200 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



a short chute passing between the spawning pond and the open cud of the spawn- 

 collector. All the overflow water must pass through the haircloth, and by means of 

 wooden slides the height and flow of the water may be regulated so that the retained 

 eggs may not be subjected to injurious pressure. The eggs are transferred from the 

 collector to the hatching boxes. 



The filtering gallery passes down the sloping bank between the spawning pond 

 and the hatching house. The floor is made of concrete, and a stair passes up the 

 center to the spawning house. On either side are arranged the filtering boxes, eight 

 in number, forming a duplicate series of four each, and through these four filters all 

 the water that goes to the hatching boxes must pass. Each filtering-box is 4 feet 

 long, 2 feet wide, and 1£ feet deep. The top is covered by a movable frame of filter- 

 ing material, made in two pieces for convenience of removal; and as the boxes are 

 arranged at different levels, in step-and-stair fashion, the water passes in succession 

 from the first to the second, and so on to the fourth, and thence to the pipe leading to 

 the hatching boxes. The filtering material on the first box is made of coarse material 

 (cheese cloth); that on the second, coarse flannel; finer flannel on the third, and still 

 finer on the fourth; but, as a rule, no sediment is to be found on this one, and the 

 water passing to the hatching house is absolutely limpid and pure. One object in 

 having a duplicate series, which can be used alternately or together, is for convenience 

 in cleaning. There is also a wooden sink, supplied with water from the waterwheel 

 shoot, in which the filtering frames may be scrubbed. 



The spawn -collector, above described, is contained in the upper part of the gallery, 

 and the shoot to the waterwheel passes down one side, near the roof. The water- 

 wheel is placed at the side of the hatching house, at the lower part of the gallery. It 

 is 5 feet in diameter, of the overshot variety, and the axle passes through the wall of 

 the hatching house, the movement being transferred to the eccentric wheel by a stop. 

 From 700 to 000 gallons of water an hour is sufficient to supply the wheel, the waste 

 water being carried off by a drain pipe. 



The tidal pond is situated about 50 yards from the hatchery, on the rocky shore. 

 It was originally a cavern,* the walls and roof being of solid rock, and the eastern 

 part closed by the castle walls. The seaward entrance has been closed up by a concrete 

 wall varying in thickness from feet to 2 feet. Through this wall two 0-inch pipes 

 are carried, one at the bottom which is controlled by a slide valve worked by a rod 

 from above; the other at a height of 5 feet. The valve in connection with the latter 

 is such that it can work automatically, admitting water when the level outside is 

 higher than that within, and preventing water from escaping when it is lower. The 

 bottom pipe is for emptying, or partly emptying the pond when the tide is low. Thus 



* It may be of interest to state that the hatchery lies within the products of one of the most 

 historic spots in Scotland — the old castle of Dunbar — associated with Scottish history for 800 years, 

 and dismantled subsequent to the tlight of Queen Mary and Both well, who took refuge in it. A 

 human skull and a Large quantity of the hones of horses were disinterred in digging the foundations 

 for the spawning pond. A portion of the cavern, now converted into a peaceful fish-pond, formed 

 the, dungeon in which the poet Gavin Douglas, Bishop of Dunkeld, and many other illustrious pris- 

 oners were confined. A dark and tortuous passage still exists, Leading upward between massive walls 

 towards the citadel. The westward opening, now closed, is conjectured to have been the portal 

 through which the brave Sir Alexander Ramsay,, of Dalhousie brought succor to Black Agnes during 

 the siege of the castle by the English under the Earls of Salisbury and Arundel in L338, and it was 

 probably by this postern that King Edward II escaped in a fishing boat after his disastrous defeat at 

 Bannockburn in 1314 





