PROCEEDINGS OF THE FARMERS' CLUB. 221 



dall, of New Lebanon Springs, was present, and was desirous of making a 

 few remarks in relation to barometers. 



Mr. Solon Robinson. — Mr. Kendall is the manufacturer of the fine aneroid 

 barometer that I presented to the Club last week, and I hope he can make 

 it apparent that barometers are generally more useful to farmers than my 

 remarks last week would indicate. 



Mr. Kendall said: 



Gentlemen of the Farmers' Club of the American Institute: I am before 

 you at my own request, to speak of the barometer, and its utility as an 

 instrument worthy to be recommended to farmers as a weather indicator. 



You are all familiar, no doubt, with the principles of the barometer, so I 

 will merely say that the Torricellian tube is made of glass, thirty-two 

 inches in length, hermetically sealed at one end, and forming a syphon at 

 the other end, three or four inches in length. The tube is then filled with 

 mercury and inverted. In the long arm of the tube the mercury rises at 

 tide water, or sea level, to about thirty inches ; in the short arm it rises 

 two or three inches. The atmosphere, pressing upon the surface of mer- 

 cury in the short arm, suspends the mercury in the long arm to about 

 thirty inches; thus the weight of the column of thirty inches forms a 

 counter balance against the weight of the atmosphere pressing upon the 

 surface of the column in the short arm. 



Other forms of construction have been introduced for the purposes of 

 convenience, ornament or portability — the latter being the greatest object, 

 as it is an exceedingly delicate instrument to handle, and one very liable 

 to derangement. The various methods used to render it portable render 

 it less sensitive to atmospheric changes. 



The aneroid barometer is a metallic instrument, the vacuum of which is 

 obtained by forming a box or chamber of thin elastic metal, about two and 

 a half inches in diameter, and one-quarter of an inch thick. From the 

 chamber the air is exhausted by means of an air pump; when thus 

 exhausted the walls of the chamber are pressed together by the external 

 pressure of the air. When the chamber is in its place in the instrument, 

 the chamber walls are suspended by a lever, and held in suspense by a 

 spiral spring placed under the long arm of the lever, thus forming a counter 

 balance, by its own strength, against the pressure of the air upon the 

 external surface of the chamber, and by a combination of levers and 

 springs motion is given to a, pointer or index, which passes over a gradu- 

 ated dial in a way to correspond with the movement of the mercury over 

 its scale, thus making an instrument answering all the purposes of a good 

 barometer, and one more sensitive, and free from every other objection to 

 the mercury barometer. 



Having given you a short description of the various forms of barometers, 

 I proceed to speak of the manner of using it. Early in my experience in 

 making barometers, I sought in all scientific works within my reach to find 

 rules for observation, and could only find this, that in clear weather the 

 mercury stood high, and before a storm it fell. I then from my own obser- 

 vation drew up the rules which 1 furnish with my aneroids, and which have 

 been read to you by my friend Solon Robinson, and after mature observa- 

 tion I am satisfied that they embrace everything necessary to be under- 



