. 20 Practical arc equal in length to oncethe radius, as eff\ drawthe line efr equal to efd\on r describe the arc jj,in length twice the radius;continue the line throughrj, which will be a rightline, and de, or e r, equalthe distance between dr,by which the distance between A and B is obtained as required. A round piece of timber being given, out of which to cut a beam^C of strongest section. Divide into three equal parts any diameter inthe circle, as A c?, e C; from d or e, erect a per-pendicular meeting the circumference
. 20 Practical arc equal in length to oncethe radius, as eff\ drawthe line efr equal to efd\on r describe the arc jj,in length twice the radius;continue the line throughrj, which will be a rightline, and de, or e r, equalthe distance between dr,by which the distance between A and B is obtained as required. A round piece of timber being given, out of which to cut a beam^C of strongest section. Divide into three equal parts any diameter inthe circle, as A c?, e C; from d or e, erect a per-pendicular meeting the circumference of thecircle, as c?B; draw AB and B C, also ADequal to B C, and DC equal to AB, and therectangle will be a section of the beam as re-quired. 18. To measure the distance betweentwo objects, both being inaccessible. From any point C draw any line C c,and bisect it in D; take any point Ein the prolongation of A C, and drawthe line E e, making D e equal to D E;in like manner take any point F in theprolongation of B C, and make D/equal to F D. Produce A D and e c tillthey meet in d, an
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectenginee, bookyear1856
