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Tidal Indicator in Delaware River, Delaware

The position of the tidal indicator established on the northern end of the ice breaker at Reedy Island Quarantine Station is shown on the charts.

The indicator appears as a large semicircle painted white, and faces up stream. The inner edge of the semicircle is divided into spaces by heavy black lines representing feet and half-feet. The longer of these division lines are numbered by figures in black.

A pointer, actuated by the rise and fall of the tide, turning about the center of the circle, sweeps along the inner edge of the graduations and indicates, at any moment, the number of feet of water above or below the plane of reference (mean low water) to which soundings on the charts are reduced. The minus sign, shown near the left edge of the indicator, indicates the number of feet below the plane of reference.

An arrowhead, placed in the center of the disk, is made to point up while the tide is rising and down while it is falling. A glance at the indicator will enable the navigator to tell the height of the tide, whether above or below mean low water, and whether it be rising or falling.

The division lines, figures, pointer, and arrowhead can readily be seen at the distance of about a mile with the aid of an ordinary marine glass.

The ebb and flood currents in the vicinity continue to flow for quite a period after the water has begun to rise or fall. The arrowhead indicates whether the water is actually rising or falling, regardless of the direction in which the current may be running at the time.

The tide tables, published annually by this office, give the times and heights of the tides for each day, but these may be greatly modified by meteorological disturbances that can not be foreseen and can not enter as elements in the calculation of the tables. The predictions taken from the tide tables may not, therefore, represent the actual condition of the tides. The tidal indicator, however, shows the actual state of the tide at all times. Outward-bound vessels, when about a mile above, should be able to read the indicator with the aid of an ordinary marine glass, observe the stage of tide, and note whether it be rising or falling.

Should it be found that a vessel is too deeply laden to cross Baker Shoal at the stage of tide indicated, she will have sufficient time to anchor before the indicator is reached, and be in a position from which it may be watched until it shows that the shoal may be safely passed.

The cut shown herewith will enable anyone to understand the operation of the indicator. It shows a falling tide at 14 feet above the plane of reference. · W. W. DUFField,

Superintendent U. S. C. and G. Survey.

Measured Mile for Speed Trials

A course of exactly one statute mile (of 5280 feet) has been laid off on the New Jersey side of the Delaware River at Deep Water Point, by the Harlan & Hollingsworth Co. Each end of the course is marked by two upright range poles, painted white, with black balls on top. The upper or northerly range poles are at Deep Water Point, and are 371 feet apart; the lower, or southerly range poles are 260 feet apart; the bearing of the mile course between the two ranges is S. W. by S. 1⁄2 S. magnetic, and the distance one statute mile of 5280 feet.

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List of Ship-Building Yards, Dry Docks, Marine Railways and Engineering Works on the Delaware River

The Wm. Cramp & Sons Ship and Engine Building

Company

The Penn Works, Neafie & Levy

The Delaware River Engineering and Iron Ship

Building Yard, Wm. Roach

The Harlan & Hollingsworth Co., Iron Ship Build

ing Yard

Pusey, Jones & Company

The Jackson & Sharp Co

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Camden, N. J.

14

(Furnished by the U. S. Coast and Geodetic Survey.)

TIDE TABLE.

Showing time of High Water at 109 Stations on the Atlantic Coast by differences from Philadelphia, Penna. To find the time of High Water at any of the following ports, apply the correction set opposite the port to the time of High Water at Philadelphia on the date wanted. Example: Find the time of the High Waters at Fernandina, Florida, on July 4, 1901.

From the table for Philadelphia it is seen that the high waters there on July 4, 1901, occur at 3:08 a. m., and 3:31 p. m., which increased by 5:50 the tabular difference for Fernandina, gives 8:58 a. m. and 9:21 p. m. as the required times.

Time of High Water at Philadelphia will be found on page 16-17.

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Newcastle Reporting Station, Delaware River

Schooner Ledge. Delaware River

Pennsylvania Quarantine Station, Delaware River

Marcus Hook Reporting Station, Delaware River

Cherry Island Flats, Delaware River

Wilmington (Ent. Christiana Creek) Delaware River
Deep Water Point, Delaware River....

Fort Delaware, Delaware River.

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Brandywine Shoal Light House, Delaware River........
Cape Henlopen, Delaware

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Delaware Breakwater Reporting Station, Del. River
Cape May City, N. J...

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North East End Light Vessel.

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Eastern Standard Time-Five Hours Slower than Greenwich Time.

Washington

TIME OF HIGH WATER AT PHILADELPHIA, PA., 1901.- Street Wharf.

Furnished by U. S. Coast and Geodetic Survey Office.

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MEAN RANGE OF TIDES AT PHILADELPHIA-6 FEET.

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