466 NATURAL SCIENCE. ^^^^.^^ 



which is, indeed, a work of Contemporary Science, he would have 

 been saved from these and worse errors. Perhaps it is because 

 the author proposes to give only the more important varieties of 

 igneous rocks that he omits all reference to the interesting group of 

 Peridotites ; but if so, on what grounds is Domite, a mere variety of 

 Trachyte, given such undue prominence ? In the definitions of the 

 different kinds of igneous rocks errors are no less plentiful than gross. 

 Basalt is assigned the "high" specific gravity of 2*4 to 2*8; 

 familiarity with the specific gravity of igneous rocks would have 

 rendered such an error as this impossible, 2*4 is a low specific 

 gravity, and the numbers should run from 2*8 to 3. Of Diorite we 

 read that mica (which species ?), epidote, and chlorite are present as 

 *' accessories." This abbreviation, which recalls the police news, is 

 hardly fairly employed in the case of the last two minerals, which, 

 using the author's phraseology, should rather be spoken of as 

 " secondaries." Syenite is referred to the " Felstone family," though 

 what this family is there is nothing in the work to show ; to the same 

 mysterious family the Mica-traps are assigned, also called Lampo- 

 phyres, so spelt in each of the three or four places where the word 

 occurs ; but we must humbly apologise for noticing a trivial error in 

 spelling ; there are much better things in the syntax, to which we 

 refer our readers for real enjoyment. In defining Andesite, the 

 author cannot go far astray, as he here commits a plagiarism (no 

 doubt unconscious) on one of those authorities (Dr. Hatch) whom he 

 " is unable to follow," either in classification or definition. Them 

 we cannot commiserate ! Trachyte is defined as consisting of 

 certain minerals, which are enumerated, and again " accessories," 

 a style of writing which reminds us of Sam Weller's " leg of mutton and 

 trimmings." We are grateful, however, for the information that 

 the mica is biotite, since, for the most part, the unfortunate mica is 

 made to do duty for all its varieties, like a maid-of-all-work. Here, 

 however, a delicious passage occurs, of which we would by no means 

 deprive our readers ; we need merely quote " The trachytes occupy a 

 position between the pitchstone lavas on the one hand, and 

 the andesites and granophyres on the other." And this is 

 Contemporary Science ! In a footnote, Mr. Allport is said to have 

 discovered " Leucite basalt" in the Wolf Rock. In another place 

 the author rightly refers to this rock as Phonolite. 



Under the head of granite we learn that the quartz is the paste 

 or ground mass in which the felspar and mica crystals are enclosed, 

 and this after the elaborate descriptions of this rock which have lately 

 appeared in the English language ; further, that "its representatives 

 among volcanic ejecta are to be found in the granophyres, quartz- 

 porphyries, felsite, trachyte(!), and rhyolites . . . and to one or 

 more of these the so-called granites of the Mourne Mountains, of 

 Arran Islands, and of Skye are to be referred." And this is Contem- 

 porary Science. Truly the author has the names of Judd, Teall, 

 Rosenbusch, and Zirkel on his lips, but their precepts are far enough 

 from him. 



The Appendix closes with some plates, which it is hoped may 

 providentially prove of assistance to somebody. If we turn to the 

 body of the work we shall find the same Babel of terms, thus (p. 70) 

 the Isles of Lipari are said to consist " of pumice and obsidian 

 passing into trachyte." Surely if the author is not familiar with augite 

 andesite, which enters into the composition of these islands, he has at 

 least heard of Liparite, and this should have prevented him from speak- 



