Re: 484 Whistle

Interesting feature of many (if not all) Powell & possibly Lunk round top 3 chimes...the tallest chamber folds over
into the hemisphere of the dome. And that I believe, is what gives them them their distinction over flat top 3 chimes.
Next time access allows, take a flashlight & inspection mirror and take a look at one.

One other thing just for clarification. The term single-chime is not really correct as chime means a set of tuned bells.
Single note or single bell is better. Lunkenheimer and some of the other major whistle manufacturers used to make and
market a 3 whistle chime which comprised of 3 single bell whistles of different lengths mounted on a manifold. The blending of
these 3 when blown then comprised a chime. Some of these were used in maritime service. Hope this is of some help.