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American Institute of Electrical Engineers, Journal of the

Issue 4 • Date April 1922

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Displaying Results 1 - 25 of 31
  • Air-break magnetic blow-outs: For contactors and circuit breakers both A-C. and D-C.

    Page(s): 257 - 266
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    Magnetic blow-outs have been used in contactors, circuit breakers and controllers for many years for rupturing both a-c. and d-c. power circuits, but their commercial use, particularly on alternating current has been largely confined to relatively low voltages. Oil circuit breakers and switches have been generally used for rupturing high-voltage a-c. power circuits, and their development has reached a high state of perfection. The air break has the advantage of avoiding the possibilities which attend the use of any inflammable material — like oil, with its possible gasification and explosion on heavy short circuits. While there are many different types of magnetic blow-outs this paper deals largely with the “individual” type, in which a blow-out coil is connected in series with each pair of current-rupturing contacts, since it is with this type that most of the progress and studies have been made in recent years. Contactors and circuit breakers with the “individual” type of blow-out are now used almost exclusively in the main d-c. power circuits of (he 1500 and 3000-volt d-c. railway systems. Oil circuit breakers have been tried for this service, but they are rather unsatisfactory because there is no periodic zero point in the current wave at which the oil can form an insulating seal between contacts. The oil under d-c. arc conditions carbonizes rapidly and involves the possible danger from explosive gases. Recently the use of magnetic blow-out contactors on a-c. circuits has been extended to moderately high voltage and capacity. Short-circuit tests on a 6600-volt, 26,700-kv-a. alternator are described towards the end of the paper. During these three-phase tests the air-break magnetic blow-out contactors successfully ruptured 17,500 amperes, the full short-circuit current, at 5500 volts. This is 170,000 kv-a., three-phase. The maximum asymmetrical peak current through the contacts during this test was 67,500 amperes, but duri- g a 2500-volt short-circuit test this peak current reached 80,000 amperes. Oscillograph records of the voltage and current in each phase are shown and also illustrations of the arcs. The contactors used were rated at 5000 volts, 3000 amperes, but they successfully ruptured a circuit of 9000 volts, 3500 amperes. The oscillographic records and illustrations of this test are shown in Figs. 25 and 26. Current-rupturing tests at 2300 amperes and 3500 amperes normal voltage are also shown for comparison in Figs. 22 to 24. In all of the tests the circuit was ruptured within the first half cycle after the tips started to part, indicating the effectiveness of this type of blow-out. The arrangement of the current-carrying and magnetic blow-out parts are shown in Fig. 15. The main current is carried through solid copper contacts mounted at the back. The auxiliary contacts in the arc chute and the blow-out coils carry current only during the time the circuit is being ruptured. These coils with their attending arcing horns are cut into the circuit in succession, so as to obtain the strongest possible final magnetic field without undue arcing at the contact tips and across the terminals of the coils when they are introduced into the circuit. Several arc suppressor plates are provided in each half of the arc chute which increases the cooling surface, and on heavy short circuits split the arc into a number of multiple paths. See Fig. 10. A brief description is given in the first part of the paper of a typical form of the “individual” type magnetic blow-out as used in contactors and circuit breakers, and photographs of a number of contactors for various a-c. and d-c. voltages are reproduced. Attention is directed to the tests with accompanying illustrations of successive positions of the arc in the chute taken with a high-speed camera, from which some interesting data were obtained on arc characteristics. The arc was photographed in its movement every three-thousand View full abstract»

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  • The effect of high currents on disconnecting switches: With special reference to the mechanical stresses resulting

