132 Mr. C. T. Coathupe on certain 



sure in proffering them to those of my philosophical brethren 

 who may feel an interest in such matters. 



Exp. 1. Two silvered brass scale thermometers, having 

 each a range of 600 Fahrenheit, were suspended from an 

 iron pin at a distance of two inches from the interior surface 

 of one of the brick pillars of the glass-house, at a distance of 

 20 feet 5 inches from the nearest point of the furnace emitting 

 flame, and during the early part of the founding process. 



They both indicated, from an average of ten simultaneous 

 pairs of consecutive observations which ranged well together, 

 a temperature of 1 94j'4 Fahrenheit. 



Exp. 2. One of the thermometer bulbs was now clothed 

 with a thin case of fine black "merino." The average often 

 simultaneous pairs of consecutive observations indicated a dif- 

 ference of temperature manifested by the clothed bulb, in ex- 

 cess of that manifested by the unclothed bulb, of 23 0> 1 Fah- 

 renheit upon each pair of observations. Hence 23'l of Fah- 

 renheit were retained by the covered bulb, which were evi- 

 dently reflected, and lost to observation, by the bright metallic 

 surface of the unclothed bulb. 



In another series of experiments wherein the temperature 

 indicated by the unclothed thermometers averaged only 124'5 

 Fahrenheit, from twelve pairs of observations, the increment 

 shown by covering one of the bulbs with a thin bag of black 

 " merino," amounted to 34*'66 Fahrenheit. Hence the quan - 

 tity of heat that is reflected from the bright surface of a ther- 

 mometer diminishes as the heat itself increases. 



Exp. 3. During the latter part of the founding process 

 and whilst the clothed thermometer suspended from the brick 

 pillar ranged from 320 to 325 Fahrenheit, a small black 

 iron cylindrical pan filled with water was placed upon a thin 

 iron shelf, which had been fixed against the pillar and close 

 by the side of the thermometer. It was reasonably antici- 

 pated that water thus placed in a temperature of 320 to 325 

 would boil ; but after waiting until the half of it had evapo- 

 rated, it showed no tendency to ebullition. 



Exp. 4. The top of the iron pan was now covered with a 

 pane of window-glass, and in a few minutes it boiled vio- 

 lently. This experiment demonstrated that the cooling pro- 

 perties of rapid evaporation can neutralize one of the direct 

 effects of heat to a very surprising extent ; and to ascertain 

 the amount of this influence the following experiment was in- 

 stituted. 



Exp. 5. A clothed thermometer, whilst the mercury was 

 indicating a temperature of 310 Fahrenheit, was immersed 



