VOL. VIII. NO. 2 DECEMBER, 1961 EDITOR: JAN HAHN Published periodically and distributed to the Associates of the Woods Hole Oceano- graphic Institution and others interested in Oceanography HENRY B. BIGELOW Founder Chairman NOEL B. MCLEAN Chairman, Board of Trustees PAUL M. FYE President and Director COLUMBUS O'D ISELIN H. B. Bigt/oiv Oceanographer BOSTWICK H. KETCHUM Senior Oceanographer The Woods Hole Oceanographic Institution • Woods Hole, Massachusetts VOL. VIII, No. 2, December 1961 THE COVER PHOTO IS BY Some Like Gales To the landlubber - or worse - to those prone to seasickness - this is a horrifying statement. Yet - yet •- to stand on a heaving, rolling, pitching i «D deck - to feel the sting of spume flying through the air - to watch a mountainous wave coming -UP — watching with awe, watching with admiration, watching with defiance and — with fear, with hidden fear, with fear released reluctantly days or weeks later -- to watch that wave break after what seems an eternity of hovering -- to watch that wave break under the ship or over the stern --to feel the ship shudder — to hold on for dear life — to hear the crash- ing and breaking of gear below decks -- to laugh at one's own or another's nasty spill. That — that -- is The Sea. The Sea The Sea that holds us in thrall The Sea that demands The Sea fhaf can be as soff as a lover The Sea fhaf can be as fierce as fove denied The Sea we pine for when ashore THE SEA Oceanus is ten years old to-day. We have weathered storms. With Poseidon's help we shall weather more. A five minute exposure of sfars crossing the equatorial zenith. The star trails, produced by the earth's daily rotation, are 7'/4° long and show by their width the steadiness of the Mark 19 vertical. 135 mm at f. 3.5 on Tr/'-X. x K. Z 0 A LEVEL surface lies exactly at right angles to the pull of gravity. On land it is a comparatively simple thing to determine the direction of gravity. One needs only to hang a symmetrical weight on a string and allow the system to come to rest or observe the reflection of one's eye in a quiet water surface to estab- lish the direction of vertical to reasonably high precision. The oceanographers' concern with matters of this kind is that we could know much more than we do now about the ocean circulations if we knew the shape of a level surface extended over the world ocean or could establish a reference to level or gravity vertical at sea. One might think that the horizon around the ship would provide a suitable refer- ence circle against which the direc- tion of gravity vertical might be easily obtained from ships at sea because it is a large scale approxi- mation of the quiet dish of water. But even when the horizon is ex- quisitely sharp, as it can be on very clear days, its direction measured from the zenith is not exactly 90° owing to the effects of meteorological refraction and the curvature of the earth. Nor is it symmetrically dis- placed from the zenith owing to horizontal gradients in the pressure of the atmosphere and the regional tilt of the sea surface associated with wind stress, tides and ocean currents. It is these last three disturbances that are of interest, particularly the tilt of the ocean surface due to ocean currents. Editor's Note: The interest aroused by the brief mention of GEON in the September issue led to this more extensive account of the system. The levels of — — I .— J sea level at sea BY W. S. VON ARX A new system of navigation may also be used for astro- nomical observations and ultimately, to measure the slope of sea level. To paraphrase Rossby's lucid state- ment of the situation: The earth's rotation around the vertical, which in a striking way is demonstrated by the slow turning of the plane of the Foucault pendulum, exerts a strong influence on the horizontal streams of the sea which tend to be deflected in opposite direction relative to the earth's own rotation. Thus, every newly formed ocean current in the northern hemisphere is deflected a little to the right. This deflection causes in turn a piling up of water (thus tilting the sea surface) which leads to high pressure on the right side of the stream and a low pressure on the left side until the resulting pressure gradient across the current prevents further deflection. This adjustment of the pressure distribu- tion to the state of motion is a fundamental property of the ocean and leads to the fact that the stream lines of the ocean currents by and large follow horizontal lines of equal pressure; isobars. To the extent that this condition is satisfied the flow is geostrophic. (adapted from C-G. Rossby, 1959, "Current Problems in Meteorology" Rossby Memorial Vol- ume, p. 22-23. If the tilt of the horizon could be measured with respect to local