Classroom clipper, Vol. IV, No. 1, October 1947

              HONOLULU
| SHANNON
LONDON
ISTANBUL
WAKE I.
TOKYO
GUAM
MANILA
KARACHI
CALCUTTA
1 BANGKOK j
October, 1947
Published by Pan American World Airways
YOL. IV, No. 1
ROUND THE WORLD THROUGH THE TIME ZONES
By George Gardner
The time zones of the world, and the framework which they provide for relating local time of day in any one place to local time of any other place in the world, might ideally be studied by flying around the world.
Such a flight actually could be made, for the Flying Clippers have been operating a round the world service to and from the United States since last summer. It also may be accomplished on an imaginary basis right in the classroom, with the aid of a globe of the world.
In addition to the globe it will be convenient to have at hand a map of the world indicating the boundaries of the time zones. (A large atlas will have one.) There are a number of local variations in applications of the principles outlined below, most of which will appear on the time zone map.
' It will be convenient also to begin the lesson with an imaginary flight that could not be accomplished in fact—a non-stop flight directly around the world at its equator. This will simplify certain of the explanations, and pave the way for an example following a course as flown across land areas of the Northern Hemisphere.
Let us suppose, then that we set out from 0° latitude and 0° longitude in a jet-propelled plane of the future which can fly 1,000 miles an hour, which will be fast enough to fly across each time zone at the equator in exactly one hour.
Our starting point is at the intersection of the Equator and the Meridian of Greenwich, in the Gulf of Guinea off the West Coast of Africa.
We are directly south of Greenwich, and take off, heading due West at 0000 Greenwich Civil Time which is the beginning of a day reckoned in Greenwich time. Since the earth is approximately 24,000* miles in circumference, and there are 24 time zones (corresponding with the 24 hours of the day) we shall traverse the width of a time zone every hour.
As we take off, it is not only 0000 GCT, but it also is midnight local time at every point along the Greenwich Meridian. In addition, it is midnight local time everywhere within the time zone of which the Greenwich Meridian is the central line.
This time zone (like all others) is 15 degrees in width, extending an equal distance eastward and westward from the
* The actual circumference of the earth at the equator is 24,902.36 miles. The approximation of 24,000 miles is chosen for this illustration for purposes of simplicity.
meridian. Since all meridians converge at the poles, the time zone does likewise, with the result that it is shaped like the skin on a slice of apple taken from the fruit by making two cuts from stem to blossom.
Each time zone is 15 degrees in width because we have divided our world into 24 time zones, and these 24 zones divide up the 360 degrees in which the world’s longitude is measured. Thus each time zone is one twenty-fourth of 360 degrees or 15 degrees. It is still 15 degrees regardless of whether at the equator or nearer to the North or South Pole where the time zone is narrower. Degrees of longitude may be converted into miles or other units
of linear measurement only by the aid of a formula which takes into account the distance from the equator.
The time zone in which we are starting our journey embraces the British Isles, France, Spain and Portugal and a strip cutting through the continent of Africa. At this moment it is midnight in local time in all those areas and above them to the North Pole.
It is midnight also in a long, thin wedge of area extending across the South Atlantic Ocean to the South Pole, but there are relatively few clocks there to register midnight. There are a few pinpoints of (Continued on Page 2)
ROUND THE WORLD ROUTES OF THE FLYING CLIPPERS
I NEW YORK
SAN FRANCISCO
LOS ANGELES
DAMASCUS
M SHANGHAI HONG KONG I
Two routes are followed by the FLYING CLIPPERS in service around the world to and from the United States, one via Hong Kong, Shanghai and Tokyo, and the other via Manila. There is a weekly service in each direction on each route—a total of four flights ROUND THE WORLD each week.
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