Price. And I by no means suppose that all the pleas for particular tariffs in order to keep up the workmen's standard of living have been well founded. All that I wish to say, after such a survey of a past period as we have been engaged upon, is that economic life has ceased to be as simple, if it ever were as simple, as those two great men, Adam Smith and Cobden, seemed to think it. It has not been so clear to the last halfcentury as it was to them that human well-being can be achieved by the application of one symmetrical cycle of principles. By the whole current of its industrial legislation the civilised world has protested against the all-sufficiency of cheapness. It has now embarked upon the double task of making a Living Wage a first charge upon the community and of giving Security a larger place in industrial life. This will be a harder business than to abolish old and often outworn restrictions on natural liberty.' Society has been so sorely disappointed in the hope that, if it sought first cheapness, all other needful things, like social peace, would be added to it, that it is in the mood to explore other avenues,' as the phrase goes-avenues as yet imperfectly charted.

SECTION G.-ENGINEERING.

A HUNDRED YEARS OF ELECTRICAL

ENGINEERING.

ADDRESS BY

PROFESSOR G. W. O. HOWE, D.Sc.,

PRESIDENT OF THE SECTION.

THIS Section of the British Association, over which I have the honour to preside, is concerned with the whole field of engineering, civil, mechanical and electrical. Within recent years the great developments which have taken place in each of these branches have necessarily led to a high degree of specialisation, with the result that a man may have an expert knowledge of one branch but a very slight knowledge of the other branches; in fact, the scope of a single branch is now so extensive and the amount of research work being done so great that it is impossible to keep abreast of the developments in one's own special subject unless one concentrates upon it to a degree that leaves little leisure for cultivating other branches of engineering. These considerations influenced my choice of a subject for this Presidential Address. As an electrical engineer, I felt that I should be expected to deal with some branch of electrical engineering-indeed, I should not feel competent to discuss any other branch but, in view of the facts to which I have referred, I decided not to deal in detail with any single section of the subject, but to review the past development and present position of the subject as a whole.

The time for such a review is opportune. William Thomson, afterwards Lord Kelvin, the only man who has ever been elected three times (in 1874, 1889, 1907) President of the Institution of Electrical Engineers, was born on June 26, 1824. He was closely associated with the British Association and for sixty years took an important part in the meetings. He was President of the Association at the Edinburgh Meeting in 1871, and was several times President of Section A. I wonder what the members of the organising committee of Section G would think if the President, in addition to reading his address, offered to contribute twelve papers to the Proceedings of the Section: this is what Kelvin did as President of Section A at the Glasgow Meeting in 1876. I can find no record of his taking any part in the proceedings of Section G, although his brother, James Thomson, was President of the Section at the Belfast Meeting in 1874.

If any one event can be regarded as the birth of electrical engineering, it is surely the discovery by Faraday in 1821 of the principle of the electromotor; that is, that a conductor carrying a current in a magnetic field experiences a force tending to move it. It is noteworthy that ten years elapsed before Faraday discovered, in 1831, magneto-electric induction; that is, the principle of the dynamo. Four years later, Sturgeon added the commutator or uniodirective discharger,' as he called it, and in 1845

Cooke and Wheatstone used electromagnets, which Sturgeon had discovered in 1825, instead of permanent magnets. It was during the years 1865 to 1873 that the shunt and series self-excited dynamo, using a ring or drum armature and a commutator of many segments, finally evolved.

The early workers in the field do not appear to have realised th intimate connection between the dynamo and the motor, for, although the principle was discovered by Lenz in 1838, it only appears to have become generally known that the same machine could be used for either purpose about 1850. The principle underlying the whole modern development of electrical engineering-viz., the generation of electrical power by a dynamo, its transmission to a distant point and its re-transformation to mechanical power by an electric motor-appears to have evolved about 1873. An interesting light is thrown on the subject by a paper read before the Institution of Civil Engineers in 1857 by Mr. Hunt on 'Electromagnetism as a Motive Power.' In this paper the possibility of driving electromagnetic engines that is, electric motors-by currents derived from voltaic batteries was discussed in the light of Jacobi's discovery of the back-electromotive force in these machines. He concluded that power so generated would be sixty times as dear as steam-power, and that it would be far more economical to burn the zinc under a boiler than to consume it in a battery for generating electromagnetic power. The leading scientists and engineers who took part in the debate all agreed that electromotive power was unpractical and impossible commercially. William Thomson sent a contribution in writing which concluded with the following sentence: 'Until some mode is found of producing electricity as many y times cheaper than that of an ordinary galvanic battery as coal is cheaper than zinc, electromagnetic engines cannot supersede the steam engine.' As S. P. Thompson says, ' Faraday's great discovery of 1831 notwithstanding, the real significance of the dynamo had not yet (in 1857) dawned upon the keenest minds of the time.' Six years before this, Thomson had suggested the experiment of driving a galvanic engine' from a thermal battery, and had stated the problem in terms which show that he already had a correct grasp of the theory of the efficiency of the electric motor.

It was at the Manchester Meeting of the British Association in 1861 that Charles Bright and Latimer Clark read a paper proposing names for the principal electrical units; the names were 'galvat' for current, ohma' for electromotive force, farad' for quantity, and 'volt' for resistance. This paper led to the appointment of the celebrated Electrical Standards Committee of the British Association, which, after six years of strenuous work, produced the system now adopted internationally.

