Can a Victorian parlour organ (which is a type of free-reed pump organ) have vibrato tones, or is vibrato only a feature of electric organs?

There are pull levers or “stops” on these organs that vary the register or octave played by a given key. It’s been so long since I’ve played one (at least 60 years) that I can’t remember if there’s one specifically for a vibrato effect. I do know that most accordions (another free reed instrument) have a register stop that will simulate a vibrato by playing two reeds of the same note which are ever so slightly out of tune.

Vibrato is a change in tone like a Whammy Bar on a guitar.

A reed organ has a single reed for each note; you can’t change the tone. Vibrato is a available on electric organs because they can change the note up or down on the synthesizer.

Tremolo is on some large pipe organs like Newberry at Yale University but that is raising and lowering the air pressure on an individual pipe not changing the note. By the way that organ in awesome, over 12,000 pipes.

In the case of the accordion “vibrato” or “tremolo” it is simulated by two distinct sets of reeds, one tuned slightly sharp or flat from the other, producing an undulating effect when they are used together. This same method may be used on some finer reed organs.