ON A PIECE OF CHALK 51 



At the same time, it became desirable to ascertain 

 and to indicate the nature of the sea-bottom, since this 

 circumstance greatly affects its goodness as holding 

 ground for anchors. Some ingenious tar, whose name 

 deserves a better fate than the oblivion into which it has 

 fallen, attained this object by "arming" the bottom of 

 the lead with a lump of grease, to which more or less of 

 the sand or mud, or broken shells, as the case might 

 be, adhered, and was brought to the surface. But, 

 however well adapted such an apparatus might be 

 for rough nautical purposes, scientific accuracy could 

 not be expected from the armed lead, and to remedy 

 its defects (especially when applied to sounding in 

 great depths) Lieut. Brooke, of the American Navy, 

 some years ago invented a most ingenious machine, 

 by which a considerable portion of the superficial layer 

 of the sea-bottom can be scooped out and brought up 

 from any depth to which the lead descends. 



In 1853, Lieut. Brooke obtained mud from the 

 bottom of the North Atlantic, between Newfoundland 

 and the Azores, at a depth of more than ten thousand 

 feet, or two miles, by the help of this sounding appa- 

 ratus. The specimens were sent for examination to 

 Ehrenberg of Berlin, and to Bailey of West Point, and 

 those able microscopists found that this deep-sea mud 

 was almost entirely composed of the skeletons of living 

 organisms the greater proportion of these being 

 just like the Globigerince already known to occur in 

 the chalk. 



Thus far, the work had been carried on simply in the 

 interests of science, but Lieut. Brooke's method of 

 sounding acquired a high commercial value, when the 

 enterprise of laying down the telegraph-cable between 

 this country and the United States was undertaken. 



