PETRY: VEGETATION OF NEW YorK STATE 205 
these conditions, the bottom is completely free from air currents 
due to winds; even on a day when the local weather bureau station 
reported a wind velocity of thirty-five miles per hour, no move- 
ment of the air was perceptible half way down the slope of the 
basin. This absence of air currents is of prime significance in the 
explanation of the striking conditions of temperature that occur 
here. 
Four stations for the securing of data on temperature and 
humidity were established in the basin. The first of these (FIG. 1, 
A) is six feet back from the rim, on the south side; it is in a forest 
of Tila and Acer saccharum. The second station (B) is fifty feet 
down the slope from A; Tilia, Scolopendrium and Impatiens are 
the characteristic plants. Station C is one hundred feet further 
down the slope, while D is at the bottom of the basin, about one 
hundred feet below C. Temperature and humidity readings 
were made at each of these stations several times during the sum- 
mer of 1916 and once during 1917; the data obtained on August 22, 
1916, the hottest day of the year, are given in TABLE I. 
TABLE I 
TEMPERATURE AND HUMIDITY DATA AT STATIONS IN PLUNGE BASIN. AUGUST 22, 
IQ1I6, 2.30—4.30 P.M. 
Temp (Fabr.) Humidity (4) 
Sta- i } i | 
tion | 3 ft. above Gin-above |... -; .. | 6in. above 4ft.above | 6in. above 
ground ground be ee soil | ground | ground | ground 
Aes 94.7 90.6 81.5 72.5 | 32 30 
B.. 90.0 | 76.6 75.2 [se es F 
Gi 90.0 78.0 | 73.0 68.5 3 43 
oe 63-5 59-7 51.3 42.5 73 71 
The remarkable character of the conditions in the plunge basin 
is sufficiently shown by the data obtained at station D, where air 
temperatures were thirty degrees below those of station A, and 
where the soil temperature at a depth of six inches was only ten and 
one half degrees above freezing point. Readings made on other 
dates gave data similar to those of TaBLe I, but in no case were 
any of the temperatures at station D higher than those given above. 
Similarly, the humidity at D varied from 75 to 85 per cent. but was 
at no time found to be below that recorded in TasLe I. 
The cause of the low temperatures in the bottom of the basin 
