Free Canal in navigation. excavation. East side .. 16·048 West side .. 11·160 Six locks .. 0·759 Deseado basin 4·220 .. San Francisco and Machado basins 11·368 .. Tola basin 5·504 .. River San Juan 64·540 .. Lake Nicaragua 56·500 .. ─────── ────── Total miles 142·132 27·907 The minimum radius of curvature is 2500, and the principal dimensions of the canal in excavation are as follows: rock, width, bottom, 80 feet; top, 80 feet; depth, 30 feet; earth—width, bottom, 120 feet, top, 180 feet; depth, 46 feet; sand and loose material—width, bottom, 120 feet; top, 360 feet; depth, 30 feet. The most important parts of the work are the construction of the harbours—Greytown on the Caribbean Sea, and Brito on the Pacific; the damming of the San Juan river, for the purpose of raising and maintaining the level of Lake Nicaragua and the river at about 110 feet above mean tide level; the formation of artificial basins at different levels by means of dams, and the use of locks to pass from one level to another. The harbour of Greytown is now closed by a sand bar, and nothing of greater draught than six feet can enter, but it is said that in three months or less from the commencement of the work vessels drawing 15 feet of water will be able to land materials. It is proposed to make this opening through the sand bar by means of a temporary jetty of brush and pile, to furnish protection to a dredger cutting through the bar. This jetty will also give the necessary protection for the maintenance of the passage by diverting the shore current which has deposited the sand. The branch mouth of the river San Juan, which at present empties into the harbour, and is constantly, with every heavy rain, adding to the accumulation of silt in it, will be cut off, and, by a short canal, diverted so as to empty by the principal mouth of the San Juan some miles to the south. The heaviest piece of work on the canal is a rock cut through the “divide” on the eastern portion of the summit level, commencing about four miles to the west of lock No. 3. This cut is about 2·9 miles long and the average depth is about 150 feet, involving a removal of about 2,150,000 cubic yards of earth, and 7,500,000 cubic yards of rock.