214 



SCIENCE. 



[N. S. Vol. XVII. No. 423. 



monnment, illustrated by a series of pho- 

 tographs. 



Rapid Primary Triangulation: John F. 



Haypord, Washington, D. C. 



This paper is a statement of the results 

 secured by a triangulation party on the 98th 

 meridian triangulation in Kansas, Okla- 

 homa, Indian Territory and Texas, during 

 the season of 1902, and of the peculiarities 

 of their methods. This triangulation is 

 fully up to the primary standard degree 

 of accuracy, and it is believed to be the 

 most economical as well as the most rapid 

 triangulation of its class yet executed. 



Reaction versus Velocity as an Active 



Agent in Removing Bars: Lewis M. 



Haupt, Philadelphia, Pa. 



Necessity for channels of larger capacity 

 across ocean bars, to keep pace with the 

 growth of vessels and commercial demands. 

 Present resources of the engineer limited 

 to concentration and dredging. Defects 

 of this system, with illustrations. 



Reaction, the cause of deep holes and 

 channels, rather than mean velocities. 

 Eddies which scour and those which de- 

 posit. Applications of reaction, as exem- 

 plified in nature, to effect similar results 

 locally across ocean bars, illustrated. Great 

 economy and efficiency of the single-reac- 

 tion breakwater as compared with other 

 methods in vogue. 



WEDNESDAY MORNING, DECEMBER ^i . 



Notes on Comparative Designs of Metallic 

 Arch Bridges: H. S. Jacoby, Cornell 

 University, Ithaca, N. Y. 

 A comparison of the weights of three- 

 hinged spandrel-braced arches for different 

 heights of the crown hinge, ranging from 

 the bottom to the top chords. The effect 

 of variations in bridge specifications upon 

 the weights of two-hinged arch ribs and 

 spandrel-braced arches. The effect of dif- 

 ferent curves for the lower chord. 



Road Material Laboratory: L. W. Page, 



Washington, D. C. 



This paper describes different road- 

 making materials and points out the wis- 

 dom of having them tested by laboratory 

 methods before they are used in construc- 

 tion. The amount of traffic on one road 

 may not require the same kind of material 

 that another road should receive. The 

 binding materials present with crushed 

 rocks of various kinds have much to do 

 with their value for surfacing roads. The 

 road-material laboratory of the Agricul- 

 tural Department makes these tests free 

 and invites an inspection of the equipment 

 and methods used in the examination of 

 road material. 



Agricultural Engineering : Elwood Mead, 

 Washington, D. C. ' 



Conditions of farm life and farm labor 

 in the United States have undergone a 

 revolution in the past fifty years. The 

 shorter hours of labor and conditions of 

 life in factories are having their influence 

 on farm work. The farmer is compelled 

 to do as the factories have done, substitute 

 power for hand labor and use the most 

 effective implements and machines. Ap- 

 plication of power to farm work is taking 

 new and significant form through the use 

 of steam, gas and electricity as substitutes 

 for animal power. Increasing importance 

 of this evolution has attracted the atten- 

 tion of European countries, where institu- 

 tions for the study and improvement of 

 farm machinery are supported by the state. 

 The agricultural colleges of this country 

 have in recent years given serious attention 

 to this subject. A committee on methods 

 of teaching agriculture has formulated a 

 course in the subject which has been pub- 

 lished in Bulletin 45, on pages 6 and 7, of 

 the Office of Experiment Stations. One 

 difficulty confronting the colleges is the 

 lack of classified and verified information. 



