174 "^ Mr. Nixon on the Theorif of the [SEyr, 



easily determine by calculation the coefficients for dry air at 

 different degrees of the thermometer. Subjoined are the coeffi- 

 cients for air in a mean state of saturation as deduced from the 

 barometrical observations of Shuckburgh, Ray, and Rumond. 



Ramond. Shuckburgh and Ray. 



Air 32° Coefficient 60345 60000 



52 63027 62922 



60 64100 64091 



72 65709 65844 



I have the honour to be, Gentlemen, 



Your most obedient humble servant, 



Leedsy May }0, \8i5. J. NiXON. 



Explanation of the Tables, 



Table I. — The degrees affixed to the dew-points being the 

 equations for saturated air under a pressure of 25 inches multi- 

 plied by 25, the equations for the dew-points at the two stations 

 are found by dividing the degrees given in the table by the 

 observed pressures in inches, and adding the sum of the two 

 equations to that of the detached thermometers, which call the 

 corrected sum of the thermometers. 



Example, 



Pressure. Air. Dew-point. 



Upper Station. 27-5 in. .. 82*2 ..70. Eq.=:152-H 27-5 = 5-5 

 Lower ditto.. 29'8 .. 84-0 .. 70 152-5-29-8= 5-1 



Sum of thermometers . . , , 166*2 Sum 10*6 



Equation for moisture .... 10*6 



Corrected sum of therms. . 176*8 



Table VI. — When the observations have been made without 

 hygrometer, the equations given in this table must be added to 

 the sum of the detached thermometers. 



Example. 



(Chimborazo) Upper station 29*1° 



(Pacific Ocean) Lower station 77*5 



Sum of thermometers 106*6 



Equation , 2*9 



Corrected sum of thermometers lOQJ 



The tabulated equations (calculated for half saturated air) may 

 be modified according to the estimated degree of saturation. 



