ASSOCIATIONS I'"K TlIK ADVAM KM i:\T OF x IFACK. 



In- development of our subject from ils earliest 



.Mm:, then along the ancient period wlien 



in i In- rhetorical Mage, approaching at in- 



.- here and then- the syncopated, llien on 



revival of learning after I he dark ages. 



:ve seen the comparatively rapid progros 



through the ^yncopated stage to tin- purely 



>lical stage, where il was at last in a shape 



.suitable for the astounding progress of the last 



(wo hundred \cars. Finally, in the present cenl- 



ur\, \se have noted the approach of multiple 



algebra from different and independent sourer-, 



who-.- value is the glorious future." 



The following-named papers were read before 

 the section : 



-<>n a D'm'e.-t <>t' the Literature of the Mathematical 

 Sciences," l>y Alexander S. t'hristic; "Latitude of 

 the Say iv observatory," by <-'. L. Doolittle; "The 

 Secular Variation ot Terrestrial Latitudes," by 

 ('. Com.-tock ; " (iroup- of Stars, Binary and 

 Multiple," by (nur_'r \V. llulley; Description of 

 the (iivat Bpeotroaoope and Spectrograph constructed 

 I'nr the HaUtcad observatory, Princeton, N. J.," and 

 "Note on Some Keeeiit Photographs it' the Reversal 

 ot the Hydrogen Lines of Solar I'romiiicnees," by 

 John A. lira-hear; "On a Modified Form of Zenith 

 pe for deterininiii!,' Standard Dccli nations," 

 and "On the Application of the 1'hotochronogruph' 

 to the Autoiiuitie Ki-eord of Stellar Oeeultations, par- 

 tieularlv Dark-limb Emersions," by David P. Todd ; 

 "The Zodiacal Light us related to Terrestrial Tem- 

 perature Variation,'' hy Orray T. Sherman; "On the 

 Long-period Terms in the Motion of Ilyperian," by 

 Ornioiul Stone; "Standardizing Photographic Film 

 without the l'.-e of a Standard Liirht" and " Exhibi- 

 tion and Description of a New Scientific Instrument, 

 the Aurora- Inclinometer," by Frank II. Bigelow; 

 "The Tabulation of Light-curves : Description, K\- 

 phuuttion, and Illustration of a New Method," and 

 "Stellar Fluctuations: Distinguished from Variable 

 Stars; Investigation of its Frequency," by Henry M. 

 Parkhurst; "On Certain Space and Surface Inte- 

 grals." by Thomas S. Fiske; "The Fundamental Law 

 of Electromagnetism," by James Loudon; "Method 

 of Controlling a Driving Clock," by Francis P. Leav- 

 enworth; "On the Kitangential of the Quintic," by 

 William E. Heal; " Paralla\ of a Leonis," by Jef- 

 ferson E. Kerehner; also, in joint session of Sections 

 A and B, "Principles of the Algebra of Physios," by 

 Alexander Macfarlane 



B. Physics. The presiding officer of this sec- 

 t ion was Prof. Francis E. Nipher, of Washington 

 University, St. Louis, Mo. He discussed the 

 " Functions and Nature of the Ether of Space." 



In former days the reasons given for the ex- 

 istence of ether do not seem conclusive now. 

 For years it was taught that light was an elas- 

 tic pulsation in an incompressible jelly-like me- 

 dium. Some of the mathematical deductions of 

 Green he could only reconcile with the observed 

 phenomena by making the ether incompressible. 

 In 18(i.~) Maxwell proposed his theory that light 

 was an electric displacement in a plane at right 

 angles to the line of propagation. Maxwell's 

 theory met with great favor, and afforded simple 

 and natural explanations for phenomena which 

 had previously been clouded by rather strained 

 assumptions. In 1888 Sir William Thomson 

 brought a powerful re-enforcement to the elastic 

 theory. He showed that the compression wave 

 might be got rid of in the theory by making the 

 velocity of the compression wave -/.era instead of 

 infinity. Thomson found that this assumption 

 did not involve an unstable condition of the 



medium, and that therefore it wusudiiiimble. It 

 was al-o shown at orn-e by Thomson, Willard 

 (iiblis, and Fit/gerald that this new -ug. 

 placed i he elastic and eh-ctric theories on tin; 

 same logical basis if the el her wa- coii-idered 

 incompressible in the electric theory ami to have 

 a rigidity zero for a compression "wave in the 

 elastic theory. The showing of light in space 

 occupied by matter shows that the ether within 

 mu.-t be less elastic than that in free -pace. It 

 is certainly dillicnlt to understand what then- 

 can be in the molecules of matter which can in- 

 crease the density of an incompressible medium. 

 The beautiful experiment of Michelson and 

 Morley shows apparently that the ether at the 

 surface of the earth moves with it. It is dragged 

 along as if it were a liquid. The field of a steel 

 magnet is, however, a rotational phenomenon. 

 It is a spin which is maintained permanently 

 without the expenditure of energy. It .seems, 

 therefore, that the resistance to shear which shows 

 itself in the adhesion of the ether to the moving 

 earth must be a rigidity due in some way to mo- 

 tion. Other experiments of Michelson and Morley 

 on the motion of light in moving columns of water 

 have been taken as proof that the ether in water 

 is condensed to nine sixteenths of its volume in 

 air. The ether in water certainly behaves as if 

 it were more dense, but it is another matter to 

 say that it is so. It is still a mathematical fic- 

 tion which covers a gap in our knowledge of the 

 ether. He thought that the experiment should 

 be repeated with water at rest within a tube 

 which should be mounted on elastic supports in 

 a moving railway car. T.he water tube and the 

 observer's seat should be rigidly connected, and 

 swung on dampened spring supports from the 

 top and sides of the car. The question to be set- 

 tled is whether the ether or any part of it is at 

 rest in space, and does it sweep through the in- 

 terior of bodies which move through it, as wind 

 sweeps through the leaves and branches of a 

 tree. This form of the experiment is the one 

 contemplated by Eisenlohr's analysis leading to 

 Fresnel s formula, and it is capable of great vari- 

 ations in the conditions of experiment. What- 

 ever its results may be, it promises to add greatly 

 to our knowledge of the physics of the ether. 



The following-named papers were then read 

 before the section : 



" On the Logarithmic Mean Distance between Pairs 

 of Points in any Two Lines," hy William Hoover; 

 A New Method for measuring the Expansion of Sol- 

 ids," by Edward W. Morley; "Measurement of the 

 Expansion of Jessup's Steel by a New Method," by 

 Edward W. Morley and William A. Rogers; "State- 

 ment of the General Law determining the Fusinir 

 and Boiling I'oint of any Compound under any 

 Pressure as Simple Function of the Chemical Consti- 

 tution of the Same," hy (iustavus Ilinrichs; "The 

 Calculation of the Boiling Point of a Liquid under 

 any Pressure"; "Determination of the Discontinuity 

 of the Fusing Points of Paraffins hy Mean- of Anaht- 

 ieal Mechanic-"; "A Scheme for a Science of < 'olor,'' 

 by William Orr; -Note on Magnetic Measurement.-* 

 at Ohio State I'nivcrsity " and " Notes on Kotatiinr 

 Contact Methods of Measurement of Variable Electric 

 Magnitudes." by Benjamin F. Thomas; "The Peri- 

 odicity of the Aurora," hy Major A. Veeder; " Some 

 Forms of Carbon and Alkaline Storage Butteries" and 

 "The Tangent Galvanometer as a Voltmeter." by W. 

 M. Stine; "Do Tornadoes whirl f" ami "Artificial 

 Kain," by Henry A. Hazeii; " Observations with a 



