[8. ; >] FISHEEIES OF THE UNITED STATES. 597 



Cans for observing Ocean Currents, devised by the late Professor Henry 

 Mitchell. Eepresented by a diagram (Sigsbee's series of plates, 

 No. 5). 



United States Coast and Geodetic Survey. 



" The two cans are made of galvanized sheet iron, and are of the same 

 shape and size — a cylinder, 11 inches long by 8 inches in diameter, the 

 upper being surmounted by a cone, 3 inches in height. At the top of 

 each is a small aperture. In use, the aperture of the lower can is kept 

 open for the entrance of water, to facilitate the sinking of the can and 

 prevent its being crushed under pressure, while that of the upper can 

 is kept closed by a cork, no water being admitted. The cans are con- 

 nected by a length of sounding wire (diameter .028 inches), and are so 

 loaded with old scraps of lead or iron, or with pebbles, that when set 

 adrift the lower can will sink to the full extent of the connecting wire, 

 while the upper can will be submerged only to the base of its conical 

 top, thus making the submerged surface of the two cans equal. For 

 observing surface currents, the lower can is sunk to a depth of one or 

 two fathoms, simply to counteract the effect of wind and surface wash 

 on the floating can. For subsurface currents, it is lowered to the depth 

 at which it is desired to know the current, the distance being regulated 

 by the connecting wire. To the upper can is attached a graduated line, 

 marked for knots and tenths, the length of each knot being 50.7 feet, 

 to correspond to a time interval of 30 seconds. Sometimes a few fathoms 

 of stray-line are interposed between the floating can and the initial 

 mark, the last being a white rag. Observations are made from the boat, 

 as a station point ; those for velocity being made after the manner of 

 observing the speed of a vessel with the log chip. The direction of the 

 movement of the can is obtained by compass from the station point." 



MAEINE ZOOLOGICAL STATIONS. 



The Agassiz Zoological Laboratory, at Newport, Rhode Island, for ad- 

 vanced students in biology. Eepresented by plans. 



Alexander Agassiz. 



In establishing this laboratory Mr. Agassiz says, "I hope, by giving 

 facilities each year to a few advanced students from the Museum (of 

 Comparative Zoology) and teachers in our public schools, to prepare, lit- 

 tle by little, a small number of teachers, who will have had opportunities 

 for their studies hitherto unattainable." 



His description of the laboratory is as follows : " The new labora- 

 tory erected by me at Newport is 25 feet by 45. The six windows for 

 work are on the north side, and extend from the ceiling to within 18 

 inches of the floor. In the spaces between the windows and the corners 

 of the building are eight work tables, 3 feet by 5, covered with white 

 tiles, 1 foot of the outer edge being covered, however, with black tiles for 



