Page:Encyclopædia Britannica, Ninth Edition, v. 2.djvu/244

Rh 226 AQUEDUCT bottoms and sides of these tubes are f inch thick, and the tops -jV inch thick, strengthened by angle and T iron. Fig. 13 shows a section of these tubes. The cast-iron troughs (fig. 14) are 8 feet broad and 4 feet deep, and f inch thick, and were capable of passing at this depth upwards of 20,000,000 gallons a day. Provision was Fia. 6. Open cutting not water-ti^ht. Fid. 7. Open cutting water-tight, but lined. Fid. 8. Open cutting in rock. made for adding 2| feet to the height of the sides when additional water was required, and this has since been done. The bottoms of the malleable-iron tubes are 3 feet below FIG. 12. Iron Aqueducts at Culegarton. the bottoms of the troughs, so that they should always be full of water, for the purpose of securing the same tempe rature both in the bottom and top of the tubes, and so pre- FIG. 13. Section through Iron Tube. Fia 14. Section through Cast-iron Trough. venting unequal expansion and contraction. The aqueduct at the crossing of small mountain streams (of which there were many) was carried in cast-iron troughs similar to those already described, supported upon cast-iron beams over the space left for the stream. The first deep valley which required to be crossed by piping is that of the Duchray water, about 55 chains wide. The pipes first laid down were 4 feet diameter in 9 feet lengths, with spigot and faucet joints, run up with lead in the usual way. At the lowest point the pipes are under a pressure of 165 feet. The river itself is crossed by cast- iron arched girders of 60 feet span ; and here, as well as at the small basins at each end of the piping, and at all other places where masonry was required, provision was made for laying two additional lines of pipes, one 4 feet and the other 3 feet in diameter. These pipes have since been laid. After passing through the ridge of Old Eed Sandstone conglomerate by the Clashmore tunnel, the aqueduct for 5 miles is for the greater part in open cutting, with masonry sides, and a dry rubble arch covered with 2 feet of puddle, and then covered in. The Endrick valley, like that of the Duchray, is crossed by cast-iron syphon pipes for 2-| miles in length. Where they cross the river Endrick at the bottom of the valley, the pipes are If inches thick, and have to sustain a pres sure of 235 feet. The pipes are carried across small depressions in the valley by resting them upon stone piers, and at the crossing of two roads, and of the Forth and Clyde railway, they are further supported by cast-iron FIG. 9. Aqueduct above surface of ground. FIG. 10. Tunnel lined. Fia 11. Tunnel through water tight rock. brackets. The pipes at these exposed places have flange joints, and they have been covered with woollen felt to prevent expansion and contraction. There is a short tunnel 110 yards long on this length of piping of dimensions sufficient to carry the three lines of pipes. The construction of the aqueduct, for the 5 miles extending from the valley of the Endrick to the valley of the Blane, pres-ants the same general features as those already described. Good building stone was abundant in this district, and the bridges are all FIG. 15. Duntreath Aqueduct. of masonry. Fig. 15 is an elevation of one of the aque duct bridges nearlvillearn at 19 miles from Loch Katrine; FIG. 16. Section through Arch. FIG. 17. Section through Pier. and figs. 16 and 17 are details of the Ballewan Aqueduct bridge (fig. 18). FIG. 18. Ballewan Aqueduct. The piping across the Blane is about 54 chains long, with a depression of 125 feet. The Blane water itself is crossed by a stone bridge, and there are basins at each end of the pipes as before. The last piece of the aqueduct is a tunnel 2640 yards long, through a ridge of amygdaloidal trap, separating the valley of the Blane from the valley of the Allander. The tunnel is 250 feet below the summit of the hill. Mr Batenian, at the banquet referred to, summarised the works along the line of aqueduct in nearly the follow ing words : &quot; There are in the whole work eighty distinct tunnels, upon which forty-four vertical shafts have been sunk for facilitating and expediting the completion of the work.&quot; Besides the tunnel at the commencement of the aqueduct, called the Loch Katrine Tunnel, 2325 yards in