3. Field of work.-Between Block Island and Gay Head.

"The hydrography of the Nantucket shoals (sketch A, No. 2) embraced the completion of the survey of the shoal to the north and west of Davis's bank, the re-examination and continuance of the survey of Davis's bank, and the determination of a part of Fishing Rip.

"The shoal north of Davis's bank is only separated from the Great Rip by a narrow slue, and may be regarded as merely the southern extremity of that shoal.

"Davis's bank is found to extend upwards of seven miles to the southward of its supposed limits in that direction, but our opportunities did not enable us to reach and determine its extreme southern point. The Fishing Rip is only generally established as to position.

"To determine its outline, extent, shoalest water, and general characteristics, will require a more extended and minute examination than it was in our power to bestow on it during the season.

"The past summer has been marked by an extraordinary prevalence of fogs and gales, which have seriously interrupted our operations, and limited the results."

On closing this part of the work Lieutenant Commanding Mc Blair, in the steamer Bibb, proceeded to Wellfleet to examine changes which were alleged to have been made, in the great storm of April last, in that harbor. The verification of the hydrography did not show such changes. The party next completed the hydrography of Salem harbor; and the means disposable for this portion of the work being exhausted, the steamer was laid up at Boston, and the officers, detailed for office duty, reported for the discharge of it at the Coast Survey office in Washington. The supplementary report of Lieutenant Commanding Mc Blair states the work in Salem harbor as follows:

"The survey embraces the harbor and approaches of Salem, Beverly, Manchester, and Marblehead.

"It has been executed almost altogether in boats, and necessarily with more than usual minuteness, in consequence of the numerous ledges and shoals which obstruct the passages.

"We commenced operations on the 3d instant, and finished on the 15th. The following table exhibits the amount of work performed, and the results obtained:

Area within limits of sounding lines..

Number of miles of soundings..

Number of casts of lead..

Depth of water sounded in.

21 square miles. 176 ..7.424

.from 3 feet to 23 fathoms.

"Observations were made in the main ship-channel, to determine the direction and force of the current."

Lieutenant Commanding Swartwout, in the brig Washington, was detached, for a part of the season, in this section, upon the survey of No-Man's-Land channel, between the island of that name and Martha's

Vineyard island, and also upon off-shore soundings, between the meridians of Gay Head and Beaver Tail.

The survey comprised an area of 14 square miles, in which 1,200 soundings were made, and 81 angles observed, the depth of water varying from 8 feet to 11 fathoms. The off-shore work consisted of 160 soundings, over 3 lines, the total length of which was 176 miles.

In execution of his instructions, Lieutenant Commanding Woodhull, United States navy, assistant in the coast survey, in the schooner Madison, has occupied 8 stations in the Vineyard sound, (see sketch A,) and 2 at the entrance of the passages between Buzzard's bay and the sound, for currents, and 9 stations for tides. The tidal observations, during two lunations, were made at eight points as nearly identical as practicable with those at which partial results were obtained last year, and after this period two of the gauges were removed to points near the middle of the length of the passage, Quicks' and Wood's Holes, and simultaneous observations were again made.

Lieutenant Commanding Woodhull states, in his report:

"During the observations I had all due care and attention paid to the regulation of the time. I visited the stations frequently, to see that the duty was faithfully and carefully performed. The books have been well kept; observations of wind and weather have been made at all the stations. The barometer and thermometer have also been recorded with great care, both at Quicks' and Wood's Holes; in fact, I feel satisfied, as far as I could control circumstances, nothing has been neglected to insure favorable results. The tidal observations have been conducted agreeably to your directions in every respect, save observing them every hour for three consecutive days. I made all my arrangements to comply with your instructions in this particular, but did not succeed, owing to the constantly unfavorable state of the weather during nearly the whole of the time comprised in the two lunations." The current observations made are thus referred to; (see also sketch A):

"In connexion with the above, the observations of currents received my attention, and, I think, will prove satisfactory. The currents were observed during the first lunation at Nos. 2, 15, 16, 17, 18, 19, and 20. On the second lunation, Nos. 3, 7, 10, 15, 16, 17, 18, and 19.

