194 FROM CONSTANTINOPLE, 
CHAP. Bauon Herbert'. To these noblemen we 
had been indebted for acts of disinterested 
■V 
friendship and uninterrupted hospitality during 
the two successive winters that we resided in 
Pera. Upon our last visit to Count Ludolf, 
knowing that we were fond of mineralogy, he 
presented to us the most magnificent specimen 
Receives a of wood-opol that has yct been discovered. It 
magnifi- i i i • i i y^ 
cent pre- had bccu givcu by the Capudan Pasha to his 
ivood-opai. famous naval architect, Le Bruyn ; but when the 
latter fled to Petersburgh, to enter into the ser- 
vice of the Emperor of Russia, it was consigned 
to the Neapolitan Minister. This enormous 
mass, consisting wholly of the sort of opal 
called Cacholon, weighs one hundred and forty- 
seven pounds eight ounces ; being three feet 
five inches in circumference, and two feet two 
inches in length. It was said to have been 
found in Bulgaria^. Among the various changes 
to which mineral substances are liable, in conse- 
quence of their exposure to the action of the 
by his brother, the Rev. Robert Tweddell, (Lond. J815): — a work of 
which it may justly be said, that nothiug like it has appeared since 
the original publication of Grat/'s Letters by Mason. 
(l) Baron De Herbert, d^s \.he Austrian Minister at ihe Porte, had 
the peculiar title of Internuncio. See the commemoration of his 
talents and virtues, iu the work above cited, p. 316. (Note.) 
(^) The son of Count Ludolf was lately in England; and visiting 
the University of Cambridge, the author had the satisfaction of 
making known to him, at his public Lectures in Mineralogy, the 
sciea^fic use to which his father's magnificent gift had been applied. 
