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This paper reports a preliminary survey of one of humanity's most historic harbors--Alexandria, Egypt. It constitutes one phase of a broader joint land/sea examination of the largest and most famous city to bear Alexander the Great's name. The research overall had two goals: 1) to resolve locational uncertainties concerning the city's past configuration, particularly its Ptolemaic antecedents; and 2) to compare electronic remote sensing survey technologies with Remote Viewing generally, and the applications methodology developed by the Mobius Groups specifically. In the area of the Eastern Harbor, the aim of the research was: 1) the location of the ancient shore line; the locaton of and predictive description of several sites including the island of Antirrhodus and the Emporium/Poseidium/Timonium complex; a palace complex associated with Cleopatra; and a further elaboration, both in terms of location and predictive description, of the Pharos lighthouse area; 2) a comparison of Remote Viewing and side scan sonar data after each approach had surveyed the same area. This paper describes the probable location of the Emporium, the Poseidium, and the Timonium, the palace complex of Cleopatra, the island of Antirrhodus, a site at the tip of Fort Sisila (known prevously as Point Lochias), new discoveries pertaining to the lighthouse, andd an associated temple. The most important discovery though is the identification and location of the ancient seawall which extends some 65 meters farther out into the harbor than was previously suspected, and whoe location resolves a key piece in the puzzle of the ancient city's layout. The discoveries reported here were principally the result of Remote Viewing. Except for one clear "hit," side scan sonar proved unproductive because of the large amount of particulate in the water.

Designing products for reduced environmental impact and improved performance requires that a diverse range of characteristics be considered. Such tradeoffs require a practicable method for combining specialized tools into an integrated analytical system. The paper describes how an integrated design tool can be constructed from modules which correspond to different aspects of the problem, such as geometry, materials and mathematical subproblems. An electronics housing design example (subject to electromagnetic, heat transfer, environmental and cost considerations) illustrates the use of the design methodology. The tool is then used to demonstrate the ability to investigate and understand interactions between different design goals.

The location of shipwrecks and other artifacts underwater, especially items buried underneath the bottom, can be aided with many scientific techniques, one of which is pulsed sound or sonar. The theory of sonar devices and several examples are discussed in this paper.

Underwater observations of moving targets in Scotland's Loch Ness, using sonar and photographic equipment, have heightened scientific speculation that the celebrated resident monster, `Nessie', may be more than a tall tale. After centuries of myths, hoaxes, and unsubstantiated claims, there seems to be some basis for the cautious change in attitude that is taking place within the scientific community. Evidence gathered over the last decade has been largely responsible for this shift.

An in-situ silhouette camera system that permits assessment of vertical and horizontal zooplankton distributions on meter scales, yet retains considerable taxonomic information, is described. Representative data are presented from initial deployments in the Gulf Stream off Miami, Florida. Advantages and disadvantages of this approach are discussed.

Nature photography was almost the first application of the electronic flash system of lighting when it became commonly available.1 Although these first units used paper capacitors charged to high voltages and discharging at microsecond rates, later ``strobes'' employed lower-voltage capacitors and operated at longer flash durations. Hence, today's conventional strobe is not suitable for the rapidly moving subjects of nature photography. This article describes a development in strobe equipment that incorporates new and improved design to create flash units of not only lighter weight, but with exposure times of less than 100 microseconds.

The problem of the pulling into step of a synchronous motor has proved very difficult to solve, since it centres about a non-linear differential equation. One solution of the equation is not enough. All possible solutions with all combinations of the coefficients need to be made and classified into two groups, those that synchronize and those that do not. Until recently this has been practically impossible because of the amount of time required to make the solutions by graphical or point-by-point methods.The development of the integraph by Dr. Bush and his associates at the Massachusetts Institute of Technology has made it possible to solve this problem by machine integration. This integraph, which performs two successive integrations simultaneously, is particularly adapted to the solution of first- and second-order total differential equations. The solutions described in this paper were obtained by using the integraph in this way.This paper presents the complete solution of the problem for the case of a non-salient-pole synchronous motor. The results are put in a simple form convenient for practical use. By means of these results all of the necessary relationships between field current, induction-motor torque and slip, which determine whether or not a given load of a definite flywheel effect can be brought into synchronism, are determined. An example of a practical application is given.

