1 8 BULLETIN OF THE BUREAU OF FISHERIES. 



underlying, smaller-meshed trays. The contents of each tray were examined in turn, 

 according to a system to be described later. 



The Tanner sounding apparatus" was employed at each of the Fish Hawk stations, 

 together with the Sigsbee "water specimen cup," and the Negretti-Zambra thermometer. 

 Thus the temperature and density were recorded, as well as the depth of the water. 

 It was later realized, however, that the figures for temperature and density obtained 

 during the regular dredging operations were not sufficiently exact for the purposes of 

 the work, and, likewise, that no fair comparison would be possible of the different 

 waters in the region unless we possessed a set of determinations which had been made 

 nearly or quite simultaneously throughout its entire extent. For this reason a new set 

 of temperature and density observations, taken with standardized instruments and 

 within the briefest period possible, was made after the completion of the dredging 

 work. Such determinations were repeated several times at intervals of a few months, 

 so that the seasonal conditions are now pretty well known. These will be discussed in 

 a later section. 



The position of the vessel was determined in the earlier part of the work by means 

 of an azimuth compass located on the roof of the deck house, just abaft the pilot house. 

 Bearings were taken upon two, sometimes three, landmarks, usually lighthouses. This 

 was commonly done just before the lowering of the dredge. The "station," as re- 

 corded on the chart, was thus the point where the dredge haul commenced, while the 

 direction and amount of the drift was estimated rather roughly.'' Later, tripods were 

 erected upon a number of Coast Survey triangulation points and sextants were employed 

 in locating the ship's position. Angles were taken simultaneously by two observers, 

 one of whom found the angular distance between X and Y, the other that between 

 Y and Z. The position of the vessel was determined both at the beginning and at the 

 end of the dredge haul, and frequently at one or two intermediate points. Thus upon 

 the maps the later stations in Vineyard Sound appear not as single circles but as straight 

 or curved lines, at intervals in which are to be found the points (a, b, c, etc.) at which 

 sextant readings were taken. 



The Phalarope is a steam vessel, originally designed as a yacht, having a length of 

 82 feet at the water line, or of 92 feet over all, and a beam of 16 feet. She draws 7K 

 feet of water, and her average speed is probably about 1 1 knots. The Phalarope carries 

 no dredging machinery and is not permanently equipped for this work. In landing the 

 dredge a small derrick was employed, this being operated by hand power. The contents 

 were emptied upon a special movable platform built over the forward cabin. A set of 

 sieves was employed similar in principle but smaller than those used on the Fish Hawk. 

 With this vessel the use of the beam trawl was impracticable, and even the oyster dredge 

 was too heavy to be employed very frequently, though it was used to advantage under 

 certain conditions. The second type of dredge mentioned above was therefore the 

 principal one employed. 



Since the Phalarope dredging was, for the most part, done within a quarter of a 

 mile from land, it was found to be possible to locate the stations with a fair degree of 

 accuracy by reference to features of the shore. Bearings upon lighthouses were not 

 commonly practicable, nor indeed were they believed to be especially desirable. The 

 soundings indicated, with sufficient precision, the distance from land, and the direction 



a For descriptions and figures see Tanner (1884. 1897). 

 b This last has been omitted frjm tiic 1903 records. 



