238 NOTES ON DOCKS AND DOCK CONSTRUCTION. 



Saddle Casting. 



Green heart Mil re 

 and Heel posts 

 Pitch Pine Ribs 

 and Sheeting. 



H.W.O.S.T. 



Barry Docks. 1 The entrance gates (Figs. 227 to 229), arc 

 constructed of iron. The rise is a quarter the span of the 

 entrance, or 20 feet. The height at the mitre-posts is 48 feet 

 10 inches, and at the heel-posts 42 feet 1 inch. The length of 



each leaf is 50 feet, and the maxi- 

 mum width 8 feet at the centre. 



When closed, the backs of the 

 gates form a continuous arc of a 

 circle of 48 feet radius, but the 

 front of the leaf is straight, and 

 closes against a straight sill. 



Each leaf is divided into fifteen 

 water-tight compartments by decks 

 and bulkheads. 



Below deck No. 5 are the air- 

 chambers, which are almost suffi- 

 cient to float the gates, leaving 

 only a small weight to be carried 

 by the roller and bottom pivot; 

 above No. 5 deck the interior of 

 the gate is open at the back, access 

 to the air-chambers being provided 

 by a trunk leading from the top 

 deck through this open portion of 

 the gate. 



The air-chambers are drained 

 to the bottom of the gates, from 

 whence the water is pumped out. 



In each leaf there are six 

 sluices, having a combined area of 

 100 square feet, worked by direct- 

 acting hydraulic gear. 



The meeting-sills, mitre- and 

 J FEET heel-posts are of greenheart, the 

 FIG. 226. latter having a radius of 15 inches. 



The heel-posts rest upon cast-steel hemispherical pivots, 

 with a sliding surface on the top, covered with a cupped saddle, 

 sufficient play being allowed to admit of the gate on opening 

 being thrown out slightly from the hollow quoin, and so prevent 

 the wearing of the heel-post and hollow quoins when the gates 

 1 M.PJ.C.K, vol. ci. p. 139. 



SCALE 

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