. "Still, it is your job and you
expect to put it first and fit your own affairs in around it. Besides,
you get used to the regularity of the hours and soon do not notice the
monotony of the rules. You can readily understand why, at all official
radio stations, somebody must always be on the watch for S O S calls.
On shipboard there are three classes of wireless stations: those
having continual service with an operator who always has his ear to
the receiver while the ship is in motion; those where the office is
open only at stated hours and an operator listening merely for a
limited time; and those whose operators have no fixed time beyond
listening in the first ten minutes of each hour."

"The ship decides which kind of station it will have, I suppose,"
Nancy remarked.

"Indeed it doesn't," Bob contradicted, with a shake of his head. "The
government saves the vessel that trouble. It defines exactly the sort
of station when it issues the license. Uncle Sam also bestows on each
of these stations a name or combination of letters by which it shall
be known and under which it is officially listed. Each country has a
prescribed number of such letters allotted for its use at the
International Convention at Berne, and our nation is authorized to use
groups beginning with N and W; also triple groups of KIA to KZZ. You
will find all these call letters in a book that contains the wireless
telegraph stations of the world, a volume issued by the international
publication office at Berne."

"Can any one get one?" inquired Walter.

"Certainly, if he has the price," smiled the older brother. "I guess
you do not need one, though. A local call book would answer most
purposes. It would hardly be necessary for you to call any foreign
offices, and I even doubt if you would need to summon Sayville,
Tuckerton, New Brunswick, Marion, or Annapolis."

"Those are our trans-Atlantic stations, aren't they?" asked Dick.

"Some of them," Bob said. "We have others, though, that can talk with
Europe. There is one at San Diego; Pearl Harbor in Hawaii; and Cavite
in the Philippines. There are also Marconi stations at Kahuka and
Bolinas. In addition to these, the government has a number of
high-power stations scattered throughout the country. Arlington,
Virginia----"

"Sends out the time," put in Walter with disconcerting promptness.

"It sure does, sonny."

"How many foreign countries can talk with us?" inquired Nancy.

"A short time ago th