SURVEY OF 1882. A very close survey has been made of the bluff with which the northerly slope of Telegraph Hill abruptly descends to the waters of the Nantasket Roads, and, so far as mean high and low water lines, also of the low land west of Telegraph Hill called Windmill Point, to the extent shown in plan of drawing. The edge (crest line) points in slope, and the base of the bluff, the Nantasket Beach Railroad, &c., have been located by measuring frequent offsets from polygonal lines and by leveling; the mean high-water line has been constructed from levels taken for that purpose, and the mean low-water line obtained by a series of range soundings. The lowwater line at springs, shown on drawing, is considered only approximately correct, as the water happened to be quite choppy when engaged in sounding and the wind stood in strong towards the shore. PLANE OF REFERENCE. The mean low water which has been adopted for the plane of reference is the average of the mean low water observed about 10 years ago at Boston Light and at Lovell's Island. BENCH-MARKS. Five bench-marks have been established on large bowlders embedded in the ground (except one); these bowlders are located, as shown on drawing, beneath or close to the Nantasket Beach Railroad track, which runs along the base of the bluff, generally but a short distance above the mean high-water line, partly on a solid dam of clay aproned with stone or on trestles well embedded in the ground. ABOVE MEAN LOW WATER. Bench-mark No. 1, on top of a slaty bowlder near the eastern end of the bluff and at the outer edge of the rail track, marked, by parallel cold chisel-cuts, thus, is in reference Bench-mark No. 2, on granite bowlder beneath trestle of railroad track, marked thus by cold-chisel cuts, is in reference... Bench-mark No. 3, on granite bowlder 21 feet distant from (below) railroad track, marked thus by cold chisel cuts, is in reference.. Bench-mark No. 4, on large granite bowlder 30 feet distant from (below) rail- Feet. 16.86 14.61 11.59 10.62 11.17 BORINGS, ETC. By boring and excavating in ten different places on the site of the projected wall, and by inquiry made of the engineer of the Nantasket Beach Railroad Company, it has been ascertained that the material at the base of the bluff, and for some distance below the mean high-water line, consists, under a top layer of from 6 inches to 14 feet in thickness of coarse gravel, shingle, cobble-stones, and bowlders, occasionally intermixed with loose clay, of more or less compact yellow clay, which in some places is mixed with sand and interspersed with gravel, cobble-stones, and occasional bowlders, some of which appear to be of large size. Good reliable ground for resting a concrete foundation is generally found about 4.5 feet below the surface of the ground. RESULT OF THE SURVEY. The bluff with which the northerly side of Telegraph Hill faces the main ship-channel and the Nantasket Roads is about 2,700 feet long, and varies in height above the mean low-water plane between 20 feet on top of the general shore crest near its eastern and western ends and 71 feet near the edge at its highest rise. For over 1,700 feet in length from its eastern end its steep ragged and deeply gullied clay slopes are bare of vegetation and clearly show signs of quite recent abrasure, which apparently is not so much caused by the undermining action of the waves in heavy storms as by the gradual but constant wear by frosts and rains. The material which crumbles from the bluff or is washed away by rains finds a temporary lodgment at its base, whence it is removed by the waves in heavy storms. The western part of the bluff, for over 1,000 feet in length, shows no signs of recent abrasure; the slopes are less abrupt and well covered with grass, and at the base no marks are left to prove a direct action upon it by the waves. The edge of the bluff, in part, has a very irregular outline, but as the slopes, even in the gullies, are closely covered with grass, recent frosts and rains cannot have affected this part of the bluff. It has been protected considerably by its more favorable location, so far as the action of the waves is concerned (being out of direct reach of the full force of the eddy wave plying on this part of the shore), and by the solid dam, aproned with stone, whereon the Nantasket Beach Railroad track rests. Wherever this track is carried on trestles, like between m and n and o, p, q, the bluff shows more rapid wearing away, which, however, must be principally ascribed to the more