men for this purpose by and at the expense of the Contractor. Specially moulded bricks of the shape shown on sheet No. of the plans, are to be used for the lower corner of the tunnel masonry, of the form shown on sheet No.

41. Brick Masonry.-All brick masonry shall be laid with bricks and mortar of the quality before described. No "bats" shall be used except in the outside ring of the covering arch, and in the backing masonry, where a moderate proportion (to be determined by the Inspector) may be used, but nothing smaller than half bricks. The bricks to be thoroughly wet just before laying. Every brick to be completely imbedded in mortar under its bottom, on its sides, and on its ends, at one operation. Care shall be taken to have every joint full of mortar. Competent mechanics shall be employed for this work; and for the invert, especially, only the best skilled labor shall be employed.

For all brick masonry the bricks shall be laid to a line, with the beds in the line of the radii of the curves; and with as close joints (not exceeding inch for either face or arch work) as may be from time to time directed. The inside faces of the joints of the bottom arch, and of the sides, shall be neatly pointed; and those of the upper arch, after the centres have been withdrawn, shall have all the mortar projecting beyond the surface of the bricks scraped off, not more than fifteen days after the arch has been covered; and shall be pointed and left in a neat condition: all pointing to be done with neat cement.

42. All unfinished work must be racked back, or toothed, as may be directed by the Engineer in each case; and before new work is joined to its surface the bricks must be scraped thoroughly clean, and scrubbed with a stiff brush, and well moistened.

43. Stone Masonry.—All stone masonry is to be built of sound stone of quality and size satisfactory to the Engineer.

44. Rubble Stone Masonry.-Rubble stone masonry shall be made of sound, clean stone of suitable size, quality and shape for the work in hand, and presenting good beds for materials of that class. Care must be taken to have the beds and joints full of mortar, and no grouting or filling of joints after the stones are in place will be allowed. The work must be thoroughly bonded.

Rubble stone masonry is to be used in any part of the tunnel, or other part of the work where it may be ordered.

In the tunnel, especially, the size and shape of the stone used must be adapted to the spaces to be filled, in order to secure absolutely compact work.

Stone from the tunnel or other excavation may be used, when suitable.

45. Cut Stone Masonry.-A small amount of cut stone masonry is to be used at the upper and lower parts of the shafts; and wherever it may be ordered by the Engineer. It is to be built of granite of first quality, free from all defects, and cut to a §-inch joint, and to the form indicated on the plans; all exposed surfaces to be finished in fine hammered (six cut) work, of the best description.. In measuring the stones when they are not rectangular, the dimensions taken for each stone will be those of a rectangular cubical form which will just inclose the same.

46. Station Plates.-The City will furnish station plates, and the Contractor is to fasten them in the manner directed by the Engineer. The number and position of these plates cannot be indicated in advance, but there is not to be more than one for each 500 feet of the Aqueduct.

GENERAL CLAUSES.

47. Grading, Cleaning and Finishing.-At his own expense, and under the direction of the Engineer, the Contractor is to clear the Aqueduct from all refuse and rubbish, and to do about the shafts all grading that may be ordered; to do all ditching and diverting of streams, and leave in neat condition the grounds occupied by him.

48. The Contractor is to give all facilities to the City or to other Contractors for performing work adjoining his own, and any difference which may arise between two contractors in regard to their adjoining work is to be adjusted by the Engineer, whose decision is to be final in the matter.

49. Lines and Grades.-All lines and grades are to be given by the Engineer, who may change them from time to time as he may be authorized and directed by the said Aqueduct Commissioners, even to the extent of lowering or raising the grade line of the Aqueduct, or of ordering vertical or side drifts.

50. Marks and Stakes.-The stakes and marks given by the Engineer, and the troughs for the plumb lines, must be carefully preserved by the Contractor, who must give to the Engineer all necessary assistance and facilities for establishing the benches and plugs, and for making measurements.

51. Engineer to Explain Specifications.-The plans and specifications are intended to be ex-. planatory of each other, but should any discrepancy appear, or any misunderstanding arise as to the import of anything contained in either, the explanation and decision of the Chief Engineer shall be final and binding on the Contractor; and all directions and explanations required, alluded to, or necessary to complete any of the provisions of these specifications, and give them due effect, will be given by the Engineer.

250

SPECIFICATIONS FOR GATE HOUSE AT 135TH STREET AND CONVENT AVENUE.

