790 



SCIENCE. 



[N. S. Vol. XVII. No. 437. 



Bird Lore for March-April has the story 

 of ' A gierra Nighthawk Family,' by Tlorence 

 M. Bailey, and of 'A Family of Barn Owls,' 

 by Thomas H. Jackson; an important brief 

 article on ' The Heath Hen in New Jersey.' 

 Anna Head describes the ' Nesting of the 

 Euby-crowned Kinglet' and Frank M. Chap- 

 man gives the third paper on ' How to Study 

 Birds,' this being devoted to the nesting sea- 

 son. There is the third series of portraits 

 of Bii-d Lore's Advisory Councilors'. There 

 are the customary notes, reviews and reports 

 of the Audubon Societies, from which we 

 learn of the spread of bird protection in 

 various states. 



SOCIETIES AND ACADEMIES. 



PHILOSOPHICAL SOCIETY OF WASHINGTON. 



The 567th meeting was held on April 11, 

 1903. Professor Marvin exhibited a seismo- 

 graph sheet showing a slight earthquake wave 

 on March 15. Professor Gore described the 

 ' International Bibliography of Mathematics ' 

 now published at irregular intervals in card 

 form. Thvis far eleven sets of one hundred 

 cards each have been published. 



Professor T. J. J. See, U. S. Navy, read 

 a ' Historical Sketch of Glaus Eoemer, the 

 Discoverer of the Velocity of Light.' Eoemer 

 was one of the greatest scientific geniuses, 

 ranking with Aristarchus of Samos, Archi- 

 medes and Hipparchus, among the ancients, 

 and with Galileo, Newton and Bessel, among 

 the moderns. As almost all of his observa- 

 tions were consumed in the conflagration 

 which destroyed a large part of Copenhagen 

 in the year 1728, his memory has been greatly 

 neglected. Yet it was Eoemer who invented 

 all the principal instruments of the modern 

 observatory — the meridian circle, the prime 

 vertical, the altazimuth and the equatorial 

 telescope. He lived very much in advance of 

 his age. 



The discovery of the velocity of light in 

 1675 was treated at length. It was made 

 from the eclipses of the first satellite of 

 Jupiter. Most of Eoemer's contemporaries 

 rejected his theory of the finite velocity of 

 light, or adopted it only after long years had 

 elapsed. The French men of science were 



slower in accepting the new idea than men of 

 science in other nations. Huygens and New- 

 ton adopted Eoemer's results, while Fontenelle, 

 the perpetual secretary of the Paris Academy 

 of Sciences had even gone so far as publicly 

 to congratulate himself on escaping the seduc- 

 tive error of believing in the gradual propaga- 

 tion of light! Eoemer gave eleven minutes 

 for the equation of light (time in coming 

 from the sun to the earth), but Newton re- 

 duced the value to between seven and eight 

 minutes. The true value found by the classic 

 researches of Michelson and Newcomb is about 

 8.4 minutes, to which Newton's was a close 

 approximation. 



The speaker said that with the exception of 

 the discovery of the law of gravitation, no 

 sublimer discovery than that of the velocity 

 of light had ever been made. Notwithstand- 

 ing the incredulty of others, Eoemer had never 

 wavered in his belief in this discovery, and 

 the speaker said that it paved the way for the 

 investigation of the velocity of electricity, 

 which had been found with much accuracy. 



Eoemer was born in 1644 and died in 1710, 

 all of his life except nine years being spent 

 in Denmark. He met Pieard when he came 

 to Denmark to determine the position of 

 Tycho Brahe's Observatory in 1671, and the 

 following year returned with him as his assist- 

 ant, and spent nine years at the Paris Observ- 

 atory, just started under J. D. Cassini. 

 Pieard was much the best astronomer of his 

 age, but had been set aside by the government 

 of Louis XIV., and a foreigner, Cassini of 

 Bologna, called to be superintendent of the 

 Eoyal Observatory at Paris. This circum- 

 stance injured astronorriy in France for many 

 years. Eoemer's association with Pieard was 

 fortunate, as this gave him the best ideas of 

 the times, though his own genius was even 

 greater than that of Pieard, who had acquired 

 an imperishable reputation by measuring the 

 arc of the meridian' used by Newton for verify- 

 ing the theory of universal gravitation in 

 1685. 



A picture of Eoemer was exhibited, kindly 

 sent by Professor T. N. Thiele, director of the 

 Eoyal Observatory of Copenhagen. This 

 showed a striking resemblance to Newton. 



