85 



-only phenomenally present any more than they can keep track of all 

 the ice in the tremendous ice regions of the north. As a matter of 

 fact, if the patrol limits its cruising activities to the important ice 

 area of 150,000 square sea miles about the Grand Banks, it is con- 

 fronted with a very sizable problem, for it has been shown that in a 

 full 15-day cruise period the patrol's own searching can be made to 

 cover but about one-fifth of such an area. 



The result is that the patrol is compelled to concentrate on the 

 most critical parts of the 150,000 square sea mile ice area south of the 

 forty-eighth parallel. It relies upon reports from passing ships for 

 its knowledge of ice in many parts of this area, as well as in the 

 surrounding northern and southern regions, that on the one hand 

 always, and on the other only exceptionally, contain ice. 



It may be of interest to state here what takes place on the patrol 

 vessel when ice or water temperature reports are received. Copies 

 of all these incoming messages are promptly taken to the chart room 

 and delivered to the ice-observation force. They first scrutinize the 

 reports for errors. The tracks and approximate positions of all 

 regularly reporting steamers while in the ice-patrol area are kept 

 plotted on special charts. If a new report is from an obviously im- 

 probable location, some distance from where the reporting ship should 

 have been at the time of origin of the message, the value is thrown out 

 if an ordinary temperature report. If it is an ice report, or a water 

 temperature value from an area that few vessels have been through 

 recently, an inquiry for verification of the questionable location or 

 other particular is promptly sent out. 



At this point it should be noted that the size of bergs seen at sea at 

 a distance of 2 or more miles is very deceptive. There is usually 

 nothing of known size near them with which they can be compared. 

 The patrol itself has frequently seen bergs that appeared to all on the 

 bridge to be very large pinnacled ice masses when they were near the 

 horizon, but which, when closely approached, proved to be rather 

 insignificant, rising less than 30 feet above the sea and being less than 

 100 feet in diameter. So it is that bergs in the frequently bright smooth 

 waters of the southern ice sectors, though reported as "large" and 

 "very large," are often found when reached to be in fact quite small. 

 They were probably sighted on the horizon line when nearly abeam 

 of the reporting vessel, which had never closely approached and 

 examined them because of the loss of valuable time that this would 

 have involved. 



The unusually large refraction values often found near the junction 

 of the warm and cold waters makes the identification of bergs diffi- 

 cult and adds to the uncertainty when determining berg sizes from a 

 distance. Sometimes bergs not over 30 feet high can be seen for 20 

 to 30 sea miles from a height of eye of 20 feet. Once during the 1929 



