In writing a turn-of-the century story, I wanted to include as much detail from the period as was practical, to give the characters a real world to live in. Young people in New York in 1900 would definitely have gone to the shore and visited the amusement park. Steeplechase Park opened in 1897 and more or less created the template for all the amusement parks that would follow.
The steeplechase ride the boys go on in A Most Personal Property looks fun and exhilarating, but it also seems very possible for people to just fall off the horses and break their necks.
The steeplechase ride was definitely in place in 1900, but I can be less sure about Blowhole Theater. References indicate that some version of it was always part of the steeplechase ride, so I chose to include it. The video is quite obviously from the mid-1920s, but you certainly get the idea!
Verisimilitude note: Today, the season at Coney Island ends at Halloween, and I have it ending in October in the book. However, it’s likely that in 1900 the season actually ended in September. I really wanted to send them to an amusement park, but it just wouldn’t have worked in the September timeline, so I used the modern schedule.