24. At noon a ship's chronometer carrying Greenwich time indicated 1:05 P.M. In what longitude was the ship?

25. A ship's chronometer carrying Greenwich time was 35 minutes slow Saturday noon and 13 minutes fast the following Tuesday noon. In what longitude was the ship at each observation? How far east or west did she sail?

26. When it is 6 P.M. Jan. 10 at San Francisco, what is the time and date at Tokyo?

FIRST SOLUTION

Since San Francisco is 122° 24′ 32" W. and Tokyo is 139° 44′ 30′′ E., Tokyo is 262° 9' 2" east of San Francisco, and consequently has 17 hr. 28 min. 36 sec. later time. Counting this time on from 6 P.M. Jan. 10, the time at Tokyo is found to be 11 hr. 28 min. 36 sec. A.м. Jan. 11.

SECOND SOLUTION

Reckoning in the other direction, Tokyo is 360° – 262° 9′ 2′′, or 97° 50′ 58" west of San Francisco, and its time is therefore 6 hr. 31 min. 24 sec. earlier.

This apparent contradiction of the first solution is explained thus: the time of Tokyo is 17 hr. 28 min. 36 sec. later than that of San Francisco, or a day later lacking 6 hr. 31 min. 24 sec. A day later than 6 P.M. Jan. 10 is 6 P.M. Jan. 11, and a day later less 6 hr. 31 min. 24 sec. gives the Tokyo time as 11 hr. 28 min. 36 sec. A.M. Jan. 11.

NOTE. When a ship sails westward over the 180th meridian the calendar is set forward one day; sailing eastward its calendar is set back one day. An irregular line corresponding in general with this meridian marks the place where the calendar changes and is called the international date line.

When the sun is on the meridian of New York, on the first day of May, find the true time and date in:

27. Manila 28. Batavia

29. Canton

30. Melbourne

31. Bombay
32. Cape Town

33. At noon, March 10, a ship weighed anchor at Hong-Kong, 114° 10' 02" E., and sailing eastward reached Honolulu, 157° 51' 34" W., at noon March 25. How long was the voyage?

263. In 1883, the railroads of the United States and Canada agreed upon a system of standard time that has come into general use because of its convenience. Under this system there are five time belts, each approximately 15° of longitude in width, and each having the time of its central meridian.

Each railway has selected the most convenient town on its own road at which to change from the standard time of one belt to that of the next. Since such towns on the various roads are seldom on the same meridian, the line connecting them forms an irregular boundary between the various belts; hence these time belts, shown on the following map, are neither equal in size nor uniform in shape.

264. The time belts are called Atlantic, with the time of the meridian of 60° W.; Eastern, with the time of the meridian of 75° W.; Central, with the time of the meridian of 90° W.; Mountain, with the time of the meridian of 105° W.; and Pacific, with the time of the meridian of 120° W.

It is evident that the time of the various belts differs by hours, the minute and second hands of all correct timepieces being the same at any instant. Central time is 1 hr. earlier than Eastern time; Mountain time is 1 hr. earlier than Central time; and Pacific time is 1 hr. earlier than Mountain time. Correct time is telegraphed each day to all parts of the United States from the Naval Observatory at Washington.

265. Standard time has been adopted by most civilized governments of the world, the time meridian chosen being, with few exceptions, some multiple of 15° from the prime meridian through Greenwich.

In exercises refer to the map on page 155 for the time meridians of cities in the United States. The standard time meridian for each foreign city will be given in parentheses in the exercises where it is needed.

WRITTEN EXERCISES

266. 1. A certain business transaction was reported by telegraph from Chicago at 10:30 A.M., to New York, New Orleans, San Antonio, and Portland, Ore. Allowing no time for transmission, when did the message reach each city?

2. If the news of the opening of the St. Louis Exposition at 12:15 P.M. was immediately telegraphed all over the world, at what time did Salt Lake City receive it? Portland, Me.? Manila (120° E.)? Bombay (75° E.)? Berlin (15° E.)? London? Tokyo (135° E.)?

3. The news of the Maine disaster was cabled to Madrid (0°) from Havana (75° W.) at 2 A.M. Neglecting the time of transmission, find the time when the news reached Madrid.

4. Dewey's flagship, the Olympia, opened fire on the defenses of Manila (120° E.) at 5:41 A.M., May 1, 1898, and ceased firing at 7:40 A.M. to allow time for breakfast. Between what hours and on what day, Washington time, did the assault occur?

5. The first news of the assault reached Madrid (0°) at 6:20 P.M. the same day. How long did it take the news to reach Madrid?

6. Cable communication with Manila was severed at 10 A.M., London time, May 2, 1898. What was the clock time in Manila (120° E.) when the cable was cut?

7. A London paper received a dispatch from Cairo (30° E.) reporting an explosion in the British barracks. If the dispatch was received in London at 3:15 P.M., at what time was it sent? 8. If 14 hours later the news was cabled to New York (75° W.), find the time that it reached New York.

9. The first shock of the earthquake at San Francisco April 18, 1906, was recorded at 5:12 A.M. at the University of California, and at 20 seconds after 8:19 A.M. at Washington. How long did it take the shock to cross the continent ?

10. The dispatch regarding the final surrender of Port Arthur (120° E.) was sent from that place at 10 P.M., Jan. 2, 1905. At what time was the news received in Tokyo (135° E.)? in St. Petersburg (30° E.)? in London? in New York?

11. The Atlantic, the winner of a yacht race from Sandy Hook (75° W.) to the Lizard, Eng. (0°), started at 12:15 P.M., May 17, and finished at 9:18 P.M., May 29. Find the Atlantic's time.

12. A ship in distress reports by wireless telegraph that she is in longitude 21° W. and has been pumping water 5 hours. A station on the English coast catches the message immediately at 2:27 P.M., Greenwich time. When did the pumps begin work?

13. Paris uses the time of her meridian, 2° 20′ 14′′ E. The Paris stock exchange, or Bourse, closes at 3 P.M. At what time will closing quotations reach New York, if cabled immediately?

14. At 12 P.M., Saturday, Dec. 31, 1904, the chief of the U. S. Signal Service sent a message from Washington around the world via Chicago, Denver, San Francisco, Manila (120° E.), Tokyo (135° E.), Melbourne (150° E.), Bombay (75° E.), Berlin (15° E.), and London. What was the date and the clock time in each city at the instant of sending the message?

METRIC SYSTEM

267. The metric system is a decimal system of weights and measures, having for its principal unit the meter, to which all other units are related.

This system originated in France. Its use is required by law in many countries, and permitted in many others, including the United States. Congress has made it the official system in our Philippine possessions.

Its most general use is in the arts and sciences, where its convenience and accuracy have specially commended it.

MEASURES OF LENGTH

268. The primary unit of length is the meter, the unit of the

The length of the meter was intended to be a ten-millionth part of the distance from the equator to either pole, but subsequent calculations have shown it to differ slightly from that.

The length of the standard meter in the United States is 39.37 inches. Other metric units of length are decimal parts of the meter and multiples of 10 times the meter.

269. The primary units of surface, volume, capacity, weight, etc., are likewise subdivided and multiplied decimally, giving the other units of those measures. Consequently, in the metric