81 



westerly set of the deeper water layers is not known, but it may have 

 ])een that these layers are affected to a greater degree by the rotation 

 of the earth. 



Another observation of the subsurface temperature was made May 

 23 at station 310, in lat. 40° 10'. long. 48° 50'. Berg 17, which was 

 nearby was drifting 170°, true, at the rate of 1.4 knots per hour. The 

 follo^^^ng temperatures were recorded : 



Surface IS. 6° C. I 250 meters . 15. 4° C. 



50 meters 17. 2° C. 450 meters 10. 2° C. 



125 meters 18. 0° C. 750 meters 15. 0° C. 



No traces of cold current from the north appear at any depth. On 

 the contrary, the high temperatures recorded show that Gulf Stream 

 water entirely surrounded berg 17. 



From this it will be seen that berg 17 had been drifting in the Gulf 

 Stream since May 19. When last seen May 25 (see chart '' C ") , it was 

 in lat. 39° 08', having drifted in the interim, in a general southerly 

 du'ection, more or less at right angles to the flow of the Gulf Stream, 

 as it is ordinarily found in this part of the North Atlantic. The phe- 

 nomenal drift of this berg corroborates the statement regarding off- 

 shore oceanic circulation that - "the extraordinary drift of ice to low 

 latitudes in the North Atlantic, is probably due to temporary surface 

 branches of warm water moving south in contradistinction to an ab- 

 normal polar current." Also \p. April, when discussing an abnormal 

 berg drift (see p. 76) ; "such tracks emphasize the fact that the Gulf 

 Stream or any other ocean current, uninfluenced by continental con- 

 tours, travels in no simple stream flow movement." 



Wrecking mines were employed in hastening the destruction of 

 berg 17. The results of the demolition work are best told in the fol- 

 lowing report of operations : 



May 20: Berg very solid. One peak about 170 feet high. Two mines lashed 

 together and suspended about 6 feet under water from a float were used. As it 

 was not deemed safe to approach the berg closely on account of overhanging 

 ledges, went to windward of berg and about 50 feet from it lowered mines and 

 float into water, hoping it would drift down on the ice. A small "sail" had 

 been rigged on the float to facilitate this. The mine, evidently caught by the 

 back lash of the sea breaking on the face of the berg, went off to one side. Then 

 attempted to tow mine against berg by towing across its face, but was unable to 

 accomplish anything. It should be mentioned that the lines attached to the 

 float and to the firing cable were buoyed at frecjuent intervals. Picked up mines 

 and backed in close to berg, lowered them into the water, and, pulling away, 

 attempted to fire: mines did not explode due to water splashed on batteries in 

 maneuvering. Picked up mines and returned to ship. In the afternoon, there 

 being a fog so dense that the peak of the berg was not visible when almost along- 

 side it, made another attempt. Placed mines attached to float over a ledge 

 projecting imder water, pulled away and fired. On account of fog little could 



' Smith, Edward H. International Ice Observation and Ice Patrol Service. U. S. Coast Guard Bul- 

 letin No 10, page 65, 1922. 



