To Gustav Magnus¹

My dear Magnus,—Though science is sure to be the gainer from our working independently at the same subject, it is not quite agreeable to find one’s own personal claims interfering with those of a valued friend. My simple course, however, is to lay before you a brief statement of the circumstances attending the investigation of the mutual action of gases and radiant heat, feeling assured that you will draw just conclusions from the statement.

It is several years since the thought of examining the absorption of radiant heat by gases first occurred to me, but until the early part of 1859 I was so much occupied with other matters that I could not turn my attention specifically to it. In 1859 I reflected a good deal on the question, made many experiments, devised new methods, and, after some weeks of successful work, communicated in a note to the Royal Society² the mode of experiment and the general character of the results. This note, which was written with the express intention of setting my mind at rest as to the possible claims of other investigators, is published in the ‘Proceedings’ of the Society for May 26, 1859. I saw clearly that the subject would occupy me for several years. A new and vast field had in fact been laid open to experiment, and having by thought and labour fairly mastered it and obtained definite results, I felt at liberty to cultivate it calmly and quietly without fear of being interfered with by anybody. In the note referred to I state distinctly that the investigation is in progress, a full account of it at a future day being promised to the Royal Society.

I continued to work; and on June 10, 1859, gave a Friday evening discourse on the subject³ before the members of the Royal Institution. The Prince Consort⁴ was in the chair; and by throwing the image of the dial of my galvanometer upon a screen, I succeeded in making the experiments on the radiation and absorption of heat by gases and vapours visible to an assembly of many hundred persons. A report of the Lecture is published in the ‘Proceedings of the Royal Institution’ for June 10, 1859.

You tell me that you had overlooked the notice in the ‘Proceedings of the Royal Society,’ and that Clausius was the first to inform you in October 1860 of my being engaged in experiments on the radiation of heat through gases. I, on the other hand, did not neglect to give my results due publicity. They were communicated to De la Rive in a letter published in the ‘Bibliothèque universelle’ for July 1859, vol. v. page 232. My lecture of the 10^th of June was also reproduced in ‘Cosmos,’ vol. xv. page 321, where you will find the following words: —‘Ces recherches de M. Tyndall sont encore à leur début, il les continuera avec ardeur; déjà il a perfectionné sa mode d’expérimentation. Il emploie un galvanomètre d’un seul fil, avec deuz sources de chaleur aggissant sur les deux faces d’une meme pile,’ &c. You will also find the subject referred to in the ‘Nuovo Cimento,’ vol. x. p. 196. Also in the ‘Comptes-rendus,’ and in other journals.⁵ When I was in Paris in 1859, my experiments formed a common topic of conversation among scientific men. Foucault, Jamin,⁶ Moigno,⁷ Wertheim⁸ and others, spoke to me about them. In fact they aroused an amount of attention far greater than I had any reason to expect.

In London it was known to everybody that I was engaged on this question; Hofmann,⁹ Williamson,¹⁰ and Frankland can all call to mind my obtaining volatile liquids from them in 1859. Faraday also recollects how often I have expressed to him my satisfaction that a new field had been opened which I might cultivate at my leisure without fear of interfering with the claims of anybody. In 1859 I had measured the absorption of oxygen, hydrogen, nitrogen, air, carbonic oxide, carbonic acid, nitrous oxide, coal gas, and olefiant gas; and I had also determined the absorption produced by the vapours of the following substances: —bisulphide and bichloride of carbon, sulphuric ether, cyanide of ethyl, chloroform, benzol, methylic alcohol, amylene, iodide of ethyl, acetate of ethyl, propionate of ethyl, formate of ethyl, iodide of amyl, chloride of amyl, ethylic ether, ethyl amylic ether, amylic alcohol, absolute alcohol, and others. In fact in 1859 I had the materials for an elaborate memoir on this subject already in my hands.

You say that I had not examined ammonia even in 1860. The fact, however is that early in 1859 I had examined it and established its great absorptive power. If you will cast your eye on my letter to De la Rive¹¹ published in the ‘Bibliothèque universelle’ for July 1859, you will see that ammonia did not escape me.

Two circumstances offered a direct hindrance to the working out of my results in 1859: the first was the desire to get the ‘Glaciers of the Alps’ off my hands; the second was a sudden call to undertake the duties of Professor at the School of Mines.¹² I resumed my experiments in 1860, and you will find a general statement of my results at pp. 244–5 of the ‘Glaciers of the Alps,’ a copy of which I had the pleasure of forwarding to Mrs. Magnus.¹³ Referring to the preface to that work, you will see that it was published in June 1860; and the preface was written several months subsequently to the pages above referred to. In fact the experimental notes now before me would satisfy you that in June 1859 I had obtained, in a substantially correct form, almost all the results of which you first heard in October 1860, and which you suppose I did not obtain until the November of that year.

Believe me ever yours faithfully, | John Tyndall

J. Tyndall, Contributions to Molecular Physics in the Domain of Radiant Heat (London: Longman’s, Green, & Co., 1872): pp. 61–3.