ASSOCIATIONS FOR THE ADVANCEMENT OF SCIENCE. (AMERICAN.) 



29 



Body," by Wilbur 0. Atwater and F. G. Benedict ; 

 "On the Availability of the Nutrients of Food Ma- 

 terials," by Wilbur 0. Atwater and A. P. Bryant; 

 "Urinary Acidimetry and Alkalimetry " and "The 

 Normal Degree of Urinary Acidity," by Heinrich 

 Stern. 



D. Mechanical Science and Engineering. At the 

 Detroit meeting Prof. Mortimer E. Cooley was elected 

 to the vice-presidency, presiding over this section, 

 but as he was unable to be present at the meeting, 

 owing to military duties in connection with the war 

 with Spain, his address was not presented, and in- 

 stead Prof. Robert H. Richards, of the Massachusetts 

 Institute of Technology, addressed the section on 

 the subject of " Ore Dressing." He called attention 

 to one of the most important types of mills for con- 

 centrating ores, that using revolving screens and 

 jigs, showing the system of sizing by screens and 

 hydraulic classification to prepare the ore for the 

 subsequent concentration by jigs and slime tables. 

 A good deal of diversity of opinion exists upon the 

 choice of the sizes of holes for the sieves which pre- 

 pare the ore for jigs. Prof. Richards then described 

 certain investigations which defined the laws gov- 

 erning this selection. His investigations into the 

 laws of jigging attribute the action of that machine 

 mainly to two causes separation under hindered 

 settling conditions during pulsion or the upward 

 movement of the water, in which the heavier par- 

 ticles form a layer below the light particles, and suc- 

 tion or the downward movement of the water, in 

 which the fine particles of the heavy mineral are 

 drawn down through the interstices between the 

 coarse grains of quartz. He further gave results of 

 investigations upon the slopes and water quantities 

 to be used upon slime tables, showing the angles at 

 which the rich mineral and the waste rock move. 

 These results indicate the lines along which the im- 

 provement in slime tables should run. 



The chosen secretary of the section, Prof. William 

 S. Aldrich, was likewise absent from the meeting 

 owing to the war, and it was decided that the offi- 

 cers of the previous year i. e., Prof. John Galbraith 

 and John J. Flather should continue to act as vice- 

 president and secretary. 



The following-named papers were read and dis- 

 cussed before the section : " The Determination of 

 the Lamp House per Day available for Electric 

 Lighting from a Storage Battery Plant driven by a 

 Twelve-Foot Aer- Motor," by C. L. Crandall ; " in- 

 struments and Methods of Hydrographic Measure- 

 ments by the United States Geological Survey," by 

 Frank H. Newell; "The Development of the Topo- 

 graphic Work of the United States Geological Sur- 

 vey and its Application to the Solution of Economic 

 and Engineering Problems," by Charles D. Wal- 

 cott; "On the Testing of Steam-Pipe Covers," by 

 Charles L. Norton ; " Time Test on Dry Long-Leaf 

 Yellow-Pine Lumber in Compression Endwise," by 

 John B. Johnson ; " High-Speed Influence Machines," 

 by Charles F. Warner ; " Proposed Methods of De- 

 termining the Frequency of Alternating Currents," 

 by Carl Kinsley ; " A 'Combined Absorption and 

 Transmission Dynamometer," by John J. Flather ; 

 "On the Use of a Platinum Resistance as a Pyrom- 

 eter in Boiler Tests " and " On the Measurement of 

 Train Resistance by Dynamometer," by Frank C. 

 Wagner; "Note on a Curious Example of Elastic 

 JSolotropy in Steel," "An Integrating Dynamometer 

 for measuring the Work done in Drawing a Train," 

 and " A Comparison of the Efficiency of the Rheo- 

 stat and the Series-Parallel Controller for Electric 

 Cars," by Thomas Gray; "The Efficiency of Re- 

 frigerating Plants," by Storm Bull ; " On the Evap- 

 oration and Seepage from Reservoirs," " Losses from 

 Rivers," and " Energy received .from the Sun," by 

 Louis G. Carpenter ; " Some Micro-photographs 



showing the Grains of Portland Cement between 

 Diameters 0.02 mm. and 0.14 mm. as separated by 

 the Schone Washing Apparatus," by John B. John- 

 son; "Some Notes on Definitions of Mechanical 

 Unit," by William Kent; and "The Theory of 

 Half-Tone Press Printing," by Roinyn Hitchcock. 



