PRS © ete r 
396 Royal Institution. 
ture. Granites, porphyries, and sienites, are the miost du- 
rable stones; micaceous. schist and serpentine are much 
more liable to decay. The most perfect of the works of 
the Egyptians, those least injured by time; are of granite. 
This stone or porphyry should be used for all grea\ publie 
monuments. Mr. Davy, in touching on. this subject, said, 
he could not avoid intweducing a few observations on the 
little attention paid to such public memorials in. this. great 
country. Yet, satd he, our materials. are copious; our 
harvests of glory are as rich, nay even more. abundant than 
those of the great elder nations.. .Why should the. spirit 
be wanting by which they are to be gathered in-and made 
permanent? We have had philosophers who are the glory 
of the whole human race; heroes and statesmeny:rivals 
of the illustrious of Athens and of Rome. Yet: this;.me- 
tropolis offers no great durable tribute of respect to our 
science, and our uaval and military glory; and in a thous 
sand years, though. there anay, be anew, and, more. magni- 
ficent city on the banks of the Thames,. yet.tbere, will 
scarcely be a wall of) shat. we new, behold standing; no- 
thing to speak to posterity, of what we are.in, these,memo- 
rable times ;_ in,our philosophy,.the guides; in our litera. 
ture, the instructors; and,in our politics, the saviours of 
Europe. aT ieee Hos : 
Nor would such works jbe; devoid, of. immediate. utility 
and beneficial effect. Hf 
A few columns raised to. the illustrious dead; a few na- 
tional laboratories, or museums, devoted to the memory of 
great men, and to the use of ‘students, would rise asi land- 
marks of fame, would continually excite to excellence. 
No motive for. exertion, is; so sttong as that founded upon 
the sympathy of the good and wise; no reward so sweet as 
that of being held up to public admiration, as a benefactor 
of the species; no glory so pure, so calculated to awaken 
great minds, as that of ismortality ! pnt 
Lecture 111.—In this lecture Mr, Davy described the se- 
condary rocks, or the rocks ‘containing fragments of the 
primary substances, and the remains. of organized beings. 
He divided these rocks into three families, and. illustrated 
their nature and their arrangements by specimens and by 
paintings. The first family, he stated, contains néarly the 
same elements as the primary rocks. It comprehends the 
secondary granites, micaceous schists, sienites, porphyries, 
&e. They differ from the primary rocks:of the same name, 
by the occurrence of fragments, principally of water-worn 
quartz; and they do not appear in considerable :masses, but 
in 
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Sea + 
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