244 



NA TURE 



{July 30, 1874 



4. In my memoir " On the production of light by heat" (Phil. 

 Mag., May 1847), I established experimentally the following 

 facts : — 



(i) All solid substances and probably liquids become incan- 

 descent at the same temperature. 



(2) The thermometric point at which some substances become 

 red hot is about 977 Fahrenheit degrees. 



(3) The spectrum of an incandescent solid is continuous ; it 

 contains neither bright nor dark fixed lines. 



(4) From common temperatures nearly up to 977 F., the rays 

 emitted by a solid are invisible. At that temperature they are 

 red, and the heat of the incandescing body being made conti- 

 nuously to increase, other rays are added, increasing in refrangi- 

 bility as the temperature rises. 



(5) Whilst the addition of rays so much the more refrangible as 

 the temperatuie is higher is taking place, there is an augmenta- 

 tion in the intensity of those already existing. 



This memoir was published in both American and European 

 journals. An analysis of it was read in Italian before the Royal 

 Academy of Sciences at Naples, July 1847, by M. Melloni, 

 which was also translated into French and Knglish. 



Thirteen years subsequently M. Kirchhoff published his cele- 

 brated memoir "On the relations between the coefficients of 

 emission and absorption of bodies for light and heat." A trans- 

 lation of this memoir may be found in the Philosophical 

 Magazine, July 1S60. 



In this memoir, under the guise of mathematical deductions, 

 M. Kirchhoff, taking as his starting-point the condition discovered 

 by Angstrom in 1S54, respecting the relations between the 

 emitting and absorbing powers of different bodies for light and 

 heat, among other things deduces the following facts. I give 

 them as they are succinctly stated by M. Jamin in his " Cours 

 de Physique de I'ecole Polytechnique " {1869). 



(i) All bodies begin to be red-hot at the same moment in the 

 same space, and become white-hot at the same time. 



(2) Black bodies begin to emit red rays near 525 C. (977 F.) 



(3) The spectrum of solids and liquids is devoid of fixed lines. 



(4) The rays first emitted by black bodies are red ; to these 

 are added successively and continually other rays, increasing in 

 refrangibility as the temperature rises. 



In his celebrated memoir, and in subsequent publications on 

 the history of spectrum analysis, M. Kirchhoff abstains from 

 drawing attention to the coincidences I am here pointing out, 

 except that in a foot-note to his memoir he makes in a single 

 word aUusion to mine. But from this no one would infer what 

 were really the facts of the case, and accordingly in the biblio- 

 graphical lists subsequently published, in works on spectrum 

 analysis, such as those of Prof. Roscoe and Dr. Schellen, my 

 memoir is not noticed. 



I earnestly solicit those who take an interest in the history 

 of spectrum analysis to compare my memoir in the Philo- 

 sophical Magazine, May 1S47, with those published by M. 

 Kirchhoflf thirteen years subsequently, on the radiating and ab- 

 sorbing powers of bodies (Phil. Mag., July 1S60), and on the 

 history of spectrum a.ialysi3 (Phil. Mag., April 1S63). 



John William Draper 



University, New York, July 8 



Sounding and Sensitive Flames 

 In Nature, vol. x. p. 223, Prof. Ilerschel describes some ex- 

 periments recently made at the Newcastle College of Science, 

 whereby sonorous vibrations are produced in tubes by means of 

 heated wire-gauze instead of the ordinary gas llame. Interesting 

 as aie these experiments, they are, however, by no means new. 

 The iulluence of heated wire-gauze in giving rise to vibrations of 

 air within tubes was, I believe, first published by Prof. Rijke of 

 Leyden. In Kcenig's catalogue for i865,^ijke's tube is adver- 

 tised (No. 27) and the method of experiment described. The 

 readiest way of making the experiment is to cut a piece of the 

 ordinary fine iron-gauze to the size of a sixpence or shilling, and 

 press it some three inches up a glass tube of corresponding bore. 

 Almost any length of tube over one foot may be employed, so 

 that notes of varying pitch can be obtained. The gauze is easily 

 healed by a little alcohol llame at the end of a bit of qudl tubing. 

