in various Substances. 419 



place, the center of its bulb coinciding with the center 

 of the globe. Through the stopple which closed the 

 end of the cylinder passed two small glass tubes, about 

 a line in diameter, which being about a line longer than 

 the stopple were closed occasionally with small stopples 

 fitted to their bores. These tubes (which were fitted 

 exactly in the holes bored in the great stopple of the 

 cylinder to receive them, and fixed in their places with 

 cement) served to convey air, or any other fluid, into 

 the glass ball, without its being necessary to remove the 

 stopple closing the end of the cylinder ; which stopple, 

 in order to prevent the position of the thermometer 

 from being easily deranged, was cemented in its place. 



I have been the more particular in the description of 

 these instruments, as I conceive it to be absolutely 

 necessary to have a perfect idea of them in order to 

 judge of the experiments made with them, and of their 

 results. 



With the instrument last described (which I have 

 called Thermometer No. 3) I made the following experi- 

 ment. It was upon the i8th of July, 1785, in the 

 afternoon, the weather variable, alternate clouds and sun- 

 shine ; wind strong at S. E. with now and then a sprink- 

 ling of rain ; barometer at 27 inches io| lines, ther- 

 mometer at i8|, and hygrometer variable from 44 to 

 extreme moisture. 



In order to compare the result of the experiment 

 made with this instrument with those made with the 

 thermometer No. 2, I have placed together in the same 

 table the different experiments made with them. 



