Detail of an 1843 cartoon by Paul Gavarni in Le Charivari of a married couple returning from a bazaar (Rijksmuseum). The gentleman has an impressive amount of chains and striped pants.
My evidence is anedoctal, but I feel like 1840s Frenchmen loved their zany pants even more than 1840s Englishmen. Farid Chenoune writes in A History of Men’s Fashion that patterned trousers were all the rage:
The “hermits” model pictured Romantic rocks and waterfalls, whereas the “demolition” model showed a Paris neighbourhood… other styles boasted umbrellas, animals, or snails. A clothier named Falckh et Guéroult had a “fox and stork” model, whereas Chatelain suggested that card sharps sport hearts, spades, diamonds and clubs down their legs.
Circa 1845 cartoon for “illustrated pantaloons” reproduced in A History of Men’s Fashion. What a deal for 70 francs!
Describing the “1840s vogue for striped and checked pants”, Chenoune notes that designs included “horizontal ‘Australian’ stripes that became narrower and narrower as they neared the ankle (sometimes starting only at the knee), or plaids that went from waist to mid-thigh and again from calf to foot.”
I have yet to find these patterns depicted, although John Leech’s cartoon “A Most Alarming Swelling” comes to mind.