DOCK GATES. 



219 



to bottom ; a clearance is given round the quoins, except at the 

 outer portion where the gate-post is in close contact with the stones 

 to prevent loose material being carried round the hollow quoin. 



Gates. These consist of two exactly similar doors, each 

 somewhat longer than half the width of the entrance, and of a 

 sufficient depth to reach from the highest water level to below 

 the sill against which they shut. 



The material to be used in the construction of the gates, 

 i.e. wood or iron, will depend greatly upon expediency, local 

 conditions, and no doubt to some extent personal prejudice. 

 An important element in the consideration of material is the 

 presence or otherwise of the marine worm. There are some 



FIG. 207. 



FIG. 208. 



parts, however, which are always constructed entirely of, or are 

 faced with wood, i.e. the heel and mitre-posts and the meeting-sill. 



The Heel-post is vertical, and formed so as to correspond with 

 and accurately fit the hollow quoin. At the bottom it is kept 

 in place by a pivot and socket connecting the gate with the 

 masonry of the gate-platform, and at the top secured by an iron 

 strap passing round the upper end of the post, and very securely 

 anchored to the masonry of the side walls (Figs. 207, 208). 



Mitre-post. Each leaf of the gate being similar, they meet on 

 the centre line of the entrance ; the meeting- or mitre-posts con- 

 stitute, or are attached to, the end framing of each leaf, and are 

 so worked that the meeting faces extend the entire depth, and 

 should consequently bear fair and true against each other, and 

 form, when closed, a tight joint. 



Timber Gates, 1 In favour of wood it is urged that, when 

 carefully selected, timber will last for a very considerable time 

 1 M.P.I.C.K,vo\. lix. p. 2. 



