514 BULLETIN OF THE BUREAU OF FISHEEIES 



The first attempt to measure the temperature of the gulf below the surface was 

 made in the summer of 1870, when Verrill (1871, p. 3) found the water virtually homo- 

 geneous, surface to bottom, in Passamaquoddy Bay, though readings with thermometers 

 of the maximum-minimum type established a considerable range of temperatures on 

 the offshore slope of Georges Bank (Verrill, 1873; Sanderson Smith, 1889, p. 887). 



Two summers later surface and bottom temperatures were taken at a large num- 

 ber of stations in the neighborhood of Casco Bay from the Fish Commission steamer 

 Blue Light (VerriU, 1874, 1874a), and also at various localities in deep water in the 

 western side of the gulf by the Coast Survey steamer Bache (Sanderson Smith, 

 1889, p. 885; Packard, 1876). As a result of this summer's work Verrill was able to 

 bring to scientific attention the contrast between the low bottom temperature and 

 the warm surface of the western side of the gulf. 



The survey was continued by the Bache in the summer of 1874 at about 40 dredg- 

 ing stations in the western side of the Gulf of Maine, in depths of 27 to 113 fathoms 

 (Sanderson Smith, 1889, p. 886). No observations were taken in the gulf in 1875 

 or 1876; but in 1877 the Fish Commission, from the Speedwell, in connection with a 

 survey of the bottom fauna, took surface and bottom temperatures in the northern 

 part of Massachusetts Bay, with serial observations at several stations on a line 

 crossing the gulf to Cape Sable. 



Unfortunately, none of the subsurface temperatures taken in the gulf up to that 

 date were even approximately dependable, according to present-day standards, 

 because the Miller-Casella thermometers employed were not only unreliable (Verrill, 

 1875, p. 413), but, being of the maximum-minimum type, they would register merely 

 the lowest temperature at each station, which was not necessarily at the level at 

 which the reading was ostensibly taken. Modern oceanographic research in the gulf 

 may therefore be dated from the summer of 1878, when the Speedwell took temper- 

 atures in Massachusetts Bay and off Cape Ann, including serials at 31 stations (San- 

 derson Smith, 1889, p. 905; Eathbun, 1889, p. 1005), with reversing thermometers. 

 This type, improved from time to time, has been employed regularly ever since. 

 The Speedwell worked again in the gulf in the summer of 1879 (Sanderson Smith, 

 1889, p. 909; Rathbun, 1889, p. 1006). In June, 1880, the Blake took surface 

 and bottom readings at three stations inside the 200-fathom contour on the eastern 

 part of Georges Bank (Rathbun, 1889, p. 972, and A. Agassiz, 1881), while in 

 August the Fish Hawlc obtained similar data off Chatham, Cape Cod, in 10 to 43 

 fathoms (Rathbun, 1889, pp. 922-923), but did not visit the more northern parts of 

 the gulf. 



The year 1882 is an important one in the annals of North American oceanography, 

 because that spring saw the oft-quoted destruction of the tilefish ^ and of the inver- 

 tebrate fauna that inhabited the warm band along the edge of the continent, pre- 

 sumably by flooding with very cold water. During the following August the Fish 

 Hawk took observations south of Marthas Vineyard and made one trip to the 100- 

 fathom line east of Cape Cod (Rathbun, 1889, p. 925). 



Surface and air temperatures were recorded from early spring to late autumn at 

 several lighthouses and lightships along the coast- of the gulf from Nantucket Shoals 

 to Petit Manan during the years 1881 to 1885, the 10-day averages of which are 



' For an account of this event and of the gradual reestablishment of the speotes see Bigelow and Welsh, 1925. 



