1 899 



THE PRESIDENT'S ADDRESS 



19 



flume, except that inside the tunnel the frame timbers are 

 connected overhead and boarded over. In the sills of the 

 frames, cuts (lin. X4in.) are made (a a) ; into these 



Fig. 3. — A flume. Plan. 



are let strips of a similar section, flush with the top of 

 the sills and running the whole length of the flume. 

 Planks are then laid lengthways down the flume, with 

 their joints immediately over the centre of the strips a a. 

 There are then nailed against the sides of the flume for 

 its entire length, i yi in. boards, rising some 4 feet up its 

 sides. Blocks of wood (c, c, c, c), 12 ins. deep, 28 ins. 



' — 



Pig. 4. — A section along line M N of Fig. 3. 



wide, are laid across the bottom of the flume ; when a 

 rank of these has been laid, a so-called " riffle-stick " 

 (d, d, d), I Yz in. x 3 in. is placed on the bottom of the 

 flume and nailed up tight against the rank of blocks ; a 

 few nails are left projecting from the opposite side of the 

 " riffle-stick," and another set of blocks is then laid and 

 driven tight up against it. Another "riffle-stick" is then 

 B2 



