Fbbkuaey 23, 1900.] 



SCIENCE. 



315 



is well shown in relation to the broader valley 

 up and down stream. Five new sheets of the 

 detailed charts, 1 : 20,000, were issued during 

 the year. 



The report on the Missouri announces that it 

 is impracticable to attain permanently useful re- 

 sults in controlling the river at the present rate 

 of expenditure ; $317,000 having been spent on 

 river corrections during the year. Along with 

 numerous maps representing various engineer- 

 ing works, the report contains a large number 

 of excellent photographs illustrative of different 

 methods of protecting the river banks, from 

 which an excellent idea of the appearance of 

 the river and of the works undertaken upon it 

 can be gained. A series of detailed charts 

 covering the river from its mouth to Kansas 

 City (400 miles) on a scale of five inches to a 

 mile with five-foot contours, have been drawn 

 but not yet published. 



GLACIAL LAKE OUTLETS IN MICHIGAN. 



The 'thumb' of Michigan, enclosing the 

 Saginaw bay branch of Lake Huron on the 

 southeast, is of moderate altitude, yet sufficient 

 to have divided two lobes of the ice sheet of the 

 last glacial epoch, which deposited their inter- 

 lobate moraines along the axis of the thumb. 

 During the retreat of the ice, the depressions 

 evacuated by these lobes were occupied by 

 lakes ; the southeastern by Lake Maumee, 

 overflowing through the outlet past Fort Wayne, 

 long ago described by Gilbert ; the northwestern 

 by Lake Saginaw, whose outlet was through 

 the Grand river channel, a magnificent ancient 

 river bed, a mile wide, fifty miles long and 

 sometimes cut over 200 feet deep in the drift. 

 Further retreat of the ice uncovered a point on 

 the crest of the thumb of less altitude than the 

 Fort Wayne outlet ; then the southeastern lake 

 drained across the thumb to the northwestern 

 lake, the connecting river carving the Ubly 

 channel, which follows the outer base of an in- 

 terlobate moraine. The channel is twenty miles 

 long, a mile wide, and from 20 to 100 feet deep. 

 At its southeastern end, its level agrees with 

 that of the shore lines of the lake that it 

 drained ; its bed is strewn with bars of gravel 

 and sand, indicating a flow from southeast to 

 northwest ; its further end opens upon a delta- 



like body of gravel at the level of Lake Sagi- 

 naw. Like the ice-border channels near Syra- 

 cuse, N. Y., discovered by Gilbert, or those of 

 north Germany recently summarized by Keil- 

 hack, the Ubly channel is a geographical feature 

 of marvellous significance in connection with 

 the glacial theory ; the interpretation of this 

 excellent example being due to Taylor, in whose 

 admirable series of independent studies it con- 

 stitutes but one of many items (Ice dams of 

 Lakes Maumee, Whittlesey and Warren, Amer. 

 GeoL, xxiv., 1899, 6-38, maps). 



CHICAGO AND ITS ENVIRONS. 



The first Bulletin of the Geographic Society 

 of Chicago contains an essay on the ' Geography 

 of Chicago and its Environs ' by Salisbury and 

 Alden (pp. 64, 30 figs.). A relief plate as 

 frontispiece shows very clearly the smooth floor 

 of the ancient expanded lake rising towards 

 the rolling uplands through which the lake 

 outlet cut its broad and well-defined channel. 

 The text describes the several physiographic 

 areas, with special reference to the succes- 

 sive stages of the falling lake, of which three 

 are recognized (Glenwood, Calumet, Tolleston). 

 The dunes of the ancient beach ridges that 

 curve around the southern end of Lake Mich- 

 igan, familiar objects to travelers by rail from 

 the east, are mapped and described. 



W. M. Davis. 



CURRENT NOTES ON METEOROLOGY. 



COMPENSATION IN WEATHER. 



The question of seasonal forecasts is consid- 

 ered in the Annual Summary for 1899 of Climate 

 and Crops : Colorado Section. The temperature 

 and precipitation data for Denver during the 

 past 28 years have been compiled in order to 

 bring out whatever relation successive seasons 

 bear to one another, in the hope of throwing 

 some light upon the so-called theory of com- 

 pensation in weather. This theory, stated in a 

 few words, is that a season with an excess or 

 defect of temperature or precipitation is fol- 

 lowed by compensating conditions in the suc- 

 ceeding season. The records show that the 

 temperature for a season, or a longer period, 

 furnishes no certain index of the conditions to be 

 expected during the coming season. An ex- 



