AEROLITES. 103 



ever, than the mean density of the Earth, they must be very 

 small nuclei, which, surrounded by inflammable vapour or 

 gas, form the innermost part of fire balls, from the height 

 and apparent diameter of which we may in the case of the 

 largest, estimate that the actual diameter varies from 500 

 to about 2800 feet. The largest meteoric masses as yet 

 known, are those of Otumpa, in Chaco, and of Bahia, in 

 Brazil, described by Rubi de Celis as being from 7 to 7 feet 

 in length. The meteoric stone of ^Egos Potamos, cele- 

 brated in antiquity, and even mentioned in the Chronicle 

 of the Parian Marbles, which fell about the year in which 

 Socrates was born, has been described as of the size of 

 two millstones, and equal in weight to a full waggon load. 

 Notwithstanding the failure that has attended the efforts of 

 the African traveller, Brown, I do not wholly relinquish the 

 hope that, even after a lapse of 2312 years, this Thraciav 

 meteoric mass, which it would be so difficult to destroy, may 



much overrated. The volume of the largest fire ball yet observed cannot 

 be compared with that of Ceres, estimating this planet to have a diameter 

 of only 70 English miles. (See the generally so exact and admirable 

 treatise, On the Connexion of the Physical Sciences, 1835, p. 411.) With 

 the view of elucidating what has been stated in the text regarding the 

 large aerolite that fell into the bed of the river Narni, but has not again 

 been found, I will give the passage made known by Pertz, from the 

 Chronicon Benedicts, Monachi Sancti Andrew in Monte Soracte, 

 a MS. belonging to the tenth century, and preserved in the Chigi Li- 

 brary at Rome. The barbarous Latin of that age has been left un- 

 changed. "Anno 921, temporibus domini Joliannis Decimi pape, in 

 anno pontificatus illius 7 visa sunt signa. Nam juxta urbem Romam 

 lapides plurimi de coelo cadere visi sunt. In civitate qua vocatur 

 Narnia tarn diri ac tetri, ut nihil aliud credatur, quam de infernalibus 

 locis deducti essent. Nam ita ex illis lapidibus unus omnium maximum 

 est, ut decidens in flumen Narnus, ad mensuram unius cubiti super 

 aquas fiuminis usque hodie videretur. Nam et ignitce faculce de ccelo 

 plurimcR omnibus in Juic civitate Romani populi visce sunt, ita ut pcne 

 terra contingeret. Alice cadentes" &c. (Pertz, Monum. Germ. Hist. 

 Scriptores, t. iii. p. 715.) On the aerolites of JLgos Potamos, which fell, 

 according to the Parian Chronicle, in the 78 1 Olympiad, see Bb'ckh, 

 Corp. Insc. Graec., t ii. pp. 302, 320, 340 : also, Aristot. Meteor., i. 7 

 (Ideler's Comm., t. i. pp. 404-407) : Stob. Eel. Phys., i. 25, p. 508) 

 (Heeren) : Plut. Lys., c. 12 ; Diog. Laert., ii. 10 ; and see also subsequent 

 notes in this work. According to a Mongolian tradition, a black frag- 

 ment of a rock, fortv feet in height, fell from heaven on a plain near the 

 eource of the Great Yellow Paver in Western China. (Abel l&mnaat. in 

 Lametheriu, Jour, de Phys., 1819, Mai. p. 2G4.i 



