I found the ad for the Yost Typewriter Co. shown above in a 1902 issue of The Connoisseur (‘A Magazine for Collectors’). Yōst is presumably shown with a macron over the ‘o’ to indicate it’s intended to rhyme with most or post rather than cost or lost. I don’t know why the couple depicted in the ad are dressed anachronistically: perhaps they’re depictions of well-known actors in roles the public might recognize?
According to the typewriter database, the Yost range current at the turn of the 20th century would have included their model 4, 5, 6, 7 and 8 - all apparently variations of the same mechanism with differing carriage sizes. I’m guessing they would have been higher-end machines - in a Harrods Catalogue (issued a decade later, in 1912), the Yost Model 15 was priced at nine shillings and sixpence more than the equivalent Underwood and Remington standard models of the time.