. The Bell System technical journal . Imk. 13—An cnlarKCfl view oi a spt-ciincn prepared fur micrnscopic cover glass shown by the circle measures y^ inch in diameter. The mmintsare transverse, radial and tangential sections of a wood specimen ami wen-stained to make their structure visilde under the microscope. The appearanriof a transverse section of Douglas Fir at 100 di;mitirs !•; •.hnwti in thelower illustration. .iM> .\in Koscory \\^ of the prtridiiii; oiKration lia\c all liccii rtninvid and fiiur mu-,estahlislKil ii) tlu- luw direction
. The Bell System technical journal . Imk. 13—An cnlarKCfl view oi a spt-ciincn prepared fur micrnscopic cover glass shown by the circle measures y^ inch in diameter. The mmintsare transverse, radial and tangential sections of a wood specimen ami wen-stained to make their structure visilde under the microscope. The appearanriof a transverse section of Douglas Fir at 100 di;mitirs !•; •.hnwti in thelower illustration. .iM> .\in Koscory \\^ of the prtridiiii; oiKration lia\c all liccii rtninvid and fiiur mu-,estahlislKil ii) tlu- luw direction. This is contiiuii-d to the 000 i).ipir,aftiT which the s|Rrinien is further |X)lished on a polishing hinehaving; a covered lap capable of being revolved at varyingspeeds to about 1,200 rpm. This lap is kept moistened with waterand tine aiunduni is used as the abrasive. This operation gives a. Fig. \S—Ticneral view of the Lal)oratory lor Technical .Microscopy. semi-polish and when properly carried out, leaves the specimen withnumerous very fine scratches. The final operation is carried out onanother lap covered with ver\- fine broadcloth anil with an exceed-ingly fine abrasive such as the finest jewelers rouge or For high-[K)wer work magnesium oxide is the only polishingmedium which has been found to yield a satisfactory surface. Thetechnique for the development of surfaces at high powers has beenworked out in our laborator>- so that it is now possible to study metalstructures with great clearness at high powers. E(|uipment forgrinding and polishing specimens is shown in Fig. 14. Metals, after polishing, as a rule, do not show their structuralcharacteristics, but must be treated in some way to etch the polishedsurface. This etching of>eration is a simple matter for low-powerwork, but as the magnification is carried higher and higher, theproblem beco
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
