« SebelumnyaLanjutkan »
56 H. Doc. 26.
Oregon inlet, which has been watched with interest as holding out hopes of a new entrance important to the navigation of Albemarle and Pamplico sounds, does not, in its present state, afford much encourage*ment to such an idea. The harbor of Beaufort appears to be less liable to deterioration than other points on this part of the coast, and may be pronounced equal, in its security and natural facilities, to any port of our eastern coast south of the Chesapeake. It allows 17 feet to be carried in at low water. A survey has been made of the Fryingpan shoals, (of which there appears to have been heretofore but little correct knowledge,) and of the approaches to the bars of Cape Fear river. The description of the shoals and channels, and the recommendations on the subject of lights and buoys, resulting from this examination, will be found at length under their proper head. A survey of Cape Fear river, interior to this, is also in progress. An examination of Hatteras inlet has been made, in reference to, which it is reported that “No important perceptible changes had taken place on the bar or in the channel, except near the anchorage; the sand and spits had become better defined, and the area of the anchoring ground had increased, with a greater depth of water as far as the bulkhead. No greater depth of water over the outer bar and on the bulkhead was found.” The deep-sea soundings and soundings for temperatures in the Gulf Stream have been prosecuted during the season in this section. Astronomical, telegraphic, and chronometer obserrations.—These were under the charge of assistant Sears C. Walker. The scheme as organized was to determine the longitude of Portsmouth, Virginia, by the aid of telegraphic connexion with the Seaton station at Washington city, and from the former to deduce that of Forbes' Point, a station about forty-five miles distant, by the daily transportation of chronometers. In preparation, the chronometers had, for six weeks, been daily compared and rated by transit observations at Washington. Assistant Pourtales and Mr. J. R. Offley conducted the chronometric expedition, comparing night and morning, by coincidence of beats, the chronometers daily exchanged between Portsmouth and Forbes' Point. The former made the transit observations at Forbes' Point, and Mr. J. C. Langton those at the Washington station. Assistant Walker superintended the exchange of clock signals on the Seaton chronograph. The observer at Portsmouth tapped on the break-circuit key every five seconds for one minute, for each chronometer, and the hour and minute thus tapped were noted, the signal being registered by the instruments at Portsmouth, Petersburg, and Washington. During seven days the success of the observations and exchange of signals had been amply favorable, when their progress was temporarily arrested by prolonged failure of the telegraph line after a storm. The operation was continued as far as the means at our disposal and the other exigencies of the season's service permitted. It is not considered, however, as completed. Reconnaissance, (sketch D.)—The party and vessel employed in the tertiary triangulation were, for about six weeks, withdrawn from that duty and assigned to the use of Major H. Prince, United States army,
assistant in the coast survey, who made the reconnaissance and accompanying sketch of the sound usually known as “Pamlico.” Major Prince refers to good maps, to the usage of the neighborhood, and to the oldest authorities, as condemning this orthography, and gives Pamplico as the name which appears to have the weight of authority in its favor.
Describing this sound, Major Prince says: “Its breadth from Roanoke island to Long shoal increases from nine to eighteen miles, and in the rest of its length it has a general breadth of from twenty to thirty miles. The general depth of the channel is from three to four fathoms." He notes the fact mentioned by Williamson, a historian of the State, forty years ago, that lands then planted with corn were covered with water at the beginning of the eighteenth century; and observes that it the same causes, whatever they may be, continue to operate, there will be large tracts of the richest possible soil reclaimed for cultivation along this coast. A growth of small live-oak about Ocracoke, it is remarked, vigilantly preserved, protects the soil from the action of the winds.
The exposure of this sound is such that navigation is often danger-, ous, and vessels have to put back some distance for refuge. Yet the desired harbors are reported to be numerous and convenient, and, to be useful, require only to be made known.