The Rapatronic camera takes still exposures of 2 to 20 μsec with a high degree of resolution. Exposure is easily synchronized with a fast-transient event, and the shutter has at least a 30-deg viewing angle with apertures in the useful range for high-speed photography. The shutter is of the magneto-optic “light valve” type, operating by the rotation of the plane of polarization of light traversing glass in a magnetic field (Faraday effect). Three polarizers, crossed at 0-90-0 deg, produce an open-to-closed transmission ratio in excess of thirty million, and removal of the magnetic field closes the shutter, allowing it to pass only one billionth of the light from the subject.

Waterproof cases for instruments, especially cameras, electronic flash lamps, and sonar drivers, are considered for external pressures up to 20,000 psi (pounds per square inch) which is adequate for the greatest known depths in the sea. Equations, charts, and experimentally determined values of failure are given for cylinders, end caps, and windows of various materials. Several types of pressure-resisting electric connections are shown and a pressure-testing facility is described.

Mechanical oscillations of synchronous motors following the application of abrupt shaft loads have not heretofore been easily calculated for cases of large angular swings, taking into account the damping currents in the rotor, except by tedious point-by-point methods. The chief difficulty has been due to the form of the basic differential equation upon which the solution of hunting problems depends. Within the last few years, Doctor V. Bush and others at the Massachusetts Institute of Technology have devised the integraph which is capable of solving the equations of the synchronous motor. Into the integraph are put curves representing the non-linear differential equations and the boundary conditions. The desired results come from the integraph as curves. In this paper, the problem of sudden load on the non-salient pole alternator is solved by the integraph for enough different conditions so that the performance of practically any machine of this type may easily be predicted from the compiled results. Knowing the moments of inertia of the machine and its load, the characteristics of the machine running as a synchronous motor and as an induction motor, the maximum amount of sudden load for which the machine will remain in synchronism may be determined for different values of initial load. Other curves give the maximum angle of the first swing of the rotor and the time interval for the rotor to change from Us initial position to this maximum angle. The simplest type of equation representing an ideal synchronous machine is solved in this paper. The integraph is capable of solving problems of a much more complicated nature than those presented. The more complicated problems pertaining to machines with unsymmetrical excitation and salient-pole rotors will probably be the subjects of future papers.

Randomly distributed pulses, of any voltage shape, and of varying magnitude, actuate an amplifier whose output meter indicates only the average rate of arrival of the pulses. Counting rates of 30 per minute up to several thousand per minute are read directly from a rugged meter. The apparatus is a.c. operated, is portable, and is particularly adapted to the study of feeble gamma‐radiation. The apparatus consists essentially of a preamplifier, a uniform pulse generator based on a relaxation oscillator or on an inverter circuit, an output amplifier stage, and a capacity‐resistance electrical tank circuit for performing the averaging process.

Design details are given for two submicrosecond flash sources for photography by reflected light, silhouette and schlieren techniques. The source for reflected-light photography uses a “guided” air spark operated at 18 kv with 0.05 μf to produce a 0.4-μsec flash with a peak light of 5 million candlepower. The flashtube, a special design, is described, together with its power supply and trigger circuit. The trigger circuit can be operated by a microphone, phototube, contactor or other electrical signal, and incorporates an adjustable time delay. A photograph taken with the unit is shown. — A small spark source capable of producing flashes of about 10 mμsec duration for silhouette and schlieren photography is described. Relative peak light output and flash duration are given as a function of pressure for air, nitrogen, oxygen, carbon dioxide, hydrogen and argon. Gap resistance is given as a function of gap length, for air.

A sonar with a short acoustic pulse and high peak power (0.1 to 0.5 ms, 108 db) has been adapted for shallow water bottom penetration by speeding up the pulse rate to 30 cps. Known as the Pinger Probe, it has evolved from the EG and G sonar Pinger for positioning deep-sea cameras and is a device especially designed to show objects submerged in the soft bottom sediments of rivers, harbors, bays and coast lines. It emits a short, relatively powerful acoustic pulse capable of penetrating certain sediments and reflecting from objects or layers of different densities as a return signal. Coupled with a high resolution Alden recorder, it has a detection capability for locating a variety of sediment layering and shallow buried objects. The increased pulse repetition rate provides much improved resolution.

