190 THE ATLANTIC. (CHAP. IIL. 
of a lump of pyrolusite, but that the glossy black film covering 
the stem and branches of the coral gave also the reaction of 
manganese. There seemed to be little doubt that it was a case 
of slow substitution, for the mass of peroxide of manganese 
forming the root showed, on fracture in some places, the con- 
centric layers and intimate structure of the original coral. The 
coral, where it was unaltered, had the ordinary composition, 
consisting chiefly of calcic carbonate. Water was obtained by 
the slip water-bottle from 300 fathoms with a specific gravity 
of 1:02510 at 21°-1 C.; from 400 fathoms, of 1:02475 at 20°-9 
C.; from 500 fathoms, of 1:02619 at 20°°5 C.; and at 200 fath- 
oms, of 1°2515 at 21°°6 C. The water from the bottom (2435 
fathoms) had a specific gravity of 1:02576 at 22° C., and the 
surface water of 1:02526 at 24°-4 C. 
On Saturday, the 8th, a sounding was taken in 2385 fathoms, 
and the tube brought up a sample of mud of a bright, light 
chocolate color, with a mere trace of calcic carbonate—nearly a 
pure red clay. We were laying our course so as to include a 
sounding of Lieutenant Lee in lat. 19° 2’ 36” N., long. 59° 33’ 
20’” W., of 3300 fathoms, and it seemed that we were gradual- 
ly passing off the plateau—which Captain Nares has called, in 
recognition of the vessel from which its position was first de- 
termined, the “ Dolphin Rise”—into the depression indicated 
by the deep sounding, and that again we had a change in 
the nature of the bottom coincident with increase in depth. 
A series of temperatures were taken, with the results tabu- 
lated : 
SUDLACEI vaste senses 23°°3 C. 900 fathoms:. ..53.:.: ecm Sereiwe 
OO star thOmis sie ssectaeeectere 21 -0 1000 . oa. 3 ates ere Seer e et PORRO. 
ZO Dimes ate Wc gre Siete s aesee 16-0 1100 ttf walle Rather ete 
SOD ert” | skit on paneer TY Ss} E200! ©  * ceeven sthenoierpeteh nea 
G10 Os A i Mirae Sef tee er Sea DSOOF 000 i? Accncie At csorepeeeenene oo 
DOOM Tey See ae tani ke 74 14008 cde cee eo 
LUO yee VaR Alo Geer, c 5 *6 1500 Erte are esc oa. 
Oa Me csigceene 5 0 2385 ef bottoms: cee ees 
7 
SOO FEN causa arecheye « 4 
