_The Propagation of Oysters._--At the recent meeting in this city of the American Fish Cultural Association, a paper was read on the propagation of the oyster, by Dr. W. J. Brook, of the Johns Hopkins University. The manner in which this propagation takes place had never before, he said, been thoroughly understood. Through studies made by him last summer, however, great light was thrown on the subject. He found that the American oysters do not breed their young in the shell, as had been supposed, and that consequently the eggs can be impregnated artificially. An average oyster contains from six to nine million eggs, and one of large size may contain fifty millions. The plan pursued by him in fertilizing these eggs was to chop the male and female oyster up together; thus the fluids are mixed and the impregnation is made complete. The process of development immediately begins, and goes on so rapidly that a change may be noted every fifteen seconds. In a very few hours the embryo is sufficiently formed to swim in the water. The shells at first are very small, and are not adjacent to each other. They grow very rapidly, closing down over the sides, and finally unite and form the hinge. In the short space of twenty-four hours the young oyster is able to take food, and from three days to a week it attains perfect form. During its early life it is a swimming animal. The oyster is able to reproduce its species at the end of a year's growth, and it is marketable at the age of three years. * * * * * S. P. RUGGLES. S. P. Ruggles died at Lisbon, N. H., May 28. He was principally known as the inventor of the Ruggles printing press, which was among the first of machine presses. His invention was what printers call an "upside-down press," the type being upside down when in the bed. About twenty-five years ago Mr. Ruggles sold out his interest for nearly $200,000, and since then has not been in active business. He was the inventor of the raised alphabet for the blind, and always showed great interest in the amelioration of the condition of the sightless. He was also a great friend of mechanical education, and has written much on the subject. * * * * * SYDNEY INTERNATIONAL EXHIBITION.--1879-1880. EXTRACTS FROM THE REPORT OF THE JUDGES IN HOROLOGY. DEPARTMENT III.--EDUCATION AND SCIENCE. _Group_--_Scientific and Philosophical Instruments and Methods._ Class 310.--Chronometric Apparatus, Chronometers, Astronomical Clocks, Watches, Chronographs, etc., etc. _Judges_.--John McGarvie Smith, New South Wales. P. E. Bound, Switzerland. H. C. Russell, B.A., F.R.A.S., Great Britain. E. Beckmann, Germany. Gregory P. Harte, United States. _To the Honorable Committee on Judging and Awards, Sydney International Exhibition._ GENTLEMEN: I have the honor to hand you herewith the report of the judges of Class 310, as above, And remain, sirs, your obedient servant,