We can form another idea of our immense distance from Sirius, by recollecting that the sun's disk forms to our sight an angle of 32 minutes, whereas that of Sirius forms only that of a second; and Sirius being a sun like ours, which we shall suppose of equal magnitude, since there is no reason to conceive it larger or smaller, it would appear to us as large as the sun, if it were but a like distance. Taking therefore two numbers proportional to the square of 32 minutes, and to the square of a second, we shall have 3,686,400 for the distance of the earth to Sirius, and one for its distance to the sun; and as this unit is equal to 33 millions of leagues, we see how many millions of leagues Sirius is distant from us, since we must multiply these 33 millions by 3,686,400; and if we divide the space between these two neighbouring suns, although at so great a distance, we shall see that the comets might be removed to a distance 1,800,000 times greater than that of the earth to the sun without quitting the limits of the solar universe, and without being subjected to other laws than that of our sun, and hence it may be concluded that the solar system for its diameter has an extent, which, although prodigious, nevertheless, forms only a very small portion of the heavens; and we must infer a truth therefrom but little known, namely, that from the sun, the earth and all the other planets, the sky must appear the same. When in a serene and clear night we contemplate all those stars with which the celestial vault is illuminated, it might be imagined that by being conveyed into another planet more remote from the sun, we should see these glittering stars larger, and emitting a brighter light, since we should be so much nearer to them. Nevertheless, the calculation we have just made demonstrates that if we were placed in Saturn, which is 300 millions of leagues nearer Sirius, it would appear only an 194,021st part bigger, an augmentation absolutely insensible; from which it must be concluded, that the heaven, with respect to all the planets, has the same aspect as it has to the earth. Therefore if even there should exist comets whose periods of revolution might be double, or treble the period of 575 years, the longest known to us; if even the comets in consequence thereof, immerse at a depth ten times greater, there would still be a space 74 or 75 times deeper, to reach the last confines, as well of the solar system, as of the sirian; so that by allowing Sirius as much magnitude as our sun has, and supposing in his system as many or more cometary bodies than there are comets existing in the solar, Sirius will govern them as the sun governs his, and there will remain an immense interval between the confines of the two empires; an interval which appears to be no more than a desart in the vast space, and which must give a suspicion that cometary bodies do exist, whose periods are longer, and which are to a much greater