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has been followed with so much success by the Coast Survey, in combining the strictest scientific methods with its practical operation. Respectfully submitted :

L. AGASSIZ. Professor A. D. Bache,

Superintendent of the Coast Survey.

APPENDIX No. 11. List of Coast Surrey maps, sketches, and preliminary charts, engraved and

engraving.

1. LIST OF MAPS ENGRAVED.

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No. 1. -New York bay and harbor and approaches....... 2. .. Do......do......do......do......No. 1...

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...Do......do......do......do......No. 6... 8. Map of Delaware bay and river and approaches, No. 1 9. Map of Delaware bay and river and approaches, 2d

engraved plate, No. 1......... 10. Map of Delaware bay and harbor and approaches,

No. 2...... 11. Map of Delaware bay and harbor and approaches,

No. 3.............. 12. The harbor of New Bedford..... 13. The harbor of New London .... 14. Fisher's Island sound....... 15. Holmes' Hole and Tarpaulin Cove harbors 16. Oyster or Syossett bay... 17. Little Egg harbor...... 18. Harbor of Annapolis .... 19. New Haven harbor........ 20. Harbor of Edgartown ..... 21. Harbors of Black Rock and Bridgeport. 22. Huntingdon bay ........ 23. Nantucket harbor ..., 24. Harbor of Sheffield and Cawkin's islands .. 25. Mouth of Chester river...... 26. Harbors of Captain's islands, east and west 27. Long Island sound, sheet No. 2.......... 28. ....Do........do......No. 3..... 29. Re-engraving lower sheet of the Delaware 30. Pasquotank river.... 31. Cat and Ship Island harbors....

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32. Harbor of Hyannis....
33. South side Long Island, No. 1.......

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34. Hart and City islands and Sachem's Head.
35. Mobile entrance.
36. Chart of Hell Gate.
37. Richmond's Island harbor.......................

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2. LIST OF SKETCHES AND PRELIMINARY CHARTS ENGRAVED.

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1. Sketch chart of Nantucket shoals, (3d edition)...... ooooo
2. ....Do.......Buttermilk channel, New York harbor 5000
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5. ....Do....... Bull's Bay harbor .....

10000 ....Do..... .. Beaufort harbor, North Carolina...

....Do..... .. St. Andrew's shoals, Georgia....... 60000 8. .-..Do....... Nantucket shoals, re-engraved and enlarged ......................

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120000 13–15. Reconnaissance chart (McArthur's) western coast. 16. Richmond's island ...

20000 17. Sketch chart of Nantucket shoals...... ......... 200'000 18–20. Second edition McArthur's chart western coast.

21. Hatteras inlet, re-survey.... 22–26. Five diagram maps Cat Island tides. 27. Reconnaissance of Mosquito inlet. .......

10000 28. ......Do....... Horn Island pass ....... 29. Sketch of Point Conception....

40000 30. Sketch of Point Pinos and bay of Monterey

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41. Holmes' Hole. 42–48. Seven maps of progress and geographical positions for

annual report.

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3. LIST OF MAPS ENGRAVING.

No. 1. General chart of the coast......

2. No. 1, Long Island sound ...
3. No. 1, Chesapeake bay..

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No. 4. Patapsco river.......

5. No. 2, south side Long Island..
6. No. 1, eastern series.
7. Boston harbor.......
8. Muskeget channel..
9. Charleston harbor.
10. Key West...
11. Connecticut river ....
12. No. 2, Mobile bay....

.... TODOS 4. List OF SKETCHES AND PRELIMINARY CHARTS ENGRAVING. No. 1. Seacoast of Delaware and Maryland; plate enlarged

by electrotyping additional engraving, work of hy

drographic parties ........... 2. Beaufort harbor..... 3. Preliminary chart of Humboldt bay... 4. Preliminary chart of the harbor of Key West Tooooo 5. Sketch of the entrance of the Chesapeake.. 6. Re-engraving Nantucket shoals...... 7. Chart of the harbor of San Diego. 8. Entrance of San Francisco ........... 9. Savannah river, vicinity of Savannah 10. Savannah entrance......... 11. Mobile bay ............... 12. Bull's bay, re-engraving...

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17. Point Pinos, view.

18. View of mouth of Columbia river. 19-26. Eight maps of progress and geographical positions.

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APPENDIX No. 12.

List of geographical positions determined by the United States Coast Survey.

The present list contains those geographical positions determined by the Coast Survey of the United States which may be supposed to be useful to the navigator, the geographer, and the surveyor. They enrbrace all the trigonometrical points of the coast survey, determined up to July, 1850, and also positions of a number of prominent objects determined by means of the plane-table.

For the purposes of the survey, the coast of the United States is divided into eleven sections, in all of which the work is carried on simultaneously. The survey being in different stages of progress in the several sections, and new results being added from year to year to those here given, the same divisions have been adopted in this publication. The several sections are defined as follows:

Sec. I. From Passamaquoddy bay to Point Judith.
Sec. II. From Point Judith to Cape Henlopen.
Sec. III. From Cape Henlopen to Cape Henry.

