$J0 Pfepofaljbr a nezv Hygrometer^ 



excefs of weight to ten parts of a grain. Lowitz remark<?d 

 that this hygrometer in continued wet weather gave a moif- 

 ture of more than 55 grains, and in a continued heat of 113 

 degrees of Fahrenheit, only ii degree of moifture. 



In my opinion, it would not be ncceffary, in order to con- 

 ftru<5t fuch a hygrometer, to procure argillaceous {late from 

 Aftracan, as feveral other argillaceous kinds of flate, as well 

 as ftories and other fubftances, pofiefs in ah equal degree the 

 fame propertv. If a perfon, for example, prcfles with the 

 finger on a marble (lab, a grey free-ftone or a piece of glafs, 

 it will immediately attract the infenfible perfpiration, and 

 become tarniihed. 



The hygrometer thus invented by Lowitz was however 

 attended with this fault, that it never threw off the moifture 

 in the fame degree as the atmofphere became drier. It was 

 alfo fometim.es very deceitful, and announced moifture when 

 it ought to have indicated that drynefs had again begun to 

 take place in the atmofphere. To avoid thefe inconveniencics, 

 I would propofe the following method : 



1. Take a fquare bar of fteel about two lines in thicknefs, 

 and from ten to twelve inches in length, and form it into a 

 kind of balance, one arm of which ends in a fcrew. On this, 

 fcrew let there be fcrewed a leaden bullet of a proper weight, 

 inftead of the common weights that are fufpended. 



2. Take a glafs plate about ten inches long and feven inches 

 in breadth, deftroy its polifh on both fides, free it from all 

 moifture by rubbing it over with warm afties, fufpend it at 

 the other end of the balance, and bring the balance into equi- 

 librium by fcrewing up or down the leaden bullet. 



3. Mark now the place to which the leaden bullet is brought 

 by the fcrew, as accurately as poffible, for the point of the 

 greateft drynefs. 



4. Then take away the glafs-plate from the balance, dip 

 it completely in water, give it a fhake that the drops may 

 run.offlrom it, and wipe them carefully from the edge. 



5, Apply 



