Light travels at the rate of about 186,000 miles a second, and therefore leaps the great gulf between our earth and the sun in about eight minutes. But even the nearest of the fixed stars--Alpha Centauri, a star of the first magnitude in the Southern Hemisphere--is so incredibly distant that light takes four years and four months to travel to us from it; while the next nearest, a small star in Ursa Major, is about seven light-years distant, and the star 61 of the constellation Cygnus, the first northern star whose distance was measured, is separated from us by two years more still. At present the distances of about 100 stars are known approximately; but it must be remembered that the approximation is a somewhat rough one. The late Mr. Cowper Ranyard once remarked of measures of star-distances that they would be considered rough by a cook who was in the habit of measuring her salt by the cupful and her pepper by the pinch. And the remark has some truth--not because of any carelessness in the measurements, for they are the results of the most minute and scrupulous work with the most refined instrumental means that modern skill can devise and construct--but because the quantities to be measured are almost infinitely small. It is at present considered that the average distance from the earth of stars of the first magnitude is thirty-three light years, that of stars of the second fifty-two, and of the third eighty-two. In other words, when we look at such stars on any particular evening, we are seeing them, not as they are at the moment of observation, but as they were thirty-three, fifty-two, or eighty-two years ago, when the rays of light which render them visible to us started on their almost inconceivable journey. The fact of the average distance of first-magnitude stars being less than that of second, and that of second in turn less than that of third, is not to be held as implying that there are not comparatively small stars nearer to us than some very bright ones. Several insignificant stars are considerably nearer to us than some of the most brilliant objects in the heavens--_e.g._, 61 Cygni, which is of magnitude 4·8, is almost infinitely nearer to us than the very brilliant first magnitude star Rigel in Orion. The rule holds only on the average.