OF WHEEL-CARRIAGES. 



103 



much greater power of crushing them than when they LECT. 

 are parallel to each other, but also endangers the over- ^^ 

 turning of the carriage when any wheel falls into a hole 

 or rut ; or when the carriage goes in a road which has 

 one side lower than the other, as along the side of a 

 hill. Thus (in the hind view of a 

 wagon or cart) let A E and B F be 

 the great wheels parallel to each 

 other, on their straight axle K, and 

 H C I the carriage loaded with 

 heavy goods from Cto G. Then as 

 the carriage goes on in the oblique 

 road A a B, the center of gravity 

 of the whole machine and load will 

 be at C ;** and the line of direction CdD falling within 

 the wheel B F, the carriage will not overset. But if 

 the wheels be inclined to each other 

 on the ground, as A E and B F are, 

 and the machine be loaded as be- 

 fore, from C to G, the line of di- 

 rection CdD falls without the 

 wheel B F, and the whole machine 

 tumbles over. When it is loaded 

 with heavy goods (such as lead or 

 iron) which lie low, it may travel 

 upon an oblique road so long as the center of gravity 

 is at C, and the line of direction Cd(as in the preced- 

 ing figure) falls within the wheels 

 but if it be loaded high with 

 lighter goods (such as wool-packs 

 from C to L, the center of gra- 

 vity is raised from C to K, 

 which throws the line of direc- 

 tion K k without the lowest edge 

 of the wheel B F, and then the 

 load oversets the wagon. 



Note 40. See Page 5 