verti- cal at sea, and the effects of the other factors removed, we would then be in a position to compute the mean field of geostrophic motion in the sea on absolute terms; that is relative to the solid earth beneath. This in combination with the exist- ing techniques of water sampling to determine the relative field of mo- tion as a function of depth, would permit us to describe, again on absolute terms, the internal field of geostrophic motion in the sea. Levels needed Physical oceanographers have realized this fact for more than fifty years. Changes of slope of the sea surface have been studied through examinations of tide gauge records made at stations bordering strong currents such as those straddling the Gulf Stream at Miami, Florida and Cat Cay in the Bahamas, or between Charleston and Bermuda. By means of tide gauging stations one can de- termine the variability of slope of sea level but not the difference in absolute level between pairs of sta- tions because we have no means for Pressure gradient across a current Levels running a level line across the ocean surface between them. Toward this end, work has recently been under- taken to adapt certain existing gyro- scopic systems, which have the property of seeking the vertical at sea, to assess the practical difficulties of precise leveling from shipboard. Versatility One of these systems, the Sperry Meridian gyrocompass Mark 19 Mod. 3a, though far from accurate enough, provides not only vertical informa- tion but the direction of geographic north as well. Since the direction of geographic north and of the zenith point defines the position of the local astronomical meridian, the Mark 19 has been used as a base for a minia- ture astronomical observatory on board the R.V. 'Chain.' Some experi- ments have been performed with this apparatus during the spring and summer months of the present year. Among these it has been possible to navigate the ship, to photograph faint star fields, to study the develop- ment of trade wind cumulus clouds with time-lapse motion picture cameras, in addition to making a study under high magnification of the optical properties of the horizon as an index of ocean surface slopes. Three steps toward the ultimate goal are planned. First, the meridian gyrocompass permits a new system of navigation to be employed, dub- bed GEON, which allows the ship's position to be determined with an accuracy of about one mile from a single sight on a single celestial object at any time of day or night that the skies are clear. Second, using a more refined version of GEON as an index of astronomical position on the sea surface and the satellite naviga- tion system, TRANSIT, it may be possible to indicate the geocentric coordinates of that same point on the earth's surface. From the differ- ence between the geographic and geocentric coordinates it should be possible to determine the regional slope of the earth's figure at that Atmospheric given point. From a combination of pressure Tilts of the Sea Surface Wind stress or tides Ld J many such slope observations geo- graphically well distributed, it should be possible to determine some qualities related to the figure of the earth in its ocean areas. Third, with more highly refined apparatus than is required for either of the first two steps, it is conceivable that one day we may be able to examine the circle of the horizon and establish its departures from level relative to the direction of local gravity. Gravity includes the centrifugal force of earth rotation, therefore astronomical latitude meas- ured with respect to gravity (by GEON) differs from geocentric latitude 0' (measured by TRANSIT) everywhere on the earth except at the poles and along the equator. CENTRIFUGAL FORCE GRAVITATIONAL PULL OF EARTH'S CENTER OF MASS OF EARTH ROTATION Applied to GEON, a navigation system in which a meridian gyro- compass and an equatorial telescope are combined, the indication of local vertical by the gyro to an accuracy of better than one minute of arc makes it unnecessary to employ the horizon as a fiducial mark. By the same token it is unnecessary to transform the celestial coordinates of a body to the horizon system or to make separate determinations of latitude and longitude if the plane of the local meridian can be known continuously from shipboard. Location The recent experiments with the Mark 19 mounted on the R.V. 