With reference to Core sound, the supposed changes of which had caused the legislature of the State to request its examination, Major Prince reports that he has carefully compared it with the chart of a survey made by Captain T. J. Lee, United States topographical engineers, in 1837. The result is thus stated: “A few small differences of soundings, (we having no tidal observations, and some small differences of the course (allowance being made for some dredging, of which I have no account, on Piney Point shoal)-in the main, leave the present channel and that of the chart, as it was fourteen years ago, alike.”
The sketch by Major Prince, above referred to, shows the scheme for the main triangulation obtained by his reconnaissance.
Secondary triangulation, (sketch D.)- In the season of eight months, (November to July,) assistant J. J. S. Hassler extended this branch of the work along Currituck sound, from Thoroughfare island to the Virginia line. The area embraced was 73 square miles; 12 stations were occupied, and 11 determined; and 871 angles measured by 5,226 observations. The party had the use of the Coast Survey schooner Vanderbilt.
A secondary triangulation, and the requisite topography connected with it, of the entrance to Cape Fear river, was executed by assistant Charles P. Bolles, aided by Mr. J. W. Gregorie, and the results immediately computed and furnished to the hydrographic party working at the same point. A preliminary base, rather exceeding three miles in length, was measured with a chain upon the beach. (See sketch D, No. 6.) From its extremities nearly every important point in the harbor can be seen, and “the triangles are so disposed as to give double determinations of nearly every point of the second order, and of every point of the third order.” The work covers an area of 33 square miles; 8 stations were occupied, and 97 angles, on 17 objects, measured with a six-inch repeating theodolite by Gambey, (C. S. No. 35.) The plane
table survey connected with it furnished 52 miles of shore line, and included the town of Smithville.
The party of assistant Bolles had already been engaged in section V, and were transferred to this section in June, remaining until the close of September.
Tertiary triangulation, (sketch D.)- A party, under sub-assistant A. S. Wadsworth, aided by Mr. C. T. Jardella, with the Coast Survey schooner Bancroft, was engaged in this triangulation from early in December until late in March. It was then withdrawn for use in reconnaissance, and, after some weeks, again occupied, for a short time, in marking with granite posts the most important stations of the preceding year.
The triangulation extended from Cape Hatteras to Ocracoke inlet, 35 miles along the coast, and covered an area of 974 square miles; 19 stations were occupied and 77 angles measured, by 450 observations, with a six-inch repeating theodolite of Gambey, (C. S. No. 29.)
Topography, (sketch D.)- Assistant Henry L. Whiting spent a month, with a party and vessel, in a topographical survey of the harbor of Beaufort. His work will, in connexion with other surveys, furnish a complete harbor chart. For the gratification of those specially interested, I annex descriptive extracts from his report. (See Appendix, No. 28.)
The amount of work accomplished may be thus stated: Area, in square miles, 22; extent of shore line, 39 miles; outline of shoals, &c., 15; length of creeks, 18; and of roads, 16 miles.
Assistant Whiting points out the causes which, in his opinion, tend to preserve the interior of this harbor from change, and the same general depth of water on the bar. These will be found in the Appendix, as above referred to; though I am not prepared to endorse the views expressed in reference to currents caused by Cape Lookout.
Hydrography.—(See the several sketches.) Lieutenant Commanding Richard Wainwright, United States navy, assistant in the coast survey, with the surveying schooner John Y. Mason, was engaged in this section during the latter part of 1850, and from April to June, 1851. The hydrography of Roanoke and Croatan sounds, with the small portion of Albemarle sound remaining from last year, has been completed, and that of Currituck sound carried north, as far as the points marked Woodis and Willet's on the sketch. Thirty-three thousand eight hundred and seventeen soundings were made; 1,066 angles taken; and 496 miles of soundings run; nearly all done in boats.
Lieutenant Wainwright also visited Oregon inlet. He found the breakers extending entirely across the bar. The bulkhead towards Albemarle sound remains unchanged, having about three feet of water at mean tide.
Lieutenant Commanding J. N. Maffitt, United States navy, assistant in the coast survey, with the hydrographic party under his command, (which has been for the most part employed in Section V,) visited this section in December last to complete the hydrography of Beaufort, North Carolina; and has furnished a chart of the bar and harbor. (Sketch D, No. 5.)
