https://en.wikipedia.org/wiki/Brooklyn_Bridge#Caissons_2
Due to the extreme underwater air pressure inside the much deeper Manhattan caisson, many workers became sick with "the bends"—decompression sickness—during this work,[90] despite the incorporation of airlocks (which were believed to help with decompression sickness at the time).[100][101] This condition was unknown at the time and was first called "caisson disease" by the project physician, Andrew Smith.[102][103] Between January 25 and May 31, 1872, Smith treated 110 cases of decompression sickness, while three workers died from the disease.[54]
