118 The American Geologist August, 1894 
correspondence bel wren the orders of eruption of the i wo series of nicks, 
the resemblance of ;i large pari of the rocks of both series, macroscop- 
ically and microscopically, and the chemical identity of all the rocks 
of both groups, il is conclusively demonstrated, that (1) the volcanic 
rocks of Sepulchre mountain and the intrusive rocks of Electric peak 
were originally continuous geological bodies; ( - 2) the former were forced 
through the conduil at Electric peak during a series of more or less in- 
terrupted eruptions; and (3) the great amounl of heat imported to the 
surrounding rocks was due to the frequenl passage of molten lava 
through this conduit. The remnant of a volcano, fractured across its 
conduit, has been faulted and considerably eroded, so that il presents 
for investigation, on the one hand, the lower portion of its accumulated 
debris of lavas, with a pari of the upper end of the conduit filled with 
the final intrusions, while, on the other hand, a section of the conduit 
is exposed within the sedimentary strata upon which the volcano was 
built. Recognizing the wide extension of similar intricacies in the 
geological and physical relations of volcanic eruptions, Prof, [ddings 
thinks it "advisable to base the classification of igneous rocks on that 
character which may be determined with certainty from the rocks 
themselves, namely, the crystalline structure, and which, at the same 
time, is to so high a degree an exponent both of the chemical composi- 
tion of the magmas and of the physical ami geological conditions at- 
tending their solidification." w. o. 
Popular Lectures and Addresses. By Sik William Thomson (Baron 
Kelvin); in three volumes. !'»/. //. Geology and General Physics. Mac- 
millan A: Co. Initio. . 600 pp.. $2. 1894. 
Lord Kelvin's addresses on physical geology in connection with the 
live question of the length of time the earth may have existed, have 
such a degree of simple mathematical expression and exactness that they 
have had much influence in recent calculations by different geologists. 
In this volume are included also addresses on various subjects of physi- 
cal science, such as geological climate, the condition of the interior of 
the earth, the earth's magnetism, the theory of polar ice-caps in rela- 
tion to changes of the sea level, sound and imperfect harmonies, the 
heat of the sun. the aurora, etc. N. H. W. 
.1 manualofthi study of documents. Persifor Frazer. .1. B. Lippin- 
cotl & Co.. Philadelphia: pp. 218, 1894. 
One of the editors of the American Geologist has produced a book 
on a branch of study which, being entirely new. he has named MbUotics. 
It is the study of writing and writing materials with the view either to 
establish the character of the writing or to discover fraud. The former. 
again, he calls grammaplieny, and the latter plassopheny. 
This curious volume follows the subject into many lines of research. 
The physical characters of a specimen of penmanship are minutely ex- 
amined into, both through ocular inspection and by microscopic.meth- 
ods, and by composite photography. It is wonderful how far these 
methods have already been employed prior to an\ attempt to define and 
