In "the old days" lecturers would obviously speak, sometimes to large crowds, without the advantage of modern sound systems - to wit, no microphone.

So this would obviously be still possible today (I reckon), but I still consider being mic'd up preferable (the speaker doesn't have to shout, the audience doesn't have to strain to hear).

As I will be portraying a lecturer from 1896 (Mark Twain, to be precise), I want to preserve the illusion of no mic being present, probably clipping it behind my bow tie.

I know nothing about sound systems/technology. Is this something I should purchase myself, which would then be easily used by any venue with a sound system?

What, exactly, would I need to do as to "set up"? Is it simply a matter of attaching the mic and turning it on? How is a connection made between the hidden and cordless mic and the sound system?

UPDATE

Adding on a bit, based on the comment from Rory Alsop:

So my question is, with regard to my wearing a wireless mic: would any venue with a sound system then be able to "attach" to this device? Or do they have to be a "matched pair" - IOW, are mics and sound systems "proprietary" such as software, where both the mic and the sound system need to be of the same "operating system"?