188 



SEASON 1875-76. 



X 



the water-trap. I built a dam, behind and partly on these blocks, 

 in the usual way with ashlar and concrete, having first cleared the 

 rock for a foundation. The top of this dam tailed at an angle to 

 the bottom of the old course, and was faced with courses set in 

 Portland cement. A second dam of wood flooring was formed by 

 slipping the boards into a groove, in two posts fitted into a wood 

 sole in front of the water-trap. A bridge was formed by two 

 planks, 2 inches apart, and holding the top of the upright posts in 

 position. Between these two planks the boards of the wood dam 

 slid so that they could be removed in a second or renewed. The 

 wood dam is a few inches higher than the stone one, and the 

 space between is roofed in by a strong frame covered with per- 

 forated zinc (No. 15). (Fig. 138.) 



K~J 



'4-W-=- -+'(("-- 



FIG. 138 wale A- 



