6S4< UTILIZATION OF THE FRUITS OF FOREST TREES. 



drums, which are driven by steam and made to rotate rapidly 

 on their axles. Their internal surface, as shown in Fig. 367, 

 is covered with little sharp, projecting cones, against which the 

 larch cones are rubbed, but the mutual friction between the 

 cones is more effective than the action of the internal surface 

 of the drums. 



Apparatus worked by steam for opening larch cones is 

 based generally on a continual friction between their scales, 

 and consequent removal of the seed without injuring it. That 

 used by Keller at Darmstadt consists of a hollow wooden 

 drum (Fig. 367), which is fixed firmly in a vertical position, 



Fig. 3H7. Drums for husking larch-cones. 



and at its axis is an iron rod provided with four arms a, 

 which support four closely-toothed iron rakes I, parallel to 

 the internal surface of the drum. This revolves rapidly on 

 its axle m n, larch cones supplied from above are rubbed 

 together so thoroughly and to a certain extent torn to pieces, 

 that they part with all their seed that collects at the bottom 

 of the drum, from which it is then removed. 



The sides of this drum are composed of plates of iron, which 

 are not quite juxtaposed, finer refuse therefore escapes through 

 the slits between them. Under the drum large sieves are kept 

 in constant motion backwards and forwards. This apparatus 

 of Keller's is preferable to all others yet invented, as it removes 

 the seed in less than half the time taken, for instance, by the 

 Tyrolese method. 



