Newspaper advertisement and report
The Chicago Tribune, Feb 10 and 14, 1882
The Chicago Water Tower—"A Castellated Monstrosity"
Letter (Oscar Wilde)
To the Hon. George Curzon
February 15th, 1882, US
In Chicago I lectured last Monday to 2500 people!
As to subject
Around this time Wilde changed the name and content of his lecture.
Merlin Holland (Complete Letters) describes how Wilde's original lecture was 'too lengthy and theoretical for many in his audience' and that Wilde shortened and retitled it to give it wider appeal.
The new lecture became variously billed as Art Decoration, Decorative Art in America, etc., and it is probable that Wilde adapted them slightly to suit different audiences' (Holland). For this reason all variants of this lectures are listed in this chronology as 'The Decorative Arts'.
But when and where did Wilde switch from The English Renaissance to The Decorative Arts? By the time of his lecture in Utica there are suggestions Wilde had already begun to include material suggestive a more domestic theme, and the transition does appear to have been an evolution. However, in accepting this, Kevin O'Brien in Oscar Wilde in Canada: An Apostle for the Arts (1982), posits that Wilde delivered The English Renaissance for the last time in Buffalo on February 8 and The Decorative Arts for the first time in this, his next lecture in Chicago. This appears to be a convenient demarcation.
See here for a review of all Wilde's Lecture Titles.