    Page(s): 267 - 277
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    In the early days of the electrical industry, disconnecting switches adequately performed their functions without the use of locking devices, except perhaps in a few isolated cases, where the blades opened downward, and some mechanism was provided to hold the blade in against the action of gravity (when subjected to jars, vibration, etc.). The generating capacity of central stations at this time was relatively small. Hence, the short-circuit currents obtaining were relatively low, and the forces resulting were insufficient to overcome the friction and other resistance offered by the blade and to cause opening. With the increase in generating capacity came a formidable increase in the short-circuit currents, to such an extent that it was not uncommon for a disconnecting switch to open, causing considerable damage, with consequent demoralization of operation. The result was that there were attempts made to attach locks to switches already installed, and to design new switches of which the lock was an integral part. Many of these locks were found to be inadequate, as opening occurred in many instances. In an attempt to prevent the possible recurrence of such unfortunate incidents the tests described in the following paper were planned; it was hoped thereby to improve the class of service rendered the public and safe-guard the lives of our employees. Specifically, it was desired in addition to a general study of the subject, to attempt to improve the locks already in use on our system and to provide locks for the switches located at dangerous points, i. e., points where short-circuit currents are likely to obtain which might open a given switch. One or more of the various types of switches in use on our system were tested, and in addition, a number of types which were considered for replacement of the obsolescent types now in use. As a result of these tests it was possible by a very simple expedient to raise the opening point of one of our switches from about 40,000 pe- k amperes to 180,000 peak amperes. A very simple lock was added to another switch largely used on the system which opened at about 51,000 peak amperes so that it would withstand the mechanical forces exerted by 143,000 peak amperes. The tests clearly demonstrated that some effective form of lock should be provided. This seems to have been generally recognized, and most manufacturers have attempted to take care of this in some way or other. Switches have been constructed (without locks) in which the current through the switch parts does not tend to open the blade. Such switches are satisfactory when used under almost ideal conditions, but certain unfavorable arrangements of the bus and leads usually found in practise, exert magnetic forces which might open the blade under short-circuit conditions, thus completely nullifying the principle of design. Although locking devices are provided they are not always effective, the various reasons being mechanical weakness of lock, current flow through lock, etc. It was noted from a study of the oscillograms that a switch seldom required more than one cycle to open, one-half cycle usually being required. It was generally recognized that there were outward forces on the blade of a switch due to the passage of high currents; but it was not generally recognized that there were also outward forces on the jaws and insulators tending to spread them apart. These forces must be recognized and dealt with by substantial design as a number of lock failures may be attributed to this. Insulators may fail due to these outward forces, and this can be remedied only by strengthening or properly supporting the insulators. View full abstract»

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  • Illumination items: By the lighting and illumination committee

    Page(s): 278 - 279
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    Illumination helps to make highway travel easier at night. It helps to reduce traffic congestion, relieves eye-strain and assists in making repairs after dark. It increases night traffic and thereby relieves day congestion. It increases running time and thereby increases road capacity. Illumination of the road-bed at night would be a big factor in reducing traffic accidents. Data presented before the Illuminating Engineering Society in October by E. A. Anderson and O. F. Haas show that nearly 18 per cent of the night traffic accidents in cities can be attributed to inadequate or improper lighting, and obviously, the percentage of traffic accidents on country roads and highways due to poor lighting is much higher. View full abstract»

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  • Color temperature and its relation to the quality of light

    Page(s): 279 - 280
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    In a paper1 presented before the Illuminating Engineering Society in October 1921 at Rochester, the subject of color temperature and its relation to the quality of the emitted light for a number of different light sources was discussed. There it was shown that by the use of the color temperature of a light source a number is given which expresses the quality of the light of those sources to which the method applies. View full abstract»

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  • Magnetic flux distribution in transformers

    Page(s): 281 - 287
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    It is customary when discussing magnetic leakage in the transformer to consider the primary and secondary windings as having a counter e. m. f. induced by a flux surrounding the coil and having the core for a part of its path. This leakage flux is frequently represented by closed lines. Since the main flux is also represented by closed lines in the core, apparently two fluxes are to be found in the core under a given coil, namely, the leakage flux and the main flux. The main flux is the flux found in the core at a point not under either the primary or secondary winding, and has been commonly considered as being the flux which causes the secondary induced voltage. If the leakage fluxes have a separate existence, i. e., if they are to be represented by closed lines, then the flux along the edges of the core would consist largely of leakage lines while that to be found in the middle portion of the core would be the main flux. Since these fluxes are out of phase with one another it should be possible to identify them if they are present as separate fluxes. Using a simple test core-type transformer, provided with belt exploring coils under both the primary and secondary windings, data concerning the magnitudes and phase positions of the fluxes in different sections of the core were secured. The results show that leakage fluxes do not exist as separate fluxes in the core. It is also shown that the primary and secondary induced voltages are equal to the primary and secondary terminal voltages diminished and increased respectively by the corresponding I R drops. View full abstract»

