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would be like without their work. Engineers are not alwaysfully conscious of the responsibility they carry on behalf of theirfellow-men. We are relied upon and trusted to a degree.

In our life-time we have seen more and more power producedby less and less coal, and eventually we shall be expected toproduce all requirements with no coal at all. In other words, theheat pile will be in operation in a very few years from now. It isclaimed that in the United States the heat pile is producing low-grade heat at 150-200° F in great and continuous quantities. Itseems reasonable to hope that a similar amount could be pro-duced at, say, 800-1 000° F, and this is in fact being tried out atthe present time. We have heard that electricity can be pro-duced from the heat pile at approximately only 20% greater costthan with coal prices at $10 per ton.

Much work is being done in the development of gas turbines,and our good wishes go to our colleagues engaged on these tasksat home and abroad.

The subject of district heating is much discussed: there is afield for this in the future, but to secure true economies it must beincorporated in a suitable and comprehensive scheme at the out-set. An endeavour to superimpose full district heating on anormally developed existing town as we know it in this countrywould be so expensive that the financial results would be disap-

pointing and discouraging. The thermal efficiencies are soattractive that at first sight steam-generated electricity convertedinto heat appears wasteful and expensive. There is, however, apoint not generally realized, namely the convenience factor.

An old German scientist, Dr. Urbanitzky, said in about 1882,"In its power to assume always that form of energy which happensto be the most useful, lies the great importance of electricity."The applications of electricity are by no means exhausted; in factwe are infants in its study.

Our old friend the sun has his violent electric frolics, coming to amaximum every 11 years or so. Enormous vortices of gasescarrying powerful magnetic charges on the sun's surface upset ourshort-wave transmission. Sir Edward Appleton tells us that theelectric emission of radio waves corresponds to an output of about1 000 million kW at a wavelength of 5 metres. This gives a littlefood for thought for the future.

Not many days ago I was fortunate enough to witness a verybeautiful display of the aurora borealis. The study of the effectof the ultra-violet light in the ionosphere and on short-wave fade-out comes within the scope of astronomers and physicists, but itleaves me with the thought that we have barely touched the fringeof what electricity can do if all these powers can be harnessed inthe service of mankind.

NORTHERN IRELAND CENTRE: CHAIRMAN'S ADDRESSBy T. P. ALLEN, M.Sc, Member.*

"SOME ASPECTS OF ELECTRONIC ENGINEERING"

(ABSTRACT of Address delivered at BELFAST, 8/A October, 1946.)

The war through which we have so recently passed, accelerated,as wais usually do, the development of new scientific devices, andencouraged scientific research in a way which, unfortunately,peace conditions do not. The results of this, in the scientificworld, do not end with an armistice; many new fields, opened upin the feverish urgency of war, leave a wealth of opportunity forresearch. Much that was evolved for weapons of defence andoffence is found to have application to peaceful pursuits, and theimmediate future should show many new scientific methods andappliances based upon such research.

This is true of probably all branches of science, but in onebranch of electrical engineering—electronics—the progress hasbeen so rapid and of such direct application, often in a ratherspectacular manner, that it has aroused an interest far outsidetechnical circles, which cannot wholly be accounted for by theveil of secrecy which so recently surrounded its manifestations.What we owe to radar for our defence, and later for the means tovictory, is common knowledge. Broadcast news and programmesare an everyday experience; and I think it would be reasonableto say that almost everyone to-day has some familiarity withthe applications of electronic devices, and that many have aknowledge of the technical side of some one application. I dofeel, however, that the immense width of application of electronicdevices to almost every field of human endeavour, is not yet fullyappreciated.

VOL. 94, PART L,Belfast College of Technology.

The term "electronic device" is not completely suitable, forall electrical devices could, in a sense, be so described. It is,however, distinctive and is generally accepted. It may be appliedto any electrical circuit which employs a current path in a gaseousconductor or in a vacuum. "Electronic engineering" might bedescribed as the design, construction, testing, adjustment, main-tenance and application of electronic devices and their associatedcircuits and apparatus.

