NOTES. cli 



origin altogether different from the formation of conical or dome-shaped trachytic 

 frameworks. 



( 587 ) p. 425. Kosmos, Bd. iv. S. 276280 (English edition, p. 230234). 



( 5S8 ) p. 426. The most complete account, based on actual measurements 

 of heights and angles of inclination and on sections, which we possess for 

 any volcanic district, is that which we owe to the fine investigations of the 

 Olmiitz astronomer Julius Schmidt, of Vesuvius, the Solfatara, the Monte' 

 Nuovo, the Astroui, Eocca Monfina, and the ancient volcanoes of the Papal 

 States (in the Alban Hills, Lago Bracciano, and Lago di Bolsena); see Julius 

 Schmidt's work, " Die Eruption des Vesuvs im Mai 1855 ; ?) and in the accom- 

 panying Atlas, Plates III., IV., and IX. 



( 589 ) p. 426. In the progressive advances which have been made in our 

 knowledge of the surface of the moon, from Tobias Mayer to Lohrmann, Madler, 

 and Julius Schmidt, the belief in the great analogies between the terrestrial and 

 lunar volcanic frameworks has, on the whole, rather lessened than increased: 

 not so much on account of relations of dimension and early recognised inter- 

 arrangement of so many annular forms, as on account of the " rills " and of the 

 " systems of rays," which cast no shadows, and are more than four hundred miles 

 long, and from two to sixteen miles broad: as in Tycho, Copernicus, Kepler, and 

 Aristarchus. It is interesting to notice that Galileo, in his letter to Pater 

 Christopher Grienberger " Sulle Montuosita della Luna," compared the lunar 

 King Mountains, whose diameters he believed to be greater than they really are, 

 to the mountain-encircled land of Bohemia; and that the ingenious Eobert 

 Hooke, in his Micrographia, ascribed the circular type, which prevails so largely 

 on the moon's surface, to the reaction of the interior of the lunar globe upon its 

 exterior. (Kosmos, Bd. ii. S. 508; and Bd. iii. S. 508 and 544: English edition, 

 vol. ii. p. 349; and vol. iii. p. 365, and Note 588.) In regard to the Eing Moun- 

 tains of the moon, I have, in recent years, felt a lively interest in the question 

 of the relative heights of the central mounts and the encircling ridges or crater- 

 margins, and in the existence of parasitic craters on the encircling ridge itself. 

 The result of all the careful observations of Julius Schmidt, who is engaged in 

 continuing and completing Lohrmann's Topography of the Moon, is to the effect: 

 " That in no single case does the one central mount attain a height equal to 

 that of its surrounding crater- wall; and that it is probable that in all cases the 

 summit of the central mount is even considerably below the surface of the moon 

 from which the crater has broken forth." Whereas the cone of scoriaa within 

 the crater of Vesuvius, which rose up on the 22nd of October 1822. according 

 to Brioschi's trigonometrical measurement passes the Punta del Palo (the high- 



