June lo, 1880] 



NA TURE 



129 



a = 5-56 lbs. ± o'i25 (possible error). 

 This result agrees closely with that calculated from the 

 Jaw of fatigue. 



It should be added that a proposal was made by Dr. 

 Haughton to Dr. Macalister to make the experiment 

 conclusive by direct amputation of his scapula, a course 

 which he, unreasonably, objected to, as he draws the line 

 of "vivisection" at frogs. 



A LACUSTRINE VOLCANO 



IN a recent number of La Nature further details, fur- 

 nished by the French Consul of San Salvador, M. J. 

 Laferritre, are given concerning the recent volcanic phe- 

 nomenon in Lake Ilopango in that State. The accom- 

 panying illustration, from a photograph, will show the 

 nature of the crater which has risen in the midst of the 



lake. Earthquakes were felt in San Salvador in the first 

 half of January of this year ; there were three strong 

 shocks, less violent, however, than those of 1876. These 

 earthquakes had their centre in the vicinity of Lake 

 Ilopango, in the midst of which rose three volcanic 

 openings connected with each other. This new crater, 

 which, seen from a distance as in the illustration, appears 

 a small islet, rises above the surface of the water, how- 

 ever, about twenty metres. An attempt was made to 

 approach it in a boat, but the waters were all in a state of 

 ebullition from contact with the burning rock, and gave 

 off torrents of steam. An abundant column of smoke 

 rose in the air, assuming the aspect of an immense cloud, 

 which was seen from a great distance, and fonned an 

 imposing spectacle. The phenomenon was preceded by 

 an exceptional rising of the lake, increased by the abun- 

 dant winter rains. According to an old tradition the 



Aspect of the Volcano in Lake Ilopango. (From a Photograph.) -; 



Spaniards maintain that when the lake rises earthquakes 

 are to be feared. Formerly, also, it was the custom to 

 dig trenches to facilitate the escape of the waters. This 

 practice was followed without intermission for a century, 

 and volcanic phenomena did not appear during all that 

 time. The present phenomena seem to justify this 

 tradition. 



If it is difficult to explain the fact it is still interesting 

 to remember that a great number of volcanoes are sub- 

 marine, that others are found for the most part in islands 

 or in maritime regions, and that water may be one of the 

 feeders of volcanic fires. Lake Ilopango, also known as 

 Lake Cojutepec, is, according to M. Laferrierc, a sunk 

 crater. It is in the volcanic line, and it is a general fact 

 in Central America that lakes alternate with volcanic 

 cones. The water of this lake is brackish, ver>' bitter, 

 and almost viscous. It gives off sometimes, here and 

 there, bubbles of sulphohydric acid gas. The lake is 

 about 12 kilometres long by 16 broad; the depth is 



unknown. It is about 12 kilometres from the city of 

 San Salvador. The Consul of France in Guatemala, 

 M. de Thiersant, states that Lake Ilopango has now a 

 temperature of 3S' C. on its shore, and is in complete 

 ebullition round the volcano. All the fishes are cooked 

 and float upon the surface, with a great number of shell- 

 fish and other aquatic animals. The volcano continues 

 to rise, and the level of the lake is being gradually 

 lowered. 



NOTES 

 The candidates whose names we gave in a recent number 

 (vol. xxi. p. 616) were elected Fellows of the Royal Society at 

 the meeting of la^t Thur.sday. They are :— Dr. Clifford AUbutt, 

 Prof. J. Attfield, Mr. H. E. Blanford, the Rev. W. H. 

 Dallinger, Mr. Thiselton Dyer, Lieut. -Col. Godwia-Austen, the 

 Bishop of Limerick, Prof. D. E. Hughes, Mr. H. M. Jefferj-, 



