[wilf leek]

Scott - I suspect that what you have is a capillary-tube operated mechanical guage, I have the same in my car. The clincher is if the engine end terminates in a large brass coloured "bulb".
The guage works by expansion of the fluid within the bulb at the engine end.
The wire wrapped tube is a small bore (usually copper) tube which allows the expanded fluid to get up to the guage, where it operates a "bellows", thus converting the fluid expansion into mechanical action. These guages usally have a 270 degree sweep of the needle, and are known as "mechanical" type guages. The spiral wire wrapping "protects" the fine bore tube - but only to a point.

If you break the tube, or it's soldered connections at either end, the guage is effectively bust. You have two options - a/ buy a new one and be careful (very) with the capillary tube) or b/ find an instrument servicing outfit that can repair it. (and still be careful with it!)

Whilst the thermocouple theory above makes sense, it is way too modern for english "period" guages. You guys do know about english electrics etc???