334 STATE POMOLOGICAL SOCIETY. 



mum pressure was attained May sixteenth, and was 39.66 feet, while the 

 greatest suction occurred June twentieth, and was -10.77 feet. The extreme 

 variation of the upper gauge was 50.43 feet. The difference between the two 

 gauges was usually from 20 to 30 feet of water; but when the pressure on the 

 lower one was greatest, the difference was 60.41 feet, in consequence of the 

 fact that the force was entirely from the root, and the wood of the vine was a 

 hindrance to the sudden upward thrust of the sap. After the foliage was de- 

 veloped the suction was limited to from -6 to -12 feet of water, on account, 

 doubtless, of the porous character of the foliage and young branches, and 

 there was no great difference between the gauges. 



THE FLOW OF SAP FROM THE SUGAR MAPLE, 



so familiar to all, and yet so variable and peculiar, was the first object of in- 

 vestigation in the beginning of these experiments in 1873, but its mysterious 

 fluctuations were not fully known nor understood until the close of the year 

 1874. The extraordinary facts that the flow occurred in midwinter and early 

 spring, when the ground was covered with snow and there were no signs of 

 life; that the flow began only during mild days immediately following a severe 

 frost, and ceased usually after a few hours ; that when a cavity was cut into 

 a sugar maple tree the sap flowed down from above, while in a birch it flowed 

 most freely from below ; and especially the fact that when a gauge was at- 

 tached to a tree, it exhibited the most surprising variations from great press- 

 ure, during the day, to powerful suction at night, — these, and other unac- 

 countable things, seemed to demand special effort to discover all the phe- 

 nomena attending the flow of maple sap ; and then, if possible, to invent some 

 rational explanation of them. 



Accordingly, a large number of experiments were devised and carried out, 

 with a very great amount of labor and no little expense. Among them were 

 the collection and weighing of all the sap which would flow from a healthy 

 tree, from November to the following May; with a careful observation of the 

 times when the flow began and ceased, in each case of good sap-weather ; the 

 collection, weighing and analysis of sap during different periods of the entire 

 season, both from the usual level and from the top of a tree thirty feet from 

 the ground ; the collection and examination of the gas which escapes with the 

 first flow of sap from the orfice first made in a tree in the spring; the effect of 

 increasing the number of holes upon the total flow of sap and the entire 

 product of sugar; the result of tapping trees at various elevations from the 

 earth, on different sides, and to different deptlis; and finally, a record for com- 

 parison and study of the fluctuations in the mercury of several gauges, 

 attached to various parts of the same tree, as observed three or more times 

 daily. 



A SHOWER OF SAP. 



Mr. Samuel F. Perley, of Naples, Maine, in an interesting communication 

 containing much valuable information derived from his large experience in 

 the sugar-bush, relates the following incident: "Happening, on a bright, sunny 

 morning, to visit a sugar tree standing in open land, and having a large, 

 spreading top, I was surprised, on walking beneath the limbs, to find quite a 

 smart shower falling upon me. On looking up I could see no clouds, yet the 

 drops were falling thick and fast in all the area covered by the branches of 

 the tree. An examination showed the drops to be drops of sap flowing from 



