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theory of the origin of the transverse valleys through backward erosion and tapping, as suggested by Heim. Wind gaps representing the backward erosion in various stages ought to exist all over the Jura Mountains, which is contrary to fact. "This theory is particularly at fault when the strange grouping of the cross valleys along lines transverse to the folds is observed." 5. Their origin from superimposition is impossible, as the geological conditions required were evidently never present. 6. Mr. Foerste considers them of antecedent origin, and says: "Although the direct evidence of the progressive erosion of the streams during the rising of the folds is lacking, the systematic arrangement of several series of the transverse valleys in straight lines is strongly suggestive of the antecedent origin of the streams. This and the failure of other explanations to meet the facts are the main support of the theory."

Professor Davis notes the bearing of these conclusions on his assumption that the Appalachian streams were consequent. The consequent origin of the Jura streams was cited in support of this assumption. In view of Mr. Foerste's conclusions, Professor Davis withdraws the assumption that the "Appalachian streams were necessarily consequent upon the structure of the mountains when they were young," but still thinks that they probably were because the deformation of the Appalachians was so much stronger than that of the Jura.

This volume gives a brief account of the work done by U. S. S. Enterprise in deep-sea sounding on a cruise from Norfolk, Va., to China and return. The route taken was via Cape de Verde Islands, Cape of Good Hope, along the coast of South Africa, thence to Madagascar, the Comoro Islands and Zanzibar, thence across the Indian Ocean to the straits of Sunda, thence to China. Soundings were taken every 100 miles, and sometimes oftener. On the return voyage a line of soundings was made from Wellington, New Zealand to Magellan Straits, and from Montevideo northward off the east coast of South America, at varying distances, as far north as the Bermudas.

On charts accompanying the volume are recorded the depth of the soundings and data concerning the nature of the material of the sea bottom. The deepest sounding was 4,529 fathoms, made to the north of Porto Rico, the position being within forty miles of the deepest sounding (4,561 fathoms) ever taken in the Atlantic Ocean. Two submarine peaks were discovered in the South Atlantic Ocean about 20° west of Cape Town, at a depth of 731 and 979 fathoms. The materials brought up were corals, sand and shells. About 20° east north-east of Montevideo an extensive sand bank was found at a depth of 390 to 500 fathoms. The text is made up of extracts from the ship's log and the captain's private journal.