SCREENS. 225 



The screens were about 18 inches below the surface of the 

 ground, and the earth sloped up from them at an angle of 45, 

 so any fish jumping too high over the screen slid back without 

 injury. The surface of the earth was about 1 foot above the 

 dividing-box, and retained by a wall of turf. No frost has ever 

 interfered with the working of either the dividing-box or with the 

 screens. These latter throw off any ice forming on them by the 

 force of the water rising through. 



The 130-feets were built all in a piece ; that is to say, the 

 skeleton was continuous. Half beech-trees were laid as anchors 

 in the banks on either side, about 6 feet from the side of the 

 ponds ; battens were laid as sleepers in the bottom of each pond, 

 at an unusually short distance apart, as in the 60-feet pond ; from 

 the ends of these battens others were raised perpendicularly, being 

 nailed to the edges of those used as sleepers. The upright battens 

 on the outer sides of the outside ponds were tied to the beech 

 anchors ; those on the inner sides were tied to the uprights of the 

 centre pond. Thus a huge skeleton was formed, and when the 

 battens were tied by the flooring being nailed on them, the whole 

 formed one body, where any local strain at once distributed itself 

 over the whole. And still further to carry out this principle, 

 bridges were thrown across each of the ponds as ranches, as well 

 as a convenience to the works. Below is a cross-section of the 

 130-feets (Fig. 158). 



FIG. 158 scale 



The first sleeper of the east 130-feet was laid on the 29th of 

 March 1877, and the centre 130-feet pond was in working order by 

 the 4th of July, same year. The three were finished on the 1st 

 October. The centre 130-feet seems to have been the only one 

 actually completed in the season (1876-77) to which this chapter 

 belongs, but it was more convenient to treat them as a whole. 



p 



