Fishplate

The name is derived from fish,[1] a wooden reinforcement of a "built-up" ship's mast that helped round out its desired profile.

[2] The top and bottom faces taper inwards along their short dimensions to create an even alignment between the two rails when the fish plate is wedged into place by tightening its bolts during installation.

The device was invented by William Bridges Adams[4] in May 1842, because of his dissatisfaction with the scarf joints and other systems[5] of joining rails then in use.

Adams and Robert Richardson patented the invention in 1847,[7] but in 1849 James Samuel, the engineer of the ECR, developed fishplates that could be bolted to the rails.

Alternatively, the blade and closure rail can be a one-piece heel-less switch, with a flexible thinned section to create the moving heel.

A fishplate joins two lengths of track.
The first railway fishplate, patented by William Adams and Robert Richardson in 1847
Fishplates provide a poor electrical bond between two rails, which is supplemented when tracks carry current by welding a length of wire spanning the rail sections directly.