THE GUIDE TO NATURE 
108 
the near-by islands. The path in which 
the eclipse can be seen as total, about 
one hundred miles wide, cuts directly 
across Australia and most of the ob- 
serving stations will be located there. 
It lasts as a total eclipse for about five 
minutes. This is a long duration for 
an eclipse. Astronomers will utilize 
it as a means for further testing the 
Einstein theory and for other pur- 
poses. Expeditions will be sent from 
United States, England. Canada and 
Germany. Special lenses for the pur- 
pose are now being made at Pitts- 
burgh. No part of the eclipse can be 
seen from here. We will see no eclipse 
in 19 22. 
^ ^ 
The Planets. 
Mercury is a morning star from Feb- 
ruary 14 to April 24 and from June 18 
to August 7 and from October 15 until 
December 8. At other times it is an 
evening star. It will be seen best in 
the early evening about May 23. Venus 
is a morning star until February 9. an 
evening star until November 25, then 
a morning star for the remainder of the 
year. It will be in best position in 
August, September and October. Mars 
will be a morning star until June 10, 
then an evening star for the remainder 
of the year. It will be nearest to the 
earth on June 18, at a distance of 43,- 
000,000 miles, and will then be brighter 
than Sirius, the brightest fixed star, 
and as bright as Jupiter, but not as 
bright as Venus. This will be quite 
a favorable year for seeing this planet 
but not as favorable as the year 1924. 
When nearest to the earth the planet 
is always far south and hence seen bet- 
ter from the southern hemisphere. 
A story has been circulated that a 
large telescope is to be constructed at 
a place in the southern hemisphere 
where Mars will be directly overhead, 
for the purpose of observing it. 1 his 
telescope is to lie made by revolving a 
large mass of mercury at the bottom of 
a well. This is not a new idea. It has 
been known for a very long time that 
a mass of fluid revolved uniformly 
about a vertical axis will assume the 
form of a paraboloid of revolution 
which is the form in which the mirror 
of a reflecting telescope is ground. 
Clean mercury is a very fine reflecting 
surface. Hence, in theory, the idea of 
such a telescope is fine. In practice 
it is different. The parabolic mirrors 
of astronomical telescopes must be 
made with an accuracy of a few mil- 
lionths of an inch. No large body of 
mercury can be revolved with a steadi- 
ness which will give the surface any- 
where nearly the accuracy of form nec- 
essary for astronomical observation. 
The experiment was tried many years 
ago by Professor Wood of Johns Hop- 
kins University. He was the first, I 
think, to try it. As was expected by 
many, he failed to have success. There 
is no likelihood that such an experi- 
ment would be any more successful 
now. I do not expect to see it tried. 
Jupiter will be a morning star until 
April 4, then an evening star until 
October 23, then a morning star until 
the end of the year. Saturn is a morn- 
ing star until March 25, an evening 
star until October 4, and then a morn- 
ing star until the end of the year. 
Uranus is an evening star until Feb- 
ruary 28, a morning star until Septem- 
ber 4, then an evening s.tar until the 
end of the year. Neptune is a morning 
star until February 4, an evening star 
until August 9, then a morning star 
until the end of the year. The planets 
will be quite interesting during the 
summer months. 
^ ^ ^ 
The Calendar. 
The Roman Emperor, Julius Caesar, 
found the calendar of his time so illogi- 
cal and confused that he determined 
to make a new one. He sought the ad- 
vice of an Egyptian astronomer, 
Sosigenes. They established the calen- 
dar which with a few modifications is 
in use today. One modification con- 
cerns us here. Sosigenes arranged the 
months alternating thirty-one days and 
thirty days except that February had 
but twenty-nine instead of thirty days 
in ordinary years. The seventh month 
of 31 days was named July in honor of 
Julius Caesar. Ilis successor, Augus- 
tus, named the eighth month August in 
honor of himself and, in order that it 
should not have fewer days than the 
month of Julius, increased its length 
from thirty days to thirty-one days, 
taking a day from February for the 
purpose. Then, in order to avoid three 
consecutive months of thirty-one days, 
September was shortened to thirty 
days and the remaining months alter- 
nating from that point as they now do. 
