168 ' REPORT— 1873. 



passage down Channel and across the Bay of Biscay encountered the weather 

 usually met with at that season of the year. 



The first deep sounding, in 1125 fathoms off, but to the southward of, Cape 

 Finisterre, was not very successful. The second trial proved more successful, and 

 some bright-coloured starfishes and other animals were brought to light. Another 

 attempt at dredging was made in nearly 2000 fathoms, but whether it fouled the 

 Gibraltar and Lisbon cable or a rock it mattered little, for after trying seven hours 

 to extricate it, the rope broke and the dredge was lost. The ' Challenger ' reached 

 Lisbon on the .3rd of January. 



On leaving Lisbon the 'Challenger' sounded in the vicinity of two rocks of 

 870 and 423 fathoms, and obtained 1270 fathoms near them and 1380 fathoms 

 between them; aud although the presumption is that they do not exist, still, 

 from what I shall have to remark as I go on, it would be almost presumption 

 to assert it; and an instance occurred the next day to bear me out in this, 

 as in dredging off Cape St. Vincent, where the dredge was let down in 525 

 fathoms, the ship drifted quickly into 900 fathoms, so steep was the incline. 

 Gibraltar was reached ou the 18th ; and on leaving it a few days after, pi"o- 

 ceeded in a westerly direction, in order to get on the direct line between Lisbon 

 and Madeira, as a telegraphic cable was to be laid between the two places. It 

 "will be observed that much deeper water was obtained ou the way out than at the 

 exti'emity of the line. In 1(P west longitude 2500 fathoms were obtained, while 

 60 or 70 miles west of it only 1500, with still shoaler water outside. 



The 'Challenger * reached Madeira on the 3rd of February, aud Tenerifie on the 5th. 

 Leaving Tenerifie for Sombrero Island on the 14th, a course was shaped to the south- 

 east, aud when 57 miles from the peak, 1890 fathoms were obtained. The weather 

 being fine, the opportunity was a good one for trjdng Mr. Siemens's ingenious 

 differential resistance-coil. It was tested in comparison with the Miller thermo- 

 meter at 100, 200, 500, 700_, 800, and 1000 fathoms respectively ; the difference at 

 100 fathoms was 2° ininus in the Siemens, which gradually changed to 2^ jjlus at 

 1000 fathoms. With any motion in the ship the difficult}' in reading off a delicate 

 galvanometer appears to be an insurmountable objection to this otherwise valuable 

 instrument, and in the absence of regular thermometers could not be depended on. 



The serial observations of the temperature of the ocean at various depths were now 

 commenced. Captain Davis here described the modus operandi of obtaining these 

 observations, and then proceeded as follows : — As might be expected in the vicinity 

 of volcanic islands, there were gi-eat inequalities in the bottom, and 50 miles out- 

 side, a depth of 1945 fathoms, 1225 were obtained, and near that, to the southward, 

 2220, showing some steep acclivities and depressions. The bottom specimens 

 brought up coincided -s^dth the soundings ; from the shallower sounding, stones, 

 sand, aud shells were obtained ; whilst from the deeper waters, Globif/erma-ooze. 

 The water deepened to 3150 fathoms at two fifths the distance on the section, and 

 then shoaled to 1900 at three fifths the distance, deepening again gradually to 3000 

 fathoms 300 miles from Sombrero, Thus there appears to be two deep' basins or 

 valleys with a rise between them, and agreeing in contour with a few soimdings 

 obtained more to the southward. The section from Cape Verdes to Bahia will be 

 most interesting in connexion with this part of the voyage and the two deeps 

 ound. 



Another point of observation in tliis line of soundings is in the nature of the 

 bottom. In all the soundings exceeding about 2700 fathoms, the bottom is red 

 clay, while in the shoaler water of the bank between it is ooze. The ' Challenger ' 

 anchored at St. Thomas on the 16th of March and sailed again on the 24th for 

 Bermuda, first taking some soundings and dredging in the immediate vicinity of 

 the islands, and then stretching away to the northward towards Bermuda. 



On the 2Gth, when only 80 miles from the land, a sounding was taken of the 

 greatest known depth in the world, viz. 3875 fathoms — nearly 4h miles. Not ima- 

 gining that so near the islands so great depth of water could be found, only 3 cwt. of 

 sinkers were used with the hydra machine ; two thermometers and a water-bottle 

 were attached to the line : the line was 1'' 12'" running out, the last 100 fathoms 

 taking 3™ 18^ The small dredge was let down and this extraordinary depth 

 dredged with 5 miles of rope ; the dredge on coming up brought a small quantity 