Sec. IV. From Cape Henry to Cape Fear.
Sec. V. From Cape Fear to the St. Mary's river.
Sec. VI. From the St. Mary's river to St. Joseph's bay.
Sec. VII. From St. Joseph's bay to Mobile bay.
Sec. VIII. From Mobile bay to Vermilion bay.
Sec. IX. From Vermilion bay to the Rio Grande.
Sec. X. Coast of California, San Diego bay, to 42d parallel.
Sec. XI. Coast of Oregon, 42d to 49th parallel

The tables give the latitudes and longitudes of the trigonometrical points in each section, and their relative azi,nuths, or bearings, and distances. The manner in which these data have been obtained may be briefly explained here:

In each section a base line of from five to ten miles in length is measured with all possible accuracy. A series of triangles, deriving the length of their sides from this base, is then established along the coast, by the measurement of the angles between the intervisible stations. In this primary series the triangles are made as large as the nature of the country will permit, because the liability to error increases with the number of triangles.

On the bases furnished by the sides of the primary triangles, a secondary triangulation is next established, extending along the coast, and over the smaller bays and sounds, and determining a large number of points at distances of a few miles apart.

The distances between the points thus determined, as given in the tables, are liable to an average error of about one foot in six miles, until a final adjustment between the base lines shall have been made.

As, on the completion of the primary triangulation in each section, the several series form one connected chain, the different bases afford verifications of each other, and of the triangulation connecting them. The first three sections are thus connected at present.

Observations for latitude and azimuth are made at a number of stations of the primary triangulation in each section. The differences of latitude, longitude, and azimuth between these and other stations are then computed, under the supposition that the earth is a spheroid of revolution of the following diinensions, which are those determined by Bessel from all the measurements made to the present time, viz:

Equatorial radius=6377397.15 metres.
Polar radius =6356079.11 “

Eccentricity = 0.0816968 It has been found that the differences of latitude and longitude, as computed in this manner from the distance and azimuth between two stations, and which are called geodetic, differ from those obtained by astronomical observations at the several stations, by quantities which are greater than the errors of the observations. Such disagreements are due to local irregularities in the figure and density of the earth, and the error resulting from them in the determinations of latitude and of the meridian plane is designated as station crror. It amounts, according to the results obtained at present, to between one and two seconds of arc in the eastern section of the survey, and to about half a second in the sections south of the Delaware.

In order to eliminate the influence of station errors on the general results, observations are made at a number of stations; the results are referred to a central station by means of the geodetic differences, and the mean of all is used for the computation of the positions given in the tables. The geographical positions inust therefore be considered as liable to future changes, from the accumulation of new observations, and the final discussion of all the results obtained.

The differences of longitude are obtained, as has been stated, by computation, from the distances, latitudes and azimuths of the triangulation. In adding up these differences, from station to station, an accumulation of the unavoidable errors is highly probable. They are checked, however, by differences of longitude, determined by means of the electro-magnetic telegraph, in every section where the introduction of the latter makes it practicable.

SEATON STATION, in Washington city, has been selected as the centre for the telegraphic differences of longitude. The Sections at present connected by telegraph are Sections I, II, III and V. The first three being also connected by triangulation, the check on the geodetic differences of longitude is here obtained, and the agreement is very close.

The longitudes from Greenwich depend upon that of Cambridge observatory, as determined by chronometric differences between Liverpool and Cambridge, and by occultations, eclipses and moon culminations, observed at various observatories in the United States, and referred to Cambridge by means of telegraphic differences. The following statement shows the result up to the present time: Longitude of Cambridge from Greenwich.

h. m. 8. By moon culminations observed at Cambridge, Hudson,

Ohio, Wilkes' observatory, and National Observatory 4 44 28.4 By eclipses and occultations at Cambridge, Brooklyn,

Philadelphia, and Wilkes' observatory............ 4 44 29.6 By chronometric differences....................... 4 44 30.1

The longitude adopted for the present is 4h. 44m. 29.5s., or 71° 07' 225.50.

In Sections IV, VI, VIII, IX, and X, the longitudes are counted from some central station in each. Sections IV and VIII will soon be connected by telegraph with Seaton station and Cambridge. In Sections VI and IX the longitudes from Greenwich will for some time depend upon less exact determinations. For the present we have the following data:

o i ir Sec. IV. Stevenson's Point, west of Greenwich......... 76 10 43.5 Sec. VI. Cape Florida..........ditto............. SO 05 00

66 66 Saud key.............ditto............. *81 52 43 Secs. VIII and IX. Fort Morgan, Mobile Point......... 88 00 25 Sec. X. Coast Survey observatory, near San Diego....*117 13 22

Explanation of the tables. The first column on the left contains the name of the several stations or triangulation points. Their general locality is indicated by the

* Corrected from data to November, 1852.

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