But besides the stars themselves, a most conspicuous object both in the northern and southern hemisphere is that wonderful irregular belt of faintly diffused light termed the Milky Way or Galaxy. This forms a magnificent arch across the sky, best seen in the autumn months in our latitude. This arch, while following the general course of a great circle round the heavens, is extremely irregular in detail, sometimes being single, sometimes double, sending off occasional branches or offshoots, and also containing in its very midst dark rifts, spots, or patches, where the black background of almost starless sky can be seen through it. When examined through an opera-glass or small telescope quantities of stars are seen on the luminous background, and with every increase in the size and power of the telescope more and more stars become visible, till with the largest and best modern instruments the whole of the Galaxy seems densely packed with them, though still full of irregularities, wavy streams of stars, and dark rifts and patches, but always showing a faint nebulous background as if there remained other myriads of stars which a still higher optical power would reveal. The relations of this great belt of telescopic stars to the rest of the star-system have long interested astronomers, and many have attempted its solution. By a system of gauging, that is counting all the stars that passed over the field of his telescope in a certain time, Sir William Herschel was the first who made a systematic effort to determine the shape of the stellar universe. From the fact that the number of stars increased rapidly as the Milky Way was approached from whatever direction, while in the Galaxy itself the numbers visible were at once more than doubled, he formed the idea that the shape of the entire system must be that of a highly compressed very broad mass or ring rather less dense towards the centre where our sun was situated. Roughly speaking, the form was likened to a flat disc or grindstone, but of irregular thickness, and split in two on one side where it appears to be double. The immense quantity of the stars which formed it was supposed to be due to the fact that we looked at it edgewise through an immense depth of stars; while at right angles to its direction when looking towards what is termed the pole of the Galaxy, and also in a less degree when looking obliquely, we see out into space through a much thinner stratum of stars, which thus seem on the average to be very much farther apart.