142 



STATICS. 



[230. 



These three equations determine N^ N^ A^, unless the three 

 points AV A 2 , A 3 be situated in a straight line ; for in this case 

 the determinant of the coefficients of N lt N^ N z vanishes, 



i I 



b l 



=o. 



The reactions become almost indeterminate whenever there 

 are more than three points of contact. 



230. In addition to the works of ROUTH, MINCHIN, PRICE, TODHUNTER 

 mentioned in Art. 199, the student is referred, in particular for the 

 more advanced parts of the subject, to W. SCHELL, Theorie der Bewe 

 gung und der Krafte, Vol. II., Leipzig, Teubner, 1880; A. F. MOBIUS 

 Lehrbuch derStatik, Leipzig, Goschen, 183 7, reprinted in MOBIUS'S Gesam 

 melte Werke, Vol. III., Leipzig, Hirzel, 1886 ; MOIGNO, Statique, Paris 

 Gauthier-Villars, 1868 ; J. SOMOFF, Theoretische Mechanik, iibersetzt von 

 A. Ziwet, Vol. II., Leipzig, Teubner, 1879 ; E. COLLIGNON, Statique 

 Paris, Hachette, 1889 ; THOMSON AND TAIT, Natural Philosophy, Part. II. 

 Cambridge, University Press, 1890. 



