VOL. LII.] I'HILOSOPHICAL TRANSACTIONS. 6l5 



earthquake, at some place un<ler the surface of the sea. The tide ebbed and 

 flowed, in about 8 minutes, between 18 inches and 2 feet, and continued so for 

 3 hours, regularly decreasing till night, when it was no more observable. 



It is very remarkable, that since that time the island had been in a very de- 

 plorable condition, having suffered under the severest colds that had been ever 

 known. The distress had been so general, that -|-|- of the inhabitants of the 

 island had felt the effects of the contagion; and to some it had been repeated 

 several times. Few however had died of it. The leeward islands had not 

 escaped it, having raged there more violently and more fatal. His majesty's 

 ships had severely felt the effects of it, some of them not being capable of keep- 

 ing the seas, for want of men fit for service. This happening at a season of 

 the year remarkably the healthiest, made it the more surprizing. Bleeding had 

 been found of great efficacy, and used, both by way of prevention and cure, with 

 great success. 



LXXVl. Observations on AuroriB Boreales in Siveden. By Mr. Torbern Berg- 

 man, of Upsal. p. 479. 



These are observations on the ordinary appearances of auroras boreales, and 

 not of importance to be reprinted. 



LXXVIl. Of the Double Refractions in Crystals. By Father John Beccaria, 

 Professor of Experimental Philosophy at Turin, p. 486. 



This is now a very common and well known property in certain crystals. 



LXXVIl L A Catalogue of the Fifty Plants from Chelsea Garden^ presented to 

 the Royal Society by the Company of Apothecaries, for the Year 1761, pur- 

 suant to the Direction of Sir Hans Sloane, Baronet. By John fVilmeVf 

 M. D. p. 4pl. 



This is the 40th presentation of this kind, completing to the number of 2000 

 different plants. 



JjXXIX. An Account of a Work, intitled, Jacobi Christiani Schaeffer Icones et 

 Descriptio Fungorum quorundam singularium et memorabilium ; simul Fungorum 

 Bavarice Icones nativis coloribus expressis editioni, jam paratce, propediem 

 evulgandcB, denuntiantur. By Mr. fVilliam Hudson,* F.R.S. p. 495. 



This treatise consists of 16 pages, and is divided into 1 parts: the first con- 



' * Mr, Hudson was by profession an apothecary in the metropolis, and on the institution of the 

 British Museum was made one of the assistant librarians in the year 1736. He resigned this office 

 however in 1758 in order to pursue his profession. In 1762 he published the first edition of his well 

 known work the Flora Anglica, in which the indigenous plants of England were arranged according 



