An eclipse of the sun will occur this year in the month of September; but it will only be central and total to the inhabitants on the southern part of our continent—America— where there are no observatories, we believe. Some of our scientific institutions should take measures to send out some of their corps, to make observations in Brazil and Peru. We are under obligations to Hon. John Cochrane, Hon. W. D. Bishop, and Hon. S. A. Douglas, for congressional documents. We have also received from Benj. C. Howard, Esq., author of Howard's Reports, a report of the discussions of the Supreme Court of the United States, and the opinions of the Judges thereon in the case of Dred Scott vs. Sandford. It is a document of legal and historical interest. The onion is a superior disinfectant. Two or three good-sized ones, cut in halves, and placed on a plate on the floor, absorb the noxious efluvia, c, which are generated in the sick-room, in an incredibly short space of time. They should be changed every few (say six) hours. To SUESCKIBEKS.—This number commences the second half of Vol. XIII, SCIENTIFIC 1 AMERICAN. NOW is the time to send in half- — yearly subscriptions.