VOL. XLIX.] PHILOSOPHICAL TRANSACTIONS. yOQ 



a little before the earthquakes ; and I frequently took notice, in the evening 

 after sun-set, very long clouds stretched out like a straight line, without any 

 breadth, and extended from the south to the north. The earth in some places 

 was broken into fissures, but not large ones. 



The writer then goes on to state, that repeated shocks were felt, but gradually 

 less violent, from the 1 8th of January till the end of the month ; that on the 

 6th and 1 8th of February violent shocks were experienced, with slight interme- 

 diate ones; «nd that they were repeated slightly till the 26th, when they ceased. 



cm. Extract of a Letter of Mans, la Condamine, F. R. S. to Dr. Maty, 

 F. R. S. Translated from the French. Dated Rome, March 11, 1756. p. 6'22. 

 The Abbe Barthelemi, who is here, has been at Naples. In the manner of 

 going on with the manuscripts there, it will require above a century to open and 

 paste them all. However it is done with great dexterity. But there is only one 

 person employed in it. The Canonico Mazzocchi, who copies them, is very 

 capableof that task. An academy of antiquaries is just founded at Naples, for 

 explaining all the antiquities dug up at Herculaneum ; but according to their 

 method of discussing things in their assemblies, they will not explain 2 dozen 

 antiquities in a year. They will alter their method, and find, that such kinds of 

 works, and perhaps all others, are not to be done by a company. The Abbe 

 Barthelemi has read very well a page, except a few words, which he had not 

 time to study. The account of the manuscript on music is true. 



The measures of the Abbe de la Caille, and those of Father Maire and 

 Father Boscovich do not agree with the elliptical curve of the meridian, or with 

 the circularity of the parallels. And the earthquakes felt on the same day on all 

 the coasts of Europe, and in Africa and America, at Ancona, Morocco, Boston, 

 and in the Baltic, may contribute to convince those who should doubt of it, 

 that the earth has immense cavities, and that it is very heterogeneous, or rather 

 of a very unequal density. Consequently its figure is a little irregular ; or, if the 

 curvature be such as the laws of statics seem to require in the hypothesis of ho- 

 mogeneity, that figure must be altered by changes happening in the internal 

 parts of the mass. It was at first supposed to be spherical, and the orbits of 

 the planets were considered as circular. It was afterwards found that they were 

 elliptical, and the earth an elliptoid. Every step made in the study of natural 

 philosophy has discovered some apparent irregularity, according to our manner 

 of conception. The refractions, the aberration of light, the nutation of the 

 earth's axis have all been reduced to a calculation. Afterwards was found out 

 the irregularity of the refractions on small eminences, which perplex astrono- 

 mers. The heterogeneity of our globe will puzzle the mathematicians ; and 

 earthquakes will perhaps do so more than all the rest. I have probably observed 

 to you before, that I am convinced, that Italy was a chain of volcanos, of which 



