Autobiography of William Joseph Dibdin F.I.C., F.C.S.
Analytical Chemist
1850 - 1925

Section 3  Chapter 4

Photometry

The work in connection with Photometry and the standards of light extended over a period from 1880 to later years, ie up to the present. My first experience after my initial entry into the mysteries of Gas Testing in 1877 was in connection with the measurement of the electric light afforded by the Jablochoff system on the Thames embankment when it was found that the so called 1000 candle power lamps were equal to only about 400 candles which was reduced by the opal globes to about 160 candles. This was confirmed later by experiments which I made at the Exhibition of Electric Light at the Albert Hall in 1881 when Sir William Preece delivered a lecture at which the Prince of Wales presided. J.W.Keates had been requested to show the photometer and appliances with which the measurements on the Thames Embankment had been made and he deputed me to set up the apparatus and show it in action. This I did and at the request of the Committee made a series of tests of the different exhibits, with the result of causing deep disgust in the minds of several Exhibitors by the ruthless way in which exact measurements discounted their optimistic estimates of the intensity of light afforded by their several inventions.

At this time the value of the standard candle as an exact and invariable measure was again called into question, largely as a consequence of certain departures which had been made in the method of its manufacture, particularly in connection with the platting of the wicks. Mr Keates had some years previously proposed a moderator lamp using sperm oil, at first arranged to give a light equal to 10 standard sperm candles and afterwards modified to 16.0 candles, the correction for varying height of flame being made by weighing the quantity of oil consumed. The question of standardising this system was an important one and it became my duty to carry out lengthy investigations on the point.

This I satisfactorily accomplished and for a time there was a great probability of this system being adopted as the English Standard Method. Doubtless Mr Keatesí death in 1882 gave opportunity for opposing methods to displace it.

In the winter of 1882-83 the great Exhibition of Gas and Electricity was held at the Crystal Palace where Siemens demonstrated the transmission of power by electricity. In conjunction with Prof. William Fisher of Middlesex Hospital, I was requested by the Committee of Management to undertake a series of tests of the respective values of different exhibits as to their merits for the development and distribution of lighting power. This work we carried out at the works of the South Metropolitan Gas Company, Old Kent Road during the early months of 1883, the results being presented in the form of a report which was published in the transactions of the Gas Institute for 1883. The various burners etc. to be tested were sent to those works where the company fitted up a special testing room for the purpose.

Prof. Fisher and I worked there nightly three or four times a week for nearly three months the work having to be done in the evenings, in consequence from other occupations during the day. I donít think I ever worked harder than at that time. Official routine at Spring Gardens 9.00 Ė 5.00 with special investigations in connection with the Inquiry on the River Thames by the Royal Commission, General analyses and committee work; supervising 20 Gas Testing Stations and 3 Gas Meter Testing Stations, employing in all and staff of about 60 inspectors assistants etc.

Then to the South Metropolitan Gas Works and then home to Tufnell Park, right across London by the old slow methods of travelling and on arrival often having to take up some private work.

No wonder that when I took a holiday in the autumn, taking the family to Folkisk in Norfolk for a month, this being the first holiday since I was married five years before, I felt "dead beat". But the sweet country air and life soon put all right and on my return (hastened by an outbreak of diphtheria in the village ) I took up a question which had arisen in connection with our tests at the South Metropolitan Gas Works viz: the Radial photometer, which Messrs Sugg & Co. made for me from my design, and in the following winter I showed it at the society of Chemical Industry. The system, I then introduced, now known as "spherical photometry" was at once accepted and most flatteringly received and now the method of the diagrammatic expression of the intensity and distribution of light of and by a luminous unit is commonly employed not only in text books but even in advertisements.

[ Refer to article on the Sugg Radial Photometer in ICE virtual Library. ]

During succeeding years various proposals were made, notably by Methvan and Harcourt for reliable standards of light in place of the sperm candle and in consequence of certain reports made by these and other investigators, I was instructed by the Metropolitan Board of Works to carry out an investigation on the subject. This I readily undertook and after a fairly exhaustive set of researches the Board authorised my obtaining a special designed instrument called the "Fourway Photometer" being an arrangement of four photometers arranged in the form of a cross with the standard of comparison placed in the centre where it could be simultaneously tested by four different observers each using one of the proposed new standards of light. In order that the personal equation might be eliminated as much as possible I was authorised to employ the services of the staff of 20 Gas examiners whose daily experience in photometrical readings were invaluable. The results were published in the form of a report and so favourably received that the British Association appointed a Committee to investigate the question. The manner of their proceeding was to me amusing. They had no money and no apparatus; They therefore invited me to become a member of their committee and on my consenting they asked me to lend them my official apparatus. This being agreed to by the Board on my recommendation, they invited my staff of Gas Examiners to assist in the work with my instruments and my staff with certain members of the British Association looking on! This was of course lightly complimentary and very nice, naturally the report of the committee was a confirmation of my official report which recommended Harcourtís 1 candle pentane air-gas flame as a standard of reference.

