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autlior in México. The explanation appears to be as foUows: — On the 

 moirntain sides atnight the clear air is cMUed by tbe radiation of tbe ground; 

 but, being too dry to deposit dew, f alls a great deal in temperature, and 

 slides into the bottom of tbe ravines. Haré it is further cbilled by radia- 

 tion, and deposits copious dew; but, still eold, it runs rapidly down to the 

 river and roUs on towards the sea. At San Blas it is checked by a line of 

 low hills, and spreads out as a lake of cold, f oggy air. It was observed that 

 everything -within about ten f eet of the bottom of small arroyos was dren- 

 ched with dew, while objects higher up were quite dry in the morning. 

 As one proceeds towards the coast the plain becomes quite flat; but hills 

 of volcanic rock rise abruptlv from it at wide intervals. The brown leafless 

 forest of small trees gives way gradually to increasing numbers of cacti, 

 especially a large varíete of pitahaya, and twisted siviris, with poisonous 

 thorns, which almost mimic a writhing knot of grey-green snakes. Whe- 

 re water is applied, the sandy plain is fertile; and the banks of the river, 

 like a little Nile, are f ringed by irrigation farms, where excellent cañe f or 

 sugar, with oranges, bananas, and maize are raised. 



The margin of the water is alive with the bright plumage and songa 

 of birds; but away from it, the plain is covered by groves of cacti, to the 

 exclusión of everything else, and their clustering, green, leafless columns 

 in endless succession, present a singular appearance. An attempt has been 

 made to irrígate on a large scale, but only a small part of the immense cac- 

 tus groves has been touched. The woody core of these plants contains tar, 

 and yields on distillation a gas of high illuminating power. There is a road 

 through the cacti to Topolobampo, a large landlocked bay which, on ac- 

 count of its possibilities as a harbour, has been caref uUy surveyed ty the 

 Hydrographic Department of the United States Cirovernment; their chart 

 shows clearly that this was the oíd estuary of the Fuerte river bef ore vol- 

 canic disturbances diverted its course. The high-tide outline of the top of 

 the bay has the appearance of a delta with numerous channels, though there 

 is now no fresh water there; and the bay, which is very beautif ul and sur- 

 rounded by steep volcanic hills, made a ñtting exit for a river having an 

 inland course of great interest and variety. The existing mouth ends ig- 

 nobly in mud-ñats infested by alligators; for the river has not had time 

 to make anything better, but ill will probable improve it in the course of 

 a f ew thousand years. In would be interesting, and probably easy, to tra- 

 ce the oíd bed of the Fuerte, and the work might result in the discovery 

 of more placers to reward the pioneer. 



; There are indications that the confluence of the Urique and Batopi- 

 las rivers, with those from Chinipas and Septentrión, was formerly along 

 way from the present f ork at La Junta; and that the wild gorge from Rea- 



