While searching for mentions of Dent's Fountain, a couple of the results mentioned the annual auction of racing ponies that was held there.
First in 1880, p.2, The China Mail, 1880-03-03:
The usual annual auction of Racing Ponies was held this afternoon at the Fountain, City-Hall. Several ponies and carriages were sold, but the prices realized were very low.
And in 1916, over 30 years later, very similar text, p.4, Hong Kong Daily Press, 1916-02-28:
The usual sale of ponies that follows upon the annual races is advertised to take place on Wednesday at the Fountain opposite the City Hall.
1900s City Hall - Sale of Racehorses by Public Auction