TO KNOW THE STARRY HEAVENS 
187 
of the time. The explanation, no doubt, 
is' that one happened each time to be 
close to the planet, and hence not vis- 
ible in his small telescope. 
From the days of Galileo these bodies 
visible in the smallest telescopes have 
had the admiration of those who have 
seen them. Five more satellites are now 
known to be moving about Jupiter, but 
Figure 3. The orbits of the five inner 
satellites of Jupiter. 
these five are so very faint that to see 
them taxes the powers of the largest 
existing telescopes. The four bright 
ones — the Galilean satellites, as they 
are known — are in a class by them- 
selves, both in respect to Jupiter’s 
satellites and those of other planets. 
In the days of Galileo, however, the 
interest in Jupiter’s satellites was of a 
different kind. It is almost impossible 
for us to realize now how important 
his discovery was in his day. They were 
the first satellites known : in fact, even 
the word satellite was yet to be formed, 
and the word telescope, too. Galileo 
called the bodies the Medicean planets, 
in honor of his patron. It was still 
pretty generally believed, as taught by 
Ptolemy, that sun, moon and planets 
revolved about a fixed earth. Coper- 
nicus had published his theory that the 
sun was the center, but only a few as 
yet accepted it. Men had difficulty in 
seeing that the moon would not be left 
behind as the earth moved about the 
sun. The satellites of Jupiter, however, 
were doing this very thing, and gave a 
model of the solar system as Coper- 
nicus claimed it to be. The satellites of 
Jupiter made an overwhelming argu- 
ment in favor of the theory of Coper- 
nicus. The phases of Venus, also dis- 
covered by Galileo, were impossible in 
the older theory. Many important 
things have since been discovered in 
connection with these satellites. Their 
motions made a very delicate test of 
the accuracy of the law of gravitation. 
From their eclipses the fact that light 
has a measurable velocity was dis- 
covered. 
Plumbers vs. Astronomers ! 
Admiral J. A. Hoogewerff, superin- 
tendent of the Naval Observatory in 
Washington, has trouble getting as- 
tronomers at $1,000 or $1,200 a year, 
which is the amount allowed for some 
of the young assistants who gaze night- 
ly at the stars. They work in a cold 
observatory all through the winter and 
the admiral says their physical suffer- 
ings are often great. They have to be 
enthusiasts in their profession. 
Such an enthusiast applied some time 
ago to Admiral Hoogewerff for one of 
the vacant places. The admiral talked 
to him for a while and discovered that 
he had no technical education or quali- 
fications for the job. 
“I’m sorry,” said the admiral, “but 
I cannot give you the position.” 
“Very well,” said the applicant. “If 
I can’t get it, I’ll go back downtown 
and keep the job I had.”, 
“What is it?” inquired the admiral. 
“I’m a plumber’s assistant. And let 
me tell you. I’m making a lot more 
money in the plumbing business than I 
can make as an astronomer.” — Brook- 
lyn Eagle. 
The astronomical instruments which 
the Germans stole from Pekin in 1901 
have at last been returned. Among 
them were several that were built in 
1673 and shortly thereafter by Jesuit 
missionaries, after the design of those 
of Tycho Brahe. A still earlier set, 
which had been displaced from use by 
those of the Jesuits, were made about 
1279 and followed Persian models. 
Among these last is the earliest known 
equatorial mounting. 
Spring is -the most becoming robe 
The old earth dons in the changing year, 
And yet through all the passing months 
We would not have it thus appear. 
For green of Summer, fires of Fall, 
And snow that forms the Winter’s pall. 
Have all their place in the scheme of things. 
And but enhance the joy of Springs. 
— Emma Peirce. 
