THE SUN. 



moon revolves round the earth, is at a distance of 240000 miles 

 from its centre, consequently it follows that the earth and moon 

 would be not only contained within the globe of the sun, but 

 the moon would be a couple of hundred thousand miles within 

 the sun's surface. 



5. But we have hitherto only spoken of the diameter of the 

 sun ; let us now consider its bulk. When we know the diameters 

 of two globes we can always, by an easy operation of arithmetic, 

 estimate their bulks. Thus, if one globe have a diameter double 

 another, the bulk of the former will be eight times that of the 

 latter. If the diameter be ten times greater, the bulk will be a 

 thousand fold greater, and so on. Now we know that the diameter 

 of the sun is about one hundred and twelve times greater than 

 that of the earth, from which we infer, by the same principles of 

 arithmetic, that the bulk of the sun must be very nearly one 

 million four hundred thousand times the bulk of the earth. To 

 make a globe like the sun, it would then be necessary to roll one 

 million four hundred thousand globes like the earth into one ! It 

 is found by considering the bulks of the different planets, that if 

 all the planets and satellites in the solar system were moulded 

 into a single globe, that globe would still not exceed the five 

 hundredth part the globe of the sun : in other words, the bulk of 

 the sun is five hunolred times greater than the aggregate bulk of 

 all the rest of the bodies of the system. 



6. The astronomer, however, is called upon to execute processes 

 more difficult and yet no less indispensable than the mere measure- 

 ment of distances and magnitudes. If we desire to know the 

 quantities of matter composing those distant orbs, we must not 

 merely measure their magnitudes and fathom their distances, but 

 we must wing our flight, in imagination, across those vast dis- 

 tances which separate us from them and weigh their stupendous 

 masses. If the popular student finds it difficult to believe and 

 comprehend how we can measure distances and magnitudes such 

 as those of the heavenly bodies, how much more will he be con- 

 founded when he is assured that we have at our disposal a balance 

 of the most unerring exactitude in which we can place those vast 

 orbs and poise them ! The globe of the sun itself, transcendently 

 greater than the earth and all the planets put together, is weighed 

 with as great relative precision, as that with which the chemist in 

 his analysis, estimates the weights of the constituents of the bodies 

 which pass under his hands. As the general principles by which 

 the weights of the bodies of the universe are ascertained is in spirit 

 the same for all, it may be worth while here to explain the method, 

 once for all, in its application to the sun. 



7. "When a body revolves in a circle, we know from common 

 102 



