and direction histograms have been given elsewhere (Halpern, 1969). We 
have included the histograms in this report for "completeness" of the 
data summary. 
2. DATA REDUCTION 
Speed was determined over a 50-second interval by counting the 
number of switch closures produced by 16 small magnets mounted on the 
Savonius rotor. The next measurement occurred 10 seconds later. The 
time series of speed was edited for zero values and for erroneously high 
values; approximately 1% of the series was replaced by linearly interpo- 
lated values. 
During the 50=-second sampling period the current direction was 
measured by the simultaneous recording of 20 instrument-vane orientations, 
which give the direction of the current relative to the instrument, and 
20 magnetic compass readings, which give the orientation of the instru- 
ment relative to magnetic north, The current direction associated with 
the 50-second averaged speed was equal to the difference between the 
vector average of each set of 20 measurements, Current direction is de- 
fined as the direction in which the water is flowing. 
The basic data consists of two time series, one of 50-second 
averages of speeds and one of 50=second averages of directions. Direc- 
tions are referred to true north. 
