Page:Popular Science Monthly Volume 3.djvu/281

Rh drifts gradually to leeward; and, when the whole (say) 18,000 feet of rope are out, C W and D might represent respectively the relative positions of the vessel, the weight attached 3,000 feet from the dredge, and the dredge itself. The vessel now steams slowly to windward, occupying successively the positions E, F, G, H. The weight, to which the water offers but little resistance, sinks from W to W’, and the dredge and bag sink more slowly from D to B. The vessel is now allowed to drift back before the wind, from H toward C. The tension of the motion of the vessel, instead of acting immediately on the dredge, now drags forward the weight (W’), so that the dredging is carried on from the weight, and not directly from the vessel. The dredge is thus quietly pulled along, with its lip scraping the bottom in the attitude which it assumes from the centre of weight of its iron frame and arms. If, on the other hand, the weights were hung close to the dredge, and the dredge were dragged directly from the vessel, owing to the great weight and spring of the rope, the arms would be continually lifted up, and the lip of the dredge prevented from scraping. In very deep dredging this operation of stealing up to windward until the dredge-rope is nearly perpendicular, after drifting for half an hour or so to leeward, is usually repeated three or four times.

"At 8.50 we began to haul in. The donkey-engine delivered the rope at the rate of rather more than a foot per second without a single check. A few minutes before one  the weights appeared, and, a little after one in the morning, eight hours after it was cast over, the dredge was safely hauled on deck, having in the interval accomplished a journey of upward of eight statute miles. The dredge contained 1½ cwt. of very characteristic pale-gray Atlantic ooze." The total weight brought up by the engine was:

As an abundant and characteristic invertebrate life is now shown to exist at such great depths, it is inferred to extend to all depths; and thus the whole ocean-bed becomes in future the domain of the inquisitive naturalist. But, as Dr. Thomson remarks, little more can be said, for his work is all before him: "A grand new field of inquiry has been opened up, but its culture is terribly laborious. Every haul of the dredge brings to light new and unfamiliar forms—forms which link themselves strangely with the inhabitants of past periods in the earth's history; but as yet we have not the data for generalizing the deep-sea fauna, and speculating on its geological and biological relations; for, notwithstanding all our strength and will, the area of the bottom of the deep sea which has been fairly dredged may still be reckoned by the square yard."