42 DISCOVERY REPORTS 



cruising speed, i.e. g knots. If, however, conditions were unsuitable for this and it was important 

 that the Une of soundings should be as complete as possible then the ship was either manoeuvred with 

 regard to sea and wind or hove-to for a few minutes until the sounding had been completed. For (b) 

 soundings were taken as often as the scale of the survey required, and in later years a continuous 

 record from the recording machines was our aim. At times this entailed twelve to fourteen hours 

 continuous running of the automatic recorders, which were fitted in recent years; but with the 

 exception of minor breakdowns these machines generally stood up well to the work. Special soundings 

 (c) were usually taken whenever any known ridge or bank was being crossed or when the hourly 

 sounding showed any marked change in depth. In the earlier years when only 'listening' sets were 

 fitted the spacing of the soundings was decided according to the condition of sea and weather, or to 

 the slope of the bottom. In recent years it was the practice to try for a continuous record over the 

 area concerned. 



In this report prominence has been given mainly to oceanic and special soundings, since the detailed 

 soundings taken on hydrographical surveys have only a limited value so far as hydrological conditions 

 in the oceans are concerned. Nor are they of much value in the determination of major geological 

 features. The soundings taken during the survey of the South Orkney Islands have already been shown 

 on the chart published with a report on those islands by Marr (1935), but the intensive soundings 

 taken in the South Shetland Islands between 1934 and 1937 have not, as yet, been examined by us in 

 detail. 



The positions of the soundings taken by the 'Discovery II' and discussed in this report were 

 determined as follows: From 1932 to 1935, by Lt. A. L. Nelson, R.N.R. ; from October 1935 until 

 June 1937 by Lt. R. Walker, R.N.R. ; and for the period of September 1937 to May 1939 by Lts. 

 L. C. Hill, O.B.E., R.N.R. and A. F. Macfie, R.N.R. The careful work and willing co-operation of these 

 officers has done much to assist me in the preparation of this report. From 1932 until early in 1936 

 all the soundings were plotted by these officers on large-scale charts, but from 1936, in order to meet 

 the wishes of the Hydrographer of the Navy, lists of soundings and their positions were prepared at 

 regular intervals, and plotting was thus discontinued except during survey work. 



This report has been considered in manuscript by Mr J. M. Wordie, C.B.E., M.A. and the Hydro- 

 grapher of the Navy (Rear-Admiral A. G. N. Wyatt, C.B., R.N.); to them I am grateful for advice 

 and valuable suggestions. It has also been read by the Superintending Scientist of H.M. Underwater 

 Detection Establishment (Mr J. Anderson, O.B.E.) and several members of his staff. To one of 

 them, Mr J. H. Hayes, a pioneer of the earlier experimental work in deep-sea echo sounding, I am 

 much indebted for very helpful criticisms and advice on certain technical points. 



In the preparation of the figures and contour charts I have received considerable assistance from 

 the Hydrographic Department of the Admiralty, especially from the Superintendent of Charts, 

 Captain E. H. B. Baker, D.S.O., R.N. Through his courtesy I have been able at any time to consult 

 our original survey charts and plans, now in the possession of the Hydrographic Department. 



Finally, I should like to express my gratitude to Dr N. A. Mackintosh for the help he has so freely 

 given me at all stages in the preparation of this report. His practical experience of the sounding 

 routine in the ' Discovery II ' has materially assisted me in the presentation of what I hope is a balanced 

 account of our sounding work. 



SOUNDING EQUIPMENT 



When the previous report was written the ' Discovery II ' was fitted with Lucas and Kelvin machines 

 for wire soundings, and with deep and shallow echo-sounding sets of the ' listening ' pattern. A full 

 description of these instruments and their positions in the ship has been given already in the earlier 



