14 University of California Publications in Zoology [ Vou. 14 
(7) The velocity of the tidal current was ascertained with a Price 
current meter,’ which was suspended from the port or starboard 
gangway, at a distance of four or five feet from the ship’s side. It 
was immersed to a depth of only two or three feet beneath the water’s 
surface. This useful instrument is represented in plate 11, which is 
reproduced by the courtesy of the manufacturers, Messrs. W. and 
L. E. Gurley, of Troy, New York. The revolutions of the wheel, 
which is construeted much like that of an anemometer, produce clicks 
which are communicated to the ear by means of a telephone receiver. 
From the number of clicks in a given interval (determined by a stop- 
watch) the velocity of the stream in feet per second can be readily 
ascertained by reference to a table. 
The instrument now owned by the ‘‘ Albatross’’ was tested by the 
Bureau of Standards. The tests of the latter were, however, made 
in fresh water. For strict accuracy, it would be necessary to apply 
a correction, owing to the higher viscosity of sea water. The extent 
of this error is not even approximately known. 
(8) Tow-net hauls were made according to the system described 
above (pp. 7 and 8). 
(9) During two of the bi-monthly periods samples of the bottom 
material for quantitative studies were taken by means of a special 
apparatus, at all of the hydrographic stations of the regular series, 
except at a very few where the bottom was too hard to allow of a 
sufficient penetration by the instrument. Samples of the same sort 
were obtained at a number of stations which did not belong to the 
regular hydrographie series. 
As above stated, portions of the bottom material, brought up by 
the dredge, were preserved at nearly all of the dredging stations, but 
these were not adapted to revealing certain important features of the 
bottom of the bay. It was regarded as an important requirement to 
obtain cylindrical samples or cores, extending into the mud or sand 
as deeply as possible and preserving whatever stratification might 
exist there. 
Two instruments of somewhat different type were tried for the 
purpose. The first was the Ekman (1905b) bottom sampler, one of 
which was constructed for us by Mr. Arntzen. A rather extensive 
trial of this apparatus was made, and bottom samples were taken at 
3 Our thanks are due to Mr. H. D, MeGlashan, of the United States Geolog- 
ieal Survey, Water Resources Division, for the loan of one of these instruments 
during the second of our periods of observation. Later one was purchased for 
the vessel. 
