A laboratory course in plant physiology, especially as a basis for ecology; . Cover the cylinder with the smoothest ob-tainable paper (if highly glazed paper is used, it will go on withoutwrinkles, but an unglazed paper will fit better if put on wet), fasten-ing it by mucilage along the free edge, which must turn in a direc-tion not to catch the pen as the cylinder revolves. Have turned ona lathe (from maple) a magnifying-wheel, forming four concentricwheels of different sizes side by side in one piece (Fig. 25), theouter 12 cm., the next 6 cm., the next 3 cm., and the smallest in diame
A laboratory course in plant physiology, especially as a basis for ecology; . Cover the cylinder with the smoothest ob-tainable paper (if highly glazed paper is used, it will go on withoutwrinkles, but an unglazed paper will fit better if put on wet), fasten-ing it by mucilage along the free edge, which must turn in a direc-tion not to catch the pen as the cylinder revolves. Have turned ona lathe (from maple) a magnifying-wheel, forming four concentricwheels of different sizes side by side in one piece (Fig. 25), theouter 12 cm., the next 6 cm., the next 3 cm., and the smallest in diameter. All are to be as thin as they can be turned, andgrooved on their rims. A very small hole, a little larger than acoarse needle, is to be turned exactly in their common axis, and the INCREASE IN SIZE. 103 whole is to be covered with a thin coat of shellac to prevent warp-ing. A support for the wheel is made by fixing (with sealing-wax ifnecessary) a perfectly bright slightly-vaselined needle in a piece ofcapillary tubing, and the wheel should turn freely upon it ; the. 1 FIG. 24.—AN AUTOGRAPHIC AUXANOMETER. FIG. 25.— ;;MFYIN<;-WHEEL,(As here shown, the pen is much too large.) IN SECTION. One-halt theOne-third the true size. true size. tubing is then to be supported horizontally on a tripod supportwith the wheel vertical. A recording-pen is to be prepared fromsmall glass tubing drawn to a capillary point and bent at right anglesas shown in Fig. 24 (though it should be of much smaller size thanthere shown) ; it is held in a loop of flexible brass to which a threadcan be attached ; into the pen a few drops of chronograph ink aredrawn. Set the wheel with one edge over the cylinder, and the other 104 PLANT PHYSIOLOGY. over the tip of the shoot. Fasten, by a small drop of glue, to one ofthe smaller wheels the end of a silk thread thoroughly waxed (tolessen changes in length through hygroscopic changes) and makeseveral turns around it. To the groove in the larger wheel
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Keywords: ., boo, bookcentury1900, bookcollection, bookdecade1900, bookyear1901
