448 



NATURE 



[March 22, 1877 



like a compound body. It would seem from this and other 

 remarks, that, from a spectroscopic point of view at least, 

 they consider an element to be not only a body which cannot be 

 decomposed into two different bodies, but a body which cannot 

 be resolved into any simpler molecular state. I have no objec- 

 tion against this if it is always clearly understood that our authors 

 include allotropic states under the denomination of compounds. 

 For instance, they lay great stress on the fact that a spectrum of 

 fluted bands is always characteristic of a compound body. Ac- 

 cording to their definition of a compound this is perfectly correct, 

 for no doubt the band spectrum belongs to a more complicated 

 molecular state, but they cannot bring this argument forward as 

 tending to show that Swan's spectrum of the candle belongs to 

 a hydrocarbon, or that the fluted spectrum of nitrogen belongs 

 to an oxide of nitrogen. The fact simply means that the mole- 

 cule which gives these band spectra is to the molecule which 

 gives the line spectra as the molecule which gives the absorp- 

 tion bands of iodine is to the molecule which gives the lines of 

 iodine. 



There is no doubt that we must be exceedingly careful, espe- 

 cially working with Geissler's tubes, not to ascribe to an element 

 a spectrum which really belongs to a combination of that element 

 with some other body present. The question what spectra an 

 element really has must be settled in each individual case by 

 careful experiments. Let us examine the two examples chosen 

 by Messrs. Angstrom and Thalen. The first is carbon. Watts 

 has already shown that the spectrum marked by him originally 

 No. 2, really belongs to an oxide of carbon. The only spectrum 

 under discussion is therefore Swan's spectrum of the candle. 

 On this point Attfield's experiments are entirely conclusive. 

 They have been amply confirmed by Watts and others. I take 

 one case out of many. The flame of dry cyanogen gas shows 

 the same spectrum brilliantly. The onus of the proof that a 

 hydrocarbon can here be present lies entirely with those who 

 make that assertion. Messrs. Thalen and Angstrom in the pre- 

 sent paper assert that this spectrum is due to acetylene. In 

 the year 1871 Prof. Angstrom published a paper, in which he 

 tried to show that Wiillner's second spectrum of hydrogen really 

 belongs to acetylene. Other experimenters have confirmed this 

 fact. In order to escape admitting that carbon has two spectra, 

 Messrs. Angstrom and Thalen are forced therefore to assume th it 

 acetylene has two spectra. 



The chief object of this letter is to say a few words on the 

 spectrum of nitrogen. In the year 1872 I published a paper in 

 which I gave an experiment tending to show that the band 

 spectrum of nitrogen really belongs to an oxide of nitrogen. The 

 experiment was this : Clean pieces of sodium were heated in a 

 tube containing nitrogen ; the band spectrum then disappeared, 

 and another spectrum came out, which I then thought to be 

 identical with the lines of nitrogen. The experiments were re- 

 peated by Stearne and Wiillner ; they also found that the bands 

 disappeared, but the lines of nitrogen did not come out. I con- 

 vinced myself that what I had seen was not the line spectrum of 

 nitrogen, but the disappearance of the bands alone seemed to me 

 to be an object of further investigation. Mr. Salet at last gave a full 

 and correct explanation of the experiment. Nitrogen is absorbed 

 by sodium under the influence of the electric spark, and the lines 

 I had seen were the lines of sodium. As Mr. Salet has shown, 

 my measurements agree belter with the lines of sodium than 

 with the lines of nitrogen. The bands of nitrogen remained if 

 care was taken that the spark did not touch the sodium. 

 If I have refrained hitherto from acknowledging the justice of 

 Mr. Salet's conclusions, it is only due to the fact that I felt a 

 natural curiosity to repeat his experiments ; I have not yet been 

 able to do so, but I have no doubt what the result would be. 

 Mr. Salet's paper was only published after Prof Angstrom's 

 death, and I cannot help thinking that the professor would have 

 considered his experiments conclusive aj^ainst the assumption 

 that the bands of nitrogen are due to an oxide of nitrogen. The 

 only argument which Messrs. Angstrom and Thalen brmg for- 

 ward to support their theory is that in a tube containing rarefied 

 air which showed the bands of nitrogen when the spark pas-ed, 

 nitric oxide was formed. But surely nitrous acid fumes are pro- 

 duced by sparks showing the line spectrum of nitrogen. Ozone 

 is formed by sparks giving the lines of oxygen, yet we do not 

 conclude that the line spectra of nitrogen and oxygen are due to 

 nitrous acid and ozone. 



