English scientist Clopton Havers (c. 1650–1702) was the first to study the internal structure of bone using a microscope. Havers’s discoveries and observations included finding channels that extend along the shafts of the long bones of the arms and legs. These channels, which allow blood vessels to penetrate dense bone, were named the Haversian canals after their discoverer. He also described cartilage and synovia. In addition, he suggested that the periosteum, which surrounds bones, was sensitive to processes occurring within the bone. This observation was not confirmed for 250 years.