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POPULAR SCIENCE REVIEW. 
allowed to drift, and to carry forward the weight w 1 , so that 
the dredging is carried on from the weight, and not directly 
from the vessel. In this way the dredge is quietly pulled 
along, its lip scraping the bottom in the attitude which it 
assumes from the position of the centre of gravity of its iron 
frame and arms, and a much smaller quantity of rope is re- 
quired in proportion to the depth than in ordinary in-shore 
dredging. For the 2,435 fathoms’ dredging, 3,000 fathoms of 
rope were employed, and during the time when the writer was 
on board, 2,000 fathoms of rope were used for depths ranging 
from 1,200 to 1,476 fathoms. 
It is with great satisfaction that we have heard that her 
Majesty’s Government have granted the use of the Porcupine 
and her apparatus for a cruise in the Bay of Biscay and the 
Mediterranean during this summer, under the same scientific 
charge as before, and that her talented and experienced captain 
will be still in command of her. The scientific public will 
await the results of this expedition with great interest. 
EXPLANATION OF PLATE. 
The plate represents the quarter-deck of the Porcupine in Galway Dock, 
June 1869 (from a photograph). 
