A writer in the _North-British Review_, No. 50, considers it strange that a variety of facts which must have presented themselves to the most careless observer should not have led to the earlier construction of Optical Instruments. The ancients, doubtless, must have formed metallic articles with concave surfaces, in which the observer could not fail to see himself magnified; and if the radius of the concavity exceeded twelve inches, twice the focal distance of his eye, he had in his hands an extempore reflecting telescope of the Newtonian form, in which the concave metal was the speculum, and his eye the eye-glass, and which would magnify and bring near him the image of objects nearly behind him. Through the spherical drops of water suspended before his eye, an attentive observer might have seen magnified some minute body placed accidentally in its anterior focus; and in the eyes of fishes and quadrupeds which he used for his food, he might have seen, and might have extracted, the beautiful lenses which they contain, and which he could not fail to regard as the principal agents in the vision of the animals to which they belonged. Curiosity might have prompted him to look through these remarkable lenses or spheres; and had he placed the lens of the smallest minnow, or that of the bird, the sheep, or the ox, in or before a circular aperture, he would have produced a microscope or microscopes of excellent quality and different magnifying powers. No such observations seem, however, to have been made; and even after the invention of glass, and its conversion into globular vessels, through which, when filled with any fluid, objects are magnified, the microscope remained undiscovered. A TRIAD OF CONTEMPORARY ASTRONOMERS. It is a remarkable fact in the history of astronomy (says Sir David Brewster), that three of its most distinguished professors were contemporaries. Galileo was the contemporary of Tycho during thirty-seven years, and of Kepler during the fifty-nine years of his life. Galileo was born seven years before Kepler, and survived him nearly the same time. We have not learned that the intellectual triumvirate of the age enjoyed any opportunity for mutual congratulation. What a privilege would it have been to have contrasted the aristocratic dignity of Tycho with the reckless ease of Kepler, and the manly and impetuous mien of the Italian sage!--_Brewster’s Life of Newton._ A PEASANT ASTRONOMER.