FLUCTUATION OF THE BAROMETER. 



found that the dew point of the breath changes with some diseases, as it 

 certainly must where the temperature of the breath itself sinks below 

 94, the knowledge of this fact may change the whole mode of treat- 

 ment for the disease. In the Asiatic cholera, for instance, if the patient's 

 breath should sink below the dew point, then, instead of evaporating 

 water from the lungs by breathing, some of the vapor inspired would 

 be condensed there, and the patient would die immediately unless he 

 were put into an atmosphere with a lower dew point. Who can tell 

 without trial that a dropsical patient would not be relieved by reducing 

 the dew point of the air which he breathes, and thus increasing the 

 quantity of vapor discharged from the lungs? It may be that nature 

 intends us to regulate the quantity of vapor in the air of our parlors, as 

 we now do the temperature or quantity of caloric. We certainly have 

 it in our power to do so, and that too with much less expense and 

 trouble. Do we wish to increase the quantity of vapor, we have only 

 to set a tin cup of water over a spirit lamp. Do we wish to diminish 

 the quantity of vapor, we can do it by placing a pan of sulphuric acid in 

 the room, with the doors and windows closed. Or, if that is not con- 

 venient, a quantity of corn meal or bran, spread out on a sheet, having 

 been previously dried very dry, or scorched in an oven, will answer the 

 purpose quite as well. A very mistaken notion on this point is univer- 

 sally prevalent, that by putting fire into a stove the air in the room will 

 be dried. Now the truth is, that the first effect of heating a room by a 

 gtove, will be to increase the quantity of vapor in the air by evaporating 

 it from all the walls and wooden materials in the room. During this 

 operation these materials would become drier, the dew point in the 

 air would rise; and then a patient breathing this air would evaporate 

 less from his lungs than before. 



The following chart of the fluctuation of the barometer, is given as 

 a specimen of the manner I adopted to discover in what direction these 

 fluctuations move, and with what velocity. Many observations are yet 

 wanting to make out a law on these points. It would appear, however, 

 from this chart, and others which I have in my possession, that it is a 

 general rule, when the barometer falls very suddenly at Nashville for ten 

 or twelve hours, it rises with great rapidity during those same hours at 

 Middletown. On the morning of the 29th of January, for example, 

 there was a very rapid fall of the barometer at Nashville, and rise at 

 Middletown. Now, on that day, as appears in article 30, there was a 

 storm of rain, at Nashville, with the wind at Philadelphia and Middle- 

 town blowing towards Nashville. In Loomis's storm, (170), the same 

 result is obtained. Besides, I have examined more than forty cases of 

 great storms at Baltimore, where, at the beginning of each storm, for 

 many hours, the barometer fell rapidly at Baltimore, and at Boston, 

 during the same hour?, it rose. 