(1.) The plans referred to in these specifications are eighteen in number, entitled The Aqueduct Commission," etc., sheets Nos. signed by the Chief Engineer and dated September

4, 1886.

"

They show the location of the work and its general character. During the progress of the work, working plans will be furnished by the Engineer.

(2.) Description of Section No 15.-Section No. 15 of the New Croton Aqueduct is shown on the plans, and in the main is to consist of the foundation walls of a gate house, and the enclosed chambers for gates, screens, drainage, etc.; the necessary excavation for such foundation walls, drains, and the excavation for the vertical end of the Aqueduct; of the trench for receiving one length of eight lines of forty-eight inch pipe; of the sewer, of a portion of the ten feet connection with the Tenth Avenue gate house, of the building or superstructure (excepting windows and doors); of all refilling, grading and wasting of materials, and of all incidental work; the gates, gate houses, gate-hoisting machinery, stopcock and screens are not included or called for in this contract.

(3.) The Contractor is to furnish all materials (except such as are obtained from the excavations; and the iron, herein specifically agreed to be furnished by the City), and all tools, implements, machinery and labor necessary or convenient for doing all the work (with safety to life and property, and within the time specified herein) required to construct and put in complete working order said Section No. 15 of said Aqueduct; and to perform and construct all the work covered by this agreement; the whole to be done in conformity with the plans and these specifications; and all parts to be done to the satisfaction of the said Aqueduct Commissioners.

(4.) Lines and Grades.—All work during its progress, and on its completion, must conform truly to the lines and levels given by the Engineer, and must be built in accordance with the plans and directions given by him from time to time, subject to such modifications and additions as he shall deem necessary during its execution; and in no case will any work in excess of the requirements of the plans, or of the specifications, be paid for unless ordered in writing by the Engineer, as hereinafter set forth.

(5.) Space Available.-Section No. 14 of the new Croton Aqueduct being now under contract, and the available space for excavating and building operations being somewhat contracted, the Contractor for this section must so conduct his work as not to interfere with adjoining work, or with traffic on the public roads, or streets; and to protect the adjoining property.

EXCAVATION.

(6.) Two Classes of Excavations.—Two classes of excavation are required, for each of which a price per cubic yard is herein stipulated.

Ist. Earth excavation in open trench, for which a price is stipulated in clause item 2d. Rock excavation in open trench, for which a price is stipulated in clause item

(7.) What Prices for Excavation are to Cover.-The prices herein stipulated to be paid for rock or earth excavation are to cover the cost of sheeting, bracing and other supports, the cost of pumping, draining, ditching, and of building bulkheads, of maintaining the cuts, of making roads and embankments, of disposing of all the materials as ordered in refilling, grading, wasting or otherwise, and all other expenses incident to this class of work.

(8.) Earth Excavation.-All excavation except solid ledge and boulders of one cubic yard or more in volume, shall be classed as earth excavation. It must be made to the lines given by the Engineer from time to time, and in estimating the quantities of earth excavation to be paid for under this contract, said lines will be used as the boundaries of the pits, trenches, or other excavations.

(9.) Rock Excavation in Open Cut.—All solid ledge excavations and boulders of one cubic yard or more in volume, or rock which is removed by blasting in the pits and trenches required to receive the various masonry structures, and for waterways, will be classed as rock excavation in open trench.

The excavations must be made to the lines given by the Engineer from time to time, and in estimating the quantities of rock excavation in open cut to be paid for under this contract, said lines will be used as the boundaries of the pits, trenches and other excavations.

(10.) No payment will be made for any excavation beyond or outside of said lines.

(11.) The sides of the excavation for the pipe trenches and for the gate-house foundation walls and gate chambers, will be ordered perpendicular to such elevations as shall be indicated.

(12.) The gate-house excavations, and all other pits and trenches, shall be taken out with slopes when ordered by the Engineer, to lines that he shall establish.

(13.) Precautions must be taken to protect the men from accidents, and to that effect loose or shaky rock

must be removed, and shelters if necessary must be provided. The Contractor is to receive no payment for the building of such shelters, nor for the removal of loose rock if it extends beyond the lines given.

(14.) In making the excavations for pipe trenches, and for the foundations of the walls, such moderate blasts shall be used that the rock taken out may be as near as practicable to the lines given.

