262 



THE PLANT COVERING OF OCRACOKE ISLAND. 



Theodor Holm has rendered valuable assistance, and lie has kindly 

 furnished the drawings for figures Nos. 1 to 8, 17, and 18. The other 

 figures were drawn from nature by the author. 



CLIMATE. 



The following data have been obligingly furnished by the United 

 States Weather Bureau. The observations were made at the llatteras 

 Station, only a few miles northeast of Oeracoke. 



TEMPERATURE. 



Readings were taken in the shade. 1 The observations at llatteras 

 cover a period of about twenty years. The average number of days 

 per annum with a temperature exceeding 6° C. (43° F.) is 365, while at 

 Norfolk, Va., the number is only 205. The sum total of temperatures 

 above 6° C. during the year averages 3,749.4° C. (i;,749° F.), which 

 is notably higher than the Norfolk figure of 3,359.4° C. (0,047.0° F.). 

 The normal mean temperature during the six consecutive hottest weeks 

 of summer is 25.9° C. (78.0° F.), as compared with the slightly higher 

 mean of 20.3° C. (79.3° F.) at Norfolk. 



The normal annual temperature is 1(5.3° C. (61.4 F.), as compared 

 with 14.8° C. (58.7° F.) at Cape Henry, Virginia, 15.0° C. (59.0° F.) at 

 Norfolk, Va., and 17.2° C. (03.0° F.) at Wilmington, N. C. 



The normal monthly temperatures are as follows: 



January . 

 February 



March 



April 



May 



June 



Degrees C 



Degrees F. 



7.6 



45.7 



s. 1 



46.6 



10.0 



50.1 



lid 



57.2 



19.1 



66. 4 



as. 3 



71.0 



July 



August 



September 



October 



November 



Doeember 



Degrees < '. Degrees F. 



so. .» 

 25.2 

 83.2 

 18.0 



l;l. l 

 0.0 



77. fl 



::a 



;::.7 



64.5 



55. e 



48,2 



The normal daily range of temperature for the whole year amounts 

 to 6.3° C. (11.3° F.),as compared with 8.2° C. (14.7° F.) at Cape Henry, 



8.8° C. (15.8° F.) at Norfolk, and 9.0° C. (17.3° F.) at Wilmington. 

 The normal daily ranges for each month are as follows: 



January . 



February 



March 



April 



May 



June 



Degrees (\ Degrees F. 



5.1 

 5.3 



6.8 



7.1 



10.11 

 !».2 

 0.6 

 10.2 

 L1.3 

 I2.X 



'Consequently they do not represent the temperature to which most of the vege- 

 tation is actually exposed, being subject to insolation during the hours of sun- 

 shine. They are chiefly valuable for purposes of comparison with other climates. 



