During the mass an acolyte bore the thurible (Ordo VI.) and three assisted at the washing of the hands.
According to Sarum and Bangor, the thurible, as well as the lights, attended the Gospel to the lectern.
Perhaps the York rubric implies that this was done when it orders (which the others do not) the thurible to be carried round the choir with the Gospel while the Creed was being sung.
The thurible, the proper ecclesiastical term for the vessel in the Western Church, is usually spherical in form, though often square or polygonal, containing a small receptacle for the charcoal and covered by a perforated lid; it is carried and swung by three chains, a fourth being attached to the lid, thus allowing it to be raised at intervals for the volume of smoke to be increased.
It is headed by a thurifer carrying a smoking thurible; then comes the sub-deacon carrying the cross between two acolytes with lighted tapers; the clergy next in order, the celebrant corning last with the deacon on his left, all carrying branches and singing antiphonally, so long as the procession lasts, the account of the entry into Jerusalem, ending with "Benedictus qui vent in nomine Domini: Hosanna in excelsis."