68 Scientific Intelligence. 
says make the Keweenaw series Potsdam, if the rocks are 
sea alents. 
. Wadsworth’s discussion of the subject will be found in his 
memoir on the Iron and Copper Districts of Lake Superior, in 
vol. i, wd the geological series of the Museum of comparative 
Zool 
~ te “The Geological and pag aie Aiistory Pig ae Minnesota. 
The 12th Annual Report, for the year 1883, N. H. WrncHeEtt, 
State Geologist. —This Report contains a bee on ei com para- 
tive on of Minnesota and New England granites, by N. 
Winch e experiments were made on 2-inch cubes unpol- 
ished aa appear to have been conducted with care. The average 
strength in pounds of 20 samples of Minnesota granites, crushed 
between steel plates, was found to be 104,800 pounds, or 26,200 per 
square inch of surface; when crushed between wooden cushions, 
93,272 pounds, or 23, 318) pounds per square inch. The tests were 
applied by Mr. James Cocroft, under the direction of Gen. 
ilmore. 
he oe obtained by Gen. Gilmore for 20 New England . 
granites (in 1875) was 59,785 pounds, or 14,946 pounds per 
square inch. 
The Minnesota granites are Archean. _ far this is the fact 
with those of New England is not know n explanation of 
the differences might be obtained by an investigation into the 
rate pata of the ro eks, or their absorbent quality, the 
amount of mica, the presence of which fissile and feebly adherent 
rineehl must "always diminish strength, and ed textural 
differenc 
Following this report on granites the volume is oceupied by a 
final report on the Crustacea of Minnesota, included in the orders 
Cladocera and Copepoda, by C. L. Herrick, assistant in zoology, 
hich e 
memoir contains also “a carne of the described npeoes in 
North Pomeneny and keys to the known species of the more 
important genera.” 
7. Report Sn “ Or abet = Ohio, i v. Heonomi¢e 
State 24 pp. 
Building = Ae Clays, and the methods “of Working pee the 
in Ohio es Professor Orton, there are among the authors 
on these subjects, A. Ro oe 28 of Mines; N. ord 0 
the Iron manufacture, _ Newton n the manufacture ‘of Coke; 
Edward Orton, Jr., on the Psa Ae their industries; E, Mc 
Millin, on Gas ‘Coals ; and for the special reports on coal regions a : 
* A. A. Wright, C. N. Brown and E, Orton, Jr. There is also & 
