The removal of the Iron Gates has always been considered a matter of European importance.  The treaty of Paris stipulated for freedom of navigation on the Danube.  The London treaty of 1871 again authorized the levying of tolls to defray the cost of the Danube regulation; and article 57 of the treaty of Berlin intrusted Austria-Hungary with the task of carrying out the work.  By these international compacts the European character of the great undertaking is sufficiently attested.

[Illustration:  THE “IRON GATES” OF THE DANUBE]

The work of blasting the rocks will be undertaken by contractors in the employ of the Hungarian government, as the official invitation for tenders brought no offers from any quarter.  The construction of the dams, however, and the cutting of several channels to compass the most difficult rocks and rapids, will be carried out by an association of Pesth and other firms.  The cost, estimated altogether at nine million florins, will be borne by the Hungarian exchequer, to which will fall the tolls to be levied on all vessels passing through the Gates until the original outlay is repaid.

Very few persons know, says the American Architect, what an enormous work has been undertaken at the Iron Gates of the Danube, where operations are rapidly progressing, mainly in accordance with a plan devised many years ago by our distinguished countryman, Mr. McAlpine.  The total length of that part of the river to be regulated is about two hundred and fifty miles, so that the enterprise ranks with the cutting of the Panama and Suez canals as one of the greatest engineering feats ever attempted.  Work has been begun simultaneously at three points:  at Greben, where there are reefs to be taken care of; at the cataract, near Jucz, and at the Iron Gate proper, below Orsova.  At Greben, where the stream is shallow, but swift, a channel two hundred feet wide is to be blasted out of the rock, and below it a stone embankment wall is to be built more than four miles long.  From a reef which projects into the river a piece is to be blasted away, measuring five hundred feet in length, and about nine feet in depth.  The difficulties of working in this part of the river are very great.  Not only is the current extremely rapid, but in certain places ridges of rock barely covered at low water alternate with pools a hundred and forty feet deep, which give rise, in the rapid current, to frightful whirlpools and eddies.  These deep pools are to be filled at the same time that the reefs are cut away, and it is estimated that nearly three million cubic feet of loose stonework will be needed for this purpose alone.  In addition to the excavation, artificial banks and breakwaters, for modifying the course of the stream, are to be built; so that it is estimated that the masonry to be executed in this section will amount to about five and one-half million cubic feet.