Some electronic devices have been in use quite a long time; themercury-arc rectifier and X-ray equipment are two familiarexamples. But the real impetus to the development of electronicdevices came when Lee de Forrest put the grid in the thermionicvalve, and the immediate application of this to communicationled to the creation of broadcasting, with its momentous influenceon society. The field was so large, technically and commercially,that development was rapid and, indeed, at the end of threedecades, shows little sign of abating.

With development.comes complexity, and to-day the techniqueof television demands a knowledge and skill far greater thanare needed for the transmission and reception of sound. To-morrow, it seems certain that frequency modulation in thiscountry will provide the engineer with additional experienceand the public with improved performance in broadcast reception.

The application of valve circuits, and the production of powerat ever-increasing frequencies, was not of value only to the com-munication engineer, though until now his has been the greatest

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interest. The development of devices for use in other fields hasbeen much slower. Only of recent years has there been anacceleration and a great increase in the variety of application.In the minds of many people this has caused electronic circuitsto be closely associated with broadcasting. This is perhapsnatural when one considers the history of that art; how many ofus have not used the expression "wireless valves"?

Most electronic engineers must find it well-nigh impossible toread more than a small fraction of the technical literature, whichseems to increase in volume every day. The electrical engineerwho has not specialized in this branch must ordinarily be lessable to appreciate the value and possibilities of electronic devices,and perhaps looks with a somewhat doubtful glance at thesenew "gadgets."

Scientific conservatism, within reason, is desirable and under-standable; it forces a proving of the new. That proving is nowin progress. Many scientific workers in our profession, and innumerous other professions, are to-day relying on electronic aidsand methods with confidence and, in many cases, with enthusiasm.In industry, in medicine and in many branches of scientificresearch, their help is already most valuable, and in some instancesthey have opened up possibilities about which one must keep atight rein on imagination.

Tt would be difficult to find a branch of science which has notdiscovered a use for the new technique, and in considering a fewexamples chosen from widely differing sciences, I am well awarethat my treatment must give an inadequate measure of the extentto which electronic methods are helping the scientist and engineer.

One of the earlier and more famiiiar products of electronictechnique, the X-ray, is being used by the plant geneticist in thestudy of heredity and the production of new types. The heredi-tary characteristics of an organism are, as is well known, deter-mined by the multitudinous genes carried on the chromosomes,which form the greater part of the cell nucleus. New combin-ations of existing characters may be obtained by cross-breeding,but new characters in plants have hitherto occurred in only a verysmall proportion of cases as an abnormal event. The genes insuch cases must have been affected by some unknown influence,and one suggestion has been that, amongst other agencies, cosmicrays are responsible.

It has been found that X-ray treatment produces mutation ofthe genes, and in certain species as many as 14% of the seeds haveproduced plants with new characters. Such experiments arebeing conducted in Northern Ireland, as elsewhere, and I amindebted to the courtesy of the Plant Breeding Division of theN.T. Ministry of Agriculture for information, and for the samplesof treated and untreated potato plants (exhibited). In com-parison with the control plant, the treated plant has smallerleaves of different shape, a deep-green instead of a yellowish-green leaf, no hairs on the leaves, and, although it has lessprofusion of growth, it has a considerably greater number ofstems. As yet, such treatment produces undirected results, butit will be valuable in providing the breeder with new types fromwhich to select, thus condensing the natural selection of centuriesinto a few plant generations. Also, it is giving valuable infor-mation which helps to a better understanding of the mechanismof heredity.

Another example from agriculture is the use of an electronicdevice for the rapid measurement of the moisture content ofseeds. Tn Northern Ireland we are very interested in flax seed;with this device, semi-skilled workers can determine, with anadequate degree of accuracy, the percentage of moisture in agiven sample. A considerable number of such instruments areused throughout the Province for this purpose, but it can also beused to test any granular substance such as plastic powders ordehydrated foods.

The field of bio-chemical research shows ultrasonic soundwaves, generated electronically, being used to disintegrate bac-terial cells and thus allow investigation of their enzyme system.Also, the technique of electrophoresis, applied to the fractionationof blood to determine its content and to obtain biological productsfor medical use, is carried out with the help of electronic controlswh-'ch allow an analysis to be made where chemical methodscannot be used. This process has permitted the separation ofalbumin from bovine blood for transfusions in human beings,and also the preparation of the antibody for tetanus from horseblood.