A precisely-timed submersible pinger has been created by the inclusion of a miniaturized precision time source in a standard Edgerton submersible pinger. The miniaturized precision time source, devised for this purpose, employs a one hundred kilocycle crystal as its frequency standard, which is counted down by five decade dividers to provide a one cycle per second synchronizing signal. The resulting precisely-timed pinger, when used in conjunction with a Precision Graphic Recorder or similar device, permits the measurement of direct acoustic travel time as well as the difference in acoustic travel time between the ping and its echo. These measurements provide a basis for the tracking of an instrument in the sea with respect to the ship. A tracking chart is presented along with the track of a deep-sea camera lowering monitored by this method.

Mechanical oscillations of synchronous motors following the application of abrupt shaft loads have not been hereto-fore easily calculated for cases of large angular swings, taking into account the damping currents in the rotor, except by tedious point-by-point methods. The chief difficulty has been due to the form of the basic differential equation upon which the solution of hunting problems depends. Within the lastfew years Dr. V. Bush and others at the Massachusetts Institute of Technology have devised the integraph which is capable of solving the equations of the synchronous motor. Into the integraph are put curves representing the non-linear differential equations and the boundary conditions. The desired results come from the integraph as curves. In this paper the problem of sudden load on the non-salient pole alternator is solved by the integraph for enough different conditions so that the performance of practically any machine of this type may be easily predicted from the compiled results. Knowing the moments of inertia of the machine and its load, the characteristics of the machine running as a synchronous motor and as an induction motor, the maximum amount of sudden load for which the machine will remain in synchronism may be determined for different values of initial load. Other curves give the maximum angle of the first swing of the rotor and the time interval for the rotor to change from its initial position to this maximum angle. The simplest type of equation representing an ideal synchronous machine is solved in this paper.

A xenon‐filled electronic flash tube with a cylindrical lighted volume of 1.2‐mm diam and 6‐mm length has been developed for use as a small source in optical systems, such as the schlieren and interferometer types. The lamp has been operated at 6000 flashes per second from a hydrogen‐thyratron driver circuit to record the density in air flow in an interferometer. Flash duration varies from 0.3 to 3 μsec, depending upon the circuit conditions. A peak brightness of 10 million candlepower per sq cm has been achieved.

This paper describes the electrical characteristics of gas‐filled discharge tubes when flashed by a condenser discharge. The object of the experiments was to determine the effects of tube dimensions, pressure, voltage, and capacity upon the performance. The results are of an experimental nature and cover a limited range of values of tubes and circuit constants. An empirical constant called tube resistance is defined and evaluated. This constant is useful in predicting the performance of tubes in electrical circuits.

An automatic stroboscopic power angle recorder developed to study directly the transient performance of synchronous machines during load disturbances is described in this paper. A portion of the machine under observation is illuminated by stroboscopic light, and its oscillations are recorded directly by a moving-film camera. The operation of the device is made automatic by connecting a suitable relay in its circuit. A typical installation on a hydroelectric generator is described.

Three important parameters are among those governing the application of the many versatile sonar techniques. Penetration and resolution depend upon pulse length and frequency. The angle of the transducer is also important?a perpendicular beam will resolve geological strata, whereas a side-looking beam. will provide a "relief map" of the ocean terrain. Finally, several different types of transducers are available, both hull-mounted and towed, to provide the user with the best instrument for a specific application.

An electronic double flash unit has been constructed to measure photographically average linear velocity of blood flow in the bulbar conjunctival vessels of the human eye. Two exposures on the same photograph separated by a predetermined time delay (adjustable from 2 to 200 msec) permit computation of velocity from the displacement of red cells per delay time. The equipment is small and mobile, the procedure innocuous.

High speed motion pictures have been found to be extremely useful in studying the motions of various types of mechanisms, especially transient high speed motions. Modern electronic devices have contributed new methods of producing accurately controlled light flashes of extremely high intensity so that now pictures may be taken by reflected light at rates up to several thousands per second.

Preliminary experiments in harbor at Boston, Mass., with a sonar that has a high peak power output (about 105 db) and a very short ping length (about 0.1 msec) show that penetration at 12 kc/s can be as much as 50 feet below the bottom. Bedrock is reached in a few places. Sediment layers, probably of glacial origin, are clearly shown in others. Two vehicular tunnels that connect Boston with the airport are shown at 10 feet under the mud. The depth resolution in the sediment is less than ½ meter because of the short length of the signal. The transducer is mounted on a fish so that it can be lowered over the bow or side of a small boat and towed for making surveys. Thus there is a greater coupling of energy into the bottom and a smaller target area to reflect the signal.