'Chain' show that vertical reference on shipboard can be relied upon to a small fraction of a minute of arc and north reference to a small fraction of a degree. Ideally, to reduce the confusion of horizontal accelerations caused by waves and steering, the merid- ian gyrocompass should be mounted near the ship's metacenter, prefer- ably between the turning center and the intersection of the pitch and roll axes of the hull. However the point from which celestial obser- vations are to be made would in consequence have to be remote from the site of the master gyropendulum. For the initial experiments then it seemed simplest to accept the dis- turbing effects of horizontal acceler- ations in order to avoid the more difficult problem of correcting angu- lar and torsional misalignments of Levels the two decks on which the master gyro and remote observing station would otherwise be mounted. For this reason the master compass was placed on the boat deck (without specific relation to the metacenter) from which position it was possible to take observations directly from the compass head. Day or night With the system thus mounted at a level on the ship that provides a clear view of the sky, 'it has been possible to adjust the polar axis and set the hour angle and declination axes of an equatorially mounted tele- scope well enough to bring the image of a bright celestial object into the field of view in either day- light or darkness. The equatorially mounted optical train used in these experiments con- sisted of a DKM-1 Kern Precision Theodolite with its azimuth circle set in accurate alignment with the former position of the objective lens of a DKM-2 theodolite. In this im- promptu arrangement there are four accurately graduated circles: (1), the azimuth circle of the lower theodo- lite to calibrate adjustment of the lower trunions, (these should lie parallel to the level east-west line maintained by the meridian gyro), (2), the altitude circle of the lower theodolite to give the altitude of the polar axis or latitude, (3), the azi- muth circle of the upper theodolite to serve as an hour circle, and finally (4), the altitude circle of the upper theodolite to serve as a declination circle. The following observational procedure proved effective: (1) set the declination of the celes- tial body on circle 4, (2) set the approximate ship's latitude on circle 2, (3) set the approximate Local Hour Angle of the body on circle 3, then, having sighted the body, make those fine adjustments of the altitude of the polar axis required to bring the object to the equatorial cross- hair, lock the polar axis, and having set the hour angle of the cross-hair slightly west of the position of the object in the field, note the Green- wich Mean Time of its crossing and the given Local Hour Angle. The latitude of the sight position is given directly upon reading circle 2. The longitude is easily reckoned from the knowledge of the Greenwich Hour Angle of the body and its observed Local Hour Angle. The whole opera- tion can be carried through in less than five minutes time. The precision and reliability of the assembly is such that once the lower theodolite is squared on the gyro head (by taking sights on the hor- izon in daylight) and the azimuth of the lower trunions is adjusted (by taking sights on celestial objects low in the eastern and western sky) it is possible without further adjustments to determine the ship's position to within 1 nautical mile during the ensuing 36 hours. The effects of atmospheric refrac- tion and hunting of the gyrocompass north point make it desirable to restrict sights to objects near the zenith. This is easily accomplished at night when the usual navigation stars are accessible but less so by day. During mid-day the sun is the obvious target, but in the early morning or late afternoon it is pre- ferable to choose a bright star or planet higher in the sky. Favoring the visibility of such objects during the early and late hours of daylight is the fact that the brightness of the sky tends to fall off rapidly with increasing angular distance from the solar disk. Under favorable condi- tions it is possible to observe in full daylight objects generally brighter than magnitude zero with astro- nomical telescopes having apertures as small as 30 millimeters and to reach first magnitude objects with apertures of about 50 millimeters. Star photos As a by-product* of the naviga- tional experiments the meridian gyro also made it possible to take at sea, half to one-hour long time ex- posures of star fields with small cameras mounted on the hour circle *See also: "Stars and Gravity", Oceanus, Vol. VIII, No. 1. Seaborne Asfronomy Two adjacent 30 minute expo- sures of the Scutum (upper left) Sagittarius-Scorpio region of the Milky Way photographed while the ship was steaming at 12 knots. X a Levels box of the upper theodolite. The diurnal motion of the earth was cancelled by manual operation of the hour circle slow motion screw and occasional corrections of the altitude of the polar axis were effected by adjusting for the latitude slow motion screw. Photographs