in some places, there is perceived a short one, running at right angles,
and communicating with other two that run parallel.

There is in this country, and in Derbyshire[14], another regular
appearance of this stone, which Cronstedt has not mentioned. In this
case, the strata are not broken in order to have the whin-stone
introduced, they are separated, and the whin-stone is interjected in
form of strata, having various degrees of regularity, and being of
different thickness. On the south side of Edinburgh, I have seen, in
little more than the space of a mile from east to west, nine or ten
masses of whin-stone interjected among the strata. These masses of
whin-stone are from three or four to an hundred feet thick, running
parallel in planes inclined to the horizon, and forming with it an angle
of about twenty or thirty degrees, as may be seen at all times in the
hill of Salisbury Craggs.

[Note 14: See Mr Whitehurst's Theory of the Earth.]

Having thus described these masses, which have flowed by means of
heat among the strata of the globe, strata which had been formed by
subsidence at the bottom of the sea, it will now be proper to examine
the difference that subsists between these subterraneous lavas, as they
may be termed, and the analogous bodies which are proper lavas, in
having issued out of a volcano.[15]

[Note 15: The Chevalier de Dolomieu, in his accurate examination of
Aetna and the Lipari islands, has very well observed the distinction of
these two different species of lavas; but without seeming to know the
principle upon which this essential difference depends. No bias of
system, therefore, can here be supposed as perverting the Chevalier's
view, in taking those observations; and these are interesting to the
present theory, as corresponding perfectly with the facts from whence it
has been formed. It will be proper to give the account of these in his
own words.

La zeolite est tres-commune dans certains laves de l'Ethna; il seroit
peut-etre possible d'y en rencontrer des morceaux aussi gros que ceux
que fournit l'isle de Ferroe. Quoique cette substance semble ici
appartenir aux laves, je ne dirai cependant point que toutes les
zeolites soient volcaniques, ou unies a des matieres volcaniques; celles
que l'on trouve en Allemagne sont, dit-on, dans des circonstances
differentes; mais je doit annoncer que je n'ai trouve cette substance en
Sicile, que dans les seules laves qui evidemment ont coule dans la m