EVAPORATION. 23 



mapl&»»!u<e scattered among the sugar trees ; for the North American 

 native forests are remarkable for the mixture of their crops. 



" The sap of the maple and of other trees with deciduous leaves, 

 which grow in the same climate, flows more freely in the early spring, 

 and especially in clear weather, when the nights are frosty and the 

 days warm ; for it is then that the melting snows supply the earth 

 with moisture in the justest proportion, and that the absorbent 

 power of the roots is stimulated to its highest activity." 



In foot notes he adds : — " Emersoa (in his Trees of Massachussets, 

 p. 493), mentions a maple, six feet in diameter, as having yielded a 

 barrel, or 31 J gallons of sap in 24 hours, and another, the dimensions 

 of which are not stated, as having yielded one hundred and seventy- 

 five gallons in the course of the season. The Cultivator, an American 

 Agricultural Journal, for June 1842, states that twenty gallons of sap 

 were drained 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 enquiry msuie on 

 my behalf. This tree 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 (History of Vermont, p. 91), says, — ' A man much employed 

 in making maple sugar, found that, for twenty-one days together, a 

 maple tree discharged 7J gallons per day.' 



" An intelligent correspondent, of much experience in the manufac- 

 ture 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 coarse of a season, and of another, some- 

 what more than three feet through, which made 420) of wet sugar, 

 and must have yielded not less than 150 gallons. 



" The same correspondent informs me that a Black Birch, tapped 

 about noon with two incisions, was found the next morning to have 

 yielded sixteen gallons. Dr Williams (History of Vermont, I. p. 91) 

 says, — ' A large birch, tapped in the spring, ran at the rate of five 

 gallons an hour when first tapped. Eight or nine days after, it was 

 found to run at the rate of about two and a-half gallons an hour, and 

 at the end of fifteen days the discharge continued in nearly the same 

 qoantity. The sap coutiaued to flow for four or five weeks, and it 

 was the opinion of the observers that it must have yielded as much 

 as sixty barrels [1890 gallons]." 



