10 ON A PIECE OF CHALK i 



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 por- 

 tion of the superficial layer of the sea-bpttom 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 10,000 feet, or two miles, 

 by the help of this sounding apparatus. 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 Glcligerincc 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 



