SCIENTIFIC TJESULTS 



123 



time the bero; was revisited in the morning;, 400 feet of the phiteaii 

 had been lost leavin^: a irreat liole sui'i-oundinfr the spot where the 

 mine had been phiced. Two (hivs hitcr. the bei<i: had faded to only a 

 shadow of its former self. From this he concludes that the use of 

 thermit, oi' other means of thermal expansion, also offers a practical 

 method of controllinir the iceberjr menace to the North Atlantic. 

 Barnes, however, does not discuss tiie difficidties connected with plac- 

 ing a sizable charo:e of thermit at a vulnerable point in a ber<r at 

 sea, and those who have had considerable experience around icebergs 

 in the North Atlantic regard this problem just as difficult as deter- 

 mining the proper reactive type of explosive. The mining of ice- 

 bergs, as developed at present, is considered justifiable in the case 



Wrecking Operations and Small-Boat Dangers 



FuJi'KE 82. — The career of Ijerjcs which drift across the trans-Atlantic steamship 

 lanes and into the Gulf Stream south of the Grand Bank, such as this one did 

 ill May. ]!t2;^. can he shortened hy the use of hinh explosives. The small hoat 

 from the U. S. Coast Guard cutter Tampa has just placed a 2.j0-pound TXT mine 

 helow the water line 'of this herg. This is one of the most difficult and dangerous 

 parts of the wrecking operations. (Official photograph, international ice patrol.) 



of only a few bergs which lie across tlie main trans-Atlantic steam- 

 ship tracks, and then only in periods of smooth sea. 



Demolition experiments have been carried out by the international 

 ice ))atrol. 1924 to 1926, on icebergs drifting far south into the Gulf 

 Stream in order to hasten their removal as a menace to navigation. 

 Owing to the swell and the smooth surface of the ice. such operations 

 always entail danger, such as members of the mining crew slij^ping 

 int(> the sea or falling onto ledges from precipitous heights, hence 

 such work should never be attf'mjjtcd exce]it at most favorable times. 

 On May 20, 192.'^. a large iceberg floating in water warmer than 60° 

 F. was mined with 250 jjounds of T. N. T. on four different occasions, 

 first on May 20; next on the 21.st and finally on May 34. with the 

 result that its life was shortened bv only one or more davs. The 



