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30 lubber line of your pelorous heading the same way as the compass. Note the course as. shown by your compass and set your pelorous card to head the same way. Now point the sight vane at the sun. The pointer below will show you the azimuth, as snown by the compass. By looking in the azimuth book you will find the cor- rect azimuth and can then tell just what is the error of your compass. Then swing your boat until your pelorous would show a _ bearing the same as the book. .For night azimuth work we must be able to pick out a few good stars and we must also understand how to change our standard time into sidereal time. Astronomers give us the posi- tions of the heavenly 'bodies in the Nautical Almanac but as their calcu-- lations are all made by sidereal time we must use sidereal time in. order to enter the Nautical Almanac at the right place. We use the same books and instruments that we did for bear- ings of the sun but we need a copy of the Nautical Almanac. This can be purchased from the Penton Pub- lishing Company, Cleveland, Ohio. The; price is 50 cents. The Nautical Almanac gives us the necessary 'ele- ments for changing standard time into sidereal time and also gives us. the positions of: all the heavenly bodies for any instant of time for the whole year. In buying a Nautical Almanac be: sure that you get one for the cur- rent year. A 1908 almanac would not 'do for 1909, The first part of' this chapter will be devoted to the study of the stars. You will find this part of the study much more easy than 'you may think. Written in as simple a manner as is possible you will find here the follow- ing subjects: The first lessons in astronomy. What we see in the heavens. How they move. Difference between planets and stars. How astronomers locate heavenly _ bodies. How to pick out one dozen bright stars for azimuth work, The times of rising and setting of these stars each night. The second part of this chapter will explain all about sidereal time and the other work necessary for night azimuth work, as follows: -Why we must use sidereal time for night azimuth work. What sidereal time is, 4 What a sidereal clock. is set by. A pelorus slate for night work. 'rush into' the band of air THE Marine REVIEW How navigators and astronomers read time, How to read a Nautical Almanac. Practice problems. We can't take azimuths of stars in all parts of the heavens. Most azimuth tables give us azimuths for only that part of the heavens that the sun travels through. Therefore we can use only those stars that happen to be in that belt. The sun works back and forth 23 degrees on each side of the equator. Therefore the Red Book gives azimuths for a belt in the heavens 46 degrees wide. How- ever the new Henrich tables take in a belt of 29 degrees on each side of the celestial equator and enables us to use several good stars that we can't use with the red book. A Few Lessons in Astronomy. Before we start our star-gazing we should go back and review a few of the simple lessons in astronomy that we were taught at school. have forgotten some of the things that we should now know in order to make our work easy. What do we see in the heavens with the naked eye? The sun, the moon, planets, and stars, with an occasional shooting star and comet. With a tel- escope we can see asteroids and sat- ellites, 'What they are: The Sun--An immense ball of fire. The Stars--Other immense balls of fire, many of them being hundreds of times larger than the sun but mil- lions of times farther away. The Planets--Immense globes hav- ing no light of their own. The earth is a planet. Light from the sun shines on them and makes them appear like stars. The Moon--A satellite; most of the planets have moons revolving around them. These moons are called the planet's children or satellites, The moon is the earth's satellite and is the only satellite visible with the naked eye. The moon has no light of its own but gets its light from the sun. Asteroids--Small planets, none of which can be se€n with the naked eye. Shooting Stars--Pieces of flery metal that seem to be hurled at us from the heavens. Astronomers tell us that- countless numbers of these things are continually racing through space at a great speed. Some of them that' sut> rounds the earth and are immediately heated into a fiery ball. The great heat causes some of them to explode like rockets before they reach the earth, while others have been: known Many of us to bury themselves in the earth, Where they gome from no one can tell. Comet--A heavenly body that ap- pears to us like an immense burning planet rushing through space and leaving a trail of fire behind it. But the substance of a comet is not known, And the tail of a comet doés not al- ways trail behind but sometimes goes ahead of the comet and is then called the comet's whiskers. Another pecul- iarity of the comet is the fact that when it passes in front of a. star it does not hide the star--the star shows through it just as brilliantly as though the comet was not there. Comets are * seldom seen. Now when we look at the heavens at night we see stars and planets, Only four planets can 'be seen with the naked eye--Venus, Mars, Jupiter and Saturn. Saturn and Mars might easily be mistaken for bright first- magnitude stars. Venus and Jupiter are generally too bright and big to be taken for stars, Our Solar System. The solar system is simply the sun and his family of planets, satellites, CLC, The sun is the center and the earth and the other planets and all the rest of his followers join in the mad race around him. "The solar system is a great whirling mass of bodies and covers & space about 6,000 million miles in diameter. And the sun is the only one of the bunch that has any light of its own. Imagine a great dark room in the middle of which is a ball of fire. Around this ball of fire you see dark bodies, mov- ing swiftly and in perfect time, Other smaller dark bodies circle around the larger dark bodies. This.is a picture of the solar system. 'The larger dark bodies are the planets; the small ones are the planet's moons, There are no stars in the solar system, they are only specks in the distance. Fach star you see is another sum and probably has a family of his own But the distance to the nearest star is so great. that but very little can be learned about them. A few of these dark planets shine in the sky like bright stars and we are apt to think they are stars. This is why we should know just what is in the heavens. The sun shines on some of these planets and makes them look like stars, Make a little model of your own and see if it will not impress on your memory just how the heavenly bodies move. Set a lamp in the center of'a table.