Added the below image and caption to the 20th Century Timeline. The artist spent the bulk of his career in Paris, so the depiction is as likely to be a French trombonist as a Spanish one.

c. 1901—Spanish artist and writer Santiago Rusiñol i Prats (1861-1930) draws a series of musicians, including a valve trombonist (see facing image; public domain; source: wikimedia commons).