of the star clouds in the Crux-Argo, Scutum Sobieski and Scorpius- Sagittarius regions of the Milky Way were obtained by these meth- ods. The moon, sun and brighter planets have also been photographed from the gyro head on a scale of one centimeter per degree. Other applications Applications of the meridian gyro to other problems in astronomical and meteorological photography and theodolite measurements from ship- board are numerous and may include direct photography of solar eclipses as well as their associated flash and coronal spectra, records of meteor and satellite trajectories, and whole- sky time-lapse auroral or cloud photographs to name a few. From shipboard all of these operations can be performed with the unusual option of placing the observing sta- tion wherever geographic and cli- matic conditions at sea are most favorable. It is worth noting that in the vicinity of the magnetic equator the absence of aurora and air glow is marked, and being far from the smoke and scattered light of popu- lated regions on land, the night sky at sea is so black that faint celestial objects are often unexpectedly easy to observe. DR. von ARX is Physical Oceanographer on our staff. He has long been concerned with the problem of measuring the oceanic circulations. This effort has pro- duced the GEK, laboratory models of the ocean circulations of each hemi- sphere and the work described in this article. He has also prepared two text books. An Introduction to Physical Oceanography for college use and Mo- tions of the Sea and Air for the general reader. As for the future of these experi- ments; steps are being taken to improve the optical system of GEON in an attempt to reduce its contribution to the errors in astro- nomical navigation, and plans are being made for the re-design of por- tions of the Mark 19 azimuth and leveling servo systems in the hope of improving its performance. If these changes permit astronomical navigation by GEON to become reli- able to 0.1 nautical mile - - the level of performance promised for TRANSIT navigation it may be possible to combine the two systems to provide information on the slopes of the earth's figure at sea to the order of 10 seconds of arc. While this is far short of the desired pre- cision for the purposes of measuring the sea slopes accompanying geo- strophic motions, much less the wind stress or tides in the open sea, it would be a firm step into an area of investigation for which there are, at present, no direct observations at all. The ultimate problem of measur- ing the regional slopes of the sea surface associated with the piling up of water in geostrophic flows is an extraordinarily difficult one and well beyond the limitations of the best inertial systems presently available or even being considered at the moment. Indeed, requirements are so stringent that the goal may never be reached. But there are alterna- tive methods of attack and the question is so basic to our ability to measure the transports of energy and substance by the oceans, that an attempt seems worthwhile especially since its by-products have already proved interesting. Wh ere ore Ti HE R.V. 'Chain' (Captain E. H. Hiller) is on cruise #21 to the Medi- terranean Sea from which she will return just before Christmas. A hydrographic program was carried out in the Eastern Mediterranean by Mr. A. R. Miller, while seismic in- vestigations were made by Dr. E. E. Hays of Dr. J. B. Hersey's group. Foreign scientists participated in the program. Since last June, the R.V. 'Atlantis' (Captain A. D. Colburn) has made a number of cruises: to the Blake Plateau, to check and service the Bermuda buoy line and to dredge bottom sediments for the collection of bottom animals. Presently she is on cruise #274 studying currents north of Puerto Rico. The R.V. 'Crawford' (Captain D. F. Casiles) has returned from observa- tions with the GEK, crossing the Florida current one hundred times along a 60 mile section off Jackson- ville, Florida. Presently the ship is out on cruise #72 toward Bermuda to study current with radio-drift buoys. The R.V. 'Bear (Captain E. My- sona) is laid up fir the winter. The R.V. 