Royal Society. 139 



facility with which the eye adapts itself to perceive near or 

 distant objects. 



Feb. 11. A letter to the President from Mr. Hamilton 

 of Nevis was read. It contained a long account of the 

 eruption of the Souffriere in the island of St. Vincent, in 

 May 1812. This volcano had not experienced an eruption 

 since 1/18; the recent one was preceded by near 200 

 shocks of earthquakes during the twelve months before 

 May. The most particular phaenomenon noticed by the 

 writer was the sound of the eruptions, which so much re- 

 sembled the alternate firing of cannon and small arms, that 

 the captain ofa ship of war convoying a fleet of merchantmen, 

 conceiving that a privateer had attacked some of the rear 

 vessels, made signal to the fleet to close, and steered to- 

 wards the place whence the sound came. It was also re- 

 marked, that the noise was much greater at the distance of 

 jTiany leagues than it was in the island ; a circumstance for 

 which Mr. Hamilton could not account. By this eruption 

 two rivers were dried upj immense volumes of thick smoke 

 were emitted before any flame appeared at the mouth of 

 the crater; the flame was accompanied by successive shocks 

 of the earth, thundering noise, and the discharge of large 

 pieces of pumice during eight hours, without intermission. 

 Several houses were thrown down in Kingston by the 

 tremor, and many negroes were wounded by the pumice 

 which struck them in their plantations. Tlie SouflViere 

 is in a part of a great chain of mountains which pass 

 through Nevis and several other of the West India 

 islands. Its crater is a mile in diameter, and about 900 

 feet deep. 



Feb. 18. In consequence of the indisposition of the 

 President, Mr. Lysons was in the chair. A paper by Sir 

 Everard Home was read, describing the head of the Narval. 

 Mr. Scoresby junior haviuo; informed him that the female 

 narval has no tu^k, and that it is a vulgar error to believe it 

 such a deadlv enemy to ihc whale, Sir E. examined the 

 bead of one in the Hunterian museum, and compared it 

 with the head ofa female, which he procured. 



He observed that the head of ihe male has a socket for two 

 tusks, but has only one, while that of the female has a place 

 for one, but has none. Hence he rhi.nks the question be- 

 yond all doubt, and that Mr. Scoresby's information was 

 correct, that ihe female narval never has any tusks. 



Dr. Wollaston communicated ttie result of his experi- 

 ments in drawing wire. Having required snme fine wire 

 for telescopes, and lemembering thai Muschenbroek inen- 



tioned 



