XXVI. 



TABLE 



FOR 



DEDUCING THE RELATIVE HUMIDITY IN HUNDREDTHS, FROM THE INDICATIONS OF 

 SAUSSURE'S HAIR-HYGROMETER ; 



Calculated from the Experiments of Melloni. 







BY M. T. HAEGHENS. 



THE Hair-Hygrometer of Saussure having been formerly used for long series 

 of observations, and being still employed by some meteorologists, notwithstanding 

 the imperfection of this instrument, on account of its giving directly the relative 

 humidity without calculation, it was desirable to ascertain the correspondence of the 

 degrees of that hygrometer with the relative humidity expressed in hundredths, as in 

 the preceding table. Though these instruments compared with each other, show 

 very often great discrepancies in their indications, yet a large number of them agree 

 sufficiently well with the experiments of Melloni, August, and others, to allow the 

 following table of comparison to be constructed, which table may be considered as 

 giving good approximations. For the calculation of it, Mr. Haeghens used the results 

 of Melloni, which agree also satisfactorily with a series of observations very care- 

 fully made by M. Delcros. See Annuaire Meteor ologique de la France, pour 1850. 



RELATIVE HUMIDITY IN HUNDREDTHS. 



156 





