FE. Nipher—Eaxpression of Electrical Resistance. 485 
heat was discovered, all the alterations being evidently the work 
of infiltrating waters continued through countless ages. 
onclusions: 1. The material of this conglomerate, all bein 
more or less rounded, and the shells, being without exception 
fragmental, must have been subjected to violent wave action 
along clitts of Copper-bearing rock at this exposed point of the 
ancient (not to say Archxan) island. 2. There was some 
evidence to show that this fifty feet in depth of conglomerate 
not only graduates into sandstone above, but also on each side. 
Hence the ridge may mark the mouth of a primordial mountain 
torrent. 3. The age of the deposit seen must be late Potsdam 
since it graduates into sandstone of that 
4. This conglomerate is not exceptional, since the Potsdam is 
conglomeritic along its shore margin in Wisconsin, and on the 
St. Lawrence River in New York (as seen by the writer). This 
conglomerate is well shown in the vicinity of Laurentian granite 
at Chippewa-Falls and Eau Claire, Wisconsin, and near Oak 
Croix above Osceola. 5. The Keweenawan series is older 
than, unconformable with, and has supplied much of the 
material for, the Potsdam sandstone. 
These conglomerates bordering the Laurentian, Huronian 
and Keweenawan areas must have supplied a large part of the 
bowlders of the drift deposits of the Northern States. | 
Arr. LV.—On the Expression of Electrical Resistance in Terms 
of a Velocity; by Francis E. N1pHER.* 
* From Trans. Acad. Science of St. Louis. Read March 17th, 1884. 
