1. The Invention of the Binishell

By the latest system of pneumatic, inflatable and deflatable forms, dock pouring, launching, floating to position and submerging in place, submarine tubes may be built at one-third the cost of suspension bridges (Mohr 1927: 83).

Curved in sky line in mass and detail, facilitated by improvement in method of construction (notably the pneumatic form […]). By this method buildings or circular form will be more economical to construct than our present rectangular system. Also being more closely natural in form, more beautiful (Mohr 1927: 84).

After plaster shell is set, the rubber form is deflated and is removed with canvas-casing, to be used over and over again. The insulation paper which prevents plaster from adhering to canvas-casing is washed away, leaving a finished blaster interior (Mohr 1933: 4).

It was important that the reinforcement rods, used to resist tension (unlike concrete which only resists compression) once lifted, would attain the position determined by my engineering calculations derived from the study of Nervi’s elegant sports arena, the Palazzetto dello Sport in Rome. Applying some creativity, the concrete metal reinforcement system of the first dome was composed of coaxial circles of steel rods, not actually engineered by design, arranged on the deflated membrane while it was still on the ground. The distance between the circular rods was secured by chain segments, which would obviously not pose any resistance to their shorter distribution on the ground. When lifted from the ring beam base, these chains would arch up in broad curves towards the pole in opposite directions, following the exact geometry of the ribbing of the Palazzetto dello Sport (Bini 2014: 28–29).