Green’s Dictionary of Slang

grapple the rails n.

[the effects of the alcohol mean one has to hang on to keep upright]

(Irish) a glass of rough whisky.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.