with earth, restoring the street and hauling away the surplus materials, as well as the whole cost of pumping, bailing, planking, and shoring, excepting such planking as may be left in by express orders as hereinbefore specified.

Bricks. All the bricks used shall be of uniform texture, hard-burned entirely through, free from lime or other impurities, that will affect them in water, and shall have straight edges and square angles. Broken bricks must not be brought on the ground, and such as are broken afterwards in handling shall be used only in making closures, or as shall be otherwise specially directed.

The bricks are to be culled as they are brought on the ground, and all bricks of improper quality thrown out and removed from the ground. The culling to be done at the expense of the contractor, who shall furnish the inspector with men for this and similar purposes, when required.

Brick Masonry.-In building brick masonry, none but careful and skillful bricklayers shall be employed.

The bricks shall be clean and thoroughly wet just before being laid, unless otherwise specially directed. Every brick shall be laid with a push joint; that is, by placing sufficient mortar on the bed and forcing the brick into it in such a manner as to thoroughly fill every joint, whether on the bottom, side or end of the brick with mortar. The joints shall be made as nearly as possible of uniform thickness, not exceeding three eighths of an inch, and in the inside of the invert or lower arch, they shall not exceed one eighth of an inch.

The bricks in each course shall be all stretchers, and to break joints with those in the adjoining courses. The bricks of the inside course shall be laid to a line and to the true cylindrical or other form given for each case. The inside course shall also be made of the smoothest and hardest bricks, carefully selected for this purpose.

The upper arch shall be built on strongly made centers, which shall be drawn with great care, so as not to disturb the brickwork. The crown of the arch shall be properly keyed with stretchers, and all the joints be well filled with the mortar. The exterior surface of the upper arch shall be covered with a coating of mortar, not less than three eighths (3%) of an inch thick.

The mortar joints on the inside of the sewer below the center line shall be carefully struck when laid, and those above be scraped smooth with the brickwork immediately after the centers are drawn, and the mortar scraped off and entirely removed from the sewer, which is to be left perfectly clean throughout.

All unfinished brickwork must be racked back in courses, except when otherwise specially directed or permitted, and

when new work is to be joined to it, the surface of the bricks must be cleaned and moistened.

Openings for branch sewers shall be made and junction pieces inserted in the main sewers in such manner and at such places as may be directed. Every junction piece shall be closed with a cover of earthenware, or with bricks and cement. All brickwork will be measured and paid for by the cubic yard of solid wall.

TUNNELING.

In tunneling, the excavation shall be made so as to conform neatly to the regular section of the sewer, and nothing will be allowed for any excavation beyond this. All holes or irregularities outside of the regular section must be filled up solid with bricks and mortar, but no extra allowance will be made therefor.

All timbers used in sustaining the excavation must be removed as the brickwork progresses.

Points, by which to get the proper line of the sewer, will be given from time to time as may be needed, and from these the contractor will be required to continue the line of the excavation at his own risk of its accuracy, and to correct at once any errors of alignment that may be discovered before the brickwork is finished.

In tunnels, the quantities paid for will be the earth or rock excavated in the regular section of the sewer, and the brick or stone masonry required for this section, together with any foundation work that may have been expressly ordered, and the amount paid for these items shall be in full for furnishing all materials, and finishing the sewer; the cost of sinking shafts, pumping water, shoring, restoring falls and all accessory works of every kind being borne wholly by the contractor. Those parts only of the sewer will be paid for as tunnels, which are so marked on the plans exhibited at the time of the letting; all the rest will be paid for as open cut, regardless of the manner in which the work is actually done.

PIPE SEWERS.

All pipe sewers shall be made of the best quality of vitrified clay pipe with smooth interior surface. Each piece shall be straight or evenly curved, as may be required, and in section shall not vary more than half an inch from a true circle. The thickness of six-inch pipes shall not be less than three quarters of an inch; of twelve-inch pipes, not less than one and one eighth inches; of fifteen-inch pipes, not less than one and one quarter inches; and of eighteen-inch pipes, not less than one and one half inches. Junction pieces, for use in brick

sewers, shall be smoothly beveled off to an angle of forty-five degrees, and be not less than two feet long, exclusive of the socket. For pipe sewers the junction piece shall be a part of the main pipe, and no right angle junction shall ever be used.

So far as the specifications for the excavation of trenches, shoring and pumping, preparation of foundations, backfilling and restoring the street surface, already given for brick sewers, can be made to apply to the construction of pipe sewers, they shall be followed.

Each pipe is to be laid on a firm bed and in perfect conformity with the lines and levels given. The bottom of the trench must be shaped so as to fit the lower half of the pipe as nearly as possible, with places cut at the joints for the sockets to rest in, so that the pipe shall have a uniform bearing on the ground from end to end.

The pipes shall be joined by filling the socket with a mortar of pure cement without sand, with only water enough to give it a proper consistency. Great care must be taken to make the joint throughout the lower three fourths of the pipe perfectly water tight. The upper one fourth of joint, when so directed, shall be left open.

