Larry, fish-plates were the plates they used to use to bolt railroads together. The name was originally a naval term for the braces on a timber mast. Similar plates were used to join lengths of timber in construction, with wooden pegs, bolts or even nails. Modern fishplates have multiple spikes, pressed into the 2 parts to be joined, usually on both sides. Here's a modern type. http://www.biosdobris.cz/obr/stycnik.jpg
