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author in Mexico. The explanation appears to be as follows:— On the 

 mountain sides at night the clear air is chilled by the radiation of the ground; 

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

 slides into the bottom of the ravines. Hare it is further chilled by radia- 

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

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

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

 everything within about ten feet 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 variete 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 fringed by irrigation farms, where excellent cane for 

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



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

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

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

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

 made to irrigate on alarge 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 carefully surveyed ty the 

 Hydrographic Department of the United States Government; their chart 

 shows clearly that this was the old estuary of the Fuerte river before 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 beautiful and. sur- 

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

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

 nobly in mud-fiats 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 few thousand years. In would be interesting, and probably easy, to tra- 

 ce the old 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 Septentrion, was formerly along 

 way from the present fork at La Junta; and that the wild gorge fromEea- 



