"Now," said Uncle Henry, "you see that if we make a black dot on one of the cardboard strips about halfway between the cardboard brim, or the earth's equator, and the pencil, or the North Pole, it will be about as far north as we are in the United States. And when Paul is in his Summer position, with the pencil slanting _toward_ the 'sun,' you see that the sun's rays beat down much straighter on the black dot than they do when he is on the other side of the lamp, with the pole slanting _away_ from the 'sun.' That is why the Winter sun appears to be lower in the sky at noon than the Summer sun, and also why the Summer sun shines hotter on the earth than it does in Winter. Notice, too, that the rays from the lamp light up Paul's head for quite a little way beyond the foot of the 'pole' when it slants _toward_ the 'sun,' while when it slants _away_ from the 'sun' the rays fail to reach the 'pole' at all. This means that in summer the sun shines a longer time upon the part of the earth that slants toward it. If you could look down from the ceiling at Paul's head in his Summer position and in his Winter one you would see why." Uncle Henry quickly drew these two pictures of the top of a globe to show the children why the days are long in Summer and short in Winter at any point in the United States. [Illustration: _The Winter Day_ lasts while the black dot on the earth travels from A to B--less than half-way round. _The Summer Day_ lasts while the black dot on the earth travels from C to D--more than half-way round.] "It's just like the hot water bottle mother kept in my bed that time I had a chill after swimming," said Paul. "The hotter it was before she put it in the bed the slower it cooled off." "That's the idea," said Uncle Henry, "the longer the sun shines on any place on the earth the hotter it gets, and when the nights are as short as they are in Summer the place hasn't long to cool off before it is round in the sun's hot rays again. Now do you see why Summer is hotter than Winter?" The children did. "There's one thing I don't understand, though," said Peter. "Why are there different stars in the sky in Winter than there are in Summer?" "That's easy to answer," said Uncle Henry. "Look at Paul again--first when it's 'night' on his face on the 'Summer' side of the lamp, and then when it is 'night' on his face on the 'Winter' side of the lamp. "At 'night' in Summer Paul looks at the pictures on one end of the room. The cardboard brim, or 'plane of the equator,' is slanted _up_, above the 'plane of the ecliptic.'" This picture shows how Paul looked. [Illustration]