'Eugenie VIIF (Captain H. H. Siebert) is in Florida for migratory game fish studies. The fishing vessel 'Cap'n Bill III' (Captain H. Klimm, Jr.) has been chartered several times and was used to check and set the buoy lines as well as for long line fishing. New Ship Ti HE Institution has awarded a $3,876,000 contract to the Mary- land Shipbuilding and Drydock Company of Baltimore for the con- struction of a 210 foot research vessel. Funds for the design and con- struction of the ship have been granted the Institution by the Na- tional Science Founda- tion. A full description of the vessel will be pub- lished in the March issue of 'Oceanus'. Edward H. Smith HE Institution deeply regrets the passing of Rear Admiral Edward Hanson Smith, U.S.C.G. (ret.), third director of the Woods Hole Oceano- graphic Institution, who was associ- ated with the Institution from 1945 until his death on October 29th. He was elected a trustee of the Institution in the summer of 1945 and continued on the board until August, 1961, when he became an honorary trustee having reached the mandatory retirement age. He became director on July 1, 1950, succeeding Dr. Columbus O'D. Iselin, and held the post for six years. During that period he was also appointed to the Institution's research staff; after he stepped down as director, he remained on the staff as an associate in oceanography. Admiral Smith's tenure as director was marked by growth and develop- ment in all phases of the Institu- tion's activity. The number of employees scientific, marine and administrative increased from about 250 in 1950 to around 350 six years later; the fleet and land-based facilities grew correspondingly. Among the highlights of this period were the construction of the Laboratory of Oceanography next to the main laboratory building; the acquisitions of the R.V. 'Bear' in 1952 and of the R.V. 'Crawford' in 1956. Other notable events were: the ac- credition of the Institution as an institution of higher education, the acquisition of an aircraft for oceano- graphic and meteorological observa- tions, the establishment of an employee's retirement plan, the formation of the Associates of the Woods Hole Oceanographic Institu- tion and the printing of the first issue of 'Oceanus'. Admiral Smith came to the Ocean- ographic Institution with a combined background of science and seafaring. A veteran of 40 years in the Coast Guard, he was a graduate of the U.S. Coast Guard Academy in New London in 1910. He studied at Harvard University, earning a mas- ter's degree in 1924 and a Ph.D. in oceanography in 1934. He worked as an oceanographer and glaciologist early in his career, served with the International Ice Patrol and took part in both the Marion Expedition to the Labrador Sea and Baffin Bay in 1928 and the Graf Zeppelin Arctic Expedition in 1931. During World War II he was com- mander of Task Force 24 for the Navy and served also as comman- dant of the Coast Guard District in the New York area. He was awarded the Navy's Distinguished Service Medal and was honored by Denmark as Commander of the Order of Dan- nebrog. From 1956 on Admiral Smith worked with the New York firm of Marts and Lundy, helping to raise funds for Cooper Union and the University College of the British West Indies. He was a member of the American Geophysical Union, a fellow of the Arctic Institute of North America and a member of the board of visi- tors in geological sciences and at the Museum of Comparative Zoology at Harvard. He also served on the Naval Research Advisory Committee and the Research and Development Board of the Department of Defense. He was a life member of Martha's Vineyard Lodge, A.F. & A.M., and belonged to the New York and Quis- set Yacht Clubs. He was born in Vineyard Haven on October 29, 1889, son of the late Captain Edward Jones and Sarah Elizabeth (Pease) Smith. 10 Deep Teredo A wooden panel hung at a depth of 9000 feet was heavily attacked by shipworms IT BY H. J. TURNER is well known that the luxuriant growths of attached marine organ- isms on all types of surfaces in the inshore waters pose a major problem in marine fouling. Since records of fouling organisms in deep water are almost non-existent, the Richardson buoy system provided an excellent opportunity to study the distribution of larvae of sedentary organisms in the deep ocean where suitable sur- faces for attachment are sparse. A series of panel assemblies was attached to several of the buoys and mooring lines at various locations and various depths to provide extra surfaces which were known to be favorable for the attachment of foul- ing organisms. Each assembly con- sisted of a one square foot pine panel attached to a one square foot asbes- tos board panel by three bolts but separated from it by two -inch spacers. The asbestos board panel was backed up with marine plywood for strength. These materials were se- lected because it is known that asbestos board sometimes will be- come populated with organisms before new wooden structures, but it seemed advisable to include a substantial amount of wood to detect the presence of shipworms. An examination of the buoys, moorings and panels by Dr. Prindle in July revealed that fouling in the open sea is limited to a very few species with no significant quantity below 500 meters. Goose barnacles of the genus LEPAS with an occa- sional specimen