1) These words are now met with frequently in accounts of dry-stone walling but they are on record in mason work from a very early date. A ‘through-stone’ extended through the thickness of a wall, and a certain number were considered essential for its stability.
The earliest example in the OED is 1805 but both terms are found in the fabric accounts of York Minster, with references to j through-stane a quarera in 1400 and in caragio vj lapidum vocatorum thurghes in 1419. In 1648, a mason who was contracted to build a house in Illingworth agreed to build up the side with competent number of throughes in the same. There are frequent references also in bridge-building documents: 1602 as many through achlers into the stone works as the overseers shall think proper, Apperley Bridge. When Methley Bridge was rebuilt, in 1793, it was agreed that the walls which formed the abutments should be not less than 12 inches in Bed, with proper throughs or Bond Stones. Occasionally, it was used as a verb, as when the wall of Kildwick Bridge was well through`d in 1755.
2) A horizontal grave-stone, sometimes supported on pillars.
1507 I will have a thrugh lade upon me after my decesse with iiij stulpis the heght of half a yerde, Kirk Smeaton
1521 I gif to order a through stone to lay on my grave withe scripture of laton of the same xls, Denaby
1542 to be buried within the church yerde ... of the northside nere myne awncetors and to have a thrughe stone laide ouer me prepared therfor, Otley
1557 a troughe [sic] stone wythe a remembrance of my selfe wyfe and chyldren in pycketures of brasse to be set ... and layd vpon the grave, Wakefield
1581 To be buried ... in the middest allie under the through stone where my father’s and mother’s corps were buried, Burnsall.