Radio-frequency heating is one of the better known develop-ments, and the field of application is constantly being enlarged.An interesting example occurs in the prepaiation of penicillin,which loses its effectiveness when kept in solution, althoughwhen dry it can be stored for a considerable time. Drying isdifficult, because the heat necessary to evaporate the water isharmful to the penicillin. One method is to freeze the solutionand, using a high vacuum, dry out by sublimation; this is lengthyand expensive. Another method employs radio-frequencyheating to a sare low temperature and a moderately low pressure.The potency of the penicillin is preserved and the time of produc-tion is reduced to about 3 % of that of the first process; the cost ofproduction also is reduced.

Radio-frequency heating has been used for the inhibition ofmould in wrapped loaves, and for the rapid defrosting of eggsused in bakeries. Tt has been used for sterilization and pasteur-ization, and for many industrial processes such as vulcanization,the heat treatment of" metals, the threadless stitching of plastics,and the rapid setting of plastic glues.

Perhaps one of the most important applications of electronicsto industry is in control apparatus. The term "control" mustbe used in a very wide sense, for it may mean anything from theautomatic candling machine for the inspection of eggs, to anelectronic door-opener to simplify the passage of tray-ladenwaitresses from the kitchen to trie restaurant. Or, again, it maymean the rapid and accurate inspection of small metal productsfor size, and the automatic rejection of any which fall outside settolerances; or the control of liquid concentrations in electro-chemical processes. The control of temperature and humidity,of the speed of d.c. motors, and of the voltage of generators, areexamples of the type which is regulating in effect. Timing isobviously of wide usefulness; spot- and seam-welding controlsare familiar forms. The protection of workers by electronicsafety devices such as the light beam in front of a stamping press,and the protection of plant by water-level indicators and alarms,are well established. Measurement of smoke density in powergeneration and of pH-values in chemistry are widely separatedexamples of control. The control of colour by comparison witha standard sample is a differential method of wide use in manyindustrial processes.

A consideration of the different methods of control and oftheir applications impresses one with the way these devices havehelped man to overcome the results of certain human limitations.The drudgery of inspection, with its consequences in fatigue andmomentary lack of concentration; the reaction time, increasingwith fatigue and age; the normal limitations in human abilitywith respect to colour, time measurement, hearing and sight—allof these, and more, find assistance from electronic devices whichare, in effect, either artificial extensions of, or deputies for, man'ssenses and abilities. Many, indeed, show a power of discrimina-tion which seems almost to approach an elementary intelligence,but the day of the machine with the power of creative thinkinghas, fortunately, not yet arrived.

Timing and frequency measurement have recently attained anaccuracy which, stated in figures, is difficult to appreciate.

ALLEN: NORTHERN IRELAND CENTRE: CHAIRMAN'S ADDRESS 115

Apparatus for everyday use can have an accuracy of measure-ment better than one part in 108. This dull logarithmic statementcan be expressed more vividly: it is about one second in 3± years.Laboratory accuracy is of the order of one second in 35 years.

Timing and counting circuits are closely allied, and electroniccounters, by the elimination of moving parts, have reachedcounting speeds of over 100 000 per second, which is muchfaster than normal industrial requirements. Action can beinitiated by the device when any arbitrarily chosen sum is reached,for example, in the packaging of buttons or pills. Accuratemeasurement of brief time intervals has been useful in determiningthe opening and closing times of circuit breakers and relays.

Counting circuits have, with other circuit developments, ledto electronic calculating apparatus. The calculators range fromsimple arrangements to the huge Electronic Numeral Integratorand Computer (Eniac) of the U.S. War Department, whichemploys 18 000 valves. In a matter of hours it can supplyprinted tables, with carbon copies, of calculations which, it isclaimed, would ordinarily require the work of 100 mathematiciansfor one year. The apparatus can store the results of subsidiarycomputations until required in a later phase of the total calcula-tions, and thus has an elementary form of memory. It issatisfying to know that this memory is limited: if the calculationsbecome too bulky the apparatus resorts to taking notes in theform of punched cards.

Electronic devices have found many applications in mechanicalengineering. In addition to the better-known ones, such asheat tieatment and control apparatus, there are the accuratemeasurement of backlash in gearing, fuel gauges for aircraft,electronic brazing in mass-production units, contouring systemswhere the operation of a cutting tool is controlled automaticallyfrom a template, high-speed X-ray photography of the transfer ofmetal during welding, and many others.

