THE SMOKINESS OF IIVDIAK SUMXHEK. 267 



2)hcrc contains vaiJor in a gaseous form ; and that ichenever this vapor 

 is cooled doivn to a certain degree below the temperature of the air, 

 ivhich contains it., it condenses into water. It matters not where the cool- 

 ing of this vapor is eflected — whether it be accomplished by a cold 

 glass, a cold wall, the cold earth, or by a colder region above us — the 

 result will be the same, a condensation of the vapor into water, in the 

 former instances producing dew, in the latter, cloud. The degree of cold 

 necessary to condense the vapor in the air is variable and indeed al- 

 ways varying — still it is always the same at the same time in the same 

 region. The highest temperature at which this vapor begins to be de- 

 posited at any one time is called the dew-point. Now if tlie dew-point 

 be ascertained we at once know the degree of temperature at which the 

 cloud, at that time, is formed ; because, as before observed, vapor is 

 condensed either into i\e\v, or cloud by the same degree of cold. And 

 if we bear in mind the scale by which the temperature of the atmos- 

 phere diminishes with its elevation, and comprehend the modifying in- 

 fluences hereafter to be noticed, we can calculate very accurately the 

 height of the base of the cloud, as well as know the temperature at 

 which that cloud is forming. 



The simplicity of this part of the subject adds to its beauty and in- 

 terest ; and in my next number 1 shall dwell in detail upon the method 

 of ascertaining the dew-point, the elevation and temperature at which 

 clouds are formed, and the quantity of vapor contained in the atmos- 

 phere. Indeed, I hope to prove, during the progress of these essays, 

 that the Laws of Storms stand as intimately related to meteorology, as 

 gravitation does to the heavenly bodies, and that the whole subject is 

 likely to be reduced as easily to calculation. 



THE SMOKINESS OF INDIAN SUMMER, &C. 



Although the design of the '^Literary Record and Journal" would 

 forbid the introduction of any thing which might savor of personal con- 

 troversy, it is nevertheless regarded as an appropriate vehicle ior the 

 comparison of opinions on interesting scientific subjects. The Associ- 

 ation, under whose superintendence this monthly is published, has for 

 its principal object the eliciting of the truths and laws of the works 

 of the Creator-. And in no way are these truths better elicited and laws 

 established, than by the collection of the observations and opinions of 

 those who have given them their particular attention. 



In the number of this .lournal, for Aprrl, 1845, it was asserted, by 



