520 



KEPOET — 1891. 



of each of the small rectangles in the quadrant HOE are 'Ol, or about 

 925,000 miles. Only the positive values of d are represented in the 

 figures. The positive vanishing point being 1"250 of these divisions above 



Fig. 2.— <w = 10° 



Fig. 3.— ei>=170°. 



0, and tlie negative vanishing point 15,174 below O, we lay off Oa 

 = \{li' + /;,")= — C'962 divisions, and draw ae for the radical axis. The 

 smallest positive value of @ is (Table II.) 3-04. As @ increases from 



Fig. 4.— <u = 20°. 



Fig. 5.-0) = 160°. 



304 the ellipse increases in size, and the innermost curve represents what; 

 it becomes when @ = 6. The second curve (separating the blank and 

 shaded areas) corresponds to @ = 20. Any parabolic comet passing 



