S52 PLOTTI?JG QUADRANT, LEVEt, AND CATXULATOR/ 



swering to the side C A, and by the ?/?// move the perpendi^ 

 cular, till B A answers to the given side B A; next bring 

 down the limb C H to touch B, and on C B mav he read 

 the other side, while H G will show rbe aiifrle C, and 1 H -f 

 Q0° the Z B, wlienee all the six parts a,e known. 



Third. — To set a triangle^ having two sides and an angle oppO" 

 sile to one of them given. 



Two sides and Let A B C be the triangle, A C and G B the given sides, 

 an angleoppo- and A the given angle ; first read the angle A on F Gj and 

 them given! ^^^ ^^'^ ^^^^^ ^ ^ thereto ; then push up the parallel lo the 

 division at A, answering to C A, and with one hand work the 

 nvt and with the other move the limb C H, till they touch at 

 B, the division answering to the side C B ; then B A is the 

 side sought, and the arc G H will show tlie Z C, and I H + 

 Q<P the Z B. 



Fourth. — To set a triangle, having two angles, and a side op^ 

 pQsite to one of them given. 



Two angles Let A B C be the triangle, A and C the given angles^ 



posite to one of ^"^ ^ ^ ^^^ given side ; first, set F G to the Z A, and G H 

 ihem given, to the Z C, then pu?h the perpendicular up or down with one 

 hand, while the other works the nut, till the given side B A, 

 on the parallel, is applied exactly between the limhs C H, 

 and C G, then I H + 90' will show the renaaining angle B, 

 and on C B, and C A, may be read the lengths of those sidesa 



Fifthk — To set a triangle ichose three sides are given. 



Three sides Let A B C be the triangle ; on the limb C H seek th<? 



point B, austvering to the side C B ; then, using one hand 



to move the perpendicular, and the other to turn the nut, let 



an assistant at the saime time, with his right hand, gently 



move the lintff C H, while you cause the top coiner of the 



perpendicular aUvays to touch the point B; at the same time 



let the assistant move the limb C G with his left hand, tiU 



the lerigths of C A, and B A, on their respettive scales, art 



found to intersect each other, when F G will show the Z A, 



G H the Z C, and H 1 -f 90^ the Z B. 



The instru- My solution to the last problem is inferior to the common 



co^^eiiient ^'* method of plotting the triangle on paper, and measuring 



the 



