554 THE AMERICAN NATURALIST.  [VOL. XXXIII, 
in the investigation of the optical constants. The methods described, 
while simple, are those in most use among practical petrographers. 
Some of them are here given for the first time in English text. 
Though the book has some faults, some of them serious ones in a 
student’s text-book, it will unquestionably be of service as affording 
a convenient summary of lecture courses. It is also a good note- 
book on the microscopical characters of minerals. 
The Fuess Catalogue.!— The author, who for several years has 
directed the optical section of the Fuess establishment, has here 
given a complete description of all the Fuess instruments made for 
optical or allied purposes, including, therefore, spectro- and refracto- 
meters and spectro-photographic apparatus, goniometers, polaniscopes 
and microscopes, section-cutting machinery, heliostats, and projec- 
tion and micro-photographic apparatus. ‘The work is really a text- 
book for the principles of construction, use, and adjustment of these 
instruments, and contains numerous additional references to the 
literature of the subject. The abundant illustrations elucidate the 
- text. 
Petrographical Notes. — Patton’ notes that mica-schists in contact 
with pegmatite veins on the Belcher Hill road between Golden and 
Central City, Colorado, are impregnated with tourmaline to a very 
great extent. Sometimes the tourmaline is noticed in the cleavages 
of the schist, when the resulting rock is a banded or laminated one. 
Where the contact action was more severe the tourmaline is in streaks, 
which, however, bear no definite relation to the original cleavage 
direction of the schist, which in many cases has been obliterated. 
The tourmalinized schists are composed of quartz and muscovite, in 
addition to the tourmaline, while the schists that have not been 
impregnated with tourmaline contain an abundance of biotite. The 
tourmaline, as seen in thin section, is discovered to: be full of quartz 
inclusions, and to enclose here and there small grains of rutile or 
zircon. The pegmatite veins that are supposed to have caused the 
alteration in the schists are thought by the author to be segregation 
veins. 
Kemp’ is continuing his studies on the geology of Essex County, 
N. Y. Ina recent report he describes briefly the rocks of the town- 
1 Leiss, C. Die optischen Instrumente der Firma R. Fuess, deren Beschreibung, 
ape ed und Anwendung. rigs 3 plates. Leipzig, W. Engelmann, 1899. 
2 Bull. Geol. Soc. Amer., vol. x, p. 2 
8 Fifteenth Ann. Rep. State tales (New York), P- 575- 
