154 BOARD OP AGRICULTURE. 



air contains 100 per cent, of moisture, or is saturated. When this 

 is the case, the slightest reduction of temperature will cause a dis- 

 charge of rain. But if the diflerence between the indications of 

 the two bulbs is several degrees, a change must take place in the 

 condition of the atmosphere before rain can fall. 



In this connection, the following fact, however, should be re- 

 membered : The condition of the air upon the surface of the 

 earth is not always the same as the condition iu a stratum above 

 the earth, so that sometimes it may be raining from a cloud above, 

 when the indications are that .the per ceutage of moisture in the 

 air is but 90 or 95 per cent. A hj'grometer half a mile above the 

 earth, would then show that the air there is saturated with moist- 

 ure. It rains, therefore, sometimes when the hygrometer does 

 not indicate 100 per cent, of moisture in the air, but it seldom 

 rains unless it indicates pretty nearly 100 per cent, at the surface 

 of the earth. 



Mr. C. Chamberlain. I would like to inquire of Prof. Fernald, 

 if we may not reasonably charge something to the electrical con- 

 dition of the atmosphere to account for the formation of showers 

 and the distribution of moisture as it occurs in this country. 



Prof, Fernald. Undoubtedly, 



Mr, Farley of Winthrop. I will state that I have had a barom- 

 eter for perhaps ten years, and have watched it very closely, 

 especially in haying time. I find that, nine times out of ten, at 

 one o'clock in the afternoon, I can tell whether we shall have a 

 shower thafafternoou. If the barometer does not begin to fall by 

 one o'clock, we are pretty sure to be free from showers. But its 

 indications are such, that so far as storms are concerned, we 

 cannot rely upon it alone. 



Prof. Fernald, I am glad to hear so good a reputation given to 

 the barometer. I hardly ventured to give it all the credit to which 

 I deem it entitled. Many people are apt to regard the barometer 

 as infallible, and other people think it good for nothing, lioth 

 are doubtless wrong. There are certain things that can be told 

 by it. It gives the pressure of the atmosphere, and alwa^^s re- 

 ports upon this correctly. We may not, however, correctly in- 

 terpret its indications. It is safe to say, however, if the barometer 

 will do for the gentleman the good service he has indicated, with 

 the hygrometer also, he would be pretty well prepared to predict 

 changes of weather fur some little time in advance. 



