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more powerful of these two ; a fact which is further con- 

 firmed by its greater influence upon the comet world. 

 Jupiter revolves upon its axis in 9 hrs. 55 min. and Sa- 

 turn in 10 hrs. 15 min. There is no doubt that the or- 

 bits of these planets will blend in one, as they widen 

 their solar circuit, and that Jupiter with Saturn will form 

 just such another double star as Albirea, and without 

 changing their several colours will shine as a double- 

 coloured sun. May we not conclude then from all this 

 that the luminous phenomena of stars is a product ot 

 stellar energy sex and development, affected by the de- 

 gree of distance from our earth? Unquestionably the 

 last-named is a factor having much significance, as we 

 can observe in the case of the sun-star Aldebrandt, 

 approaching and retiring from which we can trace the 

 change from rainbow orange light to pronounced reddish 

 yellow. 



To determine the orbits of double stars is a specially 

 difficult operation. It depends as I said upon the posi- 

 tion of the star relatively to the perpendicular of vision, 

 directed towards it from the earth's surface. For example 

 if a double star has a movement lateral to the earth then 

 its orbit is described in the form of an ellipse, and in 

 this case to determine the corners of the ellipse, and 

 consequently the orbit itself is very difficult, though in 

 picturesque effect the phenomenon gains greatly, because 

 in all such cases there are periods when one star co- 

 vers another or when both present a pair of star eyes 

 of different colour. The double stars which lend them- 

 selves most easily to astronomical research are those 

 which move perpendicularly to the line of vision directed 

 towards the North Pole, since it is almost always pos- 

 sible to determine their orbits, simply by observation 

 through the telescope, but in this case the size of the 

 orbit is not precisely known, owing to the fact that the 

 material mass of the shining globes constituting the double 

 star cannot, in the majority of cases, be measured in the 

 telescope, being so distant from the earth. And without 



