404 lite American Geologist . Docembor, 1896 
They included a little adjustable dark room which could be 
fitted to a Fuess No. 2 goniometer, so that crystals could be 
measured by daylight. Perfect signals could be obtained 
even in a well lighted room. The instrument is called the 
Traube Verdunklungsvorrichtung. The universal rotation at- 
tachment for mineralogical microscopes which has been in- 
vented by professor Klein of Berlin, for measuring the angle 
of the optic axes of microscopic crystals was also shown. 
Klein's new rotation apparatus for the orientation of thin 
sections was next described. The new attachment, which 
can be adjusted to a Fuess goniometer No. 2, for meas- 
uring the optic axes, was shown and an opportunity was af- 
forded to test it by actual experiment. The von Federow 
mica wedge (glimmerkeil) which consists of a series of super- 
posed \ undulation mica plates, and is used for all the pur- 
poses of a quartz wedge, concluded the paper. 
The third paper was by Mr. A. Chester Beatty, entitled 
"The Minerals of the Elkh'orn Mine, Montana." Mr. Beatty 
exhibited, with comments, a remarkable series of calamine, 
smithsonite, native silver and other minerals. 
Professor A. H. Chester presented a paper on the new dis- 
covery of the brassy, micaceous mineral which seems, from the 
only analysis, to be chalcodite. and which has been found in 
a quarry at Rocky Hill, New Jersey, He also exhibited a re- 
markable series of rutile from Graves mountain. Georgia. 
G. F. Kunz described a new meteorite from Guatemala, and 
read a joint paper by Dr. Hillebrnnd and himself upon a new 
discovery of prosopite in Utah. He read also a joint paper by 
Morris Heights, and by Prof. J. F. Kemp, who remarked on 
the interest attached to this association of minerals, because 
of the difference of opinion prevailing among geologists, as to 
whether they indicate contact metamorphism or merely re- 
gional metamorphism. 
The last paper of the evening was by Prof. J. F. Kemp, en- 
titled " Exhibition of interesting minerals collected during 
the summer." The speaker exhibited eovellite, goslarite, en- 
argite, chalcocite and tetrahedrite from Butte, Montana, which 
were exceptionally tine crystals. Remarkably large prisms of 
andalusite from the Black Hills were also shown, and zircons 
and allanite from Mineville, Essex county, New York. 
A collection of chalcodite from a quarry near Reading, 
Pennsylvania, was exhibited by Mr. Roebling of Trenton, New 
Jersey, in connection with the paper bj^Prof, Chester. The 
Academy then adjourned to inspect the minerals. 
J, F. Kemp, Sec. 
