428 



SCIENCE. 



[N. S. Vol. XI. No. 272. 



toward the periphery. One or two other iu- 

 stances of this are mentioned, the most closely 

 analogous being the laccolith at Umptek in Kola 

 (Finland). 



An explanation of this is given, based on a 

 process of fractional crystallization or freezing 

 of the magma, and the idea applied to other 

 cases. It is suggested that the laccoliths and 

 similar magnetic masses, which have been 

 studied, may be referred to three distinct types, 

 the differences between which would be satis- 

 factorily accounted for by the hypothesis. 



In the ensuing discussion Dr. Washington 

 pointed out that the specimens of the rocks 

 represented by his analysis had not been selected 

 in a radial line, but at various directions at in- 

 creasing distances from the central mass of 

 basic constitution. ^^^^^^ ^ j^^^^^^ 



Secretary of Section. 



TORREY BOTANICAL CLUB. 



At the meeting of January 31, 1900, six new 

 members were elected. 



The scientific program consisted of a paper 

 on the cultivation of palms, by Mr. Henry A. 

 Siebrecht. After a general discussion of the 

 palms as a botanical group, and of the various 

 types represented in tropical regions, a full and 

 interesting account was given of their cultiva- 

 tion in conservatories and as house plants, with 

 valuable suggestions for their treatment and 

 care in the household. The characters of vari- 

 ous species suitable for cultivation indoors were 

 given, especially of the genera Cocos, Kentia, 

 Phcenix, Areca, Caryota, Hcula and Thrinap, of 

 which fine illustrations were shown from Mr. 

 Siebrecht's nurseries. Among these were Cocos 

 Weddelliana, Phcenix Canariensis, P. Bupicola, 

 Areca lutescens and Licuala grandis. An account 

 of Mr. Siebrecht's extensive nurseries in the 

 tropical regions of Trinidad was afterwards 

 added by request of some of the members. 



Discussion followed by Mr. Henshaw, Mr. 

 Lighthipe and Dr. Rusby. 



L. M. Underwood, 

 Secretary pro. tern. 



PHILOSOPHICAL SOCIETY OF WASHINGTON. 



The 513th meeting of the Society was held 

 at the Cosmos Club on February 17th. Pro- 



fessor T. J. J. See, of the Naval Observatory, 

 on behalf of the committee on Mathematical 

 Science, presented a brief report on the prog- 

 ress of Theoretical Astronomy during 1899. 

 Attention was drawn to the completion of 

 M. Poincare's Methodes nouvelle de la me- 

 canique, a work of the highest theoretical 

 interest, and promising important practical ex- 

 tension in certain directions. It seemed prob- 

 able that the methods depending on periodic 

 solutions will be of much greater use in con- 

 nection with the theories of stability and limits 

 of variations, than in the practical construction 

 of tables. 



The progress of the Lunar Theory in the 

 hands of Professor E. W. Brown was noted, 

 and attention was drawn to the necessity for a 

 practical test of the theory in the way of the 

 construction of new tables for the Moon. The 

 speaker thought the Nautical Almanac Office 

 might take up the Lunar Theory in the near 

 future as one of its principal lines of work. 



The report noted the progress of Professor 

 Eichelberger's researches on the tables of the 

 Watson Asteroids, and Professor Stone's re- 

 searches on the theory of the perturbation of 

 Hyperion. Attention was also called to Pro- 

 fessor Brown's researches on the satellite of 

 Neptune, which enabled him to deduce the 

 oblateness of the planet from its perturbative 

 effect on the motion of the Satellite. 



Professor See referred to his own researches 

 on the Sun's heat, recently published by the 

 Academy of Science of St. Louis, and said he 

 had some investigations in progress which 

 would give more accurate theories of the den- 

 sities and moments of inertia of the planets. 

 In conclusion it was pointed out that if no dis- 

 covery of an especially striking character had 

 been made during the past year, it was apparent 

 that the progress was steady and continuous, 

 and touched some of the most delicate problems 

 of the heavens. 



Mr. Henry Parquhar read a paper on the 

 ' Formation of a table of nth powers by means 

 of their successive differences. ' A rule was given 

 and demonstrated for calculating any power of 

 the natural series of numbers from upwards, 

 by simple addition, combined with multiplica- 

 tion by factors in no case exceeding the index 



