June 1 6, 1881] 



NATURE 



153 



My trust is that lor the future India will throw great hght 

 upon the problem we are njw discuising. We have a distin- 

 guished meteorologist, Geaeral Strachey, as member of the 

 Council of India, we have General Walker and the trigono- 

 metrical survey staff, and we have Mr. Blandford and the various 

 meteorological and magnetic observers of India, and I am glad to 

 think that neither solar nor actiuometric observations are likely 

 t J be forgotten. 



Let me now briefly recapitulate the conclusioas we have 

 cjme to. 



In my first lecture I endeavoured to bring before you theo- 

 retical grounds for imagining that the sua is most powerful when 

 there are most spots on its surface. 



This has been supported by the evidence of a meteorological 

 nature derived from these observations of rainfall, wind, baro- 

 metric pressure, and temperature which have now beendi-cussed, 

 and likewise from such actinometric observations as have been 

 made in Mussorree and Dehra. With regard to magnetical 

 observations, we have the fact that diurnal declination ranges 

 are largest in times of maximum sun-spots, and that on such 

 occasions we have likewise a great number of magnetic storms, 

 accompanied with earth currents and displays of the aurora. In 

 fi.ie we have m^st magnetic activity when there are most spots. 

 There may perhaps be some doubt as to the exact method by 

 which solar phenomena affect the magnetism of the earth, but 

 we have already hypotheses from two distinguished physicists, 

 the late Prof. Faraday and Prof. Stoke.-, while others have 

 ld;e*ise been engaged in similar speculations. 



Thus we may hope that even'ually the truth will be attained. 

 Meanwhile however we may conclude that the earth is most 

 active both meteorologically and magnetically when there are 

 most spots on the .sun's surf.ice. And if this be so, who will say 

 tliat this is not a problem of great practical as well as of great 

 thjoretical importance ? 



ON GAS SUPPLY BOTH FOR HEATING AND 



ILL UMINA TING P URPOSES ' 

 "\A/'HEN, within the memory of living men, the gas-burner 

 took the place of the time-honoured oil-lamp, the improve- 

 ment, both as regards the brilliancy of the light and the con- 

 venience of the user, was so gieat that the ultimate condiiion of 

 perfection appeared to have been reached. Nothing apparently 

 remained for the engineer to effect but improvements in the 

 details of the works and apparatus, so that this great boon of 

 modern times might be utilised to the largest extent. It is 

 only in recent years that much attention has been bestowed 

 upon the utili,ation of by-products, with a view of cheapen- 

 ing the cost of production of the gas, and that the con- 

 sumer has become alive to the importance of having a gas of 

 high illuminating ])OH-er and free frim nauseous constituents, 

 such as bisulphide of carbon, thus providing a gentle stimulant 

 for steady progress on the part of the gas- works manager. 



This condition of steadiness and comfort has been somewhat 

 rndely shaken by the introduction within the last year or two of 

 the electric light, which, owing to its greater brilliancy and 

 cheapness, threatens to do for gas what gas did fir oil half a 

 century before. The lighting of the City of London and of 

 many public halls and works furnishes indisputable proof that 

 the electric light is not an imaginary, but a real and formidable 

 competitor to gas as an illuminant, and it is indeed time for gas 

 engineers and managers to look seriously to then- position with 

 regard to this new rival ; to decide vAhether to meet it as a foe, 

 and contest its progress inch by inch, or to accept at once the 

 new condition of things, conceding the ground that cannot rea- 

 sjnably be maintained, and to look about in search of such 

 compensating fields as may be discovered for a continuation or 

 extension of their labours. 



For my own part I present myself before you both as a rival 

 and as a friend ; as a rival, because I am one of the promoters 

 of electric illumination, and as a friend, because I have advocated 

 and extended the use of gas for heating purposes during the last 

 twenty years, and am by no means dis. osed to relinquish my 

 advocacy of gis both a-, an illuminating and as a heating agent. 

 Speaking as a gas engineer, I should be rather disposed to regard 

 the electric light as a welcome incentive to fre^h exertion, con- 

 fidently anticipating achievements by the use of gas which would 

 probably have been long postponed under the continued rt'^me 



' Paper read before tlie British Association of Gas Mana>rers at Birminff- 

 ham, Jtme 14, by C. W. Siemens, D.C.L,, F.R,S., Civil Engineer, 



of a monopoly. Already we observe, both in our thorough- 

 fares and in our apartments, gas-burners producing a brighter 

 and more powerful light than was to be seen previously ; and 

 although gas w ill have to yield to the electric light the illumina- 

 tion of our lighthouses, halls, and great thoroughfares, it will be 

 in a position, I believe, to hold its own as a domestic illuminant, 

 owing to its great convenie.ice of usage, and to the facility with 

 which it can be subdivided and reguLited. The loss which it is 

 likely to sustain in large appliances as an illuminant would be 

 more than c jm]5ensated by its use as a heating agent, to which 

 the attention of both the producer and the consumer has latterly 

 been largely directed. 



