There are two more constellations in the southern part of the sky that ought to be interesting, because they are the two hunting dogs that help Orion fight the Bull. But I can't trace these animals, and I don't believe it is worth while. The brightest stars in them everybody can see and admire--Sirius, the Bigger Dog, and Procyon, the Smaller Dog. Every one ought to know Sirius, because he is the brightest star of all. (Of course, he is not so bright as Venus and Jupiter, but they are planets.) To find him, draw a line from the eye of the Bull through the belt of Orion and extend it toward the southeast about twenty degrees. They call him the Dog star because he follows the heels of Orion. And people still call the hottest days of summer "dog days" because 400 years before Christ the Romans noticed that the Dog star rose just before the sun at that time. The Romans thought he chased the sun across the sky all day and therefore was responsible for the great heat. But that was a foolish explanation. And so is the old notion that dogs are likely to go mad during the dog days "because the dog star is in the ascendant." So is the idea that Sirius is an unlucky star. There are no lucky or unlucky stars. These are all superstitions, and we ought to be ashamed to believe any superstition. Yet for thousands of years before we had public schools and learned to know better, people believed that every one was born under a lucky star or an unlucky one, and they believe that farmers ought to plant or not plant, according to the size of the moon. Now we know that is all bosh. Those old superstitions have done more harm than good. One of the most harmful was the belief in witches. Let us resolve never to be afraid of these old tales, but laugh at them. Why should anybody be afraid of anything so lovely as Sirius? I used to think Sirius twinkled more than any other star. But that was bad reasoning on my part. I might have noticed that every star twinkles more near the horizon than toward the zenith. I might have noticed that stars twinkle more on clear, frosty nights than when there is a little uniform haze. And putting those two facts together I might have reasoned that the stars never really twinkle at all; they only seem to. I might have concluded that the twinkling is all due to the atmosphere--that blanket of air which wraps the earth around. The nearer the earth, the thicker the air, and the more it interferes with the light that comes to us from the stars. They say that Sirius never looks exactly alike on two successive nights. "It has a hundred moods," says Mr. Serviss, "according to the state of the atmosphere. By turns it flames, it sparkles, it glows, it blazes, it flares, it flashes, it contracts to a point, and sometimes when the air is still, it burns with a steady white light." (Quotation somewhat altered and condensed.)