540 EXPERIMENT STATION EECORD, 



Icukao-e from ctuuils unci overirrig'ation have destroyed the productive- 

 iK ss of hiiid by producing saturation of soils in certain localities and 

 n^sulting alkali conditions. Well-directed drainage operations, it was 

 believed, will reclaim- such lands and protect those Avhich are threat- 

 ened with the evil. 



The Ilydrographic Work of the U. 8. Geological Survey was 

 described by H. H. Presley, who reviewed the work on the measure- 

 iiuMit of streams and the relation of this to problems in irrigation. 



The Road Material Lal)()ratory of the Bureau of Chemistry of this 

 l)('l)urtment was the subject of a paper l)y L. W. Page. He men- 

 tioned the ditierent road-making materials and pointed out the wisdom 

 of Inning them tested by laboratory methods before they are used in 

 construction. Differences in the amount and character of traffic may 

 determine the kind of material that is required. The binding mate- 

 rials present with crushed rocks of various kinds were said to have 

 much to do with the value of these materials for surfacing roads. 



The Cementing Power of Road Materials was presented by A. S. 

 Cushman. The cementing value is a phenomenon of the same nature 

 as the plasticity of clays, and results in the road-material lab- 

 oratory of this Department seem to point to the fact that plasticity is 

 dependent on a colloidal condition of the particles. Surfaces of roads 

 are continually being powdered by the effect of traffic wear and weath- 

 ering, and the particles are continually being cemented and recemented. 

 If the material of the road lacks plasticity the particles blow and wash 

 away too readil3\ The binding cjuality of such rocks as limestones 

 and dolomites is a function of the hydrogel impurities, present usually 

 either in the form of silicic acid or hydrated oxid of iron. 



In a paper on The Metric System, J. Burkitt Webl) opposed the 

 introduction of this s\'stem from the standpoint of engineering. 

 Standards of length lie at the foundation of all our important and 

 accurate manufacturing and engineering work, and an exaihination of 

 the necessities of this work, in both its theoretical and practical parts, 

 was stated to show that a change to the metrical system would be not 

 only very expensive but detrimental. He argued that 16 (the sub- 

 divisions of the inch) is in many ways a better number than 10 as the 

 basis of a system; and he attempted to point out some of the peculiar 

 collateral advantages of 16. 



AGKICULTURE AND ICCONOMIC SCIENCE. 



Most of the papers presented at the meetings of the Society for the 

 Promotion of Agricultural Science have been noted elsewhere under 

 a]ipropriate headings. The presidential address, delivered by W. H. 

 Jordan, on Values in Science, will appear in the next issue of this 

 joui-nal. 



