4. Note on the Zodiacal Light

Extract

A peculiarity was observed about the vernal equinox in 1871 in the shape of the zodiacal light, which deserves to be recorded. The appearance resembled a thin cone (such as is usually seen), extending to a great height, and-rising out of a broad low cone situated at its base. This was not an effect of sunlight, for it was visible hours after sunset. It was not peculiar to any time or place, for it was seen constantly in all parts of the south of Europe, viz., in the Bay of Biscay, all along the Mediterranean, in Malta, and in Sicily. It seems not unlikely that there are periodic changes in the appearance of the zodiacal light. Hence it is well to mention any such peculiarity. I have also to confirm what has so often been stated by other observers, that the direction of the axis of the cone is not always in the direction of the ecliptic, but changes its direction from night to night.