. A complete geography. tsunrise, noon, and sunset reach each of the 360 meridians in thecourse of the day of 24 hours. Dividing 360 by 24 gives 15; thatis the number of meridians that the sunrise or sunset pass over ina single hour. Therefore, if in one place, as at Philadelphia, on the 1 It is understood, of course, that this does not apply to the frigid zone, wliere tliesun does not rise at all during a part of the year, and wliere it does not set duringanother part of the year. 42 NORTH AMERICA 75tli meridian, it is sunrise at six oclock, it will be sunrise one liourlater at all points jus
. A complete geography. tsunrise, noon, and sunset reach each of the 360 meridians in thecourse of the day of 24 hours. Dividing 360 by 24 gives 15; thatis the number of meridians that the sunrise or sunset pass over ina single hour. Therefore, if in one place, as at Philadelphia, on the 1 It is understood, of course, that this does not apply to the frigid zone, wliere tliesun does not rise at all during a part of the year, and wliere it does not set duringanother part of the year. 42 NORTH AMERICA 75tli meridian, it is sunrise at six oclock, it will be sunrise one liourlater at all points just 15° west of this, or on the 90th meridian. This explains what has determined the boundary lines of thetime belts. The time selected for the Eastern Belt is that of the75th meridian; for the Central Belt, that of the 90th meridian,which is just one hour later. What meridian is selected for theMountain Belt? (Fig. 42.) For the Pacific Belt? Each of thesemeridians runs through the middle of the belt whose time it fixes,. bTiNDVKD TIJir I\ HIE LMTED SfilES, Fig. 42. To show the standard time belts of the United States, — the actual boundaries being irregular, as you see. SO that the eastern boundary of the Central Time Belt is half-waybetween the 75th and 90th meridians, that is West Longitude 821° ;and the western boundary is half-way between the 90th and 105thmeridians, or 97|-° West Longitude. In reality the railways do not change their time exactly according tothese boundaries, for oftentimes the meridians extend through very unim-portant points, or even cross the railways far out in open country. Insteadof following the exact boundaries, they select well-known places, likeBuffalo, Pittsburg, and Atlanta, at which cities the change is made fromEastern to Central time. Therefore, the boundaries which represent theplaces where the railways actually change their time are somewhat irregu-lar, and not always on the proper meridian (Fig. 42). You see that the object of these T
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