 Employing platinum-gauze heated by an electric current, or a 

 gas tlame resting above the gauze, the sounds can be rendered 

 permanent. By ore or otiier of these methods no doubt many 

 of your readers have, like myself, often repeated this experiment 

 during the last six or seven years. 



I notice also that Prof. Herschel has kindly attributed to me 

 a modification of the ordinary sensitive flame ; the credit of this 

 belongs to Mr. P. Barry, of Cork. This arrangement simply 

 consists of a sensitive flame burning on wire gauze, instead o 

 directly from the gas jet. It was described in Nature, vol. v. 

 p. 30, and some further experiments on this kind of flame are 

 to be found in the journal of the Franklin Institute for April 

 1872. 



Perhaps it is not out of place to add here that when a sensitive 

 flame under the influence of sound is viewed in a moving mirror, 

 the state of its vibration, thus seen, reveals some interesting 

 facts. Under such circumstances, the flame is capable of show- 

 ing the nature of the different vowel sounds, and further, by the 

 broken appearance of the flame one is able to detect sonorous 

 vibrations too faint to be heard and too feeble otherwise to affect 

 the flame. I have given a representation of the flame seen in a 

 moving mirror on the plate appended to an article in the Popular 

 Science Rciino {ox h^x\\ 1S67. The flame that is most suited 

 for the vowel experiments happens to be the parent of the family 

 of sensitive flames, and is described in a little paper of mine in 

 the Philosophical Magazine for March 1867. 



W. F. Barrett 



Science Schools, South Kensington, July 27 



Aid to Private Research — Circulation of Scientific 

 Memoirs 



There are many scientific students scattered through the 

 country, as science-masters in schools, and in other capacities, 

 who are willing and competent to undertake original researches 

 in their special branches of science. The great obstacle to their 

 attempting it is, in most cases, the cost of the necessary instru- 

 ments. It is of course impossible to e.xpect such apparatus 

 as is required for original work to be supplied from the 

 science lunds of a school, these being properly applied 

 to provide only what is requisite for teaching the pupils ; 

 so that if an investigation is to be attempted, the whole 

 cost falls upon one who is probably just beginning life, and 

 is quite unable to afford it. The work is therefore postponed 

 for a considerable period, and perhaps is given up altogether. 

 Now the Department of Science and Art grants aid in fitting up 

 the schools which are under its control. If the Department 

 would give similar aid towards purchasing expensive apparatus for 

 research, or would allow competent workers to hire such instru- 

 ments for the period they require them, much of the difficulty to 

 which I have alluded would be removed. Many, I am sure, would 

 be glad to avail themselves of the opportunity, and would willingly 

 fulfil the conditions necessary to ensure the safety and proper use 

 of the apparatus. I may remark that by this means it would 

 probably be easy to organise to a certain extent the investigations 

 to be carried on, and thus render the results far more valuable 

 than they would be if isolated. Looking to the national import- 

 ance and the unremunerative character of this kind of work, few 

 will think that this appeal is exorbitant. 



I wish to allude to another point, to which attention has 

 already been drawn in your correspondence columns (Nature, 

 vol. viii. pp. 506, 550). A scientific man, unless he is fortunate 

 enough to be within easy distance of a large scientific library, 

 is practically debarred Irom reading even the most valuable 

 memoirs that are pubhshed. Abstracts, indeed, he may see ; 

 but these only serve to remind him that if he would get the 

 original memoir for himself, he must purchase with it matter 

 which is useless to him, but perhaps of the highest value to a 

 worker in another branch. If these memoirs could be purchased 

 in a separate form — or even if collections of papers bearing upon 

 closely related subjects could be obtained — another cause of the 

 costliness of science would be removed. 



It has occurred to me that something ought to be done 

 amongst ourselves to remedy our position as regards the transac- 

 tions of the learned societies and the scientific periodicals. Could 

 not a book-club be instituted, the membere of which, upon paying 

 a sm.aU annual subscription, should receive in turn the chief scien- 

 tific periodicals? Or would it be more easy (or a number of us 

 who happen to take in different journals, to exchange them ? 

 If any of your readers should be inclined to co-operate with me 

 in initiating either of these schemes, or to furnish any suggestions 

 on the subject, I should be glad if he would communicate with 



Sherborne, Dorset, July 1 1 



H. W. Lloyd Tanner 