of CONCHODERMA were found near the surface on all stations from Station C through M. However they did not occur on any structure deeper than four meters. Hydroids of various kinds were found at each station and these occurred to depths as great as 500 meters. Organisms found at greater depths proved to be pelagic organ- isms including siphonophores and large radiolarians which had acci- dently encountered and stuck to the ropes or panels. A discovery of wood borers at a depth of 3000 meters proved to be spectacular. When station D was pulled on October 28th, the inner surface of the pine panel was found to be perforated with teredo of the genus XYLOPHAGA which had at- tacked it in numbers of a hundred or more per square centimeter. The panel was one which had been sus- pended near the bottom in 3000 meters of water, approximately 10 meters off the bottom. The panel had occasionally touched bottom as evidenced by a layer of mud between the asbestos board and its plywood backing. Curiously enough, the borers had completely avoided the plywood. The occurrence of wood-boring organisms actually attacking wood at such depths and so far from land brings up the problem of their origin. All of the shipworm group of borers have a pelagic stage in their life histories with the length of the free- swimming period varying from spe- cies to species. In the case of this particular organism it must be pre- sumed that the larvae must be exceedingly numerous and the dura- tion of the pelagic phase quite long in order that several hundred thou- sands of them might find a single square foot of wood at the bottom of the Atlantic Ocean. There are several reports of borers found in waterlogged wood dredged up from great depths but it has always been supposed that the attack took place near the surface before the wood sank. In this case the wood sank so fast when the buoy was set that there is no possibility that the attack could have occurred on the way down. Consequently, the occur- rence of borers in fragments of wood dredged up by the Danish Research Ship Galathea in depths of from 6000 to 8000 meters in a Pacific trench may indicate that such organ- isms actually are true members of the benthic fauna. 11 Dromaf/c Ba/f/e of Deep Sea Squid B ELOW a deep sea camera, suspended at depths of 1200 to 1500 feet a three foot squid (Ommastrephes pteropus) has managed to hook itself by the tail on a baited hook hanging under the camera. The bait is hanging freely by the side of the tail and the trace wire is entangled round the squids' tail. Shortly afterwards another squid of about equal size attacked the hooked animal head to head. Light patches on the body of the hooked squid give evidence of the fury of the attack. The photo at the right shows another attack, this time the assailant is tackling the body of the hooked squid. Taken from a series of thirty photographs, the pictures were obtained on a cruise of the Royal Research Ship 'Discovery II' while hove-to some three miles off the western side of the island of Desertas Grande in the Madeira group. 12 A fight between two 3-foot squid in the waters of the Atlantic 13 Current Measurements •A B . . -XT ••••& 4JffromW Moored Buoys . J ' BY W. S RICHARDSON J J.HE history of the direct measure- ment of currents in the deep water of the open ocean is a rather short one. Indirect methods based on the distribu- tion of chemical and physical properties of the water masses provide us with a general picture of the deep circulation; and calcu- lations based on the distribution of density provide quantitative date. For many years oceanographers have tried to check such data by direct measurements. Many techniques for direct current measure- ment have been proposed but few have been used to any great extent. Perhaps the most powerful and most widely used method has been the Swallow float. ::: This technique, developed by Dr. John C. Swallow of the National Institute of Oceanography, utilizes a neutrally buoyant tube which can be adjusted to drift at any desired depth. The float is tracked acoustically from a ship and may be followed for a period of days or even weeks. This technique in the hands of Swallow, Volkmann, Knauss and others has given us our first glimpse of the details of the movement of the deep water and has contributed to our knowledge of several major current systems. Deep water measurements by this technique in areas well removed from major current systems showed that the deep currents are swifter and more variable than had been expected. To obtain longer time series of current measurements over more extended areas a program of direct current observations from *See: "Deep Currents". Oceanus Vol. VII. 3, pp. 2-8. ? J K SHIPS rarely collect continuous