The interior of the pipes shall be carefully cleaned from all dirt, cement and superfluous material of every description, and a wad made of a sack filled with hay, large enough to fill the pipe and attached to a rod or cord, shall, at all times be kept in the pipe and drawn forward as the swork proceed, care being taken not to loosen the joints.

After the pipes are properly laid and joined, any space between them and the sides of the excavation must be filled with sand, either washed in or well rammed, up to the middle of the pipe. From this point for at least twelve inches above the top of the pipe, the earth shall be filled in so as not to disturb the pipes, and thoroughly rammed; after which, up to the surface, it may be either rammed in layers or thoroughly soaked with water, as may be directed by the sewer commissioner, so that the least possible settling will take place after the work is completed.

Pipe sewers will be paid for by the linear foot of finished work, the price so paid to be in full payment for furnishing and laying the pipe, including the earth excavation, shoring and pumping, backfilling, restoring the street surface, hauling away surplus material, and all other work and material required by the specifications or necessary to give a finished result.

Where rock is encountered in pipe sewers, such rock excavation shall be paid for at the price named herein

-the amount to be estimated with

a base of six inches more than the inside diameter of the pipe and the side slope of one horizontal to eight vertical.

140. Specification for Sewer Pipe. The following specification for sewer pipe and specials is probably the most carefully worked out of any found in current American practice. While these specifications are very full and complete in many details which are usually overlooked, they are not unreasonably severe. They simply describe clearly what kinds of faults will serve as cause for rejection, and are as valuable to the manufacturer of the pipe in enabling him to select those specimens which he feels will be accepted, as to the inspector himself, who is called upon to accept or reject the material when supplied upon the ground. This specification, therefore, has the great merit of extreme definiteness of meaning, which is the most vital and necessary quality of all specifications. They were prepared by an engineer who knew from experience exactly what could be furnished by the best sewer pipe manufacturers without greatly increasing the cost.

Sewer Pipe and Specials-Pipe sewers are composed of straight sections which are herein termed "pipe," and of branches, bends, reducers, etc., which will here be called "specials" or "special pieces."

The main sewer, as well as all surface and lot lateral sewers, shall be constructed of the best quality of salt-glazed, vitrified stoneware sewer pipe, and all special pieces that may be required in the work shall be of the same description and quality.

The pipes and specials must be carefully selected and examined by the contractor before or while being delivered upon the street, and all such material which may be used in the work must conform to the following requirements and conditions:

All hubs or sockets must be of sufficient diameter to receive their full depth the spigot end of the next following pipe or special without chipping whatever of either, and also to leave a space of not less than 1-8 inch in width all around for the cement mortar joint. Pipes and specials which can not be thus freely fitted into each other shall be rejected.

In the case of pipes and specials of 12 inches and upward in diameter, at least 40 per cent. of all such that will be used

in the work must be truly circular or substantially circular in cross-section, and in the case of pipes and specials less than 12 inches in diameter, at least 60 per cent. of the whole number required must be truly circular or substantially circular in crosssection. Of the remainder, in each case, the allowable divergence from a truly circular cross-section shall never exceed the following limits: a. For an elliptical cross-section, the greatest internal diameter must not be more than from 6 to 7 per cent. longer than the least internal diameter in the same crosssection. b. For an oval or egg-shaped cross-section, the same rule as for eliptical cross-sections shall apply. c. Pipes and specials having cross-sections which exhibit angles, sharp curves or flat places of appreciable magnitude in the circumference, will be rejected.

A single fire-crack, which extends through the entire thickness of a pipe or special, must not be over two inches long at the spigot end, nor more than one inch long at the hub or socket end, measured in the latter case from the bottom, or shoulder, of said hub or socket. Two or more such fire-cracks, however, at either end of said pipe or special will cause the same to be rejected.

A single fire-crack, which extends through only two thirds of the thickness of a pipe or special, must not be over four inches long at either end thereof, measured in the direction of its length. Two or more such fire-cracks, however, at either end of said pipe or special will cause the same to be rejected.

A single fire-crack, which extends through only one half of this thickness of a pipe or special, must not be over six inches long at either end thereof, measured in the direction of its length. Two or more such fire-cracks, however, at either end of said pipes or special will cause the same to be rejected.

A single fire-crack, which extends through less than one half of the thickness of a pipe or special, must not be over eight inches long, measured in the direction of the length of such pipe. Two or more such fire-cracks, however, anywhere in the pipe will cause the same to be rejected.

A transverse fire-crack in a pipe or special must not be longer than one sixth of the circumference of such pipe, nor shall its depth be greater than one third of the thickness thereof. Two or more such fire-cracks will be cause for rejection.

No fire-cracks of any description shall, however, be more than one eighth inch wide at its widest point.

No combination of the foregoing six limitations will be allowed, except with the express consent of the executive board and the city surveyor, as the intent and meaning of these restrictions or limitations is to insure the furnishing of the best marketable quality of pipe and specials by the contractor. In