About this time, the question of the quality of the London Gas supply at places other than the official testing stations, arose and by the instructions of the Board I analysed in conjunction with Messrs Sugg & Co. an instrument known as the "Portable Photometer" which was a modification in a simplified form of the official instrument and could be packed and readily set up for use in any ordinary room. By it means, great discrepancies in the quality of the gas were detected and much controversy took place, eventually resulting in an application to Parliament by the London County Council for power to test the gas by its means. The Gas interests in the House, however, proved too strong and the proposal, although supported by the Metropolitan Gas Referees, failed to become law. Although I showed by a series of diagram curves, the influence that quality had on consumption, as by the larger quantity of gas of a low quality which must be consumed to yield an equal degree of illumination, the actual cost for any given definite illumination would be far greater than any possible reduction in the price of gas. This was met by the contention that the old time flat flame method of gas consumption was becoming obsolete, by the introduction of the incandescent mantle which gave more light with a very poor gas that would be given by the old time burners with the best gas. Considered, however, in regard to flat flame burners only, my results and deductions were admittedly correct.

In connection with my researches I had devised a special form of standard which I called the "Petane-Argand". This was thoroughly examined later by the Board of Trade Committee in 1894-95 with the result that it was recommended for general adoption as a working standard, the 1.0 candle air-gas flame of Harcourt being retained as the reference unit in place of the sperm candle. This committee was a very strong one, composed of representatives of all parties concerned viz: the Corporation of The City of London; the London County Council; the London Gas Companies; The Royal Society and Gas Referees. The representatives of the London County Council were Prof. E.Frankland and myself.

[ The Argand Gas Burner was a development of the Oil Lamp invented by Aime Argand in 1784. The wick is housed between two concentric cylindrical tubes. This ensures a supply of air to both the inside and outside of the flame. ]

This committee after 2Ĺ years searching investigation, recommended, in par. 10 "that the Pentane-Argand air flame furnished by a Dibdin Argand Burner, be accepted as giving the light of ten standard candle, and that this flame be authorised and prescribed for official use in testing the illuminating power of gas supply by the London Gas Companies."

For the work done in devising this standard and obtaining its recommendation by so strong a committee, the London County Council accorded me a vote of thanks. It was at once proposed to make this recommendation legal by an act of Parliament, but for some mysterious reason obstacles always cropped up. After my resignation Harcourt modified my form of Pentane-Argand by omitting the glass chimney etc and thereby destroying the beautiful steady flame. I had secured and the special form which gave its characteristic compensation shape, whereby the light of the flame might vary very largely without affecting that portion used for standard purposes. This new form gave some 9% less light than that recommended by the committee and consequently immediately found favour in the sight of the Gas Companies, who soon realised the importance of the alteration in giving them such an advantage and at once without any reference to the findings of the Board of Trade Committee, adopted it and secured it legality by embodying it in their respective Acts of Parliament. The only public comment made being that in the Journal of Gas Lighting some years after when they congratulate the Gas Companies on "getting the best of the bargain" . Net result Ė Public deprived of nine percent of its artificial light without any consideration whatever.

Having occasion to test the lighting of All Saints Church, St Johnís Wood in 1912 with a view to a new installation, I devised the "Hand Photometer" which I described before the Society of Chemical Industry, which instrument was taken up and placed on the market by Messrs Alex Wright & Co. and has met with no little success. Each instrument is standardised and certified by me.

In connection with the foregoing work I read various papers before the Society of Arts, received too silver medals: the Society of Chemical Industry; The Institute of Gas Engineers.

Amongst the amusing incidents in connection with photometry was my smashing up the reputation of the "improved" Evans closed photometer. At the Notting Hill Gas Station I frequently found that a 16.0 candle flame would be indicated as 21.0 or 22.0 candles and that the trouble was due to the defective ventilation and overheating of the candles. I called the attention of the gas referees to the matter, whereupon after much discussion they ordered the Examiner to report all results without rejecting any "on account of their seeming improbable" with the result that the tests became a laughing stock and the instrument had to be altered. It always puzzled me to understand why, when an obvious defect had been pointed out they could not have made the alteration at once and have done with it. It was not until I had stated at a meeting of the Gas Institute, with reference to this Photometer that the Gas Examiner was compelled to rightly "commit a fraud" by reporting something which he knew to be wrong, that the remedy was applied.

At the same station, an amusing incident once occurred. The apparatus had been renewed and on an appointed day the Gas Referees officially attended to certify its correctness. Mr. Sugg, as the maker of the apparatus, was there with his men; also the Gas Companyís representative, the Gas Examiner and Gas Referees. Wanting to test the thermometers Mr Harcourt ask for the standard thermometer which nobody could find, whereupon Harcourt, who had a curious temper when put out, soundly rated Sugg who turned upon his assistants for their supposed neglect. They protested and a mild "row" was going on when in walked Dr. Pole, one of the referees, who sagely informed Harcourt that he had been testing the temperature of the passage outside with the standard thermometer and had found it to be some degrees cooler than that of the room !