One method of flaw detection operates on a principle which hassome features in common with radar. Ultrasonic pulses aregenerated by electronic means and are set up in the materialto be tested by the application of a quartz resonator. Thepulses travel in the material until they are reflected by a flaw orby the boundary. On arrival back at the quartz plate, theyproduce a voltage across it. The original pulse and the reflectionare displayed on a cathode-ray-oscillograph screen. Any changein density or elasticity, such as is produced by a flaw, thereforecauses an extra reflection which is immediately noticed on thescreen, the length of time between initiation of the pulse and itsreturn giving a measure of the distance to the flaw. This methodcan detect flaws which are too small to be detected by X-rayexamination. Another advantage is that fatigue cracks can betraced in shafts and axles without dismantling them, providedone end is accessible.

The medical profession, even with its traditional caution, wasnot slow to adopt electronic aids as they were evolved. Toradiography and X-ray therapy, diatheimy used for therapeuticpurposes and bloodless surgery, and the electrocardiograph, ithas now added the electro-encephalograph, an instrument forobserving the electrical activity of the brain. From an analysisof the observations the diagnosis of epilepsy and the locating ofbrain tumours are very greatly assisted. The electro-encephalo-graph has also been used to study the effect of low oxygenpressures on the functioning of the brain, and to investigate"black-out" during periods of rapid acceleration, both of whichare matters of vital interest in aviation. The full possibilities of

this apparatus are not yet exhausted, and interesting researchwork is proceeding.

The optical microscope, invaluable as it has been to all branchesof science, has been a tool of limited performance. Our know-ledge of the minute has been limited by the wavelength of light,and even with ultra-violet illumination and immersion the highestmagnifications obtainable are of the order of 3 000 diameters.Now, as a result of the development of a new branch of physicsknown as electron optics, the electron microscope has arrived;magnifications of the order of 50 000 are obtainable in commer-cial instruments, and much greater than this in experimentalwork. Even the dullest imagination must be impressed by theadvance in knowledge which this instrument makes possible innumerous fields.

This brief consideration of the width of application of electronicmethods has not included the wide field of radiocommuni-cation, which, though extensive, is really a part of electronicengineering.

Conditions to-day are such that modern scientific methodsmust be employed to an increasing extent in industry, and oneof the most important of these is the use of electronic devices.Apparatus of this kind requires skilled engineering of a specialvariety, and I believe that the time is fast approaching, if it is notalready here, when electronic engineering must be considered asa separate branch of electrical engineering with a suitably designedcourse of training. In addition, I think that all electricalengineering students should have some training in the funda-mentals of electronics.

The young engineer who wishes to specialize in this subjectwill require a much greater knowledge of physics and mathe-matics than is at present considered sufficient for the ordinaryelectrical engineering course. The need for advanced physicsis so pronounced that there are some who feel that a physicist'straining is the best approach. It is true that electronic engineeringlies between electrical engineering and physics, but the engineerand the physicist have different functions. While their woik inthis field is complementary, 1 cannot see any justification for itsbeing competitive, and an engineering outlook in the training is,in my opinion, very necessary.

An attempt is being made in this area to meet the need fortraining of this sort. Men who hold the Higher NationalCertificate in Electrical Engineering may study for an endorse-ment of their certificate in the subject of radio. Universitygraduates in physics and electrical engineering may take a post-graduate certificate course in radio engineering. Both coursesare mainly concerned with the communication side of radio, asbeing, until now, the more important; but the fundamentals ofthis are, for the most part, the fundamentals of a broader coursewhich I believe must arise.

At present, the arrangement is a compromise which lengthensthe training and postpones specialization; it has educationaladvantages but financial disadvantages. It may be that anincrease in the time devoted to cultural studies, which I wouldheartily support, will make this longer training a normal one,but I believe that a divergence of courses in electrical engineeringmust take place towards the end of the training psriod if we areto produce the types of engineers we need. Meanwhile, ex-perience is being obtained with the interim arrangement whichwill be most valuable, and I am convinced that the teaching sideof our profession is alive to these new requirements, and will notbe slow to meet the situation.