Ferris et al. 1936's chest-external counter-shocks restored coordinate heartbeat in about 60