218 



BOARD OF AGRICULTURE. 



November. 2| P. M. 69 deg. ; lunar halo 5 A. M. of 6th ; grass 

 hoppers abundant and livolj on 9th ; ground froze first time for 

 month night of 15th; heavy snow squall at 6 A. M. of 21st; 

 ground closed night of 24th ; no sleighing during the month. 



GEORGE E. BRACKETT, Ohs. 



Belfast, 1860. 



Meteorological observations at Perrxj, Wasliington County. 

 William D. Dana, Observer. 



The Barometer a Valuable instrument for Farmers. 



The barometer is an instrument designed to indicate the weight 

 or density of the atmosphere. Its principle was first discovered by 

 Torricelli in 1G1:>. In its early form, and the usual one until a re- 

 cent period, it consisted of a glass tube, known as the Torricellian 

 tube, 'about thirty-three inches long, closed atone end and filled 

 with mercury. It is then inverted, and its lower end placed in a 

 cup, bag, or other recepticle of the same material. Upon being 

 thus inverted, the mercury produces a vacuum at the top by its 

 weight, leaving a column about thirty inches high at tlie sea level, 

 and less in proportion as the place is more elevated. The hight at 

 which the mercury stands indicates the pressure of the air. 



E.Kperience has shown that the column falls before tlie approach 

 of a storm, and rises before fair weatlicr. Ilence this instrument 



