46 HISTORY OF ASTRONOMICAL DISCOVERY. 



path of the stranger lies as far beyond what had been deemed its extreme confine, as that 

 limit is removed from the sun. The first moment of his " attack" upon Saturn, upon 

 completing the forty-feet reflector, he saw a sixth satellite, and a seventh a month later, 

 now called Mimas and Enceladus. But Herschel realised his most surprising results from the 

 observation of the sidereal heavens. The resolution of nebula) and the Milky Way into 

 an infinite number of stars the discovery of new nebulas of various forms, from 

 the light luminous cloud to the nebulous star of double and multiple stars of the 

 smaller revolving round the greater in the binary systems ; these were some of his reve 

 lations to the world, as night after night, from dewy eve till break of dawn, he gauged 

 the firmament. Caroline Herschel was the constant partner of her brother in his labo 

 rious undertakings submitting to the fatigues of night attendance braving with him 

 the inclemency of the weather noting down his observations as they issued from his 

 lips and taking, as the best of all authorities reports, the rough manuscript to the 

 cottage at the dawn of day, and producing a fair copy of the night's work on the ensuing 

 morning. He died in 1822 ; but she survived to 1848, witnessing the heir of his name 

 recognised as the heir also of his talents and fame. It was one of the conceptions of this 

 remarkable man as bold an idea as ever entered the human mind that the whole 

 solar system has a motion in space, and is advancing towards a point in the heavens near 

 the star X Herculis. General opinion is now in favour of the idea, that not only the solar 

 but the entire stellar universe revolves around some mighty centre. 



The nineteenth century commenced with a fresh ingathering of members into the 

 planetary family. It had been deemed a matter of surprise that the immense interval of 

 about 350 millions of miles between Mars and Jupiter should be void, when only spaces 

 varying from 25 to 50 millions divide Mars, the Earth, and the inferior planets. Keppler 

 had therefore started the conjecture that a planet would be discovered in the vast region 

 between the two former bodies ; and thus bring it into something like proportion with the 

 spaces between the latter. This idea was confirmed by a curious relation discovered by 

 Professor Bode between the mean distances of the planets from the sun. It is to the effect, 

 that proceeding outwardly from the sun, the interval between the orbits of any two planets 

 is about twice as great as the inferior interval, and only half the superior one, except in 

 the instance of Mars and Jupiter. Uranus had not been discovered when Bode arrived 

 at tlu's remarkable analogy, but the distance of that planet being found to correspond with 

 the law, furnished a striking confirmation of its truth. 



Write the Series, 3 G 12 21 48 96 192 

 Add to each term, 4444444 4 



The sums are, ~4 7 10 16 28 52 100 196 



If the third term 10 be taken to represent the distance of the earth, the third planet, in 

 order from the sun, the remaining terms will represent very nearly the respective distances 

 of the other planets. Thus, 



Mercury. Venus. Earth. Mars. Jupiter. Saturn. Uranus. 



4 7 10 16 28 52 100 196 



The fifth term in the series is unrepresented, except by the exaggerated leap from Mars 

 and Jupiter. It will be perceived, that while there is a striking approach to duple pro 

 gression in the succession of distances, the condition is not exactly fulfilled ; and as it fails 

 utterly in the case of Neptune, the last discovered planet, Bode's law, as it is called, is 

 purely empirical 



The void in the series between Mars and Jupiter, so convinced the German astro 

 nomers of the existence of a planet to occupy it, that a search for the concealed body 

 was commenced. The anticipation was soon substantially realised by the discovery of 



