MERCURIAL GAUGES. 



273 



TABLE 



Showing the fluctuations in Mercurial Gauges attached to the roots 

 and trunks of trees, with descriptions of the specimens under observa- 

 tion. The figures denote inches of mercury, and Avhen the minus sign is 

 prefixed they indicate suction ; otherwise, pressure. To convert inches of 

 mercury into feet of water, multiply the number by 13.60, the specific 

 gravity of mercury, and divide the product by 12. When the figures are 

 omitted for. one or more days after the record has begun.it shows that 

 in consequence of some accident no observation could be made. The 

 hour for the first observation of any day is seven a.m., that for the second, 

 is noon, and that for the third, is six P. M. 



Mercurial Gauges. 



35 



