YALE AGRICULTURAL LECTURES. 155 







ments are communicated from the centre of the cover to a 

 pointer which moves over the graduated face of a card, on 

 which inches and hundredths are inscribed. The whole apparatus 

 is encased in a brass box, about four inches in diameter and 

 two inches deep, covered with a front glass, and resembling in 

 general appearance a chronometer case. 



These instruments are now made by Mr. E. Kendall, of New 

 Lebanon Spa, N. Y., well known everywhere for his mercurial 

 thermometers. His instruments compare well with the French, 

 and with the movements of the mercurial barometer, and sell 

 for the moderate price of ten dollars, or one-third the cost of a 

 Smithsonian barometer. Although for purposes of scientific 

 accuracy nothing can replace the old form of mercurial ba 

 rometer, Prof. Silliman did not hesitate to recommend the 

 aneroid as the best barometer for the use of the farmer. 

 Numerous testimonials, from farmers who had used them, 

 showed their utility in enabling the farmer to choose the time 

 of cutting and curing his hay, planting, &c. 



Prof. Silliman explained why the words " fair," " change 

 able," " foul," " tempest," &c., <fcc., written on the scale of the 

 cheap forms of mercury barometers were entirely unreliable. 

 It was only at the sea level that the barometer stood at an 

 average height of thirty inches, and hence a mere change of 

 place, rising a few hundred feet, would make the barometer 

 fall permanently below ''''fair weather," whatever the face of 

 the sky might say to the contrary. That the use of the barom 

 eter might be better understood, he enumerated the follow-* 

 ing general rules, which embody the results of long and various 

 experience in different places : 



1. When the mercury is very low, high winds and storms 

 are likely to prevail. 



2. Generally the rising of the mercury indicates the approach 

 of fair weather ; the falling of it shows the approach of foul 

 weather. 



3. In sultry weather the falling of the inercury indicates 



