135 



TABLE 



/ 



OF 



THE ELASTIC FORCES OF AQUEOUS VAPOR, 



UNDER A PRESSURE OF 30 INCHES, EXPRESSED IN ENGLISH INCHES OF MERCURY FOR 

 TEMPERATURES OF FAHRENHEIT, ADOPTED IN THE GREENWICH OBSERVATIONS. 



THIS table contains the values of the elastic force of vapor for temperatures from 

 to 90 Fahrenheit, derived from Dalton's experiments by Riot's formula, by 

 Anderson, and published in Edinburgh Encyclopedia, Art. Hygrometry. It is re- 

 published, without the last decimal, in the volumes of the Greenwich Magnetic and 

 Meteorological Observations, and on it are based the various hygrometrical tables 

 published by Mr. Glaisher, either in the Greenwich volumes, or separately, most of 

 which will be found below, Tables XII. to XVII. 



Since Dalton published his experiments, numerous attempts have been made by 

 various skilful physicists to determine with greater accuracy the elastic force of 

 vapor. Dr. Ure in England, Regnault in France, and Magnus in Germany, deserve 

 in this respect a special notice. 



The last two experimenters having arrived simultaneously at results nearly iden- 

 tical, and their experiments having been conducted with all the care that modern 

 science requires, and the means that it can secure, their determinations seem to com- 

 mand an especial confidence, and to deserve the preference over all others. It is, 

 therefore, much to be regretted that the usefulness of the following otherwise so valu- 

 able tables, the formation of which involved so much labor, is in a measure impaired 

 by the fact that they were computed from elements which cannot be regarded as 

 the most reliable we now possess. 



B 99 



