On account of the extreme cold, the life on Saturn is still more disagreeable than that on Jupiter. If the Saturnians were brought to the Earth they would certainly die of heat even in Lapland. If the water on Saturn is of the same nature as ours, it must look like our polished stones, and spirits of wine must resemble diamond. In consequence the inhabitants of Saturn cannot but be slow and phlegmatic; they know no gaiety and remain like oysters in the place they were born in. Fontenelle continues in this way without attaining any depth, under the impression that our planet is the type of the universe. Let us now pass to the nineteenth century. Graithuisen, the Director of the Munich Observatory, published his chief works in the first thirty years of this century. His researches relative to the habitability of the planets were, therefore, made at an epoch when we already possessed important data on their physical constitution, an epoch when, thanks to the work of Bessel, the golden period of astronomy had already begun. One may therefore take it that the work of Graithuisen marks a real progress beyond his predecessors, as indeed he says himself without ceremony. But as a matter of fact he is rather fruitless, as is shown by the strange manner in which he deals with the earth-light on Venus. He already knew of the phenomenon, which is insufficiently explained even in our day, that during the phases of greatest visibility of Venus the dark side appears to have a faint luminosity. “The simplest explanation to give of this,” he says, “is that at the epochs when this faint light on Venus is visible, the inhabitants of the planet organise festivals and general illuminations, which are the easier to arrange on account of the vegetations of Venus being incomparably more luxuriant than even the virgin forests of Brazil. These festivals are probably celebrated on the occasion of political changes or according to religious periods. Now, the principal observations of the ashen light on Venus are those of Mayer in 1759 and of Harding in 1806.” Whence he draws the following conclusion: “Between the observation of Mayer and that of Harding 76 years of Venus and 47 Earth years have elapsed. If this period has a religious character, we cannot see a justification for that number of years, but it becomes more comprehensible if we assume that some Alexander or Napoleon then attained universal power. If we assume that the ordinary life of an inhabitant of Venus lasts 130 years of Venus, which amount to 80 terrestrial years, the reign of such an autocrat could easily last 76 years as reckoned on Venus. I have no intention to press this opinion and do not claim its credibility, even should it appeal to the reader’s imagination; but if my hypothesis is correct, we at least receive direct testimony to the existence of inhabitants on Venus. Even if the period were shorter, the phenomenon might still be due to some other observance. One could celebrate all