The New Bishop's Ring

REGARDING M. Forel's suggestion (see NATURE, p. 396) that persons ascending to considerable altitudes should observe whether the ring around the sun, which was so noticeable a phenomenon after the diffusion of the volcanic dust from the Krakatoa eruption in 1883, is again visible, I beg to say that, before reading his letter in La Gazette de Lausanne , I had noted the ring on August 20 from the Montanvert, near Chamonix, at an altitude of 6300 feet. The day was exceptionally clear, and when a peak hid the sun itself, the whitish glare fringed with reddish brown that surrounded it attracted my attention. Being upon the summit of Mont Blanc (15,780 feet) on September 1, in clear weather, I again Observed the ring, which, however, was no better defined than lower down on the mountain, notwithstanding the circumstance that the dark blue sky furnished an excellent background. Angular measurements there showed that the radius of the visible outer limit of the reddish ring was between 20° and 25°.