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1、QMECHANICALDRAWING.PREPAREDFORTHEUSEOFTHESTUDENTSOFTHEMASSACHUSETTSINSTITUTEOFTECHNOLOGY,BOSTON,MASS.LINUSFAUNCE.BOSTONW.J.Schofield,Printer,105SummerStreet.1887.Copyrighted,1887,byLinusFaunce.CONTENTS.Page.CHAPTERI.—InstrumentsandtheirUses5II.—GeometricalProblems13III.—Inking55"Tinting61IV.—Pro
2、jections65"Notation68"ProjectionsofStraightLines69"""Surfaces75""Solids80V.—Shadows.'...96VI.—IsometricalDrawing112"ObliqueProjections120VII.—WorkingDrawings121VIII.—Examples1272066025MECHANICALDRAWING.CHAPTERI.INSTRUMENTSANDTHEIRUSES.1.Todogoodwork,goodinstrumentsareessential.Anaccomplisheddraf
3、tsmanmaydofairworkwithpoorinstruments,butthebeginnerwillfinditsufficientlyhardtodocreditableworkwithoutbeinghandicappedbypoorinstruments.Itisalsoessentialthattheinstrumentsshouldbekeptingoodorder.Theyshouldbehandledcarefully,andwiped,beforebeingputaway,withwash-leatherorchamoisskin.Thisisespecia
4、llyneedfulifthehandsperspireperceptibly.2.Pencilling.Drawingsshouldalwaysbefirstmadeinpencil,andinkedafterwardsifdesired.Theideaofpencillingistolocatethelinesexactly,andtomakethemoftherequiredlength.Accuracyinadrawingcanonlybeobtainedbyaccu-racyinthepencilconstruction.Thereisagreattendencyamongb
5、eginnerstooverlookthisimportantfact,andtobecomecarelessinpencilling,thinkingtheywillbeabletocorrecttheirinaccuracieswheninking.Thisisaereatmistake,andoneto6INSTRUMENTSANDTHEIRUSES.beespeciallyavoided.ThisaccuracycanbeobtainedinpencilonlybymakingveryJine,lightlines,andtothisendhardpen-cils,6H,sho
6、uldbeused,andtheyshouldbekeptsharp.Fordrawingstraightlinesthepencilshouldbesharpenedtoaflat,thinedge,likeawedge.Thecompasspencilsshouldbesharpenedtoapoint.Asofterpencil,4H,sharpenedtoapoint,shouldbeusedinmakingletters,figures,etc.Itshouldbeborneinmindthata6Hpencilsharpenedtoachiselpointwillmakea
7、depressioninthepaper,whichcanneverbeerased,ifmuchpressureisputonthepencil;hence,pressverylightlywhenusingahardpencil,soastoavoidthisdifficulty.Ifadrawingisnottobeinked,butmadeforroughuseintheshop,orwhereaccuracyofconstructio
