The term "double bridge experiment" isn't a standard scientific term. It's possible there's a misunderstanding or a less common use of the term.

To help understand what you might be referring to, could you please provide more context? For example:

* What field is this experiment related to? (Physics, chemistry, engineering, etc.)

* What are the goals of the experiment? (Measuring a specific property, testing a hypothesis, etc.)

* What are the key components of the setup? (Bridges, circuits, materials, etc.)

Once I have more information, I can give you a more accurate explanation.

Perhaps you're thinking of one of these common experiments:

* Wheatstone bridge: This is a circuit used to measure an unknown electrical resistance. It involves two branches of a circuit, each with two resistors, and a galvanometer to detect the balance point.

* Double slit experiment: This is a famous experiment in quantum physics that demonstrates wave-particle duality. It involves shining light through two slits and observing the interference pattern created on a screen.

Please clarify your question so I can provide you with the best possible answer.