As an owner of a full frame camera now, only took years to get this far, I decided it was a good time to refresh some of the “taken for granted” options in this great digital world of cameras. I am amazed at how far this has all come. So when looking at the exposure mode dial, I forgot how bulb came about, you will see this as “B” on most cameras, I heard it was marked as “T” on some others.
Quoted from another website, as David Kwechansky, Toronto wrote:
“In one site area you asked why long exposure is called “bulb.” In the very early days (wet plate era) shutters were released by a squeeze bulb attached to a long, thin air hose. If you wanted the shutter to just click you set it for that, squeezed, click. If you wanted it to stay open as long as you kept squeezing the bulb, you set it for bulb, and then the bulb governed exposure.
I have no idea what happened to all those bulbs on hoses once they were obsolete but possibly the enema got its start that way. Early photographers must have fantasized about doing that with them to the guy who invented this cumbersome device.