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  • The superpower system — I

    Page(s): 287 - 291
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    The paper deals with the essential elements of the superpower plan and discusses the effect of a cheaper and more adequate power supply upon the industrial activity of the United States. The economies effected by the electric utility systems of the country in the past are brought out, while the need for greater coordination between the electric utilities through some such agency as superpower systems is emphasized. The present power production facilities within the superpower zone form an important element of the proposed superpower system. The plan does not call for the complete scrapping of existing electric utility plants or transmissions, but uses these to a very large extent as the nucleus of the system. The effect of amortizing less efficient steam-electric plants is to materially increase the resulting economy of the balance of existing plants, which, with proposed new water power developments, are used to carry the peak load impressed upon the system, permitting the base load steam-electric plants to operate at very high capacity factors with resulting low production costs. The location of base load steam-electric plants in the bituminous coal-mining region is found to be uneconomical at the present time, but the location of large stations in the anthracite region is found to yield very attractive returns. The use of process fuel is not recommended under present conditions, but provision is made in the station designs for the use of such fuel at a later date should it prove profitable. The Superpower Report sets forth principles rather than a detailed analysis of a particular situation and this report must be followed by detailed studies of different sections of the country, taking into consideration the local conditions which must be provided for. View full abstract»

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  • The superpower system — II

    Page(s): 292 - 297
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    On account of diminishing fuel supply the development of our hydroelectric resources is imperative. It is probably the most fruitful field for conservation of natural resources open to the present generation. Under modern conditions there is an increasing demand for a continuous supply of energy in all channels of industry. Development of our hydroelectric resources probably requires more careful analysis than any other engineering problem confronting us. There are three types of hydroelectric developments, (1) plants depending on uniform stream flow, (2) plants on rivers having variable stream flow, and (3) plants on streams “regulated” by storage reservoirs. The Niagara and St. Lawrence belong to the first class and are suitable for development of base load plants. The Susquehanna belongs to the second class and should be developed for “run of river” power. The third class includes the Connecticut, Hudson, Delaware and Potomac which should be developed with storage for carrying peak loads. The principal transmission lines in the superpower zone should operate at 220 kv. Where the lines are long, intermediate stations with “phase modifying” equipment may be desirable. The distribution lines should operate at 110 kv. Successful operation depends on ability to localize trouble as it is now done on large utility systems. Adequate protective devices and selective schemes for disconnecting defective circuits are essential and these are available. Voltage regulation is effected by excitation of synchronous apparatus in consumer's plants supplemented by synchronous equipment at load centers. The benefits from an interconnected system are, (1) it permits base load plants to be operated at high capacity factor, (2) it permits development of water power on rivers that otherwise would not justify it, (3) it saves fuel by permitting the less efficient plants to be shut down at times of light load and (4) it improves the service- Ninety-three per cent of the energy in the superpower zone is generated at 25 and 60 cycles and is almost equally divided between them. The demand for 25-cycle generating capacity is stationary while the demand for 60-cycle generating capacity is increasing rapidly. In an 80,000-kw. turbo generating and distributing plant the saving by using 60 cycles is 19 per cent of the utility investment and 16 per cent of the customer's investment. The total saving is 17.5 per cent. A common frequency is necessary for general interconnection and all signs indicate that this will be 60 cycles. The justification of the superpower system is the saving in cost of power. By the year 1930 the investment for energy supply will be $163,000,000 less than with individual operation. The saving in coal will be 19,000,000 tons per annum. The total annual saving in fixed charges, general expense and operating expense will be $239,000,000. A proper attitude of federal and state regulatory bodies is essential to the success of the superpower project. It should be allowed to earn a liberal income, and capital, labor and the public should share in the benefits. A superpower plan carefully worked out will be a credit to the people of this country not only as an engineering accomplishment but will show our ability to organize large things which will build up industry and at the same time prevent economic waste. View full abstract»

