370 On the non conducting power of Water. 



thermometer of T i^° of Fahrenheit. The polished metallic 

 disk was then carefully introduced, resting upon the bulb of 

 the thermometer. Ether was then again poured upon the 

 surface of the water and inflamed. In this case, the bead of 

 fluid in the stem, did not move in the least sensible degree. 

 These experiments were many times repeated, and the uni- 

 form results were, that when no plate was interposed to in- 

 tercept the radiant heat, the bead was moved along the stem 

 of the thermometer, and when the plate was interposed, no 

 appreciable effects were produced. A cannon ball heated to 

 redness, and suspended within one or two inches of the water, 

 was substituted for the inflamed ether, and with the same 

 result. 



The conclusion to be drawn from these experiments is, that 

 water is a non-conductor of heat downwards. 



Another proof equally strong of water being a non-con- 

 ductor of heat downwards, is mentioned by Mr. Perkins, in 

 his explanation of the bursting of some steam-engines. In 

 some cases, the steam above the surface of the water in the 

 boiler, was of a temperature equivalent to a red heat, although 

 the water was not heated very highly, neither was it under a 

 great pressure. In that case, had water been capable of con- 

 ducting heat downwards, a portion of it would have been 

 converted ir>to highly elastic steam, by receiving an additional 

 portion of caloric from the surcharged steam above its sur- 

 face. It appears highly probable that other fluids, elastic and 

 non-elastic, are governed by the same law as regards their 

 conducting powers. I have not performed a series of experi- 

 ments upon any other fluid than water, but it is my intention 

 so to do, as soon as I shall have completed my course at this 

 Institution. I have one remark more to make. During the 

 combustion of the ether, (in the experiment for determining 

 whether water will conduct heat downwards,) the bead of 

 fluid in the stem of the thermometer, did not move until just 

 as the flame of the last lamina was expiring. The bead then 

 commenced moving, and for an instant continued in motion, 

 after which it ceased. This tends to show that radiant heat 

 does not pass freely through ether, as it does through most 

 fluids. W. M. Mather, 



West Point, Sept. 1827. 



