Capt. C. L. Hooper says that when just north of Behring's Strait, off the American coast, in the Arctic basin, the U.S. steamer Thomas Corwin, when becalmed for 24 hours, drifted 40 miles to the northward. From all these, and other facts, and the unanimous testimony of American whalemen, who have for years spent many months annually in the Arctic, and from his own observations, he argued that a branch of the Kuro-Shiwo or Japanese warm stream, unquestionably runs northward through Behring's Strait into the Arctic basin along the northwestern coast of Alaska. Prof. Davidson then called to mind the testimony in regard to the existence of Plover Island, between Herald Island and Wrangell Land, which he said was first made public through this academy. The evidence of Capts. Williams and Thomas Long were recited and highly praised. One of the officers of Admiral Rodgers' expedition climbed to near the top of Herald Island, at a time of great refraction, when probably a false horizon existed, and hence did not see Plover Island, although Wrangell Land was in sight. Prof. Davidson thinks all the authorities are against Dr. Dall, who attributes the warm current he observed on the American coast to water from the Yukon River and to the large expanse of shallow water exposed to the sun's rays. As Dall's observations only covered a few days of possibly exceptional weather, and the whalers and Captain Hooper's cover vastly longer periods, and whalers all say it is a pretty hard thing to beat southward through Behring's Strait, owing to the northerly current setting into the Arctic, we are forced to the conclusion that Dr. Dall has mistaken the exception for the rule, and his conclusions are therefore erroneous. When, in 1824, Wrangell went north, he, like others, always found broken ice and considerable open water. In 1867, when Capt. Thomas Long made his memorable survey of the coast of Wrangell Land, the season was an exceptionally open one, and in California we had heavy rains, extending into July. * * * * * EXPERIMENTAL GEOLOGY. ARTIFICIAL PRODUCTION OF CALCAREOUS PISOLITES AND OOLITES.