XL.

A STORAGE RESERVOIR FOR A RAILROAD WATER

STATION.

BY AUGUSTUS TORREY, Mem. W. S. E.

Read August 6th, 1898.

One of the appurtenances for operating a railroad which the engineer has frequently to provide or care for, is a storage reservoir. This reservoir is apt to be somewhat out of his usual line of travel, and is in better favor with him if it or any part of it does not require much attention.

The reservoir is generally a small affair and quite frequently is dependent upon rainfall for its supply. With such reservoirs and with reservoirs for such purposes, generally the waste weir and apron are alternately wet and dry; more often dry.

It is a relief to the man responsible for a continuous supply of water and for immunity to his company against trouble, to be able to feel that the dam which holds back the water and the passages designed to take its surplus are in permanently good condition. Those of us who are heirs to reservoirs of this description have often been discouraged after viewing, so far as they can be viewed, the old cribs and other assemblages of timber and brushwood which answered well enough for dams and spillways in their youth, but which like other "ancient and holy things have faded like a dream," and come to us for our care and perpetua tion in a decrepit state. The decision that an old dam is ripe for the sickle is a hard one to make, and the decision of how to replace it cheaply and permanently and without interruption of service is sometimes harder. A plan I followed in such a predicament may possibly be interesting. At any rate, it will not take much time to relate.

At the outset I wish to disclaim having made any new discovery; although the scheme was new to me, and since having thought of this as a subject of a short paper to our society, a limited research has failed to reveal its counterpart.

The dam setting back the waters of a small watercourse at St. Thomas, Ont., making an artificial lake of about fourteen acres, was about sixteen feet extreme height and three hundred feet in length. Near the center of the dam was a crib, at one time more or less filled with brush and clay and topped with a plank floor over which the waste water ran in freshets. The side or end walls of the crib were extended above the level of the floor so as to give an available waste weir of 26 feet by 2 feet. An apron supported on timbers conducted the waters to the old creek bot

tom. This flume had an inclination corresponding to the repose. of the earth which constituted the remainder of the dam. The whole affair was old when I first saw it, and exposure to water and sun had cracked and decayed the timbers so that, in spite of the many battens on the floor of weir and apron, much water gurgled in the bowels of the crib. The timbers carrying the floor and presumably the lake were moss-grown sepulchres. It was clearly a difficult matter to replace the structure in its original form, and I decided to cut loose from such ideas of waste weirs as I knew of and had seen, and to utilize the force of the flood in taking itself beyond the dam. I lowered the pond about four feet by temporary means, which exposed the bottom for about 20 feet inside the high water shore line. I sunk without difficulty on this exposed lake bed a cylindrical caisson fourteen feet in diameter, made of three-inch plank sixteen feet long. I excavated the earth inside this caisson and built therein a basin out of concrete, cylindrical outside and in the form of a frustrum of a cone inside. The bottom was three feet thick. The lower inner diameter was five feet and the upper inner diameter was ten feet. The walls reached within two feet of the top of the dam. An iron pipe 36 inches in diameter was built into the side wall of the basin at the bottom of it and led through the end of the dam to a discharge near the old creek bed below the dam. The pipe was caulked with lead and held together with rods. I removed all the timbers I could from the old waste weir, fiiled the hole with clay, and serenely waited for the next storm. All the more serenely because I had used a 36inch pipe, while I knew a 30-inch under 12 feet head would carry all the water which the old waste weir would accommodate. At last the rains descended and the floods came, and with them the farmers from far and near, who were eager to see the 26 by 2 camel go through the 36 inch needle's eye. That waste weir entertained the visitors with music and contortions beyond the wildest speculations of anybody. Its roarings could be heard for miles, and the alternate sucking down of the flood and vomiting of it forth were features in a waste weir too new to be entirely satisfactory. The pulsations of the discharge of course interfered seriously with its volume, although I think their violence would have abated had the storm raised the pond the other ten inches there were to spare.

The waste weir was too much of a howling success to be proud

The flat bottom of the basin clearly stopped the movement of the column of water until it could get a considerable head. Immediately after that first storm I filled the bottom and sides of the basin with concrete, and now it is funnel-shaped with a curved neck joining it to the level pipe. The floods which have come since have flowed over the edges of the basin and converged into the neck as smoothly as a train enters a curve, which is linked to the tangent by a spiral, and which is elevated to suit the align

ment. I should judge that the maximum head on the pipe had been about eight feet. As the waste weir stands at present it seems to be efficient and permanent, and I certainly should not hesitate to adopt as an economical device a similar construction on a much larger scale. An earthen dam is in most cases a secure and imperishable dam if the waste weir does its work; and this kind of waste weir will do its work if properly proportioned. The force of the discharge is the only destructive agent present, and that can be spent on boulders remote from the foot of the dam.

XLI.

PARK BRIDGES.

By OSCAR SANNE, Mem. W. S. E.

Read July 6th, 1898.

Some years ago I was requested by Mr. Christian Wahl, president of the Park Commissioners of the city of Milwaukee, to prepare designs for park bridges which should fulfill not only the engineering requirements, but would be designs in every respect of the highest artistic value.

It is true not very often an engineer has an opportunity to exhibit more than what is called the practical side of his profession; it was, therefore, a great pleasure to me when I was called upon to do work more in the artistic line, and I think the more our country is settled and people commence to enjoy life and look more for an æsthetic development there will be a growing demand for a combination of engineering skill with highly artistic. achievements.

During the last five years I have designed and built for the Lake Park of the city of Milwaukee several ornamental bridges. Starting with a simple foot bridge, built as a viaduct over a very picturesque ravine, I have gradually developed a system of park bridges which are not only strictly engineering structures, but which have been very carefully laid out with the view of obtaining the most pleasing artistic effect.

To obtain this result it is necessary that the engineer, being entrusted with such an unusual task, should carefully study everything about the laws of beauty when applied to construction. To show a steel structure in the most beautiful harmony of its details is often more difficult than to solve the most complicated mechanical problem. This kind of engineering work cannot be done in a rush or by the thumb rule, but requires careful and thorough study of every detail; all proportions must be well weighed, so that a pure harmony will prevail in the whole as well as in its parts.

The development of the artistic side of the engineering profession meets to some extent with difficulties which the architect does not experience. The latter has any amount of very excellent examples from ancient time; they form the very best guides for him and with their help his way to highest perfection is comparatively smooth. Not so with an engineer. There are very few examples of important engineering structures where the lines of beauty play such a prominent part; our way of construction has been changed so very remarkably that hardly anything now can be compared with the construction of ancient time.