The average gestation period for rabbits is 31 days; however, it can vary from 29 to 35 days. Does should be pregnancy-checked 14 days after mating. If not pregnant, they can be re-bred immediately.
Buttresses and an arch of the Roselend Dam in France. A buttress dam or hollow dam is a dam with a solid, water-tight upstream side that is supported at intervals on the downstream side by a series of buttresses or supports.The dam wall may be straight or curved. Most buttress dams are made of reinforced concrete and are heavy, pushing the dam into the ground.ater pushes against the dam, but the buttresses are inflexible and prevent the dam from falling over. Buttress or hollow gravity dams were originally built to retain water for irrigation or mining in areas of scarce or expensive resources but cheap labour.
The flying buttress (arc-boutant, arch buttress) is a specific form of buttress composed of an arched structure that extends from the upper portion of a wall to a pier of great mass, in order to convey to the ground the lateral forces that push a wall outwards, which are forces that arise from vaulted ceilings of stone and from wind-loading on roofs.