SAP OF TREES. 
171 
stracted from the soil by this tree alone is measured by thou¬ 
sands of gallons to the acre. The sugar orchards, as they are 
called, contain also many young maples too small for tapping, 
and numerous other trees—two of which, at least, the black 
birch, Betula lenta , and yellow birch, Betula excelsa , both 
very common in the same climate, are far more abundant in 
sap than the maple *—are 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 most 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 stimu¬ 
lated to its highest activity.f 
to the acre, one hundred and twenty-eight of which were of proper size 
for tapping.” 
According to the census returns, the quantity of maple sugar made in 
the United States in 1850 was 84,253,436 pounds ; in 1860, it was 38,863,- 
884 pounds, besides 1,944,594 gallons of molasses. The cane sugar made 
in 1850 amounted to 237,133,000 pounds; in 1859, to 302,205,000.— Pre¬ 
liminary Report on the Eighth Census , p. 88. 
According to Bigelow, Les j&tats Unis PAmerique en 1863, chap, iv, 
the sugar product of Louisiana alone for 1862 is estimated at 528,321,500 
pounds. 
* The correspondent already referred to 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 quantity. The sap con¬ 
tinued to flow for four or five weeks, and it was the opinion of the ob¬ 
servers that it must have yielded as much as sixty barrels [1,890 gallons].” 
t “ The best state of weather for a good run,” says my correspondent, 
“ is clear days, thawing fast in the daytime and freezing well at night, 
with a gentle west or northwest wind; though we sometimes have clear, 
fine, thawing days followed by frosty nights, without a good run of sap. 
