3H NINETEENTH CENTURY. FT. in. 



three or four lines like those caused by our atmosphere, 

 showing that Jupiter must have an atmosphere partly, but 

 not entirely like ours. Mars and Saturn also both showed 

 these atmospheric lines, and so did Saturn's rings, proving 

 that a similar atmosphere must spread over them also. But 

 our moon gave none of them, and this agrees with other 

 evidence in showing that the moon has no atmosphere. 



They next passed on to examine the light of the stars, 

 and this was by no means an easy task, because the stars 

 are so far off that their light is very faint and difficult to 

 catch. Nevertheless they proved .that round one star, called 

 Aldebaran (No. 5, Plate I.), there must be an atmosphere 

 of hydrogen, sodium, magnesium, calcium, iron, tellurium, 

 antimony, bismuth, and mercury, and you will notice that 

 the last four of these are not found in the sun. In the 

 light of the star Betelgeux in the constellation Orion, and 

 in another star, called ft Pegasi, no hydrogen is found, but 

 it is found in all the other stars that have been examined, 

 together with many other substances. In some of the stars 

 there are besides lines which must be produced by the 

 vapours of substances different from any yet known upon 

 our earth. 



Dr. Huggins proves that some Nebula* are Gaseous, 

 1864. And now we come to a very interesting experiment. 

 You will remember that astronomers doubted Sir \V. Her- 

 schel when he suggested (p. 285) that some of the nebulae 

 are not made of tiny stars, but of gas which is forming into 

 stars. In 1864 Dr. Huggins began to examine these nebuloe 

 \\ith the spectroscope, and he found that they did not give 

 a band of colour with dark lines upon it as the stars do, 

 but a few faint coloured lines on a dark ground, such as we 

 know are produced by glowing gases and vapours. If you 

 compare the spectrum of sodium (No. 3), or of hydrogen 



