in various Substances. 439 



upon the tube with the point of a diamond, and the 

 cylindrical tube being left empty, the height of the mer- 

 cury in the tube of the thermometer was seen through 

 it. 



The thermometer was confined in its place by means 

 of a stopple of cork, about i^ inch long, fitted to the 

 mouth of the cylindrical tube, through the center of 

 which stopple the end of the tube of the thermometer 

 passed, and in which it was cemented. 



The operation of introducing into the globe the sub- 

 stances whose conducting powers are to be determined, 

 is performed in the following manner : the thermometer 

 being taken out of the cylindrical tube, about two thirds 

 of the substance which is to be the subject of the ex- 

 periment are introduced into the globe ; after which, 

 the bulb of the thermometer is introduced a few inches 

 into the cylinder ; and, after it, the remainder of the 

 substance being placed round about the tube of the ther- 

 mometer ; and, lastly, the thermometer being introduced 

 farther into the tube, and being brought into its proper 

 place, that part of the substance which, being introduced 

 last, remains in the cylindrical tube above the bulb of 

 the thermometer, is pushed down into the globe, and 

 placed equally round the bulb of the thermometer by 

 means of a brass wire which is passed through holes 

 made for that purpose in the stopple closing the end of 

 the cylindrical tube. 



As this instrument is calculated merely for measuring 

 the passage of Heat in the substance whose conducting 

 power is examined, I shall give it the name o^ passage- 

 thermometer^ and I shall apply the same appellation to 

 all other instruments constructed upon the same prin- 

 ciples, and for the same use, which I may in future have 



