INDEX 



ABACUS, calculating machine, 58 

 Abdera, Greek city in Thrak6, 131 

 Aberration of the stars, Bradley 's 



discovery of, 286 

 Abjuration of Galileo, 196 

 Absorption of light, 395 

 Academy, French, its expedition 



to Cayenne, 230 

 Acceleration of falling bodies known 



to the ancients, 124 

 Acceleration of *f ailing bodies first 



measured by Galileo, 198 

 Accuracy, extraordinary, of modern 



observations, 232 

 Acoustics, studied by the Greeks, 



147 

 Action at a distance, inconceivable, 



449 

 Adams, J. C., predicts an extra- 



Uranian planet, 311 

 Africa, circumnavigation of, 80, 



1 60 



Ahmes, manuscript of, 56 

 d'Ailly, his Imago Mundi, 10 



transmits Roger Bacon's ideas, 



1 60 

 Air, ancient ideas of materiality of, 



138 

 weight of, demonstrated by Tor- 



ricelli, 240 

 pump, invented by Guericke, 241 



Akosmism, Fichte's, as an alter- 

 native, 9 



Alchemy, beginnings of, 51 



d'Alembert, French mathematician, 

 296 



Alexandria, its stirring life, 80 

 its decline, 146 



Alexandrian school, its long sur- 

 vival, 126 



Algebra, early use of, 58 



Al-Hassan, founder of the Assassins, 



155 



Al-Hazen calculates the height of 

 the earth's atmosphere, 241 



473 



Almagest, Ptolemy's, Coppernicus' 



debt to, 164 

 Al-Maimum, measure of the earth, 



78 



collects a great library, 153 

 Alpha Centauri, size of, 336 

 a double star, 373 

 distance from the earth, 357 

 Alphonso of Castile, his remark, 17 

 Amber, first manifests electrical 



properties, 139 

 America, discovery of, its effect on 



Europe, 163 



Anaxagoras, ideas of the sun, 22 

 ideas of attraction, 123 

 on homeomeria or similar parts, 



136 



Andalusia, public libraries in, 154 

 Anderson, observation of new star, 



380 

 Antony, Mark, presents a library to 



Cleopatra, 152 



Apelt, his history of ideas, 10 

 Apex, stellar, the direction of sun's 



movement, 323 

 Apollonius of Perga, introduced 



conic sections, 92 

 on Mercury and Venus as satel- 

 lites of the sun, 169 

 Appearances, difficulty of over- 

 coming, 21 

 Apple, Newton's, probably a myth, 



257 



Arabian culture, its character, 156 

 Arcetri, death-place of Galileo, 207 

 Archimedes, inscription on his 



tomb, 57 



description of his planetarium 

 failure to adopt Aristarchus' 

 ideas, 116 



his " Arenarius " or sand-reck- 

 oner, in 



his greatness and limitations, 125 

 Arcturus, vast size of, 337 

 its frightful speed, 340 



