250 To all American Geologists. 
name Trachyte. The author has allowed Granite, and Syenite 
to remain as they are ordinarily written, since they are familiar 
names in common as well as scientific literature." 
In the third edition of his Alantial of Geology (1880) page 
67, the same change is formally adopted into that work. It 
has not however been sanctioned by the usage of geologists 
either American or European. It is not employed in E. S. 
Dana's Test Book of Mineralogy {Z^^ ^^-i 1880); and every 
writer in the Atnericaft yournal of Science (controlled by J. 
D. Dana) is allowed to employ his own orthography. The 
Minnesota geological survey, however, has uniformly employed 
the new spelling, and the managing editor has inti'oduced it 
into the Geologist. With any manifest tendency to adopt the 
spelling proposed by Dana, it might be desirable to expedite the 
result b}'^ promoting the multiplication of examples of approval. 
For the present however, the final verdict of geologists cannot 
be anticipated with any probability. 
TO ALL AMERICAN GEOLOGISTS. 
The International Geological Congress at Bologna determined to put 
to a practical test the best of the many schemes presented to it for unify- 
ing the colors in geological map-making, bj selecting some large area 
which should be as well known as possible to the largest number of geol- 
ogists, and which should include the greatest number of cartographical 
difficulties. Europe was naturally the area chosen. Not only is there in 
that continent a greater number of geologists to the square kilometer 
than in any other, but from the very fact that they belong to various differ- 
ent and unhappily someti:nes antagonistic nationalities, it was shrewdly 
thought that if any scheme can pass the order of acceptance there, its 
chances else-where are very good. As to the inherent puzzles of struc- 
ture, whilst it cannot be said that Europe has the monopoly of them or 
can even furnish the most difficult problems for solution, yet what there 
are have been so long and so zealously discussed by the masters in geol- 
ogy that it atones for the want of natviral intricacies by having secured 
a large amount of artificial ones. The area is therefore well chosen. 
The Congress decided to accept as a base for the map one specially to 
be prepared by Prof. Kiepertof Berlin, which is to include all the latest 
geographical data published and unpublished. As a geographical map 
alone it will therefore have the highest value. It is to be printed in 49 
separate sheets (7 in width and 7 in hight) of which each is to be about 