observations at any one place for any considerable length of time. Continuous observations of currents and other variables have been made possible by a series of anchored buoys. L M 15 Buoys anchored buoys has been developed. As an initial effort a line of stations has been set between Martha's Vine- yard and Bermuda. The System The stations themselves are rather simple. The surface float is a foam filled fiberglass doughnut eight feet in diameter with a three foot hole. It has about 6000 pounds of buoyancy which is sufficient to part the mooring warp if the mooring strain builds up excessively. The mooring warp is polypropylene rope about l/2 inch in diameter and has a breaking strength of about 5000 pounds. The rope is somewhat posi- tively buoyant in water and there- fore contributes no dead weight strain to the buoy. The rope will stretch about 40% before breaking and this permits the mooring to be set with little or no scope, this being provided by stretch as required. The warp is provided in 500 meter lengths with eyes spliced in each end; instruments are inserted as links between the lengths and must be capable of supporting the full tensile load of the warp. They can therefore be located at any 500 meter multiple in depth or at other depths if special lengths are made up. The bottom end of the deepest length of the warp is connected to a weak link with a strength of about 4000 pounds. This link should part during recovery of the mooring if the anchor is fouled. There is no electrical connection between the various instruments and the surface float. Therefore each instrument must be designed to record internally and the mooring must be pulled in order to retrieve the records. Individually instru- ments are designed to record for about four months so that recovery three or four times per year should suffice if the stations last well. The Bermuda line if completely in place involves about 150 instruments of various types, current meters, wind recorders, inclinometers, depth re- corders and tension records. Each of these is capable of storing about 10,000 readings of the variable being measured. This leads to an ultimate data reduction problem with a po- tential load of 1,500,000 readings, most of which involve more than one measurement. For instance a current measurement is both speed and direction and the directional measurement is made up of two parts, the orientation of the instru- ment in the earth's magnetic field (compass) and the relative direction of the current as detected by a vane. Because of this potentially large data reduction problem the record- ings in each instrument are made in Diagram of a moored buoy. 16 a digital format on photographic film. The film can then be scanned photoelectrically and the data buf- fered to a computing machine for processing. Photographic film was selected as the recording medium because many parallel data channels are required and power consumption is less for this type of recording than for magnetic tape or other media. Current meter The current meter, provides one example of the instrumentation. The instrument is cylindrically symmet- rical and does not require orienta- tion into the current. Current direction is sensed by a vane in the upper cage which will orient to within 10° of the current direction at .01 knot. The vane carries a magnet which couples through the end cap of the pressure case to a jewel bear- ing mounted magnet and a seven level gray binary encoding disc. When a light is flashed behind this disc the light passing through the seven channels is "piped" to the field of view of the camera by small plexiglas light guides where it ap- pears as seven spots on the film, either present or not present depend- ing upon the orientation of the vane relative to the pressure case. A similar seven level gray binary number is obtained at the same time from a compass mechanism which also carries an encoding disc. This encodes the compass direction of the instrument as a whole and the dif- erence between the vane and com- pass readings is the direction of the current. These seven level binary numbers give directions individually accurate to about 2l/z° or current direction to 5° when they are sub- tracted. The current speed is sensed by a Savonius rotor the bearings of which permit it to start rotating at speeds of less than one hundredth of a knot. The rotor is also magneti- cally coupled through its end cap to a jewel bearing mounted light chop- per which provides one pulse of light for each rotation of the rotor. This pulse is "piped" to the field of view The Buoy WILKINS Trouble WRIGHT T/ie Current Meter Buoys of the camera by a fiber optics light guide. The film is advanced at a slow uniform rate of Vs inch per minute by the