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  • The electric hammer

    Page(s): 297 - 305
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    The power hammer has been in use for a long time and there are now on the market many types of power-operated hammers which may be roughly classed according to the nature of the power as follows: Pneumatic, steam, motor and pulley; cam or crank, and electropneumatic drives. The pneumatic drive includes all riveting hammers; the steam drive includes practically all forge hammers, some drop hammers, pile drivers and steam drills; the motor and pulley drive class, includes the greater part of drop hammers; the electropnuematic drive includes only small forge hammers. The pneumatic hammer, due to its lightness, holds the field of hand-operated riveting hammers and it is hardly possible that any other means will ever surpass air for driving hand-operated riveting hammers; the steam hammer holds its own in very large forging and drop hammers and it is doubtful whether any other kind of hammer can remove it from that place. The field for very large forging or drop hammers is however rather limited; they are used only in very large plants in which all sorts of power prevail. There is an immense field, however, for medium and small forging and drop hammers which are used to produce all the small automobile and other similar parts as well as name plates, jewelry apparel, etc. It is this field which the electric hammer is supposed to cover. The present methods of driving these hammers are cumbersome, complicated, costly and very unsafe for the workman. The electric hammer has been studied and developed by the writer to a point where it seems to show superiority to the present used hammers, in simplicity, safety, running expenses, cost of installation, cost of upkeep and in many cases in the original cost. The development shown herein is of the induction motor type. Instead of the usual arrangement of concentric armature and field, the slots are punched on long strips of iron in a straight line which makes the field and armature parallel. The armature and field still face each- other but every part of the aramture is not always active under the influence of the field as is the case in the ordinary motor. In other words in a straight-line motor the armature or runner is continuously entering the field of action at one end and leaving it at the opposite end. This constitutes the main difference between the straight-line and the rotary motor. The rotating fields of an induction motor are here replaced by magnetic fields moving in a straight line. The principal elements of this straight-line induction motor hammer are shown in Fig. 3. The actual hammer as finally constructed is shown in Fig. 5 (back view) and Fig. 6 (front view.) View full abstract»

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  • A new system of electromagnetic forces needed

    Page(s): 305 - 307
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    In liquid conductors, such as exist in some electric furnaces, and especially when high current densities are used, the writer has noticed that there are some new electromagnetic forces which do not appear to be accounted for by present mathematical treatments of the subject; as such very mobile conductors respond more readily to these forces than solid conductors do, they make the presence of such forces more evident; and as most of them presumably increase with the square of the current or the product of two currents, a force which under ordinary circumstances may be unnoticed may become quite formidable at such high current densities. Moreover, for a given current the flux encircling a conductor, which is what gives rise to these forces, becomes greater with diminishing cross sections. View full abstract»

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  • Selling research

    Page(s): 307 - 309
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    When your chairman asked me to talk to you tonight it was his thought that I should give some striking examples out of my own experience to show the value of research. In considering the matter, it seemed to me that it might be more appropriate to speak of a phase of the subject which is seldom mentioned, and I think not generally well understood, namely, selling research or perhaps more properly, selling the products of research. As to the value of research it seems to me that this audience needs no arguments or examples to convince it that research is worth while. If such is needed from me, it should be sufficient to tell you that my company has for quite a number of years expended upwards of half a million dollars a year for research with an ever increasing program for the future. The present industrial depression has somewhat restricted our activities, but our plans for expansion will undoubtedly go forward as soon as business conditions warrant. View full abstract»

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  • A relay recorder for remote control by radio