"When the stations were occupied the weather was calm, occasionally foggy, with a rather smooth sea. This state of the weather, though not highly favorable, was sufficiently so to ascertain the correct directions and force of the currents. Four consecutive tides were taken at each of these stations, two ebbs and two floods, and the velocity on the surface and fifteen feet below it. You will perceive I did not fail to take advantage of all the good weather that offered, and the results. have been nearly twice that of last year, and four times as great as those of the year before."

The number of observations of tides was 2,817 during the year, and of currents 978 on 16 days.

Leaving the tidal observations in charge of a part of the officers of his party, Lieutenant Commanding Woodhull proceeded to Chatham harbor and made the preliminary survey to which I have already alluded.

The party next executed the soundings of the approach to Portsmouth harbor, New Hampshire, and of the intricate channel behind the navy-yard at Kittery, Maine. The area of the off-shore work was 77 square miles, extending to the Isle of Shoals; 231 miles were run in sounding, 4,150 casts of the deep-sea lead made, and 380 angles for position observed. Lieutenant Commanding Woodhull states that the irregularities of the bottom are such as to render the soundings of comparatively little value in determining the position of a vessel on this part of the coast in thick weather. The tides will be observed at Portsmouth during at least two lunations.

The harbor of Newburyport, Massachusetts, and the approaches, have also been sounded out, by this party, seaward, between three and four miles, and about two miles and a half on both sides of the entrance. "The inside work extends from the bar to about a mile and a half above the railroad bridge; in all, a distance of three and a half miles, varying from three-eighths to one-half a mile in width." The area embraced is 20 square miles, in which 7,500 casts of the lead have been made, 175 miles have been run in sounding, and 632 angles for position observed. Tidal observations will also be kept up at Newburyport.

Lieutenant Commanding Woodhull is now (October 15) under instructions to proceed to Connecticut river for the re-examination of the entrance, and the work done will be stated in his supplementary report.

In his report of the season's work, Lieutenant Commanding Woodhull pays a well-merited compliment to the zeal and industry of the officers of his party, through whom so large an amount of work has been accomplished.

SECTION II.-FROM POINT JUDITH TO CAPE HENLOPEN, INCLUDING THE COAST OF CONNECTICUT, NEW YORK, PENNSYLVANIA, AND PART OF DELAWARE. (Sketch B.)

The field-work of this section has been of the usual miscellaneous character; parties being occasionally occupied, as they could best be spared from other sections, in filling up portions remaining unexecuted, or in revision where it has been found necessary. The office-work has advanced according to the estimates and plans for it at the beginning of the year; and the details will be found under the head of "Officework" in this report. Eighteen finished maps and charts have been published of this section, (three of which during the year,) besides two sketches.

In the immediate necessity for practical results for our work, it is often expedient to postpone questions of interest, which have a less important bearing, and yet without the solution of which the survey will be incomplete. Of this character is the question of tides and currents at a distance from the coast, but within the limits proper to the hydrography, the form of the bottom of the sea, and the like. Sections were made two years since for the off-shore map, embracing the space between Gay Head and Cape Henlopen, which showed the curious result of the sudden and rapid slope of the bottom of the sea, after the depth of one hundred fathoms was reached. This year I have attempted the other question, and have given the necessary instructions for its solu

tion at stations within the limits of the same chart, but the stormy character of the season has materially interfered with their execution.

This off-shore chart being the first of a series, the mode of arranging the details has occupied much attention; and each case requiring study, and not being a matter of routine, much more time has been unavoidably consumed than will be necessary in another chart. Successive improvements have been made, rendering the chart more valuable, but tending to delay the publication. It is now, however, certain that all the essential data for publication have been procured, so that a first edition can be issued; leaving those refinements which it is proposed to introduce till a later period.

The items in the light-house bill referred to me for examination, under the law of March 3, 1851, by the instructions of the Treasury Department, were the following:

"Connecticut. For a can-buoy on Peafield reef, off Black Rock harbor, in Long Island sound, in addition to a former appropriation in the act of September, 1850, one hundred and thirty-five dollars.

"New York.-For a light-house on Flynn's knoll, near Sandy Hook, thirty thousand dollars.

"For a light-house on the northern extremity of Gardiner's island, six thousand dollars.

"For the completion of two beacons near Fort Hamilton, two thousand dollars.

