The force holding the hemispheres together was equal to the area bounded by the joint between the hemispheres multiplied by the difference in air pressure between the inside and the outside .
The joint between the hemispheres is a circle with a diameter of 50 cm .
The force holding the hemispheres together was equal to the area bounded by the joint between the hemispheres , a circle with a diameter of 50 cm , multiplied by the difference in air pressure between the inside and the outside .