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chain bag attached to a rectangular metal frame. Netting can be inserted in the 

 dredge and the size of the net opening will determine the size of material re- 

 tained by the dredge. Small pipe dredges can be towed behind the dredge to pick 

 up a sample of the fine sediment. Although dredging is a powerful technique for 

 qualitatively studying the bottom, it is a poorly developed method. Actually no 

 important progress has been made since the Challenger Expedition. We still 

 have no clear idea as to how the dredge is acting on the bottom, how efficiently 

 the dredge is sampling the bottom, whether or not the dredge is spilling its load 

 or how long to tow the dredge along the bottom before pulling it up. 



It is commonly stated or implied that a dredge can only sample the most 

 recent deposits. However, it has become increasingly apparent that the sea 

 floor is not everywhere a depositional surface. In many places it is erosional 

 or non- depositional -- thus, old formations outcrop along the bottom. This was 

 clearly demonstrated by the dredging of Cretaceous coraliferous limestones on 

 the Mid-Pacific Expedition. Dredging the fault scarps on the sea floor such as 

 the Mendocino Escarpment seems an especially promising method of penetrating 

 the earlier sedimentary history of the oceans. Such an approach probably will 

 yield more results than attempting to reach the older formations by coring in the 

 sedimentary basins. 



Winches, Wire Rope, etc. - Success in sampling the bottom depends as much 

 upon the characteristics of the winch, wire rope, etc. , as it does upon the sam- 

 pler. For example, the BT winch with its snnall wire (and resultant small wat- 

 er drag), its free spooling, and its rapid breaking and clutching has made possi- 

 ble the use of underway samplers. Also, the success of the heavier piston cor- 

 ing devices necessitates winches of special design. Only in recent years have 

 reliable winches been designed for handling the heavy end loads encountered in 

 coring and dredging. The winch used on the Albatross and the Galathea Expedi- 

 tions is a good example. 



The subject of wire rope is too involved to be treated here. Suffice it to 

 say that any improvements in the tensile strength, corrosion resistance, resis- 

 tance to unlaying, etc. , will be of great benefit to oceanography. Coring and 

 dredging place great loads on wire rope so that it is often difficult to stay within 

 the elastic limit of the wire. 



Although sea water is a good conductor of electricity, wire ropes are 

 even better conductors so it is possible to project some electric energy for a 

 considerable distance along a non-insulated wire rope. It seems that some use 

 could be made of this property.* 



There is often much difficulty in determining when a sampler reaches the 

 bottom because of the great weight of the wire rope as compared to that of the 

 sampler. Even with a dynamometer to measure cable strain it is necessary for 

 the end load to be at least 20 percent of the gross load. The development of a 

 more sensitive but damped oceanographic dynamometer is much needed. For 

 determining bottom contact, the Scripps "ball-buster" is a promising develop- 

 ment. This device, which can be attached to a corer or a grab sampler, im- 

 plodes a glass ball on bottom contact by a slack-wire release allowing a weight 

 to fall breaking the ball. The resultant sound signal can be picked up by a hydro- 

 phone at the ship. Use of a recorder has been helpful in positive identification of 

 the signal. However, as yet the proper functioning of this device is too uncertain 



* - Editorial Note: Apparatus utilizing this principle was initiated at Scripps 

 in 1949 and the preliminary results were very encouraging. Additional work has 

 just been reviewed. (November, 1953) 



