Gabriel Loppé was recorded to have sketched on the summit of Mont Blanc on at least eleven separate occasions but his ‘sunset’ ascent of 1873 ranks as one of his most intrepid painting expeditions. This hitherto unpublished oil study is the companion picture to his Coucher de soleil au sommet du Mont Blanc which belongs to the Amis du vieux Chamonix <FIG 2>. It depicts the sun setting beyond the Aiguille du Gouter. In 1894, in the introduction to one of the best known and loved books about the Alps, The Playground of Europe, Leslie Stephen wrote a dedication to Loppé:

My Dear Loppé,
Twenty-one years ago, we climbed Mont Blanc together to watch the sunset from its summit. Less than a year ago, we observed the same phenomenon from the foot of the mountain. The intervening years have probably made little difference in the sunset. If they have made some difference in our powers of reaching the best point of view, they have, I hope, diminished neither our admiration of such spectacles, nor our pleasure in each other’s companionship. If, indeed, I have retained my love of the Alps, it has been in no small degree owing to you

Seen from their summits, almost all mountain shadows look triangular regardless of the peak’s shape. This is caused by the perspective of looking along a long tunnel of shadowed air. The tunnel’s cross section is the shape of the mountain but its end is so far away that it looks insignificant. The finite size of the sun causes the fully shaded parts of the shadow to converge and taper away, and in Mont Blanc’s case, this is over a distance of two to three hundred miles. As Loppé painted this remarkable meteorological scene at 7.30 in the evening, from 4,810 metres up, the temperature would have begun to plummet to around -15 degrees Celsius. His climbing companions became concerned for their safety as recounted in The Playground of Europe’s chapter XI entitled, Sunset on Mont Blanc:

I had frequently wondered how that glorious spectacle would look from the solitary top of the monarch himself. This summer I was fortunate enough, owing to the judicious arrangements of one of his most famous courtiers-my old friend and comrade M. Gabriel Loppé to be able to give an answer founded on personal experience. The result was to me so interesting that I shall venture- rash as the attempt may be- to give some account of a phenomenon of extraordinary beauty which has hitherto been witnessed by not more than some half-dozen human beings.

It was in the early morning of August 6, 1873 that I left Chamonix for the purpose. Carefully calculating our time we advanced along the dromedary’s hump and stepped upon the culminating ridge of the mountain about an hour before sunset. We had time to collect ourselves to awake our powers of observation and to prepare for the grand spectacle for which preparations were already being made. There had been rehearsals enough to secure a perfect performance. For millions of ages the lamps had been lighted and the transparencies had been shown with no human eye to observe or hand to applaud. Twice, I believe only twice, before, an audience had taken its place in this lofty gallery; but on at least one of those occasions the observers had been too unwell to do justice to the spectacle.

And now we waited eagerly for the performance to commence; the cold was sufficient to freeze the wine in our bottles, but in still air the cold is but little felt and by walking briskly up and down and adopting the gymnastic exercise in which the London cabman delights in cold weather, we were able to keep up a sufficient degree of circulation. I say ‘we’ but I am libelling the most enthusiastic member of the party. Loppé sat resolutely on the snow; superior as it appeared to all the frailties which beset the human frame suddenly plunged into a temperature I know not how many degrees below freezing-point He worked with ever increasing fury in a desperate attempt to fix upon canvas some of the magic beauties of the scene.

- William Mitchell, Peaks & Glaciers 2019