    Page(s): 310 - 313
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    Relays have been used for many years in wire telegraphy and other electrical work. The practical operation of relays actuated by received radio signals is a comparatively recent development, and has been made possible by the development of the electron tube amplifier. This paper describes the development and the operating principles of a type of relay recorder which is designed to operate from the output terminals of a radio receiving set and which may also be operated by any other source of audio-frequency signal. By the use of special electron tube circuits the audio-frequency signal is caused to operate an ordinary telegraph relay. In order to avoid the necessity for using a very sensitive relay, designed to operate on currents of a milliampere or less, which would have delicate adjustments and light contacts and spring tension, advantage was taken of an electron tube amplifier, which has now become a reliable radio instrument, to increase the input voltage to the relay circuit thus making possible the use of a simple ordinary high-resistance telegraph relay. The relay device has therefore been developed to operate from the output circuit of any suitable amplifier in place of the ordinary telephone receivers. The operation of the relay may serve to work a sounder, buzzer, tape register or any mechanism for remote control by radio. Two types are described. One type is designed to be operated from batteries. The other type is designed to operate entirely from any 60-cycle 110-volt lighting circuit and this feature makes this type simple and inexpensive to operate, durable and practical. Another unique feature is described which is that of tuning to different audio-frequencies whereby any one of three signals, each of a different audio pitch, may be caused to operate the relay to the exclusion of the others. Curves and diagrams, are shown illustrating the principles of operation. By the use of two of these relay recorders connected in series across the output termi- als of a single radio receiving set, two messages sent on practically the same wave length but of different audio-frequencies, have been accurately received simultaneously. View full abstract»

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  • Electric crane controllers

    Page(s): 313 - 319
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    Other papers in the series on electrical apparatus for cranes deal with the requirements as to motors and auxiliary equipment; the latter comprising brakes, overload protective panels and limit switches. This paper on controllers reviews its subject in a general way, without going into any details of the devices employed, presenting a clear view of the fundamental considerations involved. The controlling apparatus of an electric crane is responsible for the prompt and proper accelerating of the several motions; their speed control; the safeguarding of the motors from abuse; the convenience and economy of operation; and the elimination of many dangers due to carelessness. The author touches indirectly on these points but concerns himself chiefly with the character of the controllers best suited to the bridge, trolley and hoist under various conditions. The paper deals fully with the problems concerning the selection of ohmic values for the resistors and also covers very completely the connection arrangements and resistance values involved in the dynamic braking control of lowering loads. View full abstract»

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  • Auxiliary electrical equipment for motor-operated cranes

    Page(s): 319 - 328
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    This is one of a series of papers on the selection of electrical apparatus for cranes and deals with the brakes, overload protective panels and limit switches. Other papers of the series cover the requirements as to motors and control. A magnetic friction brake is needed for every crane hoist, in addition to what may be provided in the way of dynamic braking or mechanical brakes, but its required characteristics are very definitely affected thereby. In selecting a magnetic brake the character of the service must be well understood, and the part that it plays therein, and it must possess an adequate energy dissipating capacity. A definite formula for such selection is given. The paper discusses the various service requirements and describes the several available types of magnet brakes and their particular fields of application. Limit switches, while occasionally employed to limit the travel of the trolley or bridge motions of a crane, are universally used to limit the upward travel of the hook block. Hoist limit switches may be geared to the machine or directly operated by the block. The former do not take into account the stretching of cables and require complete readjustment when new cables are installed. Switches operated by the hook block are the surest. The paper describes the various forms of geared and direct-operated limit switches and points out their relative advantages. Considerations of safety often demand that the operation of the switch not only disconnects the motor but simultaneously closes a dynamic braking circuit for quick stop. The history is given of the evolution of the modern crane overload protective equipment and devices. Fuses and railway type circuit breakers have been tried, but up-to-date equipment employs overload relays in each motor circuit operating in conjunction with magnetic switches. In the interests of safety it is possible to cut off all power instantly by tripping a switch that causes the magnetic switches to open. Safety lock- are provided that permit of locking the entire crane equipment against operation. The best results are secured by properly inspected time-element overload relays in each motor circuit and a common-return instantaneous relay. View full abstract»

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  • A. I. E. E. Spring convention

    Page(s): 71
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    As previously announced, the Spring Convention of the A. I. E. E. will be held in Chicago, April 19–21, 1922, at the Drake Hotel, which will be the Institute headquarters during the meeting. View full abstract»

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  • A. I. E. E. Annual convention

