TANGENTIAL AND NORMAL FORCES. 45 



line M E, thrice the distance E c, and mark the point F. 

 Then A F will represent the attractive force of M, on the 



waters at A. To resolve this into the normal and tan- 

 gential force, prolong the line E A, and draw the tan- 

 gent A T j draw F N parallel to A T, and F T parallel to 

 EA, then AN will represent the normal, and AT the 

 tangential force at the point A. By taking different 

 points on the circle, and determining the respective 

 lengths of the lines indicating the two forces at those 

 points, and joining the ends of the lines, curves will 

 be generated which will show the comparative amount 

 of the two component forces at the several points, as 

 in the annexed figures. 



FIG. 5. 



FIG. 6. 



NORMAL FORCE. 



The tangential force may thus be seen to be nothing 

 at the points o, 0,0,0 (fig. 5), and to reach its maximum 

 at 45 from the line drawn from the centre of the moon 

 to the centre of the earth ; and as it always acts in the 



