Mechanical Spear

[Queequeg]

Greetings,

I've been reading a bit about the brandistock, which was essentially a spear which functioned like modern gravity knives or police expandable/collapsible batons.

Does anyone know if there was such a thing as a "mechanical spear"? I'm thinking of something which appeared to be a simple staff, but at the push of a button a (narrow) spear head would have emerged straight from the interior of the shaft, much like the tip of a ball-point pen.

I can well imagine something like this having come out of the age of gears and springs in the late Renaissance.

Thanks in advance.