16 



cruising speed. This present trend to rapid surveys with one or more ships is 

 not likely to bear fruit of the necessary quality or quantity for study of the volume 

 circulation unless ships can be made to sail faster and instruments can be de- 

 vised for working at all depths at these higher speeds. According to present 

 views, increased ship speeds exclude the possibility of apparatus being towed 

 very much deeper than the 100 meter level. 



ANCHORED BUOYS AS OCEAN STATIONS 



One direction instrunmentation may take is in the development of anchored 

 apparatus designed to measure at many depths at least the scalar quantities now 

 used to describe the ocean water masses and their motions. An extended pat- 

 tern of such stations outfitted to measure the ordinary scalars at several depths, 

 on a schedule consistent with their spacing, would do much to indicate how steady 

 or unsteady is the distribution of these properties of the ocean and the motions 

 associated with them. The stations might be distributed in such a way that ap- 

 proximately equal volumes of water would pass between them. Were it conven- 

 ient to measure the velocity of water passing these stations at several depths, 

 the departures from geostrophic equilibrium nmight be detected as well as read- 

 justments of the pressure pattern. 



The stations might be equipped either to record or telemeter observa- 

 tions, or both. At first they might only make measurements of the temperature 

 at a number of levels, and of the pressure at a few levels. This simple combi- 

 nation would permit studies of the fluctuation of the level of the thermocline and 

 to some extent, the shifting boundaries of water masses having sufficient tem- 

 perature contrast. Pressure indicators would indicate how much the wire is in- 

 clined, and this would suggest the presence of strong currents, supply informa- 

 tion on their thickness and indicate the changing pattern of meanders. A light 

 intensity meter in the surface float might serve the dual purpose of marking the 

 lapse of days and estimating the cloudiness. It would also indicate the periods 

 when the surface float had been towed under. Later on, some means for meas- 

 uring salinity or density in situ would be desirable. Since these quantities are 

 approximately known or can be found at each predetermined level, differential 

 methods might be devised which use an enclosed water sample from that depth 

 as a standard. 



It is easier in several respects to develop or adapt existing instruments 

 for such stations than to provide good ideas for a solution of the permanent an- 

 choring problem. Stommel has calculated that a vertical steel wire of any dia- 

 meter will not support its own weight with a safety factor of 2 if it is more than 

 30,000 feet long. Therefore, tapered wire seems desirable if steel is used. 

 There is also the possibility of using materials other than steel which have suf- 

 ficiently low density for buoyant forces to be important. The properties of a 

 number of materials such as glass, various plastics, and non-ferrous metals 

 have been reviewed. As yet no substance has been found free of certain dis- 

 advantages but the buoyant cable principle offers promise. If measurements 

 are to be made at many levels the cable must contain electrical conductors 

 although these need not be very heavy gauge. Various types of anchors have 

 been considered. An ordinary coring tube driven into the bottom seems to have 

 many good properties, and if the chain permitting the final free fall were quite 

 long it would have a desirable shock-absorbing effect against sudden strains 

 transmitted along the cable. 



There is also a choice to be made as to whether the float at the upper 

 end of the cable should ride on the surface or be held at a certain depth below 

 it. A float at the surface would be subjected to violent wave action at certain 

 times while a submerged float would be more protected. However, the stretch- 