Having in the development of the regenerative gas-furnace 

 had exceptional opportunities of recognising the many advantages 

 of gaseous over .solid fuel, I ventured, as early as 1863, to propose 

 to the Town Council of Birmingham the estalilishment of works 

 for the distribution of heating gas throughout the town, and it has 

 occurred to me to take thi^ opportunity (when the gas managers 

 of Great Britain hold their annual meeting at the very jJace of 

 my early proposal) to place before them the idea that then guided 

 me, and to suggest a plan of operation for its realisation which 

 at the present day will not, I venture to hope, be regarded by 

 them as Utopian. The proposal of 1863 consisted in the esta- 

 blishment of separate mains for the distri'jution of heating gas, 

 to be produced in vertical retorts, that might be shortly described 

 as Ap;iold's coke oven heated by means of " producer " gas and 

 "regenerators." The heat of the retorts was to be increased 

 beyond the ordinary Unit in order to produce a coke suitable for 

 locomotive antl other purpo.es; and the ga- jiroduced being 

 possessed of less illuminating but of the same heating power, 

 and being, v\ ith a view to cheapness, less thoroughly purified than 

 ordinary retort gas, was to be distributed through the town as a 

 heating agent, to be applied to the small boilers and furnaces of 

 the numerous little factories peculiar to the district, as well as 

 for domestic purposes. The Corporation applied for an Act of 

 Parliament, but did not succeed in obtaining it, owing to the 

 opposition of the existing gas companies, whi pledged them- 

 selves to carry out such an undertaliing if found feasible by 

 them. I am ready to admit that at the time in question the suc- 

 cess of the undertaking would have involved considerable prac- 

 tical difticulty, but I feel confident that the moJified plan which 

 it i, my present object to bring before you w m'd reduce those 

 difticultie-. to a minimum, and open out on the other hand a new 

 field of vast proportions for the enterprise and energy of those 

 intere.-^ted in gas-works, and of great benefit to the public. 



The gas-retort would be the same a^ at present, and the only 

 change I would advocate in the benches is the use of the re- 

 generative gas-furnace. This was fir-t successfully introduced 

 by me at the Paris Gas-works in 1863, and has since found 

 favour with the managers of gas-works abroad and in this 

 country. The advantages that have been proved in favour of 

 this mode of heating are ecmomy of fuel, greater durability of 

 retorts, owing to the more perfect distribution of heat, the intro- 

 duction of an additional retort in each bed in the position pre- 

 viou-ly occupied by the fire-grate, and above all, a more rapid 

 di^tillation of the coal, resulting in charges of four hours each, 

 whereas six hours are necessary under the ordinary mode of 

 firing. The additional suggestion I have now to make consists 

 iu providing over each bench of retorts two collecting pipes, the 

 one being set a^ide for illuminating, and the other for a separate 

 service of healing gas. I shall be able to prove to you from 

 unimpeachable evidence that the gas coming from a retort varies 

 very greatly in its character during progre-sive periods of the 

 charge ; that during the first quai-fer of an hour after closi ig the 

 retort, the gas given off consists principally of marsh gas {CH4) 

 and other occluded gases and vapour-, which are of little or no 

 u e for illuminating purposes ; from the end of the first quarter 

 of an hour, for a period of two hours, rich hydrocarbons, such 

 as acetylene (CJI;) aid olcfiant gas (CjHj) are given off; 

 whereas the gases passing away after thii c msist for the most 

 part again of marsh gas possessing low illumi lating power. 



M. EUissen, the late chief of the experimental department of 

 the Paris Gas-works, and actual President of the French Society 

 of Gas Engineers, has favoured me with the result of a most 

 interesting series of experiments, which he carried out in connec- 

 tion with the late M. Regnault, the eminent physicist, some 

 years ago, the object of the experiments being to discover the 

 prijier period of time to be allowed for each charge. 



The results of these experiinents are given in a diagram 

 showing in a striking manner that although the average illu- 



