John Tyndall to Faraday   15 August 1857

Chamouni, July [sic] 15th, 1857.

My dear Mr. Faraday,

I felt very thankful to you for your letter¹, which quite connected me with the life of London by making me acquainted with what was going on there. I am at present seated in the house of my guide at Chamouni, with Huxley seated at the opposite end of the table at which I write. Last Sunday and Monday the rain descended heavily at the Montanvert, and snow fell upon the higher elevations. Yesterday (Friday) clouds collected around the summit of Mont Blanc, and thunder was the harbinger of heavy rain, which has continued incessantly all this day. I have thus noticed two rainy termini, between which however a sunny interval stretched, a fine clear day and a fine moonlight night, and in this interval it was my fortune, or doom, to make an attempt upon the “Monarch of Mountains”, wishing to learn something from it if possible. Accompanied by a single guide, the best part of whose valour was discretion, my friend Hirst and myself set out from the Grand Mulets at 2 o/c. on Thursday morning, and after 14 hours toil reached the summit of Mont Blanc, made some experiments upon the snow, fired a little extempore cannon, and pledged a toast to some of our absent friends. I thought you would not object to your name being linked with that of Saussure, so I pledged you both together, for to say the truth, my quantity of beverage was too scanty to afford a separate bumper to each. I had also the pleasure of carving Mrs. Faraday’s name and those of two or three other ladies upon the atmosphere at that high elevation. Our return to the Grand Mulets occupied upwards of three hours, making the excursion, from this point to the summit and back to the Mulets again, 17 hours in all. It is usually accomplished in 10. But the snow presented a fearful obstacle to our progress; we had to wade through it for hours knee deep, and sometimes actually up to the hips. The toil was excessive, and we reached the Grand Mulets just in time to prevent the peril of darkness from being added to the peril of the crevasses which beset us. Standing upon a rock in the midst of the ice and snow on Wednesday night, I noticed a singular effect of star twinkling which you have probably observed, but which was quite new to me. Supposing this to represent the Great Bear, a line drawn through the two stars a,b, and produced, cut a bright star at c. This star I noticed changed its colour incessantly, sometimes it was a bright red and the next instant it changed to a vivid green. In some cases the succession from one colour to the other was very rapid, but in others the colour remained constant for several seconds. I called Huxley’s attention to it, and he saw the green and red at exactly the same times as I did. I had also the corroborative testimony of my friend Hirst, who was with me. When Hirst and I were wandering up the ice slopes by moonlight a few hours afterwards, he noticed that the self same star, which had approached the zenith, had ceased to twinkle. Probably all this contains nothing new to you, but the vividness of the colours was to me extremely remarkable. I suppose everybody must have observed the influence of the position of a star upon its twinkling. In the squares and parks of London I have often noticed that stars near the horizon twinkled powerfully, while those in the zenith shone with an almost steady light; I think you once mentioned to me that you had observed this yourself.

Since I wrote to you last², I have been hard at work on the glacier; but the problem is a large one, and it is only now that I am commencing to feel some mastery over the particular form under which it presents itself here. It is always so. It requires long pondering and experiment before I can seize anything with clearness, and I am often disposed to consider myself a very slow coach. But I suppose I must be content with the conditions under which Nature grants me insight, and not repine because I do not possess the quick flashing intellect of other men. Since I last wrote to you I also made the ascent of the Col du Géant, with no guide, but with a little boy, who can climb well, for my companion. Neither of us knew anything of the route; and we found ourselves during part of the time surrounded by considerable perils. We succeeded however in reaching the summit, and in returning to the Montanvert without a single broken bone. The pass is, I believe, considered to be one of the most perilous in the Alps. In this way, by refusing to conform to the rules of the guides, and claiming from the Guide Chef the liberty which ought to be granted to a scientific observer, I have been able to accomplish very heavy excursions for about the tenth part of the ordinary expense.

But my work here is drawing to a close simply through the exhaustion of my funds, so I hope to be in London in about 10 or 12 days from the present time. You would oblige me by asking Anderson not to forward me any letters after the date on which this reaches you. I hope to find Mrs. Faraday and Miss Barnard and yourself well and happy on my return. I am in capital health: burnt brown as an Indian. My guide and friend are both almost blind from ophthalmia produced by the glare of the snow, but this I have escaped, and should have been hard at work today if the weather had permitted it.

With best wishes, | Believe me always, | Most sincerely yours, | J. Tyndall.