TRENCHING AND SUBSOILING. 



153 



attached to the axles, which are fixed in such a way that the 

 four points of support (that is to say, where the wheels touch 

 the ground) form a rectangle of 9ft. lOin. x 14 feet. The 

 wheels are made so that their wide rim exactly fits between 

 the flanges of rolled joist girders (5J inches) EE' (Fig. 97). 

 Each of these girders weighs 220 Ibs. They are, therefore, 

 easily managed by two men. 



Framework. A rolled joist girder Q, 21 inches wide, is 

 fixed under the centre of the truck ; the shaft of the wind- 

 ing drum revolves in its centre. Four oak beams, 8x8 

 inches section F F' and G G', are mortised on the frame on 

 a bevel, each pair joining at the top, and being each mortised 



Fig. 98.-Lucet's Motor. Front Elevation. 



