FRICTION IN MECHANICS. 



*75 



Example. If AB=r,-, BC=3, and AC=4, and 

 the weight 1 ton, then the leait moving and fultaining 

 forces will be 1825 and 702 pounds refpectivcly. 



Corollary 2. Becaufe the triangles PDO and ROm 

 are fimilar, and the ratio of PD to DO coniiant to each 

 fixed value of n. therefore the angle QRm being equal 

 to DPQ, will alio be conitam, whether the inclination 

 of the plane be variable or not; and hence the angles 

 of the direction with the plane for the draught to be 

 made with the greated advantage, are found for differ- 

 ent values of n as follows : 



N. B. The direction, or angle QRm, is to be taken 

 below the plane for the fufpending, and above the plane 

 for the moving force. 



Scholium. Though at firfl fight the former part of 

 the above Problem, which fheu s the belt method oi ap- 

 plying an a6tive force, fecnis fuperior to the other, \ct, 

 on farther confideration, the other ;ip> ears of equal 

 conlequence, and particular!) in building and fattening 

 walls, banks of earth, fortifications, &;c. and LJ e applica- 

 tion of what are called land-nes,&c. Thus it a weight, 

 for inftance, is to be drawn along the plane R>Bj ai d the 

 fri&ion be -j of the prcilure. the be ft direction n when 

 Rm makes an angle of 1 8°. 26 above the plane ; out if 

 the weight is a quantity of earth or itone, or any thing 



to 



