One of the mest cnrions discoveries of astronornical science has just beau madR by Prof. V. W. Campbell, sou of William Campbell, of Pittsfield. Prof. Campbell gradnat.ed f rom tbe U. of M. in 1886 and was for a time instructor in astronomy at the 'juiversity bere. He afterwards was made director of the Lick Observatory of California aud it was vfith that. telescope that he has made a discovtry that makes his fa ui e everlasting. His discovery is that the North Star is not one star, but three. This star, which is 5,000.000,000 miles away trom the earth, has been one of tbe most familiar objects in the firmament since the beginniug of creation, aud yet its trne nature was cot even suspected until the other day. The North Star is one of the most brilliantly beautiful in color and is the star which the children are h'rst tacght to distinguish. It points constautJy to the Noith Pole of the earth aud has boen of more aid to navigators and travelers in nnknowu regions than anv other celestial body which illuminates the night It was by means of the spectroscope attached to the great tbirty-six-inch iefracting telescope at the Lick Observatory that the existence of two companions of the North Star was discovertid the other day Only. one star is visible to the eye, even with the greatest telescopes, but the spectroscope reveáis tbe existence cf two otbers with mathematical accuracy, The spectroscope is an instrument which seperates light into its component colors. When the light from the North Star was examined in the spectroscope attached tu the Lick telescope the other day changes in the lines of color were observtd which conld only be acconnted for by the fact that there were other bodias present. From this point it was only a matter of matbematics to calcúlate tlieir number, position and movements. The North Star, which is called by astronomers Polaris, is really a great snn. It isaccompanied by two invisible stais just discovered by the spectroscope One of these revolves abont the other and the tworevolve aboutPolaris, just as tbe earth aud moon do arouud the sun It is. calculated that it reqnires fonr years for the two invisible bodies to revolve around Polaris. Thus year tbere is four times longer than onrs. The bnght Polaris revolves on its axis once in four years. Polaris is approaching the solar sys:em at a varyiog rate which nas reach ed as high as 16 miles a second. Tbe vanatiou is due to the attraction of the two bodies upou the tbird This was another fact ■which proved to the astronomers the right nature of the star.