exposed position of this part of the bluff. The shore in front of the bluff is more or less densely covered with coarse gravel, shingle, cobble-stones, and bowlders, some of which are weighing 12 tons and more. Under this stony coverlet, clay, mostly compact and sticky, forms the bottom. Owing to the more favorable formation of the shore, and its being covered with stone, no such rapid wearing away of the bluff has taken place as was reported for the bluffs at Great Brewster, Point Allerton, Gallop's Island, Long Island, &c., before sea-walls were built for their protection. The last reliable survey of Nantasket Beach, &c., was made in 1860, by H. L. Whiting, assistant United States Coast Survey, but as I bave only an old and much-used tracing copy of this survey in the office. I cannot say that I could make a very reliable comparison, the less so as leading points which might have served for that purpose, like, for instance, the cupola of a tower of the Oregon House, have been materially changed or entirely disappeared; yet sufficient proof has been obtained that considerable abrasure of the bluff has taken place since 1860. The edge (crest line) of the bluff has retreated at an average of perhaps 30 feet, probably more, and the mean high-water line advanced into shore more than 40 feet. No material change seems to have occurred in the mean low-water line; in a few places it has moved further out, the extreme change being about 20 feet. The material which has been abraded from the bluff, and also from the northerly shore of the low land (Windmill Point) west of it, has mostly been built in under the lee of Windmill Point, except the gravel, cobble-stones, and bowlders, which have remained and are scattered below the mean high-water line. PROTECTION OF NORTHERLY SIDE (BLUFF) OF TELEGRAPH HILL. In making up a project for its protection, the existence of the track of the Nantasket Beach Railroad, right at the base of the bluff, had to be entirely ignored, as the road occupied just the site whereon the sea-wall or any other work of protection would have to be located. The Nantasket Railroad Company have, by right of eminent domain, control over a strip of land 5 rods in width, except at the extreme western end of the bluff, where the width is reduced to 3 rods or thereabouts. Of the 5 rods, 18 feet in width falls below the center of the track and 644 feet above it. The railroad has, therefore, almost sole control over the ground which would have to be acquired in fee simple before any sea-wall or other work of protection could be built. Referring to the drawing of survey, &c., sent herewith for information of details, the project of protecting the bluff of Telegraph Hill comprises the following items. viz: 1. Spreading rubble-stone in apron, inside red line extending for 1,055 feet from A to B, for the protection of the western end of the bluff, viz, 5,800 tons, of 2,000 pounds each, at $3 $17,400 00 2. Building 980 linear feet sea-wall, on heavy red line on plan, extending from B to C, as per dimensions shown in profile on line No. 9, viz, 9-0 feet, at $80.27 .. 78,664 60 Estimated price per linear foot of wall, viz: Granite masonry in 7 facing courses and coping course, viz, 47,062 cubic feet, at $22 per cubic yard.. $38 35 Concrete in foundation and backing of facing courses, viz, 91,833 cubic feet, at $7 per cubic yard. 24 84 Granite paving and bedding of gravel back of wall, viz, 15 superficial feet, at $5 per superficial yard.. 8 33 To excavating in compact clay, mixed with stone, bowlders, &c., viz, 4 cubic yards, at $1 4.00 To back filling and grading of bluff, 94 cubic yards, at 50 cents 4 75 80 27 Total 96,064 60 3. Building 745 linear feet wall, on heavy red line on plan, extending from Granite masonry in 6 facing courses and in coping course, viz, Granite paving and bedding of gravel back of wall, viz, 15 superficial feet, at $5 per superficial yard.... Excavation in compact clay, mixed with stone, bowlders, viz, 4 cubic yards, at $1 $35 82 21 92 8 33 4.00 54,995 90 Back filling and grading of bluff, viz, 93 cubic yards, at 50 cents... Total per linear feet wall 4 75 73 82 4. Spreading for 100 feet in length rubble-stone in apron, in front of east- Adding thereto expense for spreading rubble-stone in apron, in front The grand total will be ... Or, say, in round numbers, $181,000. 