17G ANNUAL OF SCIENTIFIC DISCOVER V. 



OCEAN TEMPERATURE. 



Some interesting: information lias been given by Captain Pullen, R. X., of 

 H. M.'s ship Cyclops, relative to the temperature of the Atlantic and Indian 

 Oceans at great depths, in his recent voyage to the East. The first soundings 

 for temperature was in 32 13' X., long. 19 D 15' W., where, at 400 fathoms, 

 the minimum temperature was 59'5, the surface at the time being 70 3 . Sub- 

 sequently, two thermometers were sent down at 500 and 800 fathoms; at the 

 greater depth, the minimum temperature was 44*5, at the lesser 50. The 

 next sounding was in lat. 10 7' X., long. 27 32' "W., when there was no bot- 

 tom with 2000 fathoms of line. In 4 16' X., and 28 42' TT., two thermome- 

 ters were sent down to 1-300 and 1000 fathoms, the greater depth showing" a 

 minimum temperature of 39'4 3 , the lesser of 42 - 5. In the next cast, in lat. 

 2 20' X., long. 28 3 44' W., ninety miles from St. Paul's Island, two ther- 

 mometers were sent down on a regular deep-sea line, with bottom at about 

 10SO fathoms : the thermometer showed a minimum temperature of 3S'5 at 

 the lowest depth, and 46'2 at G80 fathoms. An attempt to get a cast di- 

 rectly on the Equator was unsuccessful, resulting in the loss of a large 

 portion of the line. After crossing the Equator, thermometers were sent 

 down at nearly every tenth parallel, three at a time, at 12, 8, and 400 fath- 

 oms, and portions of the water brought up were reserved to be sent home 

 for analysis. In lat. 26 46' S., and long. 23 52' W., soundings were ob- 

 tained at 2700 fathoms. A thermometer sent down to this depth came in. 

 showing a minimum temperature of 35 Fahrenheit; the bottom brought up 

 in the valve was a very fine, brown-colored sand. Running the casting down 

 between the parallels 35 and 38 S., to outside the Mauritius, the lead was 

 brought into play on the Brunswick shoal, which is marked 85 fathoms, but 

 bottom was not reached with 1410 fathoms. Then came the Atalanta, 

 marked as an extensive shoal; here a cast was obtained with bottom at 1120 

 fathoms. The bottom consisted of what appeared to be very fine sand cov- 

 ering a hard substance, supposed at first to be coral, but which, under the 

 microscope, was found to be some very beautiful specimens of Diatomacea}. 

 Steering now to pass to the east of Mauritius, a little south of parallel 20 D , 

 abotit ninety miles from land, there was no bottom with 1375 fathoms of 

 line. Captain Pullen states that this gave him the first idea that his previous 

 opinion of the Indian Ocean not being so deep as the Atlantic was wrong. 

 Forty or fifty miles west of the northern part of Cargados, 1400 fathoms of 

 line reached the bottom ; at the doubtful St. George's Island, bottom was not 

 reached with 2000 fathoms of line. Steaming then for Rose Galley Rocks, 

 bottom was obtained with 2254 fathoms of line; the minimum temperature 

 was 35. A thermometer was sent down at 2000 fathoms, and returned with 

 a minimum temperature of 38'5. Xow 35 was the minimum temperature 

 at 2700 fathoms in the Atlantic, further south than this cast. Captain Pullen 

 was therefore inclined to think that this is the minimum temperature of the 

 great depths of the ocean, and that it commences soon after passing 2000 

 fathoms. 



HALL'S THERMOGRAPH. 



A thermograph, invented by Mr. S. "VV. Hall, of Philadelphia, consists of a 

 spiral glass tube, terminated outwardly in a branch, which is prolonged with 

 a smaller curvature; this tube is delicately balanced upon a horizontal axis. 



