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LATITUDE AND LONGITUDE
Of the Principal Points on the Pacific Coast, determined by George Davidson, U. S. Coast Survey.
Name or Station.
Coast Of California.
Point Lnma Ligkt-Houu
Point Cnncrption Liqht-Houee.
San Luis Obispo
Coast Of Oregon.
Coast Of Washington.
San Plego Bay
Observatory Hill, near La Playa
North Anchorage of Island, Santa Barbara Channel.
Island of San Miguel,
Valley of "El Coxo,"""
Beach west of Creek
Near the Landing
Near Monterey, Monterey Bay
Off the entrance to Pan Francisco Bay
South Head ot entrance to San Francisco Bay
Near Presidio of San Francisco
Near McGregor's Observatory
South side of entrance to San Francisco Bay
Sir Francis Drake's Bay
Bodega Hay, west end of Sand Spit
On Bluff near Landing
III.—TIDES AT SAN FRANCISCO, CAL.
[By Prof. A. D. Bache, Superintendent U. S. Coast Survey.]
Besides the ordinary changes in the time and hight of the tides known to all navigators, it is important to note the following, generally applicable to the Western Coast, and particularly to San Francisco Bay. They relate to peculiarities in the tides which occur on the same day, the necessity for knowing which is shown by the fact that a rock having three and a half feet of water upon it at low tide, may, on the same day, at the succeeding low water, be awash:
1. The tides at Eincon Point, in San Francisco Bay, consist generally of a large and small tide on the same day; so that of two successive high waters In the twenty-four hours, one is much higher than the other, and of the two successive low waters, one is much lower than the other.
2. The difference in hight of two successive tides, either high or low waters, varies with the moon's declination. When the declination is nothing, the difference is nothing or very small. When the declination is greatest, whether North or South, the difference is greatest. When the moon's declination is nearly nothing, the intervals between two successive high, or two successive low waters, are nearly twelve hours, and differ most from this when the moon's declination is greatest
3. The inequalities in the hights of successive low waters are more considerable than those of successive high waters; while, on the contrary, the inequalities in the times of high water are more marked than those of low.
4. The average difference between the hights of two successive high waters is one foot four and a half inches, and of two successive low waters two feet four inches. The average difference of these same hights, when the moon's declination is greatest, is for the successive high waters two feet, and for the low waters three feet six inches.
6. The average variation from twelve hours, in the interval between two successive high waters, is three-quarters of an hour, and between two successive low waters, half an hour. The average variations of the same intervals when the moon is furthest from the Equator, are, respectively, one hour, and three-quarters of an hour.
6. When the moon's declination is North, the higher of the two high tides of the twenty-four hours is the one which occurs about eleven and a half hours after the moon crosses the meridian; and when the moon's declination is South, the one which occurs about one and a half hours after the moon's meridian passage.
6. Bis. Or, the following rule may be used, which applies when the moon crosses the meridian between midnight and 11£ A. M., or between noon and Hi P.M.
If the moon is South of the Equator and passes the meridian in the morning, the high water will be higher than the afternoon high water; if it passes the meridian in the afternoon, the afternoon high water will be the higher.
If the moon is North of the Equator, and passes the meridian in the morning, the afternoon high water will be the higher.
T. The lower of the two successive low waters of the twenty-four hours, occurs about seven hours after the higher of the two high waters.
8. The average difference between the hight of the higher high water and of the lower low water, is five feet eleven and a half inches, and the greatest difference is seven feet ten inches.
The above rules were drawn up so as to avoid technical terms.
IV.—METEOROLOGICAL OBSERVATIONS, Made At San Francisco, From January, 1851, To January, 1858.
[By Henry Gibbons, M. D.]
Most of the subjoined tables explain themselves sufficiently. Those relating to rain being of the greatest interest and importance to California, are given in detail. Table 6 shows every rain that has fallen since 1850. December appears to have been the most rainy month, but there is one day, the 8th of December, on which no rain fell in the entire period of seven years. A marked abatement of rain is observable from about the middle of January to the middle of February. One-third of the average yearly rain falls before the first of January, one-third in January and February, and the remaining third subsequent to the first of March. March and April supply nearly as much rain as any other two months. In 1853, there was nearly five inches in April, and in 1855 upwards of five and a half inches. In the latter year more than two inches fell in May.
1. TABLE OF MEAN TEMPERATURE, Showing the Mean Temperature of each Month at Sunrise and at Noon, and the Mean of the
2. TABLE OF CLOUD AND MIST FOR 1857,
Showing the proportionate Time in each Month when the Sky was Clear and Cloudy, given in Days; the number of Days when the Sky was Clear, from Sunrise to Sunset, and the number Cloudy; the number of Days on which Rain fell, and the number of Days on which there was more or less Mist.
3. TABLE OF WINDS FOR 185*.
The direction of the Wind is noted three times a Day, so that three Observations in the Table
From the foregoing table it appears that the greatest degree of cold at San Francisco, in seven years, was twenty-five degrees, or seven below the freezing point. This may be set down as nearly the extreme cold ever felt here. In three of the years the mercury did not fall to the freezing point In 1853 the lowest point was eight degrees above freezing.
The extreme of heat was ninety-eight degrees—a very unusual temperature for San Francisco, though much below the greatest heat in the interior. In 1856 the highest temperature was eighty-five, and in 1851 the thermometer did not rise above eighty-four.