DOCK GATES. 



241 



mention getting it at the mitre-posts at the same time. The 

 engineer therefore determined to provide some means of wedging 

 up the gates so as to make the joint at the mitre-posts water- 

 tight. This was effected by adjustable thrust-blocks. These 

 consist of cast-iron frames bolted to the gates and containing 



_ fc 



blocks faced with brass, which can be shoved out or in by 

 means of tapered keys, or wedges, worked in a similar manner 

 to the brasses of the connecting-rod of an engine. When the 

 gates were erected in position, the blocks were tightened up 

 until a perfect joint was obtained at the mitre-post. In order 