(15.) Extra Excavation.—The Engineer may order at any time additional excavations for any purpose; and the Contractor is to do such excavation, which is to be measured according to the lines of the crosssections determined by the Engineer, and paid for by the cubic yard.

If after the excavation has been made of a certain size by direction of the Engineer, he is of opinion that the nature of the rock or other material is such that the form and dimensions of the masonry for which said excavation was intended must be increased, he may order an enlargement of the excavation for the purpose of building masonry of greater thickness, and the Contractor is to make such enlargement, which is to be measured according to the lines given by the Engineer, and paid for at the price per cubic yard herein stipulated.

(16.) Excessive Excavation.-If, in the opinion of the Engineer, the Contractor by the use of too high explosives, bad location of drill holes, defective arrangement of timbers or other supports, or want of proper skill and attention, shall excavate to greater dimensions than is required for the proper building of the masonry, the excess thus formed shall be filled solid, at the expense of the Contractor, with such kind of masonry (brick, concrete, cr rubble masonry, as herein specified), or other material, as the Engineer may direct. (17.) Blasting. In rock excavation the drilling and blasting must be conducted with all possible care, so as not to shatter the rock outside of the prescribed lines and especially in the vicinity of the existing buildings the blasting must be so regulated as not to cause any injury to said buildings. The Contractor will be held responsible for all injuries to the said buildings caused by his work.

All blasting shall be conducted in conformity with the ordinances of the City of New York directing the manner of blasting and the precautions to be taken.

(18.) Ground for Plant, Dumping, &c.--Sufficient ground is to be furnished by the City at or near the excavation for the establishment of the working plant, but no material from the excavation shall be dumped thereon except by order of the Engineer. All excavated material is to be removed by the Contractor (except such as shall be required for the refilling of trenches and for grading about the gate house), who must furnish the necessary dumping grounds for the same. The cost of such removal and of procuring such dumping ground is to be included in the price herein stipulated for excavation. And the Contractor, at his own expense, must provide sufficient and proper drainage for all water discharged from the excavations. (19.) Fences.-The Contractor, whenever so ordered, shall erect and maintain fences along the streets, roadways, and around the grounds occupied by him. These fences must be of such a character as to be sufficient, in the opinion of the Engineer, for the protection of the adjoining property.

(20.) Prices.-Two prices only are to be paid for materials excavated in open trench, viz.: One for rock, including solid rock and boulders of one cubic yard or more in volume; and one for earth, including all other materials. Whenever the rock is of such a nature that it can be removed by picking, it shall be classified as earth.

(21.) Refilling in Trenches.-All refilling in open trenches for pipes, &c., must, if so ordered by the Engineer, be made with selected materials, in layers of not more than six inches in thickness.

(22.) Prices.-The prices bid for rock or earth excavation, in open trench, are to include the cost of sheeting, bracing, and other supports; the cost of pumping, draining, and all other expenses incidental to the excavation, maintenance, &c.

(23.) Soiling. Before beginning the work the soil is to be removed wherever directed by the Engineer and put in spoil banks, to be again placed over the restored surface. The quantities of soil removed will be measured in the spoil bark, and the price paid for soiling will cover the cost of removing, storing and replacing the soil wherever ordered by the Engineer.

(24.) Refilling.-A portion of the excavated materials is to be used for refilling between the masonry structures and the sides of the excavations. Such refilling is to be done with care, the material to be tamped whenever ordered, and to be lowered into place, if so directed.

A large quantity of the excavated material is to be used in restoring to grade the grounds about the gate house.

TIMBERING, DRAINAGE, POWER, ETC.

(25.) Timbering or Other Supports.-The Contractor shall be responsible for properly supporting the sides of the cuts and trenches or other excavations, with timber or other supports. If, however, the Engineer is of opinion that at any point sufficient or proper supports have not been provided, he may order additional supports, or order them modified or replaced, at the expense of the Contractor; and the compliance with such orders by the Contractor shall not relieve or release him from his responsibility for the sufficiency of such supports.

(26.) Timber to be Removed.-All timber work is required to be removed from the excavations; but if in the opinion of the Engineer, any timber work be so located in the pits or trenches that its removal

would endanger the safety of the masonry, it shall be left in; and all cavities about it shall be filled with masonry or with such other material as he may order; but no payment is to be made to the Contractor for such timber.

