October 4, 1912] 



SCIENCE 



425 



cessors of perhaps a hundred years hence 

 to determine with great aeeuraey the rela- 

 tive places of stars that form globular 

 clusters. It is only in this way that we 

 shall ever be able to say what the motions 

 within these clusters are; and this in turn 

 will go far toward telling us what these 

 objects themselves are, and what place 

 they occupy in the universe of stars. A 

 third research that we contemplate is the 

 determination of the brightness of faint 

 stars by means of extra-focal images, or 

 otherwise expanded star disks. This 

 method for determining stellar magnitudes 

 is surpassed in accuracy only by the 

 selenium photometer, which is however not 

 applicable to faint stars. 



These are the things that we have in 

 mind, but we reserve the right to alter 

 these intentions as soon and as often as 

 circumstances may demand. I should not 

 wish to commit myself, much less any other 

 man, to an unalterable routine of work. 

 But I do wish that it were in my power to 

 commit the present staff and its successors 

 to the policy of doing that thing which is 

 most in need of attention, within the limits 

 set by our resources and equipment, both 

 personal and instrumental. If we do not 

 succeed in contributing our fair share to 

 the progress of our science, I think it will 

 not be because we have not tried; and I 

 believe I can make this promise for those 

 who are to come after us, as well as for 

 ourselves. For it would be a strange thing 

 if the devotion that has been lavished upon 

 the Allegheny Observatory by "William 

 Thaw and his sons, by Langley, Keeler, 

 Wadsworth and Brashear — it would be a 

 strange thing, I say, if the example of such 

 devotion should ever cease to be a com- 

 pelling incentive to any who may have the 

 privilege of working within these walls, 

 and if the tree that these men have planted 



and nourished should cease to bear fruit 

 for many a season to come. 



Frank Schlesinger 

 Allegheny Observatory 



M. SENSI POINCABE 

 The city of Paris is commonly regarded as 

 the greatest mathematical center of the world, 

 and Henri Poincare stood for a number of 

 years at the head of the Paris mathematicians. 

 He was a mathematician in the broadest as 

 well as in the deepest sense of this term. He 

 started as an engineer in 1879, but soon there- 

 after he entered upon his life work as univer- 

 sity instructor, first at Caen in December, 

 18V9, and afterwards at Paris from October, 

 1881, until his death on July 17, 1912. His 

 positions in the University of Paris were as fol- 

 lows: Maitre de conferences d' analyse, charge 

 du eours de mecanique physique et experi- 

 mentale ; prof esseur de physique mathematique 

 et de calcul des probabilites, and professeur 

 d'astronomie mathematique et de mecanique 

 celeste. 



He was born at Nancy, April 29, 1854, and 

 was educated successively at the Lyeee de 

 Nancy, I'Ecole Polytechnique and at I'Ecole 

 nationale superieure des mines, receiving his 

 doctor's degree from the University of Paris in 

 1879. He was a very bright student and re- 

 ceived first rank at the entrance examination 

 of I'Ecole Polytechnique. At the early age of 

 32 he was elected as a member of I'Academie 

 des Sciences, and for this occasion he prepared, 

 in 1884, a statement entitled " Notice sur les 

 travaus scientifiques de M. Henri Poincare." 

 Although this " Notice " was written less 

 than five years after Poincare had begun the 

 publication of his researches, it reviews a large 

 number of his published articles along the fol- 

 lowing tliree lines : (1) Differential equations, 

 (2) General theory of functions, (3) Arith- 

 metic or the theory of numbers. He empha- 

 sizes the fact that he did not pursue his re- 

 searches in these three directions indepen- 

 dently of each other, but that the results ob- 

 tained along these Tarious lines threw light 

 on each other, and that his work along each 