900 00 12,600 00 16,456 05 181,016 55 In further explanation of this project, I should state that a sea-wall was adopted as moans of protecting the bluff between B and Don account of the greater exposure in that locality to the direct action of eddy waves, and the fact known to me that heavy bodies of drift ice will occasionally lodge there. As the wall between C and D has been located much above the high-water line, the bottom of its concrete foundation could be laid in a higher plane of reference without risk. The apron of rubb'e-stone at the westerly end of the bluff is believed fully to suffice for the protection of this less vulnerable part of the shore. I think that the construction of the projected works of improvement may well be postponed for a year or two. Meanwhile additional information may be gathered and changes in shore formation easily and reliably ascertained by referring them to the lines of the survey, the leading ores of which have been well staked out and properly marked. Very respectfully, your obedient servant, Col. GEORGE THOM, H. F. BOTHFELD, Corps of Engineers. B II. PRELIMINARY EXAMINATION OF IPSWICH RIVER AND HARBOR, MASSA CHUSETTS. UNITED STATES ENGINEER OFFICE, Portland, Me., October 7, 1882. GENERAL: In compliance with instructions contained in Department letter of the 27th of September, I have the honor to state in further response to Department circular of August 11, in relation to the proposed survey of Ipswich River and Harbor, Massachusetts, whether, in my opinion, this river is "worthy of improvement and that the work is a public necessity." On referring to my special report of December 6, 1870, on the survey of this river, the following facts will be found, to wit: This river is navigable at high water from its mouth, where it empties into Plum Island Sound, up to the wharves at Ipswich, a distance of 3 miles. The entrance to this river is now about one mile southeast of Plum Island, in Ipswich Bay, where vessels can cross the "outer bar" in 6 feet of water at mean low water. From this bar to the mouth of the river, a distance of 2 miles, the channel deepens and offers no obstruction to navigation; while between the mouth of the river and Plum Island (in Plum Island Sound) there is anchorage in from 3 to 5 fathoms of water. On entering the mouth of the river, between Little Neck and Castle Neck, the inner bar, opposite Lower Gravelly Point, is crossed, where the channel has a width of 60 feet for a depth of 4 feet at mean low water. The mean rise and fall of the tides is 8.4 feet. From the mouth of the river up to Barras Turns, a distance of 2 miles, there is an unobstructed channel of not less than 60 feet in width and 4 feet in depth at mean low water (or 12 feet at mean high water), but from Barras Turns up to the Ipswich wharves the channel is very narrow and tortuous, having in some places not more than 2 feet of water at mean low water, or about 10 feet at ordinary high water. The act of Congress providing for the survey of Ipswich River and Harbor calls for "estimates of cost of dredging the river so as to give 9 feet depth at mean low water." This work would require the dredging of the whole length of the river, from its mouth up to the wharves in Ipswich, together with the excavation of a large quantity of ledge, the cost of which, for a channel 60 feet in width, would probably be not less than $300,000; a work which, if its accomplishment should be deemed warranted by the small amount of commerce that would be benefited by it, would prove to be but temporary, unless maintained in its full dimensions by constant dredging. But this is not deemed practicable, as in every easterly storm the sand outside the mouth would b. washed inside, and reproduce, to a greater or less extent, the inner bar near Gravelly Point; while the channel across the other bar is so variable in depth and locality that any attempt toward its improvement could not be otherwise than futile. Under these circumstances, I have had prepared a project for the improvement of this river at and above Barras Turns, by which the same depth of the water as below shall be carried up to the wharves at Ipswich (that is, 4 feet at mean low water), for a width of not less than 60 feet, so that vessels of 12 feet draught may be taken up there at ordinary high water, the greatest depth that it would be practicable to maintain. As bearing upon the facts which show to what extent the commerce of the country would be promoted by the improvement of this river as above projected, I will state that I am informed by the United States collector of customs of this district that "during the fiscal year ending June 30, 1875, there were sixty arrivals