METEOROLOGY. 469 



Around tlie base of the cone, round, heavy rocks lie tliickly scattered, from 

 four to five feet in diameter, Imt much the larger portion of tliem have broken 

 into fragments. The cone itself is 200 feet high, with a crater in the top of 

 200 feet in diameter and about the same in depth. The inside of the crater, the 

 same as the outside, is covered with hard, broken rocks, generally less than a 

 foot in diameter. A long ridge of black scoria leads out from the branch crater 

 in a northeasterly direction. The slaggy, lava-like scoria which first issued from 

 the main crater is now principally covered up with the hard plutonic rocks which 

 came out from profound depths with the last discharges. The forest, for leagues 

 around, is scarred and maimed with the sharp cutting storms of sand, and near 

 the volcano the trees lie, cut into numerous fragments, half bmied beneath the 

 sand and rocks. 



The volcano was an active and interesting sight for 16 days, and now in its 

 repose affords an ample and instructive field for the geologist. Indeed, no 

 country in the world presents a more interesting study than the plain of Leon. 

 Twenty volcanic cones are seen rising from it at a single view. Its soil is inex- 

 haustible in fertility, as finely pulverized and as evenly distributed as that of 

 the valley of the Nile or the Mississippi, not however by water, but by fire. It 

 has literally rained down from the volcanoes, richly freighted with fertilizing 

 materials. 



Humboldt regretted, before his death, that men of science had not more fully 

 investigated this remarkable region of country, and it is sincerely to be hoped 

 that it ma}^ not much longer remain neglected by them. 



The recent fall of sand has been followed by a shower of rain, and though 

 but a few da^'S have since elapsed, corn, cotton, and grass have grown more 

 rapidly under its fertilizing influence than I have ever seen plants grow before. 

 Some weeds and plants it kills; others it starts forth with renewed life and vigor. 



I send herewith a specimen of the sand, gathered at Leon before the rain, 

 hoping that it may be analyzed. 



It may be proper in this connection to call attention to the recent destructive 

 storms, earthfpiakes and eruptions which occun-ed on and around the island of 

 St. Thomas during the same period of time which I have been describing, and 

 Avhicli undoubtedly sprang from the same general cause, as those earthquakes 

 were distinctly felt at Leon. 



SECOND COMMUiSriCATION. 



I have the pleasure to acknowledge the receipt of a letter from the Smith- 

 sonian Institution, containing a number of questions in regard to the recent vol- 

 cano in Nicaragua, which I will endeavor to answer as accm'ately as possible. 



The latitude of the volcano is 12° 30' }iorth, the longitude 86° 45' west from 

 Greenwich, according to the government map of Nicaragua. Its distance from 

 the Pacific ocean is 40 miles. 



The strong east wind prevailing here at this season of the year, and particu- 

 larly during the late volcanic eruption, brought the sand mostly to the west- 

 ward, but as fine sand was also carried in lesser quantities many leagues to the 

 eastward, it probably also partially entered the upper and counter current of air. 

 It is known to have extended 100 miles to the westward, covering a belt about 

 100 miles in width. At the commencement of the rain of sand the wind car- 

 ried it in a northwest direction; but for the last 24 hours of the sand storm the 

 wind earned it to the southwest. 



Over an area of about 100 miles in diameter the sand averages at least one- 

 eighth of an inch in thickness. 



The rainy season usually commences here about the middle of May and ends 

 the middle of November; the remainder of the year being the dry season. The 

 rainy season is without wind, but during the diy season high winds sweep over 



