NEWS FROM HERSCHEL S PLANET. 139 



time we should be able to detect no sign of polar 

 flattening even though Uranus were shaped like a 

 watch-case. At the opposite part the other pole is as 

 directly turned towards the earth. Only at the parts 

 of his path between these two can any signs of com 

 pression be expected to manifest themselves; and Uranus 

 occupies these portions of his path only at intervals of 

 forty-two years. 



Herschel would have failed altogether in determining 

 the pose of Uranus but for his discovery that the 

 planet has moons. For the moons of the larger planets 

 travel for the most part near the level of their planet s 

 equator. We can, indeed, only infer this in the case 

 of Uranus (for even the best modern measurements 

 cannot be regarded as satisfactorily determining the 

 figure of his globe), but the inference is tolerably safe. 



For six years Herschel looked in vain for Uranian 

 satellites. His largest telescopes, supplemented by his 

 wonderful eyesight and his long practice in detecting 

 minute points of light, failed to reveal any trace of 

 such bodies. At length he devised a plan by which 

 the light-gathering power of his telescopes was largely 

 increased. On the llth of January, 1787, he detected 

 two satellites, though several days elapsed before he 

 felt justified in announcing the discovery. At intervals, 

 during the years 1790-1798, he repeated his observa 

 tions; and he supposed that he had discovered four 

 other satellites. He expresses so much confidence as to 

 the real existence of these four bodies, that it is very 

 difficult for those who appreciate his skill to understand 