One of the earliest applications of the dynamo was for lighting arc lamps in lighthouses; in 1863 Thomson, writing to a friend on the relative merits of the Holmes direct-current and the Nollet alternating-current lighthouse machines, says: 'Thus Nollet escapes the commutator, a great evil, and gets a flame which does not burn one of the points faster than the other. The reverse of each proposition applies to Holmes. The commutator is a frightful thing . . . the thing to be done at the requisite speed is appalling. However, Holmes does it successfully. But I believe it cannot be done except theoretically without great waste of energy and consequent burning of contact surfaces. ... But I believe a large voltaic battery will be

more economical than any electromagnetic machine. I am not quite confident about this, but shall be so soon, as I am getting a large voltaic, and I shall soon learn how expensive its habits are, and multiply by the number required for a lighthouse.' This was thirty-two years after Faraday had discovered the principle of the dynamo.

In after years Kelvin lost his dread of the commutator and championed direct against alternating current on every possible occasion. In 1879, when giving evidence before a Select Committee of the House of Commons on Electric Light, he even assured them that there would be no danger of terrible effects from the employment of electric power, because the currents would be continuous and not alternating!

The fifteen years following 1863 saw a great development of the dynamo, and in 1878, when a paper was read before the Institution of Civil Engineers on the improvements introduced by Siemens, Thomson made a remark, following a suggestion by Dr. C. W. Siemens, that showed that he had by this time thoroughly grasped the possibilities. He said that he believed that with an exceedingly moderate amount of copper it would be possible to carry the electrical energy for one hundred or two hundred or one thousand electric lights to a distance of several hundred miles. Dr. Siemens had mentioned to him that the power of the Falls of Niagara might be transmitted electrically to a distance, and he need not point out the vast economy to be obtained by the use of such a fall as that of Niagara or the employment of waste coal at the pit's mouth. In his evidence before the Select Committee referred to above he gave an estimate of the copper required to transmit 21,000 horse-power from Niagara to a distance of 300 miles.

In 1881 Thomson returned to the subject in his Presidential Address to Section A at York and said, High potential, as Siemens, I believe, first pointed out, is the essential for good dynamical economy in the electric transmission of power.' He mentioned 80,000 volts as a suitable voltage. In a paper before the Section he developed the now well-known Kelvin Law of the most economical cross-section of the conductor. In 1890 the American promoters of the project for utilising the power of Niagara turned to Thomson for his advice, and he became a member of the Commission of Experts. He was throughout stubbornly opposed to the use of alternating currents; he wrote, I have no doubt in my own mind but that the high-pressure direct-current system is greatly to be preferred to alternating currents. The fascinating character of the mathematical problems and experimental illustrations presented by the alternating-current system and the facilities which it presents for the distribution of electric light through sparsely populated districts have, I think, tended to lead astray even engineers, who ought to be insensible to everything except estimates of economy and utility.' He was in a hopeless minority, however, in this view, and the Falls of Niagara were harnessed to two-phase alternators with an output of 3,500 kilowatts each. Kelvin was present at the meeting of the British Association held in this city in 1897, and shocked many people by saying that he looked forward to the time when the whole water of Lake Erie would find its way to the lower level of Lake Ontario through machinery; 'I do not hope,' he said, 'that our children's children will ever see the Niagara Cataract.' Although he was apparently very much impressed with the success of the Niagara system, he was not converted

from his allegiance to direct currents, for at his last appearance at the Institution of Electrical Engineers, in 1907, he said, 'I have never swerved from the opinion that the right system for long-distance transmission of power by electricity is the direct-current system.'

The development of the dynamo during the seventies and the simultaneous development of the incandescent lamp led to the general introduction of electric light during the eighties. Attempts to make incandescent electric lamps had been made as early as 1841, when de Moleyns patented one having a spiral platinum filament, and in 1847 Grove illuminated the lecture theatre of the Royal Institution with such lamps, the source of power being primary batteries; but it was not until 1878 that the commercial development of the incandescent electric lamp was begun by Edison and Swan.

One of the earliest complete house-lighting installations was put in by Kelvin in 1881. A Clerk gas-engine was used to drive a Siemens dynamo, a battery of Faure cells was fitted up, and every gas-light in his house and laboratory at Glasgow University was replaced by 16 candle-power Swan lamps for 85 volts. He had to design his own switches and fuses, etc., for such things were almost unknown.

For about twenty years the carbon-filament lamp held the field without a rival for interior illumination, and, although attempts were made to improve its efficiency by coating the filament with silicon, the plain carbon filament only gave way finally to the metal-filament lamp. One of the most interesting developments in the history of electric lighting was the Nernst lamp, which was introduced in 1897; the filament consisted of a mixture of zirconia and yttria, and not only had to be heated before it became conducting but also had to be connected in series with a ballast resistance in order that it might burn stably. The way in which these difficulties were surmounted and the lamp, complete with heater, ballast resistance, and automatic cut-out, put on the market in a compact form occupying little more space than the carbon-filament lamp was, in my opinion, a triumph of applied science and industrial research. The efficiency was about double that of the carbon lamp. About this time, however, a return was made to the long-neglected metal filament. The osmium lamp invented by Welsbach in 1898 was put on the market in 1902, to be followed two years later by the tantalum and tungsten lamps. The latter was greatly improved by the discovery in 1909 of the method of producing ductile tungsten and by the subsequent development of gas-filled lamps in which the filament can be run at such a temperature without undue volatilisation that the consumption is reduced in the larger sizes to 0.6 watt per mean spherical candle-power. This improvement of eight times as compared with the efficiency of the carbon-filament lamp has led to the gradual replacement of the arc lamp even for outdoor illumination. The arc lamp was introduced at about the same time as the carbon-filament lamp, the Avenue de l'Opéra having been lit with Jablochkoff candles in 1878. The open arc was developed during the eighties; the enclosed arc, giving long burning hours and thus reducing the cost of re-carboning, was introduced in 1893, and the flame arc in 1899. During the first few years of this century the flame arc was brought to a high stage of development and the consumption brought down to about 0.25 watt per candle-power, but the necessity of frequent cleaning to prevent the reduction of efficiency by dirt and the