S.D 



THE 



EDINBURGH ENCYCLOPAEDIA ; 



CONDUCTED BY 



DAVID BREWSTER, LL.D. 



F. R. S. LOND. AND EDIN. AND M. R. I. A. 



CORRESPONDING MEMBER OF THE ROYAL ACADEMY OF SCIENCES OF PARIS, AND OF THE ROYAL ACADEMY OF SCIENCES OF 

 PRUSSIA; MEMBER OF THE ROYAL SWEDISH ACADEMY OF SCIENCES; OF THE ROYAL SOCIETY OF SCIENCES OF DENMARK; OF 

 THE ROYAL SOCIETY OF GOTTINGEN, AND OF THE ROYAL ACADEMY OF SCIENCES OF MODENA ; HONORARY ASSOCIATE OF THE 

 ROYAL ACADEMY OF SCIENCES OF LYONS; ASSOCIATE OF THE SOCDZTY OF CIVIL ENGINEERS ; MEMBER OF THE SOCIETY OF THE AN- 

 TIQUARIES OF SCOTLAND ; OF THE GEOLOGICAL SOCIETY OF LONDON, AND OF THE ASTRONOMICAL SOCIETY OF LONDON : OF THE 

 AMERICAN ANTIQUARIAN SOCIETY; HONORARY MEMBER OF THE LITERARY AND PHILOSOPHICAL SOCIETY OF NEW YORK; OF THK 

 HISTORICAL SOCIETY OF NEW YORK ; OF THE LITERARY AND PHILOSOPHICAL SOCIETY OF UTRECHT ; OF THB PHILOSOPHICAL 

 SOCIETY OF CAMBRIDGE; OF THE LITERARY AND ANTIQUARIAN SOCIETY OF PERTH, OF THE NORTHERN INSTITUTION, AND OP 

 THE ROYAL MEDICAL AND PHYSICAL SOCIETIES OP EDINBURGH ; OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA ; OF 

 THE SOCIETY OP THE FRIENDS OF NATURAL HISTORY OF BERLIN J OF THE NATURAL HISTORY SOCIETY OF FRANKFORT J OF THE 

 PHILOSOPHICAL AND LITERARY SOCIETY OF LEEDS J OF THE ROYAL GEOLOGICAL SOCIETY OF CORNWALL, AND OF THE PHILOSOPHICAL 

 SOCIETY OF YORK. 



WITH THE ASSISTANCE OF 



< 



GENTLEMEN EMINENT IN SCIENCE AND LITERATURE. 



IN EIGHTEEN VOLUMES. 



VOLUME XVII, 



EDINBURGH: 



PRINTED FOR WILLIAM BLACKWOOD ; 



AND JOHN WAUGH, EDINBURGH; JOHN MURRAY; BALDWIN & CRADOCK; 

 J. M. RICHARDSON, LONDON ; AND THE OTHER PROPRIETORS. 



M.DCCC.XXX. 



