422 APPENDIX. 



blower, of thrice the dimensions of the wooden lubes, in excessive 

 hot and calm or sultry days, when not a breath of air is stirring. 

 By this simple process, artificial currents may be at any time pro- 

 duced, and a hot, impure, stagnant atmosphere is speedily drawn 

 out ; fresh, cool, and pure air, rising through the openings from be- 

 neath, until the whole interior air is completely changed. I must 

 observe, that, in warming the apartments by this mode, it is absolutely 

 necessary that a small portion of moisture or steam should be infused 

 along with the heated air. The silk-worms require it.* 



In most of our northern cities, at this day, numerous private 

 dwellings, and public houses and churches, and most of our great 

 manufactories, are warmed in this way, by currents of heated air 

 from the cellar ; this being the most economical and perfect mode 

 which has hitherto been devised. But during the calm and sultry 

 days, and days of excessive heat, in some parts of India, the apart- 

 ments of the opulent are refreshed by cool breezes artificially pro- 

 duced, a man standing at the door with a vast fan. 



It has been very lately stated by Dr. Ure, that the five-guinea 

 fan of Messrs. Lillie and Fairbairns operates to admiration. In 

 some of those vast manufactories of Manchester, where its use has 

 been introduced, the whole impure and unwholesome air is com- 

 pletely and suddenly expelled and driven out, its space being sup- 

 plied by air, pure, fresh, and wholesome. 



THE THERMOMETER is an instrument of the most simple kind, 

 which measures the degrees of heat and cold with as unerring cer- 

 tainty as a watch measures time. A child may learn its use in a 

 moment, and be able to teach its use to thousands. It consists 

 of a small bulb of glass, of the size of a bullet, connected with a 

 small glass tube : the bulb and part of the tube being filled either 

 with quicksilver, or with pure alcohol, double distilled from purest 

 rum or brandy, the 'top of the glass tube is hermetically sealed, by 

 melting the glass, by aid of a blowpipe, in the blaze of a lamp ; a 

 scale of thin brass, iron, or wood being now added, it is graduated 

 by another thermometer. As the heat of the atmosphere increases, 

 the spirit expands and rises in the tube ; by cold, the spirit contracts 

 and descends. > The cost of the instrument need not exceed a dollar, 

 and it can never get out of order. In regulating the temperature of 

 apartments, of baths, in evaporation, and in distillation, its use is 

 necessary, and in breweries and in hot and green : houses it is indis- 

 pensable. They are found in the mansions of our citizens in every 

 town and village of our land ; and those gentlemen who, while they 

 approve, yet discourage the use of this instrument, have egregiously 

 mistaken the character of our countrymen. Eminently useful as it 

 is, they will both know and possess the instrument. 



The Chinese regulate the temperature of the apartments devoted 



* Flame fires are not approved for giving warmth to the apartments of 

 the silk-worms, in recent practice. They do indeed promote circula- 

 tion, but they scorch the air. An iron stove heated to redness burns the 

 vital air, consuming' the oxygen as much as does burning charcoal ; although 

 it inav emit no mephitic vapor, yet it renders the air obnoxious to men and 

 all animals that breathe. 



