Stewart's Extra Subjects. Physical Geography. 1st (-3rd) Year

Stewart's Extra Subjects. Physical Geography. 1st (-3rd) Year

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1884 edition. Excerpt: ... diurnal rotation on its axis from west to east. Thus at Ushant, off the north-west coast of France, if the meridian of that point be under the moon at twelve o'clock, it is not till three o'clock that the high tide is perceived. This is because it takes some time to set the water in action in raising up the crest, and this action keeps on for some time after the cause is withdrawn. You can understand this by thinking of the similar effect of the sun in causing the seasons. The hottest time of the year is not on the longest day, and when the sun is most nearly vertical overhead, but some time after this, as in the month of July in the northern hemisphere. So again the coldest day is not on the shortest, but some time after, as in the month of January in the northern hemisphere. Again, the tides do not rise and fall always to the same extent respectively at spring and neap tides, but sometimes we have extreme spring tides, when the rise and fall are greater than the average of spring tides, and at other times we have more limited neap tides, when the rise and fall are less than the average of neap tides. This is because the moon is not always at the same distance from the earth. That point of time when the moon is nearest the earth is called her perigee, and it is then that the highest tides take place, since the attraction of the moon on the earth is dependent on her distance from us. It might be thought that the difference of distance between the moon at perigee, dhd her distance at apogee, when she is farthest removed from us, would make but little difference on the relative rise and fall of the tides, as this difference oi distance is but small; but it must be remembered that the attraction does not vary as the distance, but inversely as the...
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Product details

  • Paperback | 40 pages
  • 189 x 246 x 2mm | 91g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 123663344X
  • 9781236633446