 Stuewer (1993) has suggested that Cockcroft and Walton use mass-energy equivalence to confirm their hypothesis about what happens when \({^7}\Li\) is bombarded by protons. Hence, it does not seem we ought to regard this experiment as a confirmation of \(E_o = mc^2\). However, if we take some of the other evidence that Cockcroft and Walton provide concerning the identification of the products in the bombardment reaction as sufficient to establish that the products are indeed \(\alpha\)-particles, then we can interpret this experiment as a confirmation of mass-energy equivalence, which is how this experiment is often reported in the physics literature.