June ii, 1896] 



NA TURE 



129 



composed of a mound of loose lubljle stone, is designed 

 to be formed across the San Juan River at Ochoa, below 

 the confluence of the river San Carlos, 44^ miles from the 

 lake, in order to raise the \vater-le\el of the river to that 

 of the lake along this distance, amounting to an elevation 

 of 56 feet at the site of the dam ; but, considering that 

 it is proposed to place this dam on the unstable sandy 

 bed of the river, and that the floods of the river will 

 pass over its crest, the design has not been given ade- 

 quate solidity. The dam at La Klor, for the Tola basin 

 on the Pacific coast, is to be yi\en a masonry core ; 

 and dams will have to be formed for retaining the water 

 in the San Francisco and Deseado \ alleys ; and upon the 

 security of these dams, and the pro\ ision for the discharge 

 of the surplus water of the rivers, will depend the safety 

 of the canal. Mr. Menocal, the engineer of the Nicar- 

 agua Canal, estimated the cost of the works originally 

 at J|{| 1 3,000,000 ; but, after rexising the estimates, and 

 making allowance for contingencies, the capital has been 

 fixed at ^20,000,000 ; though on this point Mr. Colquhoun 

 remarks that, " taking into consideration all the circum- 

 stances — especially the climate, its debilitating character 

 generally, and the excessive rainfall on the eastern side, 

 the volcanic question, the difficulties as regards labour 

 — I am inclined to think that /^3o,ooo,ooo in genuine ex- 

 penditure on the work will be found nearer the mark 

 than the present estimate." 



The sites of the two rival schemes for piercing the 

 isthmus of Panama, though differing greatly in their 

 general configuration, are very similar in respect of un- 

 healthiness and excessive rainfall on the Atlantic slope and 

 the nature of the strata to be traversed by the excava- 

 tions ; whilst, though a greater height has been adopted 

 for the summit-level for the Panama Canal with locks, 

 necessitating a larger number of locks than for the Nicar- 

 agua Canal, the excavation for the Panama Canal has 

 been reduced considerably below the amount required at 

 Nicaragua, and the maximum depth of the Culebra cutting 

 is now- about I 50 feet less than that of the cutting" through 

 the Eastern Divide. The Panama scheme has a greater 

 length of restricted water-way ; but this will be com- 

 pensated for by the much shorter length of the canal, and 

 by the proposed damming-up of the river Chagres, providing 

 free navigation along one or two of the reaches, as well as 

 controlling its floods. The chief difficulty in the con- 

 struction of the Panama Canal, as now designed, consists 

 in the control of the discharge of the torrential Chagres, 

 which has, however, been greatly minimised by the intro- 

 duction of locks ; whilst not less difficult problems con- 

 front the promoters of the Nicaragua Canal, in ensuring"- 

 the stability of the dams for raising the water-level, the 

 control of the floods of the rivers impounded to form the 

 w-ater-way, and the formation and maintenance of a deep- 

 water entrance through the advancing sands encumber- 

 ing the approach to Greytown. Nicaragua, moreover, 

 is much nearer the zone of \-olcanic disturbances than 

 Panama ; and severe shocks from this cause would be 

 fatal to the stability of the dams. The estimated cost of 

 completing the Panama Canal is indeed greater than the 

 highest estimate quoted for the Nicaragua Canal, and 

 more searching investigations of the site are in progress, 

 which may possibly lead to an increase in the estimates : 

 but, on the other hand, the recent very adverse report of 

 the United States Commission on the Nicaragua Canal, 

 both as regards construction and cost, shows that no 

 reliance can be placed on the estimates hitherto pre- 

 sented, and that the designs of the dams and other im- 

 portant works will have to be entirely remodelled. A 

 considerable amount of interesting information about the 

 Nicaragua Canal, and its prospects and probable influence 

 on trade, is given in the first five and two last chapters 

 out of tne fourteen contained in the book, the description 

 of the project being naturally largely derived from the 

 reports by Mr. Menocal, the originator of the schenie, 



NO. 1389, VOL. 54] 



often in the very words of the proi-i-ioter. In comparing, 

 however, the Nicaragua Canal with the Panama Canal, it 

 is evident that Mr. Colquhoun adopts the part of an in- 

 terested advocate instead of an impartial critic. Thus, 

 after alluding to the main points of the Panama Canal and 



Tehuantepec Ship Railway, he concludes the first chapter 

 with the statement, that — 



" The greatest obstacles met with in other localities 

 are : (l) high elevations in the Cordillera separating the 

 two oceans, requiring tunnelling ; or (2) a high summit- 