I once had the great satisfaction of pleasing Prof. Tyndall, who was one of the Gas Referees. Nothing interested him more than the demonstration of a fact by the simplest means. We were at the Tooley Street Gas Testing Station on one occasion when they were testing the apparatus. I had pointed out certain defects on the ventilation of the photometer and taking up a sheet of newspaper I tore it into the shape I required and placing it on the instrument over the burner to regulate the air currents so as to secure a practically absolute steady flame from the Argand burner instead of the irregularly waving forked abomination generally obtained. Tyndall was so pleased with this simple method that he walked up and down, stopping every time he passed the burner to look at it and give a grunt of satisfaction. The idea was adopted and the instrument in the new form became known as the "Tooley St." pattern of the "Tower" photometer which Sugg had designed to meet the difficulties, I had formerly pointed out in the Evanís photometer at Notting Hill as already related.

When the London County Council applied to Parliament in 1898 for powers to employ the portable photometer, expert evidence was given by Fairley, The public Analyst and a Gas Examiner at Leeds, my self and others. I had made a large number of tests of the light afforded by different burners when burning different quantities of gas of various quality and Fairley made comparison tests of the Calorific Power of the gases so used at the same time. Some of these were made in my laboratory at Westminster, where we made the gases required in my experimental gas plant and others at the Gas Works at Widnes Near Liverpool. Fairley and I stopped at Liverpool for a week. While there we had the pleasure of being shown over the Liverpool street lighting system by the corporation lighting and tramway superintendent Mr. Bellamy whose successful work in connection with street lighting caused the corporation to place him in charge of the Electric Tramways. He told us of the incident and his astonishment when the proposal was made. He told the committee that he knew nothing of tramways electricity; when they replied "Never mind that, we want a good man in charge. Go and get all the expert advice you want, but take the job in hand." On this understanding he did with complete success.

Amongst various experiences the testing of gas in out of the way places gave me some amusing incidents. I well remember having to test the calorific value of the gas at Carlisle on one occasion in a small bathroom with several officials looking on Ė close quarters indeed. On my return to town once with the complete set of photometric calorimetric apparatus, contained in some 6 or 7 boxes, large and small, just as there were deposited on the pavement outside my laboratory Dr. Dupre came by and seeing all the collection, exclaimed " Oh samples, wholesale and retail" . Sample to an analyst being the joy of his existence.

Amongst other work, I was rash enough to undertake an investigation for the Royal Society on Stellar Photometry with the special view of determining the intensity of the light of the stars in terms of a known terrestrial unit, viz: the standard candle.

In 1887 I had been presented with a "Teeford Premium" by the Institute of Civil Engineers for my paper on London Sewage, the Premium being in the form of a astronomical telescope and being a photometricist I naturally at once began to try and estimate the value of the light I looked at and devised for that purpose my series of stellar units. This I once showed to Mr Chaney the Supt. of the Weights and Measures Dept. of the Board of Trade who was so struck with it that he spoke of it to the Astronomer Royal who came to my laboratory to see it. The outcome was that the Royal Society gave me a grant which enabled me to build my observatory at Sutton and get the necessary apparatus. To save money I built the observatory myself often being at work on it at five oíclock in the morning and again in the evening and fitted up all the electrical plant. Although working under great difficulties, I succeeded in my main object and embodied the results in a paper contributed to the Royal Society in 1892. Illness however prevented my continuing the work in several directions I had contemplated and I found that the long succession of years of day and night working without holidays utterly unfitted me for continuing such heavy night work and I had to give up with great reluctance. However, I put in a fair amount of time and have ever since had the gratification arising from the experience and insight into matters astronomical. Few moments in our lives are sweeter than those which come to one in the quiet and still hours of the early morning when all humanity is asleep and the "music" of the spheres is a living voice speaking in silence as one may say, and successful work gives a sense of quiet satisfaction and happiness rarely attained during the bustling hours of daylight.

[ In 1892 W.J.Dibdin published, for the Royal Society, the results of the comparison of the candle power of twenty-one stars ranging to sixth magnitude and found the light of a second magnitude star equal to that of a candle at 1260ft. ]

In 1889 I published my book on "Practical Photometry", which was well received and in 1903 I edited the IVth volume of Churchillís Dictionary of Chemistry and wrote the section on Photometry. In 1902 I published my work on "Public Lighting etc" . These two volumes being in the press at the same time, to a great extent, which I found to be a great nuisance as I had to manage so as not to overlap more than absolutely necessary. When Churchillís asked me to edit their book I told them of "Public Lighting" they said it did now matter and would not interfere, so I went ahead.

 

Amongst other investigations I carried out a series of experiments about 1894 on the effect of the variation of strength of current on the light afforded by incandescent electric lamps for the London County Council, the results being embodied in a printed official report. These showed that a drop of 10% in the voltage caused a diminution of about 50% in the light and I pointed out the necessity for maintaining the intensity of the current up to a standard quite as much as for maintaining the illumination power of coal gas, for which purpose London maintains a staff of Gas Examiners etc., but no action was taken to protect the public in this, electricity evidently being the pet of the lighting family.