Xll. 



March "jt/i, 1887. 



President Nipher in tlie chair ; eleven members present. 



Mr. Engler made some remarks on the method for generating 

 a helicoid without the use of the helix, and exhibited a model of 

 the surface thus constructed. 



Mr. James A. Seddon described some experiments which he 

 had made to determine the form of the cross section of the chan- 

 nel of alluvial rivers, and exhibited diagrams showing how the 

 forrn of section was dependent on the slope of the consequent ve- 

 locity variations. 



March 21st, 1887. 



President Nipher in the chair ; six members present. 



Prof. Nipher presented a paper on the "Characteristic of the 

 Series Dynamo," in which he showed that the relation existing 

 between electromotive force, speed, and current, when represented 

 on three axes mutually at right angles, was expressed by a hyper- 

 bolic paraboloid to a degree of accuracy much within the limits 

 of error of the machine. By the use of this surface it was possi- 

 ble to determine what speed the machine with constant resistance 

 must be run to produce a given horse-power. The paper was re- 

 ferred to the Committee on Publication. 



On motion, Mr. M. L. Gray, Dr. Sander, and Mr. Rob't Moore, 

 were appointed to draw up resolutions expressing the sentiments 

 of the Academy concerning the death of Capt. James B. Eads, a 

 life-member. 



April ^th, 1887. 



Dr. Hulbert in the chair ; twelve members present. 



A paper by Prof. Trelease, entitled "Revision of North Ameri- 

 can Linaceas," was presented by sketch, and referred to the Com- 

 mittee on Publication. 



Mr. Engler exhibited models of a hyperbolic paraboloid. 



The following resolution of respect to the memory of Capt. 

 James B. Eads, a life-member, was received, ordered spread on 

 the records, and the committee discharged ; 