"For a beacon on the Sand Spit, in the harbor of Sag Harbor, seven hundred dollars.

"For four spar-buoys at Fire Island inlet, three hundred dollars. "New Jersey. For a fog-bell at the Newark light-house, two hundred and fifty dollars.

"For the completion of the beacon in Passaic river, four spar-buoys in the same, a spar-buoy at Mill Rock, and a beacon at the Corner Stake, near Elizabethtown Point, eight hundred dollars."

The spar-buoys for Fire island having been recommended by me on the report of Lieutenant Commanding Woodhull, the recommendation was simply repeated.

An examination of Flynn's knoll by the Light-house Board, raised a doubt as to the expediency of placing a light-house on that shoal. I suggested the alternative of range-lights, similar to the one approved for the main ship-channel, from its elbow near the Southwest Spit shoal through the Narrows-(see report to the Secretary of the Treasury in Appendix No. 23;) one set of ranges to lead from the entrance from Gedney's channel, through the main ship-channel, to the range for changing course to northward; another range to lead through the Swash channel, the importance of which cannot be exaggerated. The project includes the substitution of a beacon-light for the Elm Tree beacon. The two small, beacon-lights required by this plan for the main ship-channel will be screened by the woods, through which the range lines will be cut at Point Comfort, (see sketch B, No. 5,) on the New Jersey shore; or artificially, so as to be seen on the range, and at a moderate distance on each side only. The same precaution will be taken in regard to the Swash range, so as to avoid confusion from multiplying the number of lights. A distinction of colors may also be in

troduced with advantage. The first range requires the lights to be seen at from eight to ten miles, and the second at about six and a half and eight and a half miles. The beacon-lights at Fort Hamilton must be seen eight miles.

Items numbered nine (9) to nineteen (19) inclusive, were referred to Lieutenants Commanding Thornton A. Jenkins and Maxwell Woodhull, United States navy, assistants in the coast survey, for examination and report. On the information received from them I reported, (June 13,) recommending the buoy on Peafield reef, No. 9; a light-house on Gardiner's island (No. 11,) to show a red light; the beacon in Sag Harbor, (No. 12;) the two beacons near Fort Hamilton, New York harbor, (No. 13;) a fog-bell for Newark light; the beacons in Passaic river (No. 14;) and the beacon near Elizabethtown Point.

The four buoys (No. 14) in the Passaic river and the one on Mill Rock were found to have been already placed. An additional buoy off Black Rock harbor (Connecticut) was recommended, for which no appropriation had been made.

My report to the Treasury Department, together with the reports of Lieutenants Commanding Jenkins and Woodhull, are in the Appendix No. 24, and show the reasons for these recommendations. The maps referred to are published maps of the coast survey, which embrace the localities named, upon which the positions designed for the beacons and buoys were marked. No new surveys were required in these cases, but merely an examination of the localities with the charts in hand, by persons acquainted with the details of such work.

The different operations in this section will be briefly noticed in their order:

1. The triangulation of the Hudson river has been continued by assistant Edmund Blunt, aided by Lieutenant Joseph S. Totten, United States army, assistant in the coast survey, and during a brief period by assistant W. E. Greenwell. The connexion with the former triangles was made through stations Diddery and Buttermilk Hill; the scheme has been extended to Bear Mountain, (see sketch B.) This party, having supplied points for the hydrography of the entrance to the Chesapeake, was temporarily withdrawn from Section III, during the part of the season unfavorable for primary work there, and has made the following determinations: for primary triangulation 49 angles, and for secondary triangulations 213 angles, have been measured by 2,357 observations.

The work in the Chesapeake was resumed in November.

2. The following observations were made for the coast survey at the observatory of the Central High School, Philadelphia, by Professor E. O. Kendall, for longitude:

"Forty-five transits of the moon have been observed, of which twen-* ty-nine were of the first limb, and sixteen of the second. In most cases four moon-culminating stars were observed, and as many of the fundamental stars as were necessary for the determination of the corrections of the instrument, and that of the clock. The number of occultations observed during this period is seven. This is a smaller number than usual; and it may not be improper to say, by way of explanation, that during the first half of this year (1851) the prevalence of cloudy