Anihracits Coad of Pennsylvanui. 339 
tally from 65° to 72° or 73° of Fahr’t. Itis not difficult to raise 
éhe heat higher ; but in winter weather, a regularly diffused 
temperature of 70° is perhaps high enough, both for health 
and comfort. The temperature is very nearly equal through 
. the whole of the apartments warmed, and often formany hours 
searcely varies a degree or two; at least this is true of the 
parts that are not warmed immediately by the radiation. In 
a room warmed by a common fire-place, it is not unusual for 
the temperature of 80° or 85° to exist immediately before the 
fire, and perhaps 40° or 45° or 50° in the remote parts of the 
room. [tis acommon error to suppose that an atmosphere, 
uniformly and comfortably warmed, exposes peopie to take 
cold. Experience does not confirm this impression, nor ought 
theory to induce such aconclusion. Colds arise much more 
frequently from the currents of a room very unequally warm- 
ed, or from the cold air in halls and passages, &c.; and there 
is no danger in going from the most comfortable temperature 
into the cold, if we adopt proper precautions, and especially if 
we continue active, while we are exposed. This evening, 
9 o’clock, Jan. 31, 1826, the thermometer has gradually sunk 
from 0 to 5° below,* while the temperature of the parlour 
has been 71° for three hours—but there is no wind, and there 
is no fire on the hearth, the fire-board being shut asin sum- 
mer. The adding of more fuel depresses the thermometer a 
little until the fire burns actively again. 
There is some difference of opinion as to the comparative 
value of the Lehigh and Schuylkill coal. The value of both 
is very great, and although there are points ef difference, a 
comparison will not be invidious. A correspondent under 
date of Jan. 1, 1826, writes thus, respecting the Lehigh coal. 
*¢ The structure of the Lehigh coal is more dense and com- 
pact, and consequently as the heat is less rapidly absorbed, 
it does not ignite quite so readily, as the Schuylkill; it makes 
fess ashes, enduring from 15 to 20 per cent. longer, and pro- 
duces a more intense heat than can be produced by any other 
known fuel. It is, generally speaking, free from sulphur, a. 
point of great importance to malsters, iron workers, &c. Some 
experiments have been made in smelting iron with it and 
charcoal mixed, but with various success. Some think the 
heat produced, is so great as to burn up a portion of the iron. 
No theory bas yet been formed of any value, nor will there 
be perhaps jor some time to come. 
* At 11 o cleck, P.M. it was 14° belew 0. 
