GENERAL INTRODUCTION TO THE ZOOLOGICAL REPORTS. 3 



we had become accustomed to our own plans, and could depend almost with certainty 

 upon the amount of work we .could do within a certain time, I thought it better to 

 continue steadily throughout as we had begun, and to secure the largest possible series 

 of similar and comparable observations, rather than run the risk of losing time through 

 possible failures. 



The Trial Cruises of the Porcupine. — The Porcupine was a 382-ton gunboat 

 fitted up for the surveying service, in which she had been employed for some years 

 among the Hebrides, and afterwards on the east coast of England. She was assigned 

 for our special work in 1869 with all her ordinary surveying fittings, and certaiu 

 imj^ortant additions A double-cylinder donkey-engine, which worked to about 12 horse- 

 power, was set up on deck amidships, and was fitted with large drums for bringing 

 up light weights rapidly, and smaller drums for heavier work ; to either of which, lines 

 might be led either from fore or aft. We almost always used the large drum both in 

 dredging and sounding, and except on one or two occasions, when an enormous load 

 came up in the dredge-bag, the deck-engine delivered the rope steadily at the rate 

 of a foot per second during the whole summer. A powerful derrick projected over 

 the port-bow. A large block was suspended at the end of the derrick by a rope, which 

 was not directly attached to the spar, but passed through an eye, and was attached 

 to a " bitt " on deck. On a bight of this rope was lashed a strong combination of 

 Hodge's "accumulators" {p. 14), an arrangement invaluable in dredging from a large 

 vessel. From the great strength of these springs the dredge is usually drawn along 

 without stretching them to any great degree ; they become tense and taut, and 

 yield with a slight pulsation only, to the rise and fall of the vessel. Whenever the 

 accumulators run out it is a sure indication that the dredge has caught, or that the 

 weight in it is too great ; and that the dredge-rope ought to be reheved by a turn 

 of the paddle-wheel or screw. A second derrick, nearly equally strong, was rigged 

 over the stern (fig. 3), and we dredged sometimes from one and sometimes from the 

 other. 



We had an excellent plan for stowing the dredge-rope in the Pokcupine (Fig. 3), 

 a plan which made its manipulation easy, notwithstanding its great weight. A row 

 of about twenty large iron pins, about 2-g feet in length, projected over one side of the 

 quarter-deck, rising obliquely from the top of the bulwark, and ending over the deck in 

 smooth white balls. Each of these held a coil of from 200 to 300 fathoms, and the rope 

 was coiled continuously along the whole row. When the dredge was going down, 

 the line was taken rapidly by the men from the pins, and in hauling up a relay 

 of men carried the rope along the deck from the surging-drum of the donkey engine, 

 and laid it in coils on the pins in inverse order ; in letting go, the rope passed to the 

 block of the derrick directly from the pins ; in hauling up, it passed from the block to 



