Identifier: elementsofastro00youn (find matches)
Title: The elements of astronomy; a textbook
Year: 1919 (1910s)
Authors: Young, Charles A. (Charles Augustus), 1834-1908 Young, Anne Sewell, b. 1871., ed
Subjects: Astronomy Constellations
Publisher: Boston, New York (etc.) Ginn and Company
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
ree then travels northward through the Atlanticat the rate of nearly 700 miles an hour. It is about forty hours oldwhen it first reaches the coast of the United States in Florida; andour coast is so situated that it arrives at all the principal ports withintwo or three hours of that time. It is 41 or 42 hours old when itreaches New York and Boston. To reach London, it has to travelaround the northern end of Scotland and through the North Sea, andis nearly 60 hours old when it arrives at that port, and at the ports ofthe German Ocean. In the great oceans, there are thus three or four tide crests travel-ling simultaneously, following each other nearly in the same track,but with continual minor changes. If we take into account the tidesin rivers and sounds, the number of simultaneous tide crests must beat least six or seven; i.e., the tidal wave at the extremity of its travel(up the Amazon River for instance) must be at least three or fourdays old, reckoned from its birth in the Pacific.
Text Appearing After Image:
196 TIDES IN RIVERS. (§ 276 276. Tides in Rivers. — The tide wave ascends a river at a ratewhich depends upon the depth of the water, the amount of friction,and the swiftness of the stream. It may, and generally does, ascenduntil it comes to a rapid where the velocity of the current is greaterthan that of the wave. In shallow streams, however, it dies out ear-lier. Contrary to what is usually supposed, it often ascends to an eleva-tion far above that of the highest crest of the tide wave at the rivers mouth.In the La Plata and Amazon, it goes up to an elevation of at least 100feet above the sea level. The velocity of the tide wave in a riverseldom exceeds 10 or 20 miles an hour, and is usually much less. 277. Height of Tides. — In mid-ocean, the difference be-tween high and low water is usually between two and threefeet, as observed on isolated islands in deep water; but oncontinental shores the height is ordinarily much greater. Assoon as the tide wave touches bottom, so to spea

Note About Images