A Great Telescope

We read that " the groat equatorial telescope, now being constructed ut Cambridge, Mass., for the Naval Observatory," will be finisbed by the lst of October and shipped to Washington. The new building in which it is to be mounted is nearly oompleted, and the new instrument will be ready for work about the middle of November. The great glass, carefully finished by the delicate inanipulations of Alvin Clark, the most painstaking and suocessful of teleseope-makerg, is expected to reveal some new and interesting truths concerniug certain stars of which we as yet really know scarcely anything. Among other things we may hope for a better view than has ever yet been obtained of the ruddy planet Mars and possibly also of Júpiter and Saturn - those vast and mysterious sister planeta which still mock the efforts of the dwellers on earth to penétrate their secreta.