 



40 



37 



35 



33 



30 



28 



64 



62 



59 



51 



55 



52 



50 



48 



45 



43 



41 



38 



36 



34 



31 



29 



65 



63 



60 



58 



56 



53 



51 



49 



46 



44 



42 



39 



37 



35 



32 



30 



66 



64 



61 



59 



57 



54 



52 



50 



47 



45 



43 



40 



38 



36 



33 



31 



67 



65 



62 



60 



58 



55 



53 



51 



48 



46 



44 



41 



39 



37 



34 



32 



68 



66 



63 



61 



59 



56 



54 



52 



49 



47 



45 



42 



40 



38 



35 



33 



69 



67 



64 



62 



60 



57 



55 



53 



50 



48 



46 



43 



41 



39 



36 



34 



70 



68 



65 



63 



61 



58 



56 



54 



51 



49 



47 



44 



42 



40 



37 



35 



71 



69 



66 



64 



62 



59 



57 



55 



52 



50 



48 



45 



43 



41 



38 



36 



72 



70 



67 



65 



63 



60 



58 



56 



53 



51 



49 



46 



44 



42 



39 



37 



73 



71 



68 



66 



64 



61 



59 



57 



54 



52 



50 



47 



45 



43 



40 



38 



74 



72 



69 



67 



65 



62 



60 



58 



55 



53 



51 



48 



46 



44 



41 



39 



75 



73 



70 



68 



66 



63 



61 



59 



56 



54 



52 



49 



47 



45 



42 



40 



76 



74 



71 



69 



67 



64 



62 



60 



57 



55 



53 



50 



48 



46 



43 



41 



77 



75 



72 



70 



68 



65 



63 



61 



58 



56 



54 



51 



49 



47 



44 



42 



78 



76 



73 



71 



69 



66 



64 



62 



59 



57 



55 



52 



50 



48 



45 



43 



79 



77 



74 



72 



70 



67 



65 



63 



60 



58 



56 



53 



51 



49 



46 



44 



80 



78 



75 



73 



71 



68 



66 



64 



61 



59 



57 



54 



52 



50 



47 



45 



81 



79 



76 



74 



72 



69 



67 



65 



62 



60 



58 



55 



53 



51 



48 



46 



82 



80 



77 



75 



73 



70 



68 



66 



63 



61 



59 



56 



54 



52 



49 



47 



83 



81 



78 



76 



74 



71 



69 



67 



64 



62 



60 



57 



55 



53 



50 



48 



84 



82 



79 



77 



75 



72 



70 



68 



65 



63 



61 



58 



56 



54 



51 



49 



85 



83 



80 



78 



76 



73 



71 



69 



66 



64 



62 



59 



57 



55 



52 



50 



86 



84 



81 



79 



77 



74 



72 



70 



67 



65 



63 



60 



58 



56 



53 



51 



87 



85 



82 



80 



78 



75 



73 



71 



68 



66 



64 



61 



59 



57 



54 



52 



88 



86 



83 



81 



79 



76 



74 



72 



69 



67 



65 



62 



60 



58 



55 



53 



89 



87 



84 



82 



80 



77 



75 



73 



70 



68 



66 



63 



61 



59 



56 



54 



90 



88 



85 



83 



81 



78 



76 



74 



71 



69 



67 



64 



62 



60 



57 



55 



91 



89 



86 



84 



82 



79 



77 



75 



72 



70 



68 



65 



63 



61 



58 



56 



92 



90 



87 



85 



83 



80 



78 



76 



73 



71 



69 



66 



64 



62 



59 



57 



93 



91 



88 



86 



84 



81 



79 



77 



74 



72 



70 



67 



65 



63 



60 



58 



94 



92 



89 



87 



85 



82 



80 



78 



75 



73 



71 



68 



66 



64 



61 



59 



95 



93 



90 



88 



86 



83 



81 



79 



76 



74 



72 



69 



67 



65 



62 



60 



96 



94 



91 



89 



87 



84 



82 



80 



77 



75 



73 



70 



68 



66 



63 



61 



97 



95 



92 



90 



88 



85 



83 



81 



78 



76 



74 



71 



69 



67 



64 



62 



98 



96 



93 



91 



89 



86 



84 



82 



79 



77 



75 



72 



70 



68 



65 



63 



99 



97 



94 



92 



90 



87 



85 



83 



80 



78 



76 



73 



71 



69 



66 



64 



100 



98 



95 



93 



91 



88 



86 



84 



81 



79 



77 



74 



72 



70 



67 



65 



The bulbs of both thermometers should be covered with a fold of white silk or muslin, and pure 

 water supplied to one of them from a phial or other vessel placed near it, by a thread of floss silk acting 

 as a siphon. The cover of the moistened bulb and the thread must be renewed occasionally. 



The above table is sufficiently accurate for all practical purposes, but the true decreasing ratio is 

 233 for each degree of depression indicated by the moistened thermometer. 



To find the corresponding degree of Leslie's hygrometer, multiply the number of degrees of differ-" 

 ence between the dry and moistened thermometers by 6. 



