of Heat and LigJit icJien ii'ansmitted through Glass. ^60 



emits flame, and 38 feet from the most distant flame that can 

 emanate from the same side of the furnace. ' 



[f.) A thermometer suspended from a pin fixed into one 

 of the window bars during the process of founding, and 

 hanging at a distance of one inch from the glass, exterior to 

 the apartment, usually indicates a temperature of from 180° 

 to 190° Fahrenheit, when a thermometer suspended at pre- 

 cisely the same distance from the same pane of glass in the 

 interior of the apartment indicates only a temperature of 

 from 120° to 130*^ of Fahrenheit. A difference of distance 

 of only two inches, when influenced by the interposition of a 

 plate of glass only Jg th of an inch thick, effects a difference 

 of 60 degrees of temperature under the circumstances stated 

 above. 



(o-.) Having suspended a thermometer in a flint glass bottle 

 of 5 inches in diameter, and placed the stopper loosely in situ, 

 I placed the bottle upon a non-conductor of heat (several 

 layers of felt) just exterior to this window. The thermome- 

 ter gradually rose, as might be expected, to 178 degrees of 

 Fahrenheit. It was then placed upon the window frame, by 

 sliding to one side the moveable part of the window until 

 there was just sufficient space to admit the diameter of the 

 bottle; another thermometer was suspended round the neck 

 of the bottle, and adjusted so as to hang close to that surface 

 of the bottle which presented to the interior of the apartment. 

 The internal thermometer remained constant at 178 degrees, 

 and the external thermometer, which faced the interior of the 

 apartment, never indicated a higher temperature than 110 de- 

 grees of Fahrenheit. 



(A.) A little moisture adhered to the interior of the bottle 

 when thus introduced, and the dew became deposited upon 

 that side which was most remote from the fire. 



(z.) A bottle containing a piece of camphor was now sub- 

 stituted for that which contained the thermometer. In four 

 minutes the side of the bottle which was most distant from 

 the fire became beautifully spangled with crystals of camphor. 



(/".) Cress seed which had been sown in a wooden trough 

 supported beneath this window in the interior of the apart- 

 ment, vegetated rapidly ; but although it remained constantly 

 exposed to a very brilliant fire light, its appearance was pre- 

 cisely similar to that which vegetated in the dark (viz. exhi- 

 biting white and attenuated stems, with pale yellow leaves). 

 There was no tendency in the plants to grow towards the fire 

 light. 



I believe that whensoever dew is perceived upon one side 

 only of a vessel containing water, the side upon which 



