Hi,

I think you are correct that it’s made as a Mercury switch.
The up hill angle of its body is there for the purpose of keeping the mercury laying at the lowest end.

If the car goes down a really steep hill the switch will open.
It could be considered a safety feature to prevent operation during mountain driving. It’s best not to use your cruise control under this condition anyways!
I found, in East Scotland, one 20% grade for a couple miles and that made eyes bug out!
I had rented a Ford Mondero, like a Mustang and the Second gear screamed 4,000 rpm’d the engine going down hill!
I had plenty of speed, thank you!

The next reason for the angle is if the car has a sudden stop, like a crash or panic stop conditions.
I surmise that the circuit it is on, is one in the same as the foot pedals are on, or the stalk / turn signal switch. If those don’t work it will!
Actual power in or to a grounding point, I don’t know, but possible? So breaker, maybe, sort of?

For information:
Mercury switches were commonly used on low voltage controls, like home thermostat devices.
Mercury is not limited to these type of applications, as I have seen them use in convection reheat ovens, as a main contactor or relay to turn on and off heating elements with a one horsepower blower fan.
Very very reliable and must still be used for quite awhile.
40-50 amperages @ 480 volts of three phase power is lots of watts! Trust me, the disconnect plug-in cords on these ovens were huge! Two handed huge!

The beauty of Mercury it is a liquid that continually rotates its contact surfaces so there is far less pitting or arcing residue complaints. In most cases, they are forever operational.
For humans to care about, that’s a while! (:-)

A thought on these switches is that, they disappeared due to Mercury’s toxicity!
Consequently these switches in our trunk & dome lights in the older cars, will be no more!
Temporarily, we went back to mechanical levers and weighted types that are more subject to weathering and corrosion damage.
Thankfully or NOT? The introduction of more black boxes with “CAN buses,” the digital age has replaced many applications.
I wonder how It works with massive amounts of semiconductors to carry the high wattage jobs, reliably, since I retired 15 years ago, so maybe, not completely!

That picture, in the other post, is a snap shot for history and Volvo car buffs!
Yes, that what I was trying to describe, Art!
Thanks,

Phil