irrigation purposes was commenced in 1755 and completed in 1789, was
filled for the first time in February, 1802, and two months later gave
way, destroying part of the town of Lorca and devastating a large tract
of the most fertile country, and causing the death of 600 people. The
immediate cause of failure in this case the author has been unable to
ascertain. In Algeria the Sig and Tlelat dams were destroyed in 1865; and
in the United States of America, at Williamsburg, Hampshire Co.,
Massachusetts, in 1874, an earthwork dam gave way, by which 159 lives
were lost and much damage done to property. In another case, viz., that
of the Worcester dam, in the United States of America--impounding a
volume of 663,330,000 gallons, and 41 ft. high, 50 ft. broad at the
crest, and formed with a center wall of masonry, with earthwork on each
side--which gave way in 1875, four years after its completion; here, as
in almost all other instances of failure, the leakage commenced at a
point where the pipes traverse the dam. In this case they were carried in
a masonry culvert, and the leak started at about 20 ft. on the up stream
side of the central wall. The opinion of Mr. McAlpine as to the cause of
failure, which agrees with that of the most eminent of our own water
engineers, was to the effect that "earthen dams rarely fail from any
fault in the artificial earthwork, and seldom from any defect in the
natural soil. The latter may leak, but not so as to endanger the dam. In
nine tenths of the cases, the dam is breached along the line of the water
outlet passages."

The method of forming the discharge outlet by the construction of a
masonry culvert in the open has no doubt many advantages over that of
tunnel driving through the hill side clear of the dam, permitting as it
does of an easy inspection and control of the work as it proceeds; but a
slight leakage in the instance of a side tunnel probably means nothing
more than the waste of so much water, whereas in the case of the culvert