of Heat and Light *when transmitted through Glass. 469 
emits flame, and 38 feet from the most distant flame that can 
emanate fl’om the same side of the furnace. 
(/■) A thermometer suspended from a pin flxed 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 1 80^ 
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 ^^th of an inch thick, effects a difference 
of 60 degrees of temperature under the circumstances stated 
above. 
(g.) 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. 
(h.) 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. 
(k.) 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 sid^ upon which 
