774 EIGHTH PACIFIC SCIENCE CONGRESS 



channel axes must be erroneous. Multiple meter suspension was first 

 used with 80-inch buoys. They do not have enough reserve buoyancy 

 to carry the extra weight satisfactorily in strong currents. One-hundred- 

 twenty-inch buoys are now being used with much better results. Their 

 use also makes it possible to employ heavier "sinkers" and heavier ball- 

 bearing swivels between meters. 



For routine current work in the past, when velocities at levels 

 other than surface were desired, observations were made at two-tenths, 

 five-tenths, and eight-tenths of the depth at the station. In an effort to 

 determine the behavior throughout the depth, observations have been 

 made at varying intervals from surface to bottom. The larger num- 

 ber have been made at levels of 6 to 12 feet below the surface, at mid- 

 depth, and at a minimum of about 3 feet above the bottom, irrespective 

 of the rise and fall of the tide. The Woods Hole Oceanographic In- 

 stitution has devised an experimental mounting for use in shoal water 

 where velocities are desired at fixed levels within 1.5 to 3.0 feet from 

 the bottom. 



Equipment Availability and Cost 



The Roberts Radio Current Meter and equipment is not patented. 

 It is currently being used by several federal agencies and one or two 

 oceanographic institutions. One English instrument maker has ob- 

 tained a set of specifications and has, it is presumed, produced instru- 

 ments for Admiralty use. Those used in the United States have been 

 produced by three different "low-bidding" instrument makers, none of 

 whom have produced them for general sales. The radio transmitters 

 and sequence switches have been procured in much the same manner. 



The major items of special equipment necessary to operate a cur- 

 rent survey party using a launch and shore-based receiving station are 

 listed below, with the approximate total cost. 



1. Buoy, 120-inch 6 @ |760.00 - $ 4,560.00 



2. Roberts Radio Current Meter 



3. Radio transmitter for buoy . . 



4. Radio receiver for shore station 



5. Chronograph, tape recording . 



6. Voice radio, for launch and 

 shore station 2 



7. Ground tackle, per buoy 

 Sequence switch 6 



Total $21,275.00 



