100 



SCIENCE. 



[N. S. Vol. V. No, 107. 



this a geometric construction was given. 

 The constructions involve the ruler alone, 

 as is proper when a single point is to be 

 found. 



Prof. Alexander S. Chessin, of the Johns 

 Hopkins University, gave a brief ac- 

 count of his investigations on the motion 

 of a physical pendulum, taking into ac- 

 count the rotation of the earth about its 

 axis. He showed that when the relative 

 velocity of the pendulum is zero, as in the 

 famous experiment of Foucault, the motion 

 of the axis of the pendulum can be repre- 

 sented as composed of two simultaneous 

 motions : (1) of the motion on a very flat 

 closed conic surface, this surface having a 

 plane of symmetry which would be the 

 plane of oscillations of the pendulum, but 

 for the disturbance due to the rotation of 

 the earth ; and (2) of the rotation of this 

 conic surface about the vertical of the 

 point of suspension.* The conic surface 

 being very flat, it will seem to an observer 

 as if the axis of the pendulum oscillated 

 in the plane of the vertical of the point of 

 suspension, while at the same time this 

 apparent plane of oscillations rotated about 

 the vertical. In Foucault's experiment the 

 rotation of the apparent plane of oscilla- 

 tions took place clock-wise. Prof Chessin 

 showed that this rotation depended on 

 the construction of the pendulum; namely, 

 if the pendulum be properly constructed 

 and the amplitude of oscillations be suf- 

 ficiently great, then the rotation of the 

 apparent plane of oscillations could take 

 place as well clock- wise as contra clock- 

 wise or even not take place at all. This in- 

 teresting phenomenon could be observed 

 best at places near the equator, because the 

 angular velocity of rotation of the apparent 

 plane of oscillations is composed of two 

 terms, one proportional to the sin, the other 



* &e.e American Journal of Maihematics, Vol. XVII., 

 p. 86; Johns Hopkins University Circulars, Vol. 

 XIV., No. 118, p. 64. 



to the cos of the latitude of the place of 

 observation. The contra clock-wise rota- 

 tion is due to the presence of the cosine 

 term and is maximum on the equator. In 

 concluding. Prof. Chessin emphatically 

 urged experiments which would verify his 

 calculations. 



Prof. E. W. Brown, of Haverford Col- 

 lege, made a brief statement of the prog- 

 ress of his calculation of the solar in- 

 equalities in the lunar theory. The mo- 

 tion of the node was compared with Han- 

 sen's result and with that given by ob- 

 servation. An explanation was also given 

 of the slow convergence of the series which 

 represents the principal part of the secular 

 acceleration of the moon's mean motion. 



Following a pleasant custom of previous 

 years, several of the members dined together 

 after the meeting. F. N". Cole, 



Secretary. 



CURRENT NOTES ON ANTHROPOLOGY. 

 DIVINATORY AND CALENDEICAL DIAGRAMS. 



At the American folk-lore meeting Mr. 

 Stewart Culin exhibited and explained 

 several divinatory diagrams from Thibet, 

 China and Corea, and called attention to 

 their close similarity to the so-called ' cal- 

 endar-wheels ' and the tonalamatl, or book 

 of days, of ancient Mexico. He pointed out 

 that the fundamental conceptions of both 

 are identical, and that both developed in- 

 to games, such as parcheesi in India and 

 patolli in Mexico, the Chinese game of ' pro- 

 motion,' and the European ' game of goose.' 



These all begin with the numerical con- 

 cept of the four, expressed in four arms, 

 like a cross, or four ' houses ' or squares, 

 which latter, by multiplication, may be 12, 

 16, 64, etc. This primary concept ex- 

 pressed the original notion of the ' four 

 quarters,' i. e., of the world, and, by exten- 

 sion of the cosmos, time as well as space. 

 The relation of each individual to the All 

 was the notion which imparted the divina- 