camera motor and the rotor pulses appear as a succession of spots on the film which can be counted photoelectrically. Difficulties Tests of the mooring system were made in 1500 fathoms off Bermuda during December and January 1960- 61. Tension measurements were made which showed a maximum during this period of about 800 pounds under heavy storm condi- tions and a typical tension of 100 to 300 pounds. It thus appeared that the design was reasonably conserva- tive for a moderate current environ- ment and the instruments required for the line were constructed during the spring of 1961. Stations A, R, C and D were set in early May. Fail- ures of the shallow stations A, R and C occurred after a week or two and this was traced to failure of the bails on the current meters caused by vibration. This fault was corrected and the rest of the line was set in early June. Station H failed and was recovered purely by chance by the 'Atlantis' while on a cruise some 200 miles away. Failure was attributed to stress corrosion of the tie rods of the upper-most current meter, pos- sibly caused by overstressing during assembly, and the entire assembly was lost. Station G failed a few weeks later for the same reason, although evidence for this mode of failure was not available soon enough to allow us to realize that this was to be a serious problem. Stations I and J (the remaining Gulf Stream stations) were operative for several weeks but were not found when the line was visited for recov- ery of records in late July. The surface float of station I, together with the upper-most current meter, was recovered by a freighter in October but was set adrift again without retaining the instrument. Thus a good set of Gulf Stream current measurements is still drift- ing around in the ocean. The surf- ace float from station J has never been reported. Stations A, B, C, D, E, F, K, L and M have been Diagram of the buoy system between Gay Head and Bermuda. Circles indicate current meters, black dots represent depth records and crossed dots refer to inclinometers. The depth scale is in meters. The numbers on the sea surface indicate the degree of north latitude of the buoy positions. SURFACE 1000- 2000- 3000- 4000- 5000- 6000- 33 r 32 / BERMUDA 100:1 18 Buoys maintained with reasonable success from May or June until late Sep- tember when the visitations of hurricanes Esther and Frances, caused considerable difficulty. The deep stations D, E, F, K, L and M, which were in place, survived the storms suffering only damage to their towers. However, the shallow stations A, B and C are now adrift, although it appears that C was on station some ten days after the pass- age of hurricane Frances. To summarize, we have been quite successful with deep stations except those in the Gulf Stream where we have had no success at all. The DR. RICHARDSON is Physical Chemist on our staff. He has worked extensively on the development of modern oceano- graphic instruments and techniques, such as the continuous temperature re- corder, and the airborne radiation ther- mometer. shallow stations in less than 100 fathoms have been reasonably suc- cessful during the summer months but have fallen victim to the fall storms. The work of data reduction has just begun. Hopefully we will be able to report on this in the near future. Current meters for the buoy system were assembled and calibrated at the Institution under the supervision of Mrs. H. Anderson. Notice to Mariners -DEGINNING on or about 11 May 1961, the Woods Hole Oceanographic Institution will establish 20 moored buoy stations along the rhumb line between Gay Head, Martha's Vine- yard, Massachusetts, U.S.A. and Ber- muda. These stations will consist of a surface float of toroidal (doughnut) shape painted orange on which is mounted a tripod tower. The floats are eight feet in diameter and the towers are ten feet high. Located below each station is a set of scien- tific instruments spaced along the mooring line and extending to the bottom. Each station float is equip- ped with a flashing white light having a repetition rate of approxi- mately one second and a radio which broadcasts in Morse code the letters KC2XGF followed by a station designating letter A, B, C, etc. These transmissions are at a frequency of 2398 KC and occur for Vz minute out of every 20 minutes. Each surface float is marked with its identifying letter and also a notation that it is the property of the Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, U.S.A. It is requested that any sightings of these stations be reported to the Institu- tion, attention W. S. Richardson. 19 z z D LJ Z Trie a/'r over the Gulf of Maine outdid any theatrical producer's attempts at using dry ice. Arctic sea smoke twisted and spiraled upwards.