LIFE OF SIR ISAAC NEWTON. 23 theory ot light, that I blamed my own imprudence for parting with so substantial a blessing as rny quiet to run after a shadow.7' In a communication to Mr. Oldenburg, Secretary of the Royal Society, in 1672, our author stated many valuable suggestions re lative to the construction of REFLECTING MICROSCOPES which he considered even more capable of improvement than telescopes. He also contemplated, about the same time, an edition of Kirickhuysen's Algebra, with notes and additions; partially arranging, as an introduction to the work, a treatise, entitled, A Method of Fluxions ; but he finally abandoned the design. This treatise, however, he resolved, or rather consented, at a late period of his life, to put forth separately ; and the plan would probably have been carried into execution had riot his death intervened. It was translated into English, and published in 1736 by John Colson, Professor of Mathematics in Cambridge. Newton, it is thought, made his discoveries concerning the INFLECTION and DIFFRACTION of light before 1674. The phe nomena of the inflection of light had been first discovered more than ten years before by Grimaldi. And Newton began by re peating one of the experiments of the learned Jesuit — admitting a beam of the sun's light through a small pin hole into a dark chamber : the light diverged from the aperture in the form of a, cone, and the shadows of all bodies placed in this light were larger than might have been expected, and surrounded with three coloured fringes, the nearest being widest, and the most remote the narrowest. Newton, advancing upon this experiment, took exact measures of the diameter of the shadow of a human hair, and of the breadth of the fringes, at different distances behind it, and discovered that these diameters and breadths were not pro portional to the distances at which they were measured. He hence supposed that the rays which passed by the edge of the hair were deflected or turned aside from it, as if by a repulsive force, the nearest rays suffering the greatest, the more remote a less degree of deflection. In explanation of the coloured fringes, he queried : whether the rays which differ in refrangibility do not differ also in flexibility, and whether they are n