RUDDER TRIALS, U. S. S. STERETT. 331 



and starboard propellers; and the time record a notch for each | second of 

 time. To estimate the ship's speed in approaching the turn, time and 

 revolutions over any chosen interval were counted on the record roll. Then, 

 since time can be read to the nearest half -notch, i. e., to | second, and since 

 the revolutions can be read to o.i space, or one revolution, the possible error 

 in time for an interval of 30 seconds is W, or less than 0.5 per cent; and 

 the possible error in revolutions is -^hi, or less than 0.5 per cent. We may 

 therefore conclude that the precision of revolutions per minute, as obtained 

 from the record, is within i .0 per cent. 



