OYSTERS, AND ALL ABOUT THEM. 



the currents, the speed of the vessel, and the difficulty of 

 handling a long staff, but few determinations of the cha- 

 racter of the substratum were made when the depth of 

 water was greater than three fathoms. 



CURRENTS. 



The currents were measured by a current meter, or by 

 an ordinary chip log, though the latter was not used fre- 

 quently. 



* 



NUMBER OF OYSTERS TO THE SQUARE YARD. 

 The number of oysters to the square yard was found 

 by using a ground log in connection with the dredge. 

 From the information derived from experienced oystermen, 

 and from our own examination of those beds that had been 

 dredged, I was of the opinion that a dredge, when of con- 

 siderable size, and dragged slowly, usually collected every- 

 thing met by it in its course. Considering that, at the sug- 

 gestion of Mr. Rice, I used a small ground log to measure 

 the distance travelled by the dredge. As that instrument 

 was exactly one yard in width, it was concluded that it 

 swept approximately clean one square yard for every linear 

 yard it passed over. The ground log consisted of a small 

 lead, a few ounces in weight, attached to a light line 1000 

 feet long ; between the lead and line was a length of 

 copper wire of 20 feet ; the line was marked every five 

 fathoms, and kept in a tub or on a reel ready for use ; the 

 lead was conical in shape, to prevent its catching on shell 

 clusters. When the dredge was thrown over, the lead was 

 dropped to the bottom and allowed to remain there, the 

 line running out freely until the dredge was lifted off the 

 bottom, when the line was stopped and the number of 

 fathoms run off with the number of oysters in the dredge 

 recorded. The dredge was not^allowed to remain on the 



