2 2 EXACT ASTRONOMY. 



sion would retard, contraction accelerate, the velocity of ro- 

 tation. Consequently, the day which is the measure of the 

 tangential force would vary by the expansion or contraction 

 of its subdivisions, as the square root of the equatorial radi- 

 us; and the sidereal year would vary in the same proportion, 

 inversely. Hence, the cube of the constant R, divided by 

 the square of the varying T, would always express the solar 

 parallax, — their duplicate ratio the mean orbital radius, with- 

 out change of abstract time or distance. The whole as- 

 sumption of my critics is sophistical and devoid of honesty. 



The Velocity of Light. 



The progressive motion of light is demonstrated by the 

 annual apparent oscillation of stars in the ecliptic, which be- 

 comes an oval of decreasing eccentricity with increase of the J 

 star's declination. The center of this apparent motion is the 

 star's real place, and can arise only from the projection 

 on the vault of the celestial sphere of the terrestial orbit 

 seen in perspective and, consequently, foreshortened to its 

 major axis by the apparent motion of a star in the plane of 

 the real orbit and perpendicular to its major axis. All other 

 stars in the ecliptic trace, of course, the diameter that is per- 

 pendicular to each. The longest diameter of the oval traced 

 by stars having latitude is, of course, that diameter of the 

 orbit parallel thereto. 



The assumption of the text-books that all the stars in 

 the plane of the orbit exhibit the maximum amount of aber- 

 ration, and that a star exactly at the pole would apparently 

 describe a circle, is manifestly erroneous. The phenomenon 

 of aberration results directly from the earth's orbital velocity, 

 being a sensible fraction of the velocity of light, which pro- 

 jects the orbit on the sky, at a distance Rxl from the eye, . 

 R representing the semi-diameter, V and v the velocities. 



