Definition of "gatewise"

[...] they are ioyned by two and two together, and every couple sustaineth a third stone lying overthwart, gatewise, which is fastened by the meanes of tenons that enter into mortaises of those stones not closed with any cement.

1876, William Long, Esq., Stonehenge and its Barrows. From the Wiltshire Archæological and Natural History Magazine, etc. [With maps and wood-engravings.]‎, page 25