of coastwise vessels at Ipswich with coal, lumber, lime," &c., and that the number would, in his opinion, be increased if the proposed improvements were made in Ipswich River, and much-needed buoys were placed at the bar and in the harbor. In view of the above facts, and of those stated by the United States collector of customs, it would appear that the channel of the river is worthy of improvement and that the work is a public necessity. Respectfully submitted. UNITED STATES ENGINEER OFFICE, Boston, Mass., November 5, 1883. GENERAL: In compliance with instructions contained in your letter of April 24, 1883, I have the honor to submit the following remarks upon the proposed improvement of Ipswich River, Massachusetts. An elaborate survey of this river and harbor was made, under the direction of Col. George Thom, Corps of Engineers, by Mr. Sophus Haagensen, assistant engineer, in June and July, 1875. A report upon the improvement of the river based upon this survey was submitted by Colonel Thom on December 6, 1875. (See Report of the Chief of Engineers, 1876, Vol. I, page 198.) Referring to the proposition to dredge the river so as to give 9 feet depth at mean low water, Colonel Thom remarks as follows: This work would require the dredging of the whole length of the river from its mouth up to the wharves in Ipswich, together with the excavation of a large quantity of ledge, the cost of which, for a channel 60 feet in width, would probably be not less than $300,000; a work which, if its accomplishment should be deemed warranted by the small amount of commerce that would be benefited by it, would prove to be but temporary unless maintained in its full dimensions by constant dredging. But this is not deemed practicable, as in every easterly storm the sand outside the mouth would be washed inside, and reproduce, to a greater or less extent, the inner bar near Gravelly Point, while the channel across the outer bar is so variable in depth and locality that any attempt toward its improvement could not be otherwise than futile. In these views I fully concur. Colonel Thom submits a project for the improvement of the river at and above Barras Turns by which the same depth of water as below shall be carried up to the wharves at Ipswich (that is, 4 feet at mean low water) for a width of not less than 60 feet, so that vessels of 12 feet draught may be taken up there at ordinary high water, the greatest depth that it would be practicable to maintain. This project proposes the opening of a new channel across the flats at Barras Turns, and the construction of a stone jetty at Button Point to close the old one, the widening and deepening of the channel at Labor in Vain, the excava tion of a ledge in mid channel opposite Nabby's Point, the dredging of a shoal between Nabby's Point and Rogers Point, and the removal of Heard's Point Ledge to a depth of 2 feet below the plane of mean low water. The proposed improvements are clearly shown on the map transmitted by Colonel Thom and now in the possession of the Department. The whole work is estimated to cost $25,000. Referring to this project in his letter to the Department dated October 7, 1882, Colonel Thom says: In view of the above facts and of those stated by the United States collector of customs, it would appear that the channel of the river is worthy of improvement and that the work is a public necessity. I have given this project careful consideration, and if the commercial interests involved are thought to justify the expenditure demanded I do not think it can be modified with advantage. It certainly should not be extended so as to involve a greater expenditure. In case these commercial interests should be deemed too small in amount and too local in character to justify so large a disbursement by the Government, it may be well to remark that the proposed project consists in reality of three separate improvements, quite independent of each other, the first or first and second of which may be executed, while the second and third or third may be omitted. These partial projects as as follows: 1. Removal of Heard's Point Ledge to a depth of 2 feet below mean low water, and the excavation of the ledge in mid-channel opposite Nabby's Point. This will give a continuous channel 2 feet deep at mean low water, and 104 feet deep at ordinary high water up to the wharves of Ipswich. The estimated cost is $15,900. 2. Widening and deepening the channel at Labor in Vain and dredg. ing shoal between Nabby's Point and Rogers Point. This, in connec |