256 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



far the surveys to the south could be profitably carried on 

 in the valley of the Atrato. Commander Selfridge, who was 

 assigned to this duty, entered on his labors in January last, 

 with the co-operation of the Tuscarora^ under Commander 

 Belknap. The route selected by Commander Selfridge iji- 

 cludes one hundred miles of river navigation of the Atrato, 

 found to be capable of navigation by the largest ocean 

 steamers. Between the Atrato and the Pacific, a canal or 

 artificial cut is required, twenty-eight miles in length, twenty- 

 two miles of which passes through a plain, with a gradual 

 rise of ninety feet. The remaining six miles will require a 

 moderate open cut, and three miles of tunneling. The work 

 is estimated to cost from fifty to sixty millions of dollars, and 

 to be capable of completion within ten years. A survey of 

 the Atrato has shown that the head of ship navigation was 

 reached but a short distance above the line selected for the 

 canal, with this favorable indication as to the difficulties of 

 the work, that the region is believed to be quite as healthy as 

 any that has been examined. 



The Nicaraguaian survey was placed in charge of Com- 

 mander E. P. Lull, who was absent from December, 1872, un- 

 til July, ISYS. This ofl[icer reports a practicable route for an 

 interoceanic ship canal, having Lake Nicaragua as its sum- 

 mit level. A canal about sixteen miles in length will con- 

 nect the lake with the Pacific ; and its heaviest work will be 

 an excavation of 7^ miles, of 54 feet in depth. For the 

 rest of the distance an embankment will have to be built. 

 Ten locks and one tide lock will be required between the 

 lake and the sea. There will be fifty-six miles of lake navi- 

 gation, and slack- water navigation is proposed in the San 

 Juan from its head to the mouth of the San Carlos. Four 

 dams will be required to improve the river. The total 

 length of the canal will be 67|^ miles, of which about 47 

 miles are in excavation and embankment. The mouth of the 

 San Juan River has been filled very much by the silt from 

 the San Carlos and other tributaries. If, however, these 

 branches are made to empty into the Colorado mouth, it is 

 expected that the channel can be opened and kept clear. 



Lake Nicaragua is believed to be amply sufficient to fur- 

 nish all the water necessary for this canal. No statement of 

 the exact estimate of expenses by this route has been given. 



