103 



this circle is completed, each boat has described three circles 

 with the inspection barque as a centre. And, in this way, 

 twelve circles in all are described by the four boats. The 

 oysters are then brought to the ship, counted, and put in 

 sacks daily, until a sufficient number (15,(>00) to form a 

 sample for washing and valuation by experts has been col- 

 lected.^ The coxswain of each boat records on a diagram, 

 provided by the Inspector, the approximate position of each 

 dive which is made, the nature of the bottom (a triangle = 

 rock, a circle =: sand, and a cross = oysters), and the number 

 of oysters lifted. Diagram A represents the day's work 

 done by one boat over ground which, with the exception of 

 a sandy patch between the north and east f mile buoys, was 

 rocky, and on which oysters were plentiful except over a 

 portion of the outer circle. Diagram B, made up from the 

 four coxswains' reports, represents a single day's work done 

 by all the boats, and shows the distribution of the oysters 

 over the area inspected, and the limits of the bank. As 

 soon as the buoys have been taken up by the tug the inspec- 

 tion barque is moved to a new position 1 ^ mile distant from 

 its former one, and the buoys are again laid out in circles, to 

 act as guides to the boats in the next day's work. Without 

 the assistance of the buoys the boats would not be able to 

 describe separate circles, but would work in an irregular 

 manner, and two or more boats would, very probably, go 

 over the same ground. But, with the assistance of the 

 buoys, the whole bank can be systematically surveyed. 



The Muttuwartu Par, which was fished in the spring 

 of 1889, is situated about 5 miles from the seaward shore 

 of Dutch Bay, and covers an approximate area of 3 x 1 J 

 miles, the depth of water over the bank ranging from 5 

 to 10 fathoms with an average of about 7 fathoms. The 

 temperature of the water at the bottom, registered with a 

 Negretti and Zambra's deep-sea thermometer, varied from 

 80° to 82° between 8 a.m. and 5 p.m. The specific gravity 

 of the surface water, tested with a Twaddell's hydrometer 

 regulated for a temperature of 84°, was, approximately, 

 1"025. Between the bank and the shore is a coral reef, the 

 presence of which was indicated by the waves breaking over 

 its outer face amid a prevailing calm, and by gulls resting 

 on the coral blocks. The most conspicuous Madreporaria 



* If a young bank is being inspected, samples are brought up by the 

 divers, but they are not \« ashed for valuation. 