The statistics of this supplementary work in Beaufort harbor are as
interior dhe bar. am not prepy Cape
follows: 53 miles sounded over by 1,289 soundings; 88 angles mea-
Area of hydrographic sheet---------------------- 250 sq. miles.
The report of Lieutenant Commanding Jenkins on the Fryingpan shoals, and his suggestions in reference to the facilities required for navigation, are of such interest that I extract them in full: “The Fryingpan shoals—extending from the southeast point of Cape Fear, in almost a SSE. direction from Bald Head light-house to the distance of twenty nautical miles, to ten fathoms water, with an average width of four miles—and the approaches to the main and New Inlet bars at the mouth of the Cape Fear river, have been carefully surveyed, and the sheet is now nearly ready for reduction to the publication scale. “The pilots and others in the vicinity had little correct knowledge of these dangerous shoals, and the great distance to which they extend from the shore rendered the work one of more than ordinary difficulty. “The shoalest spot outside of Bird shoal, (near the point of the cape,) has 7, 8, and 9 feet water on it at low water, distant 13 nautical miles from Bald Head light-house, and bearing NNW. from it by o: “There is another shoal spot with ten feet water at low tide, 14%
nautical miles from Bald Head light-house, and bearing NNW. A. W. from it. Two small shoal spots, 16 and 18 miles from light-house, with 16, 17, and 18 feet water on them at low water, bearing SSE. E. to SE. by E. from light-house. The sea breaks on these shoals, except in very calm weather. “Bald Head light-house bears by compass NW. # N. from the eastern point of the Fryingpan shoals, in 6, 7, and 8 fathoms water; coarse gray sand, broken shells, and pebbles, at the distance of twenty nautical miles. “Bald Head light-house bears per compass NW. by N. from the southeastern point of the Fryingpan shoals, in 8, 9, and 10 fathoms; fine gray †. black specks; distant twenty nautical miles. “Not less than 16 feet water will be found outside of the ten-feet shoal, which bears SSE. A. E., distant fifteen nautical miles from the Bald Head light-house. “The bottom is well marked on either side of the shoals. On the west side, and at the southeastern extremity of them, fine gray sand with black specks will be found. On the eastern and northeastern side of them broken shells, coarse sand, pebbles, and occasionally small pieces of coral. “A line made good, SSE. by compass, from the main bar of Ca Fear, will clear the western edge of the three-fathoms curve of the shoals. “Wessels bound around the shoals to the eastward from the bar should steer out S. by E. to the distance of sixteen to eighteen miles, in eight to ten fathoms water, when an east course will pass on the outer part of the shoals in three fathoms to seven fathoms water. “These shoals may be said to be continuous from the point of the . to ten fathoms water, although at the distance of fourteen nautical miles, Bald Head light-house bearing NNW., there is a channel running SW. by S., and NE. by N., of upwards of a nautical mile in width, through which a depth of three and half to five, six, and seven fathoms water may be carried at low tides; but the shoals on either side, with only seven, eight, and nine feet to the northward, and ten feet to the southward and eastward, and nothing but the compass and lead to guide the navigator, in the absence of a light-vessel or buoys, render it too dangerous to be available. “Vessels drawing not more than nine and ten feet water can cross the shoals at low water by steering ENE., and WSW., at the distance of three to four nautical miles from the point of Cape Fear; and there is a channel between the distances of five and a half to eight and a half nautical miles, through which vessels drawing ten and a half and eleven feet can pass with perfect safety at low tide; the channel is three nautical miles wide, and with the exception of two or three small spots of ten and a half and eleven feet water, thirteen to fifteen feet will be carried through it; the courses are from NE. to ENE., and SW. to WSW. “At a point of the shoals (Bald Head light-house distant eleven nautical miles, and bearing N. by W. H. W.) there is a channel of two and a half fathoms water, upwards of a nautical mile wide. It is in