50 BULLETIN OF THE BUREAU OF FISHERIES. 



elsewhere recorded within the region, owing to the conservative influence of the ocean 

 in retaining the heat received during the summer. It would have given no surprise, 

 therefore, to find the mean annual temperatures approximately the same throughout all 

 these waters. Unfortunately we have no data for the coldest period of the winter. 

 Reference to the temperature curv'es for the Woods Hole station shows that the water 

 cun'e reaches its lowest level on February 19. It was planned, accordingly, to obtain a 

 series of observations in Vineyard Sound and Buzzards Bay at about that date in 1908. It 

 is a matter of much regret that no boat was available for this purpose until a month later, 

 when the water temperature throughout the entire region had risen to nearly 37° F. 

 At this time, as has already been pointed out (p. 44), a great uniformity in water tem- 

 perature prevailed throughout the region explored, and the outlying waters, off Gay 

 Head and Cuttyhunk, did not differ appreciably from those of the other portions of 

 Vineyard Sound and Buzzards Bay. It will be recalled that in November there was 

 likewise a large measure of uniformity, though at that time the outlying waters were 

 somewhat warmer than the rapidly cooling waters of the upper half of the Bay. In 

 the absence of further data it might be contended that at the time the November obser- 

 vations were made the inshore temperature was just passing the ocean temperature 

 in its annual decline, while, on the other hand, it might be supposed that the March 

 temperatures were taken at a time when the inshore temperature curve was again about 

 to cross that for the ocean temperature. And indeed it is possible, that in the inter- 

 vening months the latter did remain somewhat higher than the former. 



But even on the impossible supposition that 36° F. represents the minimum tem- 

 perature of these outlying waters,'' this figure would be only about 7° higher than the 

 lowest recorded elsewhere (i. e., the freezing point of sea water), whereas in summer 

 the extremes of temperature varied as widely as 15°. Thus, in any case, the mean 

 annual temperature of the bottom waters in the outlying portions of Vineyard Sound 

 and Buzzards Bay is undoubtedly lower than that of the more inclosed areas to the 

 northeast. For Vineyard Sound the mean bottom temperature of the stations lying 

 to the seaward of Robinsons Hole, as based upon the four seasonal averages obtained 

 by us, is 50.53°. The corresponding figure for the remainder of Vineyard Sound was 

 found to be 53.31°. This difference, however, is entirely determined by the June and 

 August results, so that for the summer months alone the difference would be about 

 twice as great. 



Another plain deduction from the foregoing figures is that the total annual range 

 of temperature in these outlying waters is far less than in the more inclosed waters 

 of the region. For the former the temperature range is probably about 30° F. ; for 

 the latter it may reach 45° or more. 



The occurrence in summer of colder waters in the ocean immediately beyond the 

 mouth of Vineyard Sound was pointed out by Verrill as long ago as 1871, and a few 

 definite temperature figures were then presented by him. These last were also included 

 in the chart accompanying the "Report on the Invertebrate Animals of Vineyard 

 Sound." On September 9 the lowest figure recorded by Verrill was 57° F., which 

 was the bottom temperature at a point several miles beyond Gay Head. Within the 



o Rathbun (iS.*^;) in a chart (No. 17), giving temperatures taken during 6ve >-ears at the Vineyard Sound Lightship, off 

 Sow and Pigs Reef, records figures as low as 29" and 30" during January and February. For most of the time durin- these 

 months, moreover, the temperature remained below 35°. These were surface temperatures, it is true, but it is likely, ;is above 

 stated, that the figures for surface and bottom are not far from equal in winter. 



