jury rigging

an example of some jury-rigged plumbing

A plumber working at my house recently said that he could "jury rig something until I get the parts I need."  I know he meant that he could do a temporary fix, but then I wondered (as I often do here) about where the term originated.

It didn't seem to have any connection to the common use of jury as related to a courtroom trial. Is it about a lawyer trying to rig the member of a jury to work to his client's advantage? In fact, it doesn't have any connection to that use of jury.

Jury rigging (AKA "jerry rigging") is both a noun and a verb describing makeshift repairs made with only the tools and materials at hand. 

Its origin comes from the world of boats and ships, particularly sail-powered ones. After a dismasting, a replacement mast, often referred to as a jury mast and some sail, would be fashioned so that the craft could continue on its journey. That explains the "rigging" part as it is the system of ropes, cables, or chains employed to support a ship's masts and to control or set the yards and sails. 

But what about the "jury" part?

Using "jury" as an adjective, in the sense of makeshift or temporary, has been said to date from at least 1616. There are two parts to the origin of this usage. Part one is that this is a corruption of the French jour meaning "a day." Go back further to the Latin adjutare ("to aid") and the Old French ajurie ("help or relief").

So, my plumber (who likely did not know any French or Latin or has spent much time on ships) was saying that he could "give me some relief for the day."