184 SAP OF SUGAR MAPLE. 
Flow of Sap. 
The amount of sap which can be withdrawn from living trees 
furnishes, not indeed a measure of the quantity of water sucked 
up by their roots from the ground—for we cannot extract from 
a tree its whole moisture—but numerical data which may aid 
the imagination to form a general notion of the powerful action 
of the forest as an absorbent of humidity from the earth. 
The only forest-tree known to Europe and North America, 
the sap of which is largely enough applied to economical uses 
to have made the amount of its flow a matter of practical impor- 
tance and popular observation, is the sugar maple, Acer saccha- 
rinum, of the Anglo-American Provinces and States. In the 
course of a single “sugar season,” which lasts ordinarily from 
twenty-five to thirty days, a sugar maple two feet in diameter 
will yield not less than twenty gallons of sap, and sometimes 
much more.* This, however, is but a trifling proportion of the 
* Emerson (Z7’rees of Massachusetts, p. 493) mentions a maple six feet in 
diameter, as having yielded a barrel, or thirty-one and a half gallons, of sap in 
twenty-four hours, and another, the dimensions of which are not stated, as 
having yielded one hundred and seventy-five gallons in the course of the sea- 
son. The Cultivator, an American agricultural journal, for June, 1842, states 
that twenty gallons of sap were drawn in eighteen hours from a single maple, 
two and a half feet in diameter, in the town of Warner, New Hampshire, and 
the truth of this account has been verified by personal inquiry made in my 
behalf. Thistree was of the original forest growth. and had been left standing 
when the ground around it was cleared. It was tapped only every other year, 
and then with six or eight incisions.- Dr. Williams ([istory of Vermont, i., p. 
91) says: ‘‘A man much employed m making maple sugar, found that, for 
twenty-one days together, a maple-tree discharged seven anda half gallons 
per day.” 
An intelligent correspondent, of much experience in the manufacture of 
maple sugar, writes me that a second-growth maple, of about two feet in 
diameter, standing in open ground, tapped with four incisions, has, for several 
seasons, generally run eight gallons per day in fair weather. He speaks of a 
very large tree, from which sixty gallons were drawn in the course of a sea- 
son, and of another, something more than three feet through, which made 
forty-two pounds of wet sugar, and must have yielded not less than one hun- 
dred and fifty gallons, 
