contributory

Of, pertaining to, or involving a contribution.

Tending to contribute to a result.

Paying tribute, tributary.

My Lord the great Commander of the worlde, Besides fifteene contributory kings, Hath now in armes ten thouſand Ianiſaries, Mounted on luſty Mauritanian Steeds, […]

A person or thing that contributes.

The response to firing is remarkable, and though the 280 lb. pressure seems more in the nature of a reserve for emergencies than a continuous working figure, even with the present-day apology for coal it seldom fell below 250 lb., and could always be brought up to blowing-off point with little difficulty. To this liveliness of steaming the thermic syphons are doubtless the chief contributory.