WAIDNER, DICKINSON AND CROWE : OCEAN TEMPERATURES 409 



while to record, however, the general mipressions of the authors, 

 unfamiliar with such matters, that the effects of cannon fire were 

 disappointingly small and the utility of powerful searchlights 

 surprisingly limited. Altho the lookouts were provided with spy 

 glasses or with binoculars, it is of interest to note that the ice- 

 bergs were invariably first seen with the unaided eye. The dif- 

 ficulty of picking up icebergs under some conditions is illustrated 

 by the following incident. While the ship was steaming toward 

 a large berg in sight, a heavy fog fell. One lookout was in the 

 crow's nest, four were on the bridge, and two in the ship's eyes. 

 Notwithstanding this the berg was first picked up from the 

 quarterdeck after the ship had passed the berg some 200 yards 

 abeam. 



Samples of ice broken from the berg by gun fire were taken 

 aboard ship. These contained considerable amounts of included 

 air, which probably accounts for their white appearance. The 

 ice was surprisingly hard and free from any definite cleavage 

 planes. The whitish appearance was generally characteristic of 

 all the 'bergs met with. In some instances there were narrow 

 streaks of ice, transparent and of a blue color, that penetrated 

 entirely thru the bergs. 



The water resulting from the melting of the iceberg was found 

 to have the same density as that of distilled water. It was free 

 from any characteristic taste. So far as our observations go, 

 the temperature of the air furnishes no evidence of value as to 

 the proximity of a berg. 



Discussion of observations. An examination of the tempera- 

 ture records which were obtained under a variety of conditions, 

 in the region 37° to 43° 30' north latitude and 43° to 53° west 

 longitude, at once impresses one with the difficulty of separating 

 the large and sudden variations of sea water temperature, so 

 frequently met with, from any variations that may be caused 

 by the proximity of icebergs. We have obtained records in 

 some parts of the ocean in which the temperatures were practi- 

 cally constant to a few tenths of a degree for many hours. On the 

 other hand, some of the records show that the temperature vari- 

 ations in other parts of the ocean, where no ice is near, are as 

 great and as sudden as any observed in the neighborhood of 