E. Geology and Geography. The presiding offi- 

 cer of this section was Prof. Herman L. Fairchild, 

 of the University of Rochester, who addressed the 

 section on the subject of " Glacial Geology in Amer- 

 ica." He said : " The life of this association, with 

 that of its predecessor, covers precisely the period 

 since the glacial theory was introduced'to American 

 geologists. It seems highly appropriate, upon the 

 occasion of the jubilee meeting of the society, to 

 review briefly the history and growth of glacial 

 geology in the country, and to give credit to the 

 men who were pioneers, or who have been most in- 

 fluential in the development of this young and vig- 

 orous branch of earth study. Our early geologists 

 had by no means neglected the study of the ' drift ' 

 of the country, but the formation of this was attrib- 

 uted to the action of great floods, so that the word 

 ' diluvial ' is of common occurrence in the early 

 essays of our self-taught geologists. The first sug- 

 gestion of ice as a contributory agent seems to have 

 been made by Peter Dobson, of Connecticut, who, 

 in a communication to ' Silliman's Journal.' spoke 

 of the agency of icebergs. This was in 1825, and 

 Murchison gives to Dobson the credit of suggest- 

 ing the iceberg hypothesis to him. Conrad seems 

 to have been the first of our students who suggested 

 the agency of land or glacier ice, and this idea was 

 taken up by Hitchcock. 



" A question of great popular interest concerning 

 glaciation is that of time time in years since the 

 disappearance of the ice. That the time is very 

 brief, judged by geologic standards, since the ice 

 sheet disappeared from our region seems certain. 

 Judging from the freshness of the glacial scorings 

 and the deposits, five thousand or ten thousand or 

 fifteen thousand years is thought by many glacial- 

 ists to be a fair estimate of the length of their ex- 

 posure. But no reliable chronometer has yet been 

 found." 



On Aug. 23 the Geological Society of America 

 met with the section, at which time members of 

 that society presented the following papers : " Some 

 Features of the Drift on Staten Island, N. Y.." by ' 

 Arthur Hollick; "Spacing of Rivers with Refer- 

 ence to the Hypothesis of Base Leveling" and 

 " Loess Deposits of Montana," by Nathaniel S. Sha- 

 ler ; " Glacial Waters in the Finger Lake Region of 

 New York," by Herman L. Fairchild ; " The Strati- 

 fication of Glaciers," by Harry F. Reid ; " Evi- 

 dences of Epeirogenic Movements causing and 

 terminating the Ice Age," by Warren Uphain ; 

 " Clayey Bands of the Glacial Delta of the Cuya- 

 hoga River at Cleveland, Ohio, compared with 

 those in the Implement-Bearing Deposits of the 

 Glacial Delta at Trenton. N. J.," by G. Frederick 

 Wright ; " The Middle Coal Measures of the \Vest- 

 ern Interior Coal Field," by H. Foster Bain and A. 

 T. Leonard ; " The Principal Missourian Section," 

 by Charles R. Keyes; "Tourmaline and Tourma- 

 line Schists from Belcher Hill, Jefferson County. 

 Colorado," by Horace B. Patton ; " Note on a 

 Method of Stream Capture " and " Magmatic Dif- 

 ferentiation in the Rocks of the Copper-Bearing 

 Series," by Alfred C. Lane ; " The Volume Rela- 

 tions of "Original and Secondary Minerals in 

 Rocks," by Charles R. Van Hise; "The Develop- 

 ment of the Ohio River," by W T illiam G. Light; 

 " Classification of Coastal Forms." " Dissection of 

 the Ural Mountains," and " Note on Monadnock," 

 by F. P. Gulliver: and " The Continental Divide in 

 Nicaragua," by C. Willard Hayes. 