If anyone still beheves that an element can only have one 

 spectrum at the temperature of the electric spark, I propose to 

 him the following problem : — Let him take the three gases, car- 

 bonic acid, aceiylene, and oxygen. If he investigates their 



spectra carefully he will at least find ten different spectra (two of 

 them I only discovered lately). Out of carbonic acid alone he can 

 obtain six. Let him find a sufficient number of possible com- 

 pounds to account for all these spectra. Arthur Schuster 



The Annual Parliamentary Grant for Meteorology 



The Meteorological Department of the Board of Trade was, 

 as is well known, constituted by Government in 1856 with the 

 object of collecting and discussing facts and observations too 

 numerous to be collected and discussed by private persons. The 

 Department continued for ten years under the sole direction of 

 Admiral Fitzroy, who, by his self-denying exertions and en- 

 thusiasm, and a genius for developing meteorology in certain of 

 its practical applications, gave a great and withal healthy im- 

 petus to a sound study of the laws of weather. 



In consequence of the recommendations of a committee of 

 inquiry appointed after Admiral Fitzroy's death to review the 

 results of the labours of the department, its control was trans- 

 ferred to a Committee of the Royal Society, who, in return for 

 an annual grant of 10,000/., agreed to carry out the duties con- 

 nected with the office. The Committee were left perfectly free 

 in their method and in their choice of labour, the only condition 

 attached to the grant being that an annual account be rendered 

 to Parliament of the expenditure and of the results obtained in 

 each year. 



The support of the public was freely given to the Committee 

 in the work they had undertaken, but in the course of a few 

 years an opinion took root and gradually extended to the effect 

 that the methods of inquiry adopted by the Committee and the 

 work of the Meteorological Office were so seriously faulty as to 

 call for inquiry. To some of these points attention was drawn 

 in Nature (vol. xii. p. loi), your criticism being limited to 

 little more than the baldest statement of facts, which anyone 

 could easily examine for himself, a criticism which, so far as we 

 are aware, still remains unanswered. 



Upwards of a year ago the Lords of 11. M. Treasury, seeing 

 that the Meteorological Committee had received nearly 100,000/., 

 considered that the time had arrived for an inquiry, the grant 

 being so considerable that they did not think they could be justi- 

 fied in continuing it for any lengthened period without satisfying 

 themselves that the results obtained were such as to warrant the 

 application of so large a sum of public money. A Treasury 

 Commission was accordingly appointed on November 2, 1875, 

 to inquire into the work of the Meteorological Committee, par- 

 ticularly that portion of it referring to storm- warnings ; and, in the 

 event of their deciding to recommend the continuance of the 

 grant, to consider further upon what system it may be best ad- 

 ministered. In connection with the latter part of the inquiry the 

 Lords of the Treasury gave expression to their wish that the 

 claims of the Scottish Meteorological Society for aid from the 

 State should receive the consideration of the Commission. The 

 Commission consisted of Sir W. Stirling Maxwell, Chairman, 

 Mr. Brassey, M.P., Mr. Lingen, permanent Secretary of the 

 Treasury, Mr. Farrer, permanent Secretary of the Board of 

 Trade, Dr. Hooker, President of the Royal Society, Mr. F. 

 Galton, and Gen. Strachey. Considering the many scientific 

 questions of a strictly technical character which were to be dealt 

 with, it is to be regretted that such names as Sir G. B. Air^ 

 and Prof Balfour Stewart were not placed on the Commission ; 

 an ! it was perhaps unfortunate that Mr. Galton and Gen. Strachey 

 were on it, seeing that they were also members of the Meteoro- 

 logical Committee whose work was to be inquired into by the 

 Commission. The name of Mr. Milne Home, chairman of the 

 Council of the Scottish Meteorological Society, was on November 

 29 added to the Commission. 



On looking over the Report of the Commission, I am sur- 

 prised to find an inattention to several important matters remitted 

 to them by the Treasury. I do not find, for instance, that the 

 methods adopted by the Meteorological Committee for the obser- 

 vation of the temperature of the British Isles, to which serious 

 objection has been taken, and the character of the work of the 

 office, to which also serious objections have been made, have 

 been inquired into ; and I find that the consideration of the 

 claims of the Scottish Meteorological Society for aid from the 

 State have been all but ignored in the Report of the Com- 

 mission. 



Passing on, however, to the recoihmendations or the Report 

 we find that it recommends that the annual grant be increased 

 from 10,000/. to 14,500/. ; that, at least provisionally, some 

 a-siitance b; given to the Scottish Meteorological Society ; that 



