sundial, or perhaps by a mark at the corner of the house, which
showed where the shadow of the house fell at noon. Very rude
indeed was this method; and it was uncertain for another reason.
It is not always exactly twenty-four hours between two noons by
the sun, Sometimes for two or three months the sun will make it
noon earlier and earlier every day; and during several other
months later and later every day. The result is that, if a clock
is perfectly regulated, the sun will be sometimes a quarter of an
hour behind it, and sometimes nearly the same amount before it.
Any effort to keep the clock in accord with this changing sun was
in vain, and so the time of day was always uncertain.

Now, however, at some of the principal observatories of the
country astronomical observations are made on every clear night
for the express purpose of regulating an astronomical clock with
the greatest exactness. Every day at noon a signal is sent to
various parts of the country by telegraph, so that all operators
and railway men who hear that signal can set their clock at noon
within two or three seconds. People who live near railway stations
can thus get their time from it, and so exact time is diffused
into every household of the land which is at all near a railway
station, without the trouble of watching the sun. Thus increased
exactness is given to the time on all our railroads, increased
safety is obtained, and great loss of time saved to every one. If
we estimated the money value of this saving alone we should no
doubt find it to be greater than all that our study of astronomy
costs.

It must therefore be conceded that, on the whole, astronomy is a
science of more practical use than one would at first suppose. To