472 Scientific Intelligence. 



the velocity of elastic waves, increases from the surface down- 

 ward to a stratum of maximum velocity, probably at a considera- 

 ble depth, and then diminishes again. The conclusion of Pro- 

 fessor Omori from records in Italy and Japan, that the velocity 

 of the first tiftmor is almost always equal to 13 kilometers per 

 second, while longitudinal waves in steel have only a velocity of 

 6*2, is difficult to account for; it may be explained by the proba- 

 ble supposition that the rocks deeper in the earth's crust have 

 elastic constants several times greater than those near the sur- 

 face. The velocity named would roughly correspond to the 

 values E = 6 X 10 12 and p = 3-5. The high value of the elastic 

 constant relative to the density is not impossible, since, in passing 

 from Tertiary to Archean rocks an increase of density from 2 to 

 3 is here shown to be accompanied by an increase of the modulus 

 of elasticity more than ten times in some cases. 



4. The Graduate Bulletin of the University of Nebraska. 

 Volume I, No. 1, pp. 1-68. Lincoln, Nebraska, 1900. — Among 

 the papers here published is one by E. J. Rendtorff, on acro- 

 matic polarization with crystalline plates ; another by C. C. 

 Engberg on the Cartesian oval, and one by C. A. Fisher on the 

 geology of Lincoln and environs. 



5. National Academy of Sciences. — The autumn meeting of 

 the National Academy was held at Providence, Nov. 13-15th. 

 The following is a list of the papers read (several by title): 



J. Trowbridge: Investigations of light and electricity with the aid of a battery 

 of twenty thousand cells. 



Alpheus H'iATT: Progressive evolution of characters in the young stages of 

 Cephalopods. Descriptive method of presenting the phenomena of the cycle of 

 evolution among Cephalopods. 



T. W. Richards: The porous cup voliameter. An account of the study of 

 growing crystals by instantaneous microphotography. 



S. L. Penfield : Stereographic projection and some of its possibilities from a 

 graphical standpoint. 



C. S. Minot: On the development of the pig. Normal plates illustrating the 

 development of the rabbit and the dogfish. 



T. 0. Mendenhall: Note on the energy of recent earthquakes. 



A. A. Michelson: Spectrum of sodium in a magnetic field. Progress in the 

 Echelon spectroscope. 



H. A. Rowland: A report of the spectrum work carried on with the aid of a 

 grant from the Bache Fund. On the explanation of inertia and gravitation by 

 means of electrical phenomena. 



A. S Packard: Distribution of philogeny of Limulus. Male preponderance 

 (androrhopy) in Lepidopterous insects. 



A. Michael: The synthesis and reactions of sodium acetate ester, and their 

 relation to a new interpretation of chemical metathesis On the genesis of 

 matter 



C. BaruS: Demonstration of the projection of one grating by another. Exhibi- 

 tion of certain novel apparatus : A wave machiue ; an expansion lens ; a record- 

 ing system pf two degrees of freedom; A tube showing colored cloudy condensa- 

 tion On stability of vibration and on vanishing resonance. Hysteresis-like 

 phenomena in torsional magnetostriction and their relation to viscosity. 



Charles D. Walcott: Folding and faulting of strata in the Cordiileran Area. 



J. M Crafts : Report on the Meeting of the Committee of the International 

 Association of Academies held at Paris. 



