-368 KANSAS ACADEMY OF SCIENCE. 



Hundreds of other stars are spectroscopic doubles, as shown by the 

 periodic doubling of their lines. These may be embryo solar systems. 

 The periods of these are so short as to suggest this. The theory of 

 the younger Darwin, that tidal waves of the nebulous and molten 

 matter, in the new-made world, and the aqueous surface of cooler bod- 

 ies, regulate the distances and periods of stellar companions. These 

 tides retard the rotation and increase the velocity of revolution until 

 a balance is established between the tangential and gravitational 

 forces. According to this theory, planets and other satellites began 

 their career with much less periods and shorter distance from their 

 centers of revolution than they now occupy. A short period, there- 

 fore, probably indicates a new-born world, and a large orbit and long 

 period, maturity. 



It has long been known that many stars have a proper motion at 

 right angles to the line of vision. Motion directly toward or away 

 from the solar system was thought to be beyond our ken. The spec- 

 troscope, however, shows in a moment of time whether the star is ap- 

 proaching or receding from us, and even the rate can be accurately 

 computed from the displacement of its lines in the spectroscope. 

 Nearly all, if not entirely all, so-called "fixed stars" are shown to be 

 in rapid motion, varying from 10 to 300 times as swift as a projectile 

 from a modern gun ; 1830 Goombridge and 243 Cordalea, sometimes 

 called "the runaway stars," have such trememendous velocities that 

 the gravitation of the stellar universe is not sufficient to account for 

 them. Possibly these are stellar missiles swiftly traversing our uni- 

 verse from the infinite depths beyond. 



Our own sun is found to be moving like its neighbor stars. It is 

 drifting at a rate of from twelve to sixteen miles per second toward a 

 point some thirty degrees from the pole of the ecliptic. The earth 

 and other planets are thus tracing out mighty spiral courses through 

 the universe, never returning to the same point again, unless the sun's 

 motion be an orbital one. If this is true, the curve is probably around 

 the common center of the galaxy, or possibly a spiral one due to the 

 common form of nebulae. One investigator says the concept of this 

 swift but silent flight of the sun, with his attendant planets, is the 

 most overwhelming thought the human mind can grasp. 



We should not leave out of our category of telescopic aids the 

 ■chronograph and the bolometer and radiometer. The two latter in- 

 struments are inventions of Americans, and are invaluable in measur- 

 ing the heat radiations of the stars, the moon (over its dark surface), 

 and planets. These instruments are so delicate as to give accurate 

 data, after making due allowance for absorption from the atmosphere. 

 They are said to be able to detect and measure the radiations of a 

 <5andle several 'miles distant, or of even a human face a mile away. 



