450 



BUI/LETIN OF THE BUREAU OF FISHERIES. 



are presented in a series of tables, and likewise on charts 211 to 214, giving the 

 location of the stations. 



The average monthly temperature of the water off the Government wharf in Great 

 Harbor, Woods Hole, for the years 1902-1906 (five years) is given in table 10, page 

 47, and the seasonal changes are portrayed graphically in chart 219. It will be seen 

 that during January, February, and March the mean temperature was below 35° F. 

 The period when the temperature was below 35° actually extended from about 

 December 25 to March 15, and this may be considered the winter season. After March 

 1 5 the temperature rose rapidly, passing 60° about June i ; this constitutes a spring 

 season. Between June i and October 12 the temperature remained above 60°, holding 

 between 69° and 71° from July 11 to August 28, a period of 48 days; this is the long 

 summer season of warm water. After October 12 the temperature fell rapidly from 60°, 

 until December 11, when it reached 37°, and it remained between 37° and 35° until 

 December 26, when it passed below 35°; this period may be considered the autumn 

 season. A table of averages such as that of table 10 does not give the extremes of 

 temperature, the lowest of which was 28>^° in January and February, and the highest 

 74° in July and 74.5° in August. It should also be remembered that the extremes are 

 much greater in situations more sheltered than Great Harbor, Woods Hole, as, for 

 example, in the upper portions of Buzzards Bay, where the water may be heaxdly frozen 

 for several weeks and the summer temperature probably rises close to 80°. 



It is very important to contrast the seasonal range of temperature at Woods Hole 

 with that of the bottom water between Gay Head and the ledges of Sow and Pigs, for 

 in this region of the survey the range of temperature is the least. On August 16, 1907, 

 the bottom temperature off Gay Head was 57.2° F. {16}^ fathoms) and 59.2° (iiK 

 fathoms), off Sow and Pigs 60.1° (loK fathoms), and in Vineyard Sound between these 

 two points 55° (17K fathoms) ; the surface temperature at these stations was from 3° to 

 5° higher. On November 12, 1907, the bottom temperature off Gay Head was 51.9° 

 (io>^ fathoms), off Sow and Pigs also 51.9° (8 fathoms), and in Vineyard Sound between 

 these points 52° (18 fathoms); the surface temperature at these points was about 1° 

 lower. On March 20, 1908, the bottom temperature off Gay Head was 36.6° (8 fathoms), 

 off Sow and Pigs 36.6° (5 fathoms), and in Vineyard Sound between these two points 

 37.4° (18 fathoms); the surface temperatures being almost the same. On June 6, 1908, 

 the bottom temperature off Gay Head was 57.6° (12K fathoms), off Sow and Pigs 55.1° 

 (7^2 fathoms), and on June 5 in Vineyard Sound between these two points 53.3° (18 

 fathoms) ; the surface temperature at these points was then from 1° to 3° higher. These 

 data are presented in tabular form below, the surface temperature being given above 

 the line and the bottom temperature below. 



Aug. 16, 1907. 



Nov. 12, 1907. 



Mar. to, 190S. 



June s-6. 1908. 



off Gay Head 



Off Sow and Pigs 



Between Gay Head and Sow and Pigs 



^T (loK fath.) 

 60. 1 



— ^-(iTXfath.) 



55 



5°-7 



-^^ (loH fath.) 



?^% (8 fath.) 

 SI. 9 



Sii (18 fath.) 



36- 8° 



j-ftTeS (8 fath.) 



~K (s fath.) 

 56.6° " 



36.7° 



(18 fath.) 



521I5 (uM fath.) 

 S7- 6 (June 6) 



5tl!(7K fath.) 

 55- 1 (June 6) 



-5^ (18 fath.) 

 53- 3 Oune s) 



