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visible, and all the relative positions of the different constellations.

James. What are constellations, sir?

Tutor. The ancients, that they might the better distinguish and describe the stars, with regard to their situation in the heavens, divided them into constellations, that is, systems of stars, each system consisting of such stars as were near to each other, giving them the names of such men or things, as they fancied the space which they occupied in the heavens represented.

Charles. Is it then perfectly arbitrary, that one collection is called the great bear, another the dragon; a third Hercules, and so on?

Tutor.

It is; and though there have been additions to the number

of stars in each constellation, and

various new constellations invented by modern astronomers, yet the original division of the stars into these collections was one of those few arbitrary inventions which has descended without alteration, otherwise than by addition, from the days of Ptolemy down to the present time.Do you know how to find the four cardinal points, as they are usually called, the North, South, West, and East?

James.

O yes, I know that if I look at the sun at twelve o'clock at noon, I am also looking to the south, where he then is; my back is towards the north; the west is on my right hand, and the east on my left.

Tutor. But you must learn to find these points without the assistance of the sun, if you wish to be a young

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Charles.

I have often heard of

the north pole star; that will perhaps answer the purpose of the sun when he has left us.

Tutor.

You are right do you see those seven stars which are in the constellation of the Great Bear? -some people have supposed their position will aptly represent a plough; others say, that they are more like a waggon and horses: the four stars representing the body of the waggon, and the other

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ing of it; a b d g represent the four stars and b z B the other three.

Charles. What is the star P? Tutor. That represents the polar star to which you just now alluded; and you observe, that if a line were drawn through the stars b and a, and produced far enough, it would nearly touch it.

James. Let me look at the heavens for it by this guide. There it is, I suppose; it shines with a steady and rather dead kind of light, and it appears to me that it would be a little to the right of the line passing through the stars b and a.

Tutor. It would, and these stars are generally known by the name of the pointers, because they point to the north pole, which is situated a little more than two degrees from the

star P.

Charles. Is that star always in the same part of the heavens ?

Tutor. It may be considered as uniformly maintaining its position, while the other stars seem to move round it as a centre. We shall have occasion to refer to this star again; at present I have directed your attention to it, as a proper method of finding the cardinal points by starlight.

James. Yes, I understand now that if I look to the north, by standing with my face to that star, the south is at my back, on my right hand is the east, and the west on my left.

Tutor. This is one important step in our astronomical studies; and we can make use of these stars as a kind of standard, in order to discover the names and positions of others in the heavens.

Charles. In what way must we proceed in this business?

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