L. B. F., of N. Y.—The power to direct safeguards in the use steam boilers,and to provide for the inspection of stationary steam boilers is vested la the local bo aria ofhealth by the Statutes of New York. These boards are, we believe, appointed by .supervisors, unless the Boards are organized under a special commission like the Metropolitan Board of Health, and have power to enforce their req.uireme.rit8. There is no general law requiring the use of lock-up safety valves on such boilers. A. F. W., of Mass.—To set the tail-stock of a lathe so as to tarn a taper , you must set it off the center half the amount of the taper. A good practical way to do this is to turn down the work at each end to the size you want it before altering the lathe. Then set your tool accurately to the larger end of the work, and run it along opposite the smaller end and use it as a gage in moving the tail stock off the center. J. A. M., of N. Y.—A wheel intended to roll around a, circle eight feet in diameter, "would need, in order that it should not grind but rollfreely around the circle, to be beveled so as to incline the outer surface one foot from the perpendicular. W. H. Gr., of Ohio.—We have no report upon the experiment j of carrying fresh meats in the ship Henry Taber, constructed for that j purpose. If it succeeds we shall certainly hear of it and will publish the tact. i C. P., of N. H.—The light minerals yon send are common' quartz crystals. The red colored specimens are garnets. They contain silicate of alumina, iron, etc. I J. L. T., of Me., and J. A. B., of Mass.—The Report of the Smithsonian Institute is prepared by Prof Henry, Washington, D. C. You had better write to him on the subject. R A. G-., of Mass.—" Byrne's Practical Metal-workers' Assistant," contains the exact information you require. Published by Henry Carey Baird, Philadelphia. D. W. H.,of Mich.—Your question cannot he answered without diagrams, and it is not of enough general interest to warrant our doing tUis. J. R., of Iowa.—The protoxide of chromium is a compound ol 26 parts of the metal chromium and 8 of oxygen. C. C.j of O.—The best food for Wishes, in a fresh water aquarium is dried beef cut up yery finely. G, B., of Me.—We have had no personal experience in the lumber trade, and cannot answer the point of your inquiry. F. H. Gr., of Mass.—The mineral you send appears to he a species of conglomerate. We discover no siiells. F. D., of La.—The red-colored mineral contains iron ore. S. K. P., of Del.—We cannot explain the phenomenon io which you refer ;but your only relief consists in thorough drainage. C. S. J., of N. Y.—You can render mull or jaconet much stiller than starch can make it by the use of is in glass size.
This article was originally published with the title "Answers to Correspondents" in Scientific American 21, 26, 410 (December 1869)