HIGH-SPEED properly describes single exposure photographs that are taken with exposures shorter than about 1/10,000 second, and motion pictures taken at speeds above 300 pictures per second. The unaided camera, with mechanical shutter, cannot take such pictures, because of both photographic and mechanical limitations. The development by Edgerton, et al.14 of electrical apparatus for producing intermittently flashing (stroboscopic) illumination and for high-speed photography has provided a superior technic for investigating and recording rapid motion. The technic also offers advantages in "still" photography-in " stopping" motion as a result of the short duration, high intensity illumination. In addition to its ability to record and to "stop" rapid motion, highspeed photography is useful for measurement and analysis. Since in multiflash and in motion pictures the interval between flashes may be predetermined, the observer is able to record an action as a function of time. Likewise the velocity, shape, and acceleration of the

The Differential Analyzer at the Massachusetts Institute of Technology has made possible the rapid and accurate solution of the idealized non-linear differential equations of motion of synchronous motors which describe the pulling-into-step transients. The purpose of this paper is to present the results of these solutions in a useable form. These results give a rather complete analysis of the phenomena, and thus enable the determination of the performance of practically any machine. One of the factors which is considered in this paper is the time constant of the field circuit with the armature short-circuited. Curves are given showing the additional load which may be synchronized when the field switching is angularly controlled to the best angle. The influence of salient poles has been considered as well as non-uniformity of the amortisseur winding. The practical application of the study is indicated by a numerical example.

It is pointed out that the trend of modern electronic flash equipment is toward longer flash duration. After proposing a method of defining duration, an approximate method of calculating duration is given, together with resistance constants of commonly available flashtubes. Some information is given regarding the production of short flashes of light in the microsecond and submicrosecond range.

The growth of the luminous area of a high current discharge in an electronic xenon‐filled flashtube has been studied by means of a sequence of timed short‐exposure photographs taken with a magneto‐optic shutter. Electrical measurements show that the tube conductance is approximately proportional to the luminous area of the arc channel. The ionized gas has a volume conductivity of about 90 mho/cm averaged over the luminous path during the buildup for the conditions investigated.

Photoelastic photographs, with exposures of approximately one-millionth of a second, were taken of transient stresses in glass before, during, and after fracture. The longitudinal and transverse waves in glass have been photographed and their velocities measured (18,000 and 11,000 ft. per sec, respectively). It was also found that under special conditions cracks may travel slower than .5000 ft. per sec, the value previously given as the crack propagation velocity.

A grid-controlled arc-discharge tube which requires neither power nor time for heating the cathode, but in which a discharge of several hundred amperes is controlled by an extremely small amount of power in the grid circuit, is described in this paper. The tube has characteristics especially useful In circuits requiring large peak current but low average current, some examples of which are given here and is applicable particularly as a light source in stroboscopes.

By means of the “differential analyzer,” the equations describing the pulling-into-step transients of a synchronous motor can be solved readily and accurately. The results of such solutions give a rather complete analysis of pulling-into-step phenomena, and thus make possible the determination of the performance of practically any synchronous motor. Practical application of the study is illustrated by a numerical example.

The possibility of using intense intermittent light for motion pictures and special photography is discussed. Physical limitations of sources of intermittent illumination are reviewed. The characteristics of the mercury-arc thyratron which give it advantages as an intermittent light source are enumerated, viz., (1) the light is photographically actinic; (2) the duration of a light flash can be made less than ten microseconds; (3) the light intensity is high; (4) the frequency of flash is easily and accurately controlled by means of a grid. An example of the use of intense intermittent light is given, showing how stroboscopic motion pictures of the angular transients of synchronous motors are taken.

The boomer, an electromagnetically driven sound source for seismic profiling, consists of a triggered capacitor-bank that discharges through a flat coil or coils. Eddy currents are induced in aluminum plates that are held against the coil by heavy springs or rubber bumpers. The plates are violently repelled, and a cavitation volume is produced in the water which acts as a source of low-frequency sound. The boomer has been used as the transmitter of a continuous seismic profiling system at sea. A 1000-joule system has been used in shallow, fresh and salt water. Reflections from sediment layers at least a kilometer below the bottom of the Puerto Rico trench have been recorded by Hersey and his group aboard the Woods Hole Oceanographic Institution's R.V. Chain with a 13,000-joule (maximum) boomer.