Assertion: siding's rail | /r/AtLocation | position
Facets:
value: by iron wedges
type: CAUSE
Source sentences:
text: By the 1820s the first shaped rolled rails had begun to be produced initially of a T shape which required a chair to hold them; the rails were held in position by iron wedges (which sometimes caused the rail to break when forced in) and later by wooden wedges, which became the standard.