The Practical mechanic's journal . ntary colours, by means of a gotbicwindow, with small pieces of sulphate of lime, or mica, of various thick-nesses, representing the panes of glass. When this miniature window isplaced upon the polarizing stage, and viewed in the analyzing plate, itappears to be of stained glass, aud when set at the different azimuths,the panes continually change their tints, forming a very brilliant spec-tacle. Indurated animal substances, as quills, horn, jellies, and albumen,also give out beautiful tints under the polariscope. The crystallinehumour of the eye, especially t
The Practical mechanic's journal . ntary colours, by means of a gotbicwindow, with small pieces of sulphate of lime, or mica, of various thick-nesses, representing the panes of glass. When this miniature window isplaced upon the polarizing stage, and viewed in the analyzing plate, itappears to be of stained glass, aud when set at the different azimuths,the panes continually change their tints, forming a very brilliant spec-tacle. Indurated animal substances, as quills, horn, jellies, and albumen,also give out beautiful tints under the polariscope. The crystallinehumour of the eye, especially that of fishes, when placed in oil of thesame density, is a fine substance for the pursuit of the same experiments. By an experimental test, the author has discovered, that when thethin portion of the scapula of a fish is placed on the polarizing stage, aseries of beautifully lucid fringes, of all the colours of Newtons table,occurs at the azimuths of revolution of 45°, 135°, 225°, and 315°. 176 THE PRACTICAL MECHANICS HUNTS METALLIC PACKING FOR STUFFING-BOXES. An ingenious metallic packed gland has recently been registered byMr. T. Hunt, the superintendent of locomotives at the Preston stationof the London and North-Western Railway. Our engraving representsa vertical section of the improved packing, as applied to the stuffing-boxof a locomotive engine, and is on a scale of one-sixth the original gland and cover is bored out asusual in the fitting in of hemp pack-ing, but is lined with a hollow metalcylinder, A, bored out conically to re-ceive a series of conical brass or tinrings, E b, each with one diagonal cut,to admit of contraction. These ringsare so placed that no two cuts shall beopposite to one another, thus breakingbond and preventing the passage ofany steam through. The contractiveadjustment of these riugs is effectedsimply by the screwing down of thegland, the bottom of which pressesupon the upper ring of the series, andforces each ring to take
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Keywords: ., bookcentury1800, bookdecade1840, bookidpra, booksubjecttechnology