(27.) Power and Appliances.-The Contractor is to use such appliances for pumping, drilling, blasting, hauling or hoisting materials, and for all other operations connected with the excavation and support of the pits and trenches, as will be required to complete the work of this section at or before the time hereinafter specified. If, at any time before the inception, or during the progress of the work, such appliances appear to the Engineer to be inefficient, or inappropriate for securing the quality of the work required, or the rate of progress that will in the opinion of the Engineer insure the completion of the work within the time named, he may order the Contractor to increase their efficiency or to improve their character, and the Contractor must conform to such order; but the failure of the Engineer to demand such increase of efficiency or improvement shall not relieve the Contractor from his obligation to secure the rate of progress established in these specifications.

MASONRY.

(28.) The masonry of the gate house, foundations, gate chambers, inlet and outlet chambers, and other structures and appurtenances, shall be of the class, form and dimensions that may be designated by the Chief Engineer from time to time. The general forms and dimensions of the various structures are shown on the plans.

Prohibition.-No mason work of any description is to be laid between the first of November and the first of April, except by special permission of the Engineer.

(29.) Weepers.-Weepers shall be built in the masonry whenever directed.

(30.) All masonry is to be laid in hydraulic cement mortar, unless otherwise specified.

The Contractor, at his own expense, must conduct the water away from any point where masonry is being laid, by the use of pipes or other efficient means, and must prevent water from flowing over or exerting pressure upon the masonry until it is fully set. Under no circumstances shall masonry be laid in water.

(31.) The work in all cases shall be well and thoroughly bonded; and the system of bonding ordered by the Engineer shall be strictly followed.

(32.) Centres.-Strong centres, made to fit the curves in the line of the masonry, and satisfactory moulds or forms, shall be provided by the Contractor; and when they lose their proper dimensions or shape they shall be replaced by others. They shall, before use, be scraped free from cement or other dirt. The centres upon which the top arch of the aqueduct connection is formed shall be slightly lowered before the backing is placed on said arch, but not until in the opinion of the Engineer the mortar has sufficiently set.

(33.) Change of Shape.-At all places where there is a change in the shape of the masonry, at all angles, wells, chambers, etc., and at all other parts that may be ordered, the masonry is to be built carefully to the curves and forms given by the Engineer.

(34.) Iron Work.-All iron work for permanent use will be furnished by the Contractor, with the exception of that above mentioned; it shall be built in the masonry wherever and in the manner directed by the Engineer; but all iron piping that may be needed during the progress of the work to facilitate the construction and setting of the masonry, shall be furnished by the Contractor at his own expense; and left in, if so ordered.

(35.) Cement.-The greater part of the masonry is to be laid in American cement mortar; but Portland cement is to be used whenever directed. The American cement must be equal in quality to the best Rosendale cement; it must be made by manufacturers of established reputation; must be fresh and very fine ground; and put in well made casks. The Portland cement must be of a brand equal in quality to the best English Portland cement. To insure its good quality, all the cement furnished by the Contractor will be subject to inspection and rigorous tests; and if found of improper quality will be branded, and must be immediately removed from the work; the character of the tests to be determined by the Engineer. The Contractor shall at all times keep in store at some convenient point in the vicinity of the work, a sufficient quantity of cement to allow ample time for the tests to be made without delay to the work of construction. The Engineer must be notified at once of each delivery of cement. It shall be stored in a tight building, and each cask must be raised several inches above the ground, by blocking or otherwise.

(36.) Mortar.-Mortar shall be prepared from cement of the quality before described, and clean sharp sand free from loam. These ingredients shall be thoroughly mixed dry, in the following proportions: one part by measure of cement, to two parts by measure of sand; and a moderate quantity of water is to be afterwards added to produce a paste of proper consistency; the whole to be thoroughly worked with hoes or other tools. In measuring cement, it shall be packed as received from the manufacturer. The mortar shall be freshly mixed for the work in hand, in proper boxes made for the purpose; no mortar to be used that has become hard or set. Whenever the Engineer may order it, the above proportions of cement and sand shall be changed to one part by measure of cement and one part by measure of sand.

