132 INTRODUCTION TO GENERAL SCIENCE 



finite number of triangles can be constructed upon a given 

 line, any combination of two forces may be obtained which 

 are at right angles to each other. 



Any force which is not applied in the direction of the de- 

 sired movement has a component of loss. Thus the traces 

 of a harness should be as nearly parallel to the ground as pos- 

 sible, and the tow rope of a towboat should be moderately 

 long to avoid the sidewise pull. Similarly, a sprinter in 

 starting should keep his " push-off " leg parallel to the ground. 



References : 



1. 1803 : 14-19. Composition and Resolution of Forces, 



a. 1607 : 492-493. The Best Position of the Traces of a Har- 

 ness. 



6. 1801 : 42. Resolution of a Force. 



c. 1802 : 80-81. Resolution of Forces. 



d. 1804 : 62. Resolution of Forces. 



e. 1805 : 44-47. Resolution of Forces. 



/. 1806 : 116-117. Composition and Resolution of Forces. 



g. 1807 : 54. Resolution of a Force. 



h. 1808 : 46-47. Resolution of Forces. 



i. 1809 : 74-79. Composition of Forces. 



j. 1810 : 53-55. Resolution of Forces, Velocities, and Accel- 

 erations. 



k. 1811 : 366-369. The Resolution of Forces. 



Experiment 50. Resolution of Forces. 



Apparatus : Block of wood 6" X 3"X J", set of weights, spring 

 balance, protractor, board 3'X5"Xf" with a narrow strip of 

 wood nailed along one edge, two thumb tacks, string. 



a. Drive a nail in the center of the flat side of the 6"X3" 

 block, and fasten the protractor with thumb tacks so that its 

 diameter lies lengthwise of the block, its center point against 

 the nail. Tie a string to the nail and make a loop at its end 

 for the spring balance. Place the block on the long board, 



