SCIENTIFIC RESULTS 



123 



(ime the bei<: was revisited in the mornin«r. 400 feet of the phitcau 

 had been lost k^avin«f a <rreat liole surr()nndin<j: the spot where the 

 mine had been phiced. Two days htter, tin- bei<r had faded to only a 

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

 thermit, or other means of thermal expansion, also offers a practical 

 method of controlling: the iceber*! menace to the North Atlantic. 

 Barnes, however, does not discuss the difficulties connected Avith plac- 

 in<r a sizable charfje of thermit at a vulnerable point in a berff at 

 sea. and those Avho have had considerable exi)erien('e around icebei'<rs 

 in the North Atlantic re^^ard this problem just as difficult as deter- 

 mining the proper reactive type of explosive. The niinin<r of ice- 

 berfifs. as develo]-)ed at present, is considered justifinliU* in tlie case 



Wrecking Operations and small-Boat Dangers 



Figure 82. — The career of bergs which drift across tlie trans-Atlantic steamship 

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

 ill Ma.v. 1923. can lie shortened by the use of high explosives. The small boat 

 from the U. S. Coast Guard cutter Tampa has just placed a 250-pound TNT mine 

 below the water line 'of this berg. This is one of the most difficult and dangerous 

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



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

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



Demolition experiments have been carried out by the international 

 ice patrol, 1924 to 1926, on iceljergs 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 oi)erations 

 always entail danger, such as members of the mining crew s]ii)ping 

 into the sea or falling onto ledges from precipitous heights, lience 

 such Avork should never be attempted except at most favorable times. 

 On May 20. 1928. a large iceberg floating in water warmer than G0° 

 F. was mined Avith 250 pounds of T. N. T. on four different occasions, 

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

 result that "its life Avas .shortened by only one or more days. The 