(37.) Concrete.-The concrete shall be formed of sound broken stone, not exceeding two inches at their greatest diameter. All stone in any way larger is to be thrown out. The materials to be cleaned from

dirt and dust before being used; to be mixed in proper boxes, with mortar of the quality before described, and in the proportion of five parts of broken stone to one part of cement; to be laid immediately after mixing, and to be thoroughly compacted throughout the mass till the water flushes to the surface. The concrete shall be allowed to set for twelve hours, or more if so directed, before any work shall be laid upon it; and no walking over or working upon it shall be allowed while it is setting. When stone obtained from the excavation is of proper quality, it may be used for making concrete. Whenever ordered by the Engineer, the concrete shall be formed of broken stone not exceeding one inch at their greatest diameter, used in the proportion of three parts of broken stone to one part of cement; the mode of mixing, the quality of the materials, and the manner of using, to be the same as above described.

(38.) Brick.—The brick shall be of the best quality of hand-made hardburnt bricks; burnt hard entirely through, regular and uniform in shape and size, and of compact texture. To insure their good quality, the bricks furnished by the Contractor will be subject to inspection and rigorous tests, and if found of improper quality will be condemned; the character of the tests to be determined by the Engineer. They are to be culled on the surface, before laying, at the expense of the Contractor; the Engineer to be furnished with men for this purpose by and at the expense of the Contractor.

Face Brick.-Brick equal in shape and quality to Philadelphia front pressed brick shall be used to line the inside face walls of the gate-house superstructure.

That portion of said wall forming the wainscoting shall be laid in red mortar, and that portion of said wall above the wainscoting to be laid with buff-colored brick, with black bands, as shown on sheet No. .

(39.) Brick Masonry.-All brick masonry shall be laid with bricks and mortar of the quality before described. No bats" shall be used; except that in the outside backing masonry a moderate proportion (to be determined by the Inspector) may be used; but nothing smaller than half bricks. The bricks must be thoroughly wet just before laying. Every brick must be completely imbedded in mortar under its bottom, on its sides, and on its ends, at one operation. Care shall be taken to have every joint full of mortar. Competent mechanics shall be employed for this work; and only the best skilled labor shall be employed for all face work. (40.) For all brick masonry the bricks shall be laid to a line, with the beds in the line of the radii of the curves; and with as close joints (not exceeding inch for either face or arch work) as may be from time to time directed. All exposed faces shall be neatly pointed; after the centres have been withdrawn, shall have all the mortar projecting beyond the surface of the bricks scraped off, not more than fifteen days after the centres are drawn; and shall be pointed and left in a neat condition; all pointing to be done with neat cement.

(41.) All unfinished work must be racked back, or toothed, as may be directed by the Engineer in each case; and before new work is joined to its surface the bricks must be scraped thoroughly clean and scrubbed with a stiff brush, and well moistened.

64

STONE MASONRY.

(42.) Stone masonry will be classed under the following heads:

Ist. Rubble-stone masonry.

2d. Cut paving.

3d. Cut facing stone masonry.

4th. Granite dimension stone masonry.

5th. Dimension stone masonry for exposed face of base of superstructure, having rock face.

6th. Broken ashler masonry for portion of superstructure.

(43.) All the stones used must be of good shape and quality, of compact texture and free from loose seams or other defects that will impair their strength or durability.

When laid they must be thoroughly cleaned.

(44.) All stone masonry shall be laid in hydraulic cement mortar, made (except when otherwise ordered by the Engineer) with one part of American cement and two parts of clean sand, as before described.

(45.) The stones must be well bedded in the mortar, and care must be taken to fill solid all the joints. No grouting of joints will be allowed.

(46.) Stone masonry is to be measured for payment according to the dimensions specified or ordered but in measuring dimension stone masonry, when the stones are not rectangular, the dimensions taken will be those of a rectangular cubical form which will just inclose the said stones. The prices herein stipulated, for any class of masonry, cover the building in and securing of pipes, steps, railings, and of all other iron work (except the gate machinery) which the Engineer may direct to be built in and secured.

(47.) Rubble-stone Masonry.-Rubble-stone masonry is to be made of stone of suitable size and shape for the particular work in hand.

Stones from the excavations may be used when of suitable shape, size and quality. The stones must have good beds; no spauling up under them will be allowed after they are laid.

(48.) Paving. Cut paving will be laid for the floors of the gate chambers, and wherever else the Engineer may direct. The stones are to be rectangular in shape, of the full depth of the paving, and are to be laid in courses not less than 9 inches nor more than 18 inches wide, with joints of not more than half an inch in thickness. The paving, when laid, to present an even and smooth upper surface.