these caissons on both sides of the bridge, both ends of the bridge, he come part of the -- they become part of the permanent structure, they were filled with cement and remain underneath the east river. they are still part of the structure. you can imagine, it is 1869, not a shovel of dirt has been turned at the site or location of the brooklyn bridge, but john roebling and his eldest son are there surveying. as they are standing on the pier, a ferry boat approaches and crashes into the pier. it crushes roebling's foot and it ultimately becomes a mortal injury because he contracts tetanus. not being one who believes in traditional medicine -- he believed in water therapy, he throws the doctors out of the apartment where he was living and staying and work and says, water, water. they kept pouring water on the wound. this, of course, does not work. tetanus is not a fun experience, nor is any illness, but it is an excruciating way to go. he suffers and passes within days, and washington roebling, his eldest son, becomes the chief engineer on the brooklyn bridge project. it took an additio