470 METEOROLOGY. 



the country to the westward. This wind usually commences about the 1st of 

 December, but this last year it commenced about two weeks earlier, which was 

 about the time the volcano broke out. The rainy season closed also the 1st of 

 Noveml)er last. The usual appearance of the sun and sky in November is 

 remarkably bright, spotted over with white, fleecy clouds. But during- the latter 

 part of the volcanic eruption, and for two weeks after its close, the atmosphere 

 was greatly disturbed, and for several days in succession scarcely a patch of 

 clear sky was visible ; dark gray clouds were constantly whirling in heavy 

 masses to the westward, alarming the inhal)itants with their sombre and threat- 

 ening appearance. The explosions and the crackling roar of the volcano were 

 heard for a distance of over 100 miles, to the west, northwest and southwest. 



On the evening of November 22, while the volcano was in an active state, I 

 started from Leon a little after midnight, to make a visit to the volcano before 

 daylight, and on that occasion, at 2 o'clock in the morning, about 10 miles to 

 the vvest of the volcano, I encountered, very much to my surprise, a heavy 

 shower of rain, accompanied by thunder and lightning. The thunder, howevei", 

 was not easily distinguished from the roar of the volcano. 



My attention was then particularly called to the fact that the storm came out 

 of the dense black cloud which ascended in a vast column from the crater, and 

 overhung the surroimding country for several leagues in extent. It was bright 

 starlight when I started from Leon, and no other cloud was visible. I could 

 also still see the clear, star-lit horizon on every side of me, except that of the 

 black cloud from the crater. During this evidently volcanic shower I was first 

 stnick with the peculiar, oflensive odur of the volcano, which I afterwards became 

 familiar with. After approaching nearer to the volcano, and far enough to the 

 eastward to see through the cloud, I saw that the horizon was also cloudless in 

 that direction. I passed the limits of the shower to the north and west, and 

 also to the east. The shower was confined enth'ely to the west side of the vol- 

 cano, extending fifteen miles to the westward, and covering a belt about 10 

 miles in width, which showed from standing water and muddy ground that this 

 was by no means the first shower. 



I have since ascertained from natives of the country that during the eruption 

 showers in that vicinity were almost daily, and that on one occasion it rained 

 hot water. But a single shower, however, reached as far as Leon. Brilliant 

 flashes of red and white were constantly darting from the crater into the cloud 

 above, and the lightning struck out in every direction from the jet of eruption 

 where it came in contact with the cloud. 



With regard to the earthquakes I am unable to answer your questions satis- 

 factorily. It was distinctly felt here, and several others have also occurred 

 since that time, but they have all been so slight and little noticed that the direc- 

 tion or extent of the earth-wave has not been observed. It is reported to me, 

 also, that shocks of earthquake have been quite frequent of late in San Salvador. 



Permit me to thank you for your account of the examination of the volcanic 

 sand which I had the pleasure to receive by last mail. 



[The following is an account of the examination of the specimens by Profes- 

 sor George J. Brush, of Yale College. — J. 11.] 



The volcanic sand appears to consist mainly, if not entirely, of three minerals : 

 1st. An olive-green mineral, in angular fragments, which is evidently c^?7/50?/fe, 

 (olivine). 2d. A colorless, transparent mineral, also in angular fragments, is 

 probably a feldspar, but what particular species I am unable to say. 3d. A 

 grayish black to black substance, in many cases with the edges rounded from 

 semi-fusion ; appears to be an iron angife, (or hornblende.) It is magnetic, as is 

 the case with the fused iron angites. These minerals are constantly found in 

 the ejections from volcanoes and are constants of many lavas. 



