Ig1t] BURNS—HURON RIVER VALLEY III 
graph was then inserted in the side of the opening parallel to the 
surface for about 18 inches (45.8 cm.), and the piece of peat was 
replaced. The surface arrangement was left as nearly normal as 
possible. Some of the records were made at Dead Lake, but most 
of them were made at First Sister Lake. 
in 
555533° 2:52 
BE: waae baa? 422 ie 332 
5 eiiiet an idl lituubasa LEE fi 
Puta a capemnee ie ave 
SiEScaeGatdeugetses SUGUNMERESEERSESESS an 233 
ie STL SUETHLNE nT 
SES EuG DENEES UE SER NESEEA AREEEE REREEE Sau a 
fii Veit 
Hci “AME 
Hay 
ee 
Hi ett 
Fic. 3.—Temperature record of the air for the week July 2-9, 1906, taken in the 
sedge zone at First Sister Lake; the highest was 31° C., the lowest 3°5 C.; this occurred 
about 5 A.M., July 6. 
Fig. 4 shows a partial record of the results which were obtained 
at the latter lake at different depths in the tamarack zone. A 
is taken from the figures of TRANSEAU (18, p. 421) and gives the 
readings at a depth of 1 inch (25 mm.). At this depth the rise 
in temperature is quite rapid and resembles that of the adjacent 
uplands. At the time the leaves began to appear, May 27, it had 
reached 17° C. Line B gives the record for a depth of 4 inches 
APRIL MAY JUNE SJULY AUG. 
4g _ [4 4 / 3 i 2. Z, 
1-4 
/o ea a 8 OS ee : --C 
ee POT -D 
Fic. 4.—Diagram showing variation in temperature at different depths and at 
different seasons in the tamarack zone; A, 25 mm.; B, 10.2 cm.; C, 20.4 cm.; D, 
45.8 cm. below the surface. 
(10.2 cm.) to June 1. The temperature at this point does not 
rise so rapidly as that just given, and on May 25 had reached 
9° C. The dotted line C gives the temperature at 8 inches (20.4 
cm.). This record shows that during the spring, when leaves are 
unfolding, the soil temperature at this depth remains compara- 
tively low; not until July 22 did it reach 14° C. This was held 
for about a month (July 22—August 24), when it gradually began 
