Unravelling the Mystery of the Atomic Nucleus is a history of atomic and nuclear physics. It begins in 1896 with the discovery of radioactivity, which leads to the discovery of the nucleus at the center of the atom. It follows the experimental discoveries and the theoretical developments up to the end of the Fifties. Unlike previous books regarding on history of nuclear physics, this book methodically describes how advances in technology enabled physicists to probe the physical properties of nuclei as well as how the physical laws which govern these microscopic systems were progressively discovered. The reader will gain a clear understanding of how theory is inextricably intertwined with the progress of technology. Unravelling the Mystery of the Atomic Nucleus will be of interest to physicists and to historians of physics, as well as those interested development of science.