6^o 



THE POPULAR SCIENCE MONTHLY. 



MISCELLANY. 



The Cruise of the " Challenger." Na- 

 ture, for June 1st, gives an exceedingly in- 

 teresting account of the voyage round the 

 world recently completed by the Chal- 

 lenger. This voyage was undertaken 

 chiefly for scientific purposes, the principal 

 object being to "determine as far as pos- 

 sible the physical and biological conditions 

 of the great ocean-basins of the Atlantic, 

 the Southern Sea, and Pacific." 



Important discoveries made during re- 

 cent expeditions on the European border 

 of the Atlantic and in the Mediterranean, 

 by Dr. Carpenter, Mr. Gwyn Jeffries, and 

 Prof. Wyville Thomson, stimulated a de- 

 sire for further investigation, and this great 

 voyage under direction of Prof. Thompson, 

 as chief of the civilian staff, was inaugurated 

 and carried through to a successful issue. 



The ship left England on December 21, 

 1872, and returned to Spithead on May 24, 

 1876, having been absent a little less than 

 three and a half years, and making a voyage 

 of nearly 69,000 miles. 



During this voyage 362 observing-sta- 

 tions were established, at each of which 

 the depth and bottom temperature of the 

 ocean were ascertained, and samples of the 

 water, mud, and animals of the bottom, 

 brought up for examination. 



The direction and rate of currents 

 were carefully studied, and " serial sound- 

 ings "were made with special instruments 

 to determine the temperatures at different 

 depths. Upward of 50,000 meteorological 

 observations were made during the first 

 twelve mouths of the cruise. 



The regular work of the expedition be- 

 gan at Teneriffe, from which point a line 

 of soundings was carried across the Atlan- 

 tic to the small island of Sombrero, a dis- 

 tance of 2,700 miles. 



At 1,100 miles from Teneriffe, and 1,600 

 miles from Sombrero, bottom was found at 

 3,150 fathoms, which consisted of "per- 

 fectly smooth red clay, with scarcely a trace 

 of organic matter," but at depths of only 

 2,200 fathoms the bottom was one mass of 

 calcareous shells of foraminifera. 



The red clay was found to be almost 

 pure clay and a red oxide of iron with 

 some manganese. This material is sup- 



posed by Prof. Thomson to be the residue 

 or ash from decomposition of the shells. 

 Experiments were made by Mr. Buchanan, 

 of the staff of scientists, confirming this 

 conclusion. He subjected globigerina ooze 

 to the action of a weak acid, and found 

 that after the carbonate of lime was re- 

 moved there remained about one per cent, 

 of a reddish mud, consisting of silica and 

 alumina, and a red oxide of iron. 



The globigerina shells were abundant at 

 depths not exceeding 2,200 fathoms, but at 

 greater depths a gray ooze occurred, the 

 shells being in a state of decomposition ; 

 in deeper parts this disappeared, leaving 

 the residuum of red clay. 



This clay was found to be widely dis- 

 tributed in both the Atlantic and Pacific 

 Oceans, and in many places contained con- 

 cretions of the peroxide of manganese. 



The specific gravity of ocean-water was 

 carefully tested by Mr. Buchanan, and very 

 unexpected results were obtained. The 

 notion that the specific gravity increases 

 with increase of depth seems unfounded, as 

 it was ascertained to be greatest near the 

 surface, diminishing to a depth of about 

 500 fathoms. From this downward it is 

 nearly uniform. 



Dredgings at great depths usually 

 brought to the surface living organisms. 

 At 3,150 fathoms (upward of three and a 

 half miles) on the Atlantic cruise, only 

 foraminifera were found, but other organ- 

 isms were abundant at similar depths else- 

 where. 



By the serial temperatures taken in sev- 

 eral places, it is evident that conditions ex- 

 ist which may greatly modify the distribu- 

 tion of the deep-sea fauna. Near Raine 

 Island, not far from the entrance to Torres 

 Straits, there was found at 2,650 fathoms, 

 with bottom of red clay, a temperature of 

 35 Fahr. But it was also found that the 

 same temperature occurred at a depth of 

 only 1,300 fathoms. Here, then, the waters 

 through 1,350 fathoms of depth, were of a 

 uniform temperature. Over a wide area 

 similar results were obtained, and the con- 

 clusion is, that this area, known as the 

 Melanesian Sea, is so surrounded by a reef, 

 rising to within 1,300 fathoms of the sur- 

 face, that free communication of its waters 

 with the outside ocean is prevented. 



Animal life was found to be scarce in 



