luid
state, but in that of very compressed gases, which are kept from
becoming solid or even fluid by the very high temperature which exists
in them. This view is apparently supported by the fact that, while the
pressure upon its matter is twenty-seven times greater in the sun than
it is in the earth, the weight of the whole mass is less than we
should expect under these conditions.

As for the temperature of the sun, we only know that it is hot enough
to turn the metals into gases in the manner in which this is done in a
strong electric arc, but no satisfactory method of reckoning the scale
of this heat has been devised. The probabilities are to the effect
that the heat is to be counted by the tens of thousands of degrees
Fahrenheit, and it may amount to hundreds of thousands; it has,
indeed, been reckoned as high as a million degrees. This vast
discharge is not due to any kind of burning action--i.e., to the
combustion of substances, as in a fire. It must be produced by the
gradual falling in of the materials, due to the gravitation of the
mass toward its centre, each particle converting its energy of
position into heat, as does the meteorite when it comes into the air.

It is well to close this very imperfect account of the learning which
relates to the sun with a brief tabular statement showing the relative
masses of the several bodies of the solar system. It should be
understood that by mass is meant not the bulk of the object, but the
actual amount of matter in it as determined by the gravitative
attraction which it exercises on other celestial bodies. In this test
the sun is taken as the measure, and its mass is for convenience
reckoned at 1,000,000,000.

TABLE OF RELATIVE MASSES OF SUN AND PLANETS.[2]
+------------------------------------------------------------+
| The sun 1,000,000,000 |
| Mercury 200 |
| Venus 2,353 |
| Earth 3,060 |
| Mars 339 |
| Asteroids ? |
| Saturn 285,580 |
| Jupiter 954,305 |
| Uranus 44,250 |
| Neptune