    Page(s): 71 - 72
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    The Annual Convention of the Institute to be held at Niagara Falls, Ontario, during the week of June 26–30, is expected to be one of the best attended conventions which the Institute has ever held on account of its central location, the natural attractions of Niagara and the number of interesting applications of electricity which have been developed in this neighborhood through the use of electric power from the Falls. View full abstract»

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  • Future section meetings

    Page(s): 72 - 73
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    Freely Available from IEEE
  • A. I. E. E. directors meeting

    Page(s): 73
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    Freely Available from IEEE
  • Professional ethics

    Page(s): 74
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    The A. I. E. E.'s permanent Committee on Code of Principles of Professional Conduct reported to the Board of Directors of the Institute, at a recent meeting, recommending that “to serve as a guide for the membership and for future decisions, the findings of the committee upon cases brought before it be published in the Institute Journal.” This recommendation has been approved; and in accordance therewith, attention is called to the following statements covering recommendations made recently by the committee, and which were later approved by the Board of Directors: View full abstract»

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  • American Engineering Council

    Page(s): 75 - 76
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    On February 18, 1922, President Harding signed the Lampert Patent Office Bill, H. R. 7077. This action marks the end of a long fight waged by the engineering societies through American engineering council to obtain from Congress much needed relief from conditions which were rapidly tending to place the Patent office in a state of uselessness. View full abstract»

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  • National Research Council

    Page(s): 76 - 77
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    The sixteenth meeting of the Division of Engineering of National research council was held in New York City on February 14, 1922. In addition to the members of the Division attending, there were present, by invitation, Herman Lemp, of the General Electric Company, Prof. V. Karapetoff of Cornell University, and Col. K. G. Maxwell of the research department, Metropolitan-Vickers Company, Ltd., London, as speakers; Capt. Walter Graham, Scientific Associate, Research Information Service; and the following members of the Advisory Board on Electrical Engineering Reserach: E. B. Craft, E. E. F. Creighton, W. A. Del Mar, Bancroft Gherardi, L. F. Morehouse, and S. S. Wheeler. View full abstract»

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  • Institute of radio engineers

    Page(s): 77
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    At a meeting of the Institute of Radio engineers to be held in the Engineering Societies Building, New York City, on April 5 at 8:15 p. m., a paper on the “Resistance and Capacity of Coils at Radio Frequencies,” by Professor John H. Morecroft of Columbia University, will be presented. The paper describes theoretically and experimentally the behavior of numerous types of inductances at radio frequencies and contains important design data. View full abstract»

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  • Personal mention

    Page(s): 78 - 79
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    W. C. Starkey has become vice-president of the Stevenson Gear Company, Indianapolis, Ind. He was previously with The Ohio Brass Company, Mansfield, O. View full abstract»

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  • Obituary

    Page(s): 79
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    Freely Available from IEEE
  • Engineering societies library

    Page(s): 80 - 81
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    The library is a cooperative activity of the American Institute of Electrical Engineers, the American Society of Civil Engineers, the American Institute of Mining and Metallurgical Engineers and the American Society of Mechanical Engineers. It is administered for these Founder Societies by the United Engineering Society, as a public reference library of engineering and the allied sciences. It contains 150,000 volumes and pamphlets and receives currently most of the important periodicals in its field. It is housed in the Engineering Societies Building, 29 West Thirty-ninth St., New York. In order to place the resources of the Library at the disposal of those unable to visit it in person, the Library is prepared to furnish lists of references to engineering subjects, copies or translations of articles, and similar assistance. Charges sufficient to cover the cost of this work are made. The Director of the Library will gladly give information concerning charges for the various kinds of service to those interested. In asking for information, letters should be made as definite as possible, so that the investigator may understand clearly what is desired. The library is open from 9 a. m. to 10 p. m. on all week days except holidays throughout the year except during July and August when the hours are 9 a. m. to 6 p. m. View full abstract»

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  • Past section and branch meetings

    Page(s): 81 - 85
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    Freely Available from IEEE

Aims & Scope

This Magazine ceased publication in 1923. The current retitled publication is IEEE Spectrum.

Full Aims & Scope