THE FUTURE OF OUR COTTON MANUFACTURE. 311 



forces tending to concentrate the more important branches of the 

 cotton manufacture along the south shore of New England. I 

 hesitate to treat the subject of the influence of relative and abso- 

 lute humidity upon cotton spinning and weaving, because none of 

 us have yet any very accurate or scientific knowledge upon the sub- 

 ject ; but, in order that a beginning might be made and the basis 

 of an investigation might be laid down, I wrote to General A. 

 W. Greely, giving the terms of the problem in a general way, and 

 he has very kindly and carefully prepared tables for me which it 

 might be judicious to incorporate in this report, giving the mean 

 relative humidity three times a day at 7 A. m., at 3 p. m., and at 

 11 p. m. as well as the temperature. These observations are aver- 

 aged separately for each month in the year, and in the accom- 

 panying tables the mean for five years, 1881 to 1885, is charted. 

 My hypothesis had been that somewhere between the elbow of 

 Cape Cod and Staten Island the cotton manufacture of the United 

 States would gradually concentrate. That hypothesis, so far as 

 relative humidity may be a factor in the case, is fully sustained 

 by these tables. From General Greely's figures I have taken the 

 mean temperatures at the same hours of the day and the mean 

 relative humidity in New London, Conn., and Augusta, Ga. The 

 conditions are shown by curves on these charts. 



As is quite well known, the term " relative humidity " defines 

 the ratio of the moisture in the air to the amount which would 

 saturate the air at a given degree of heat. Saturation being called 

 one hundred, this factor is represented on the chart by percentage. 

 The absolute humidity, or absolute number of grains of moisture 

 contained in each cubic foot of air, will of course vary with the 

 temperature of the atmosphere, and the absolute humidity at the 

 South may be greater than that of the North, owing to the higher 

 degree of heat. 



I think all will agree with me that spinning and weaving 

 depend more upon the uniform conditions of relative humidity in 

 respect to spinning, perhaps more on absolute humidity in respect 

 to weaving, than upon almost any other climatic condition. Gen- 

 eral Greely remarks : " In locations distant from the coast there 

 is a greater diurnal range of relative humidity in the atmosphere, 

 owing to the heating effect of the sun's rays upon the atmosphere, 

 causing the temperature of the air to increase more rapidly than 

 the dew-point, thus making the air relatively dry during the 

 working hours of the day. It is possible that this condition 

 has tended to drive the cotton-mills toward the southern coast 

 of New England, where they are more completely covered by the 

 vapor laden winds from neighboring ivaters, causing a reduced 

 diurnal range in temperature and a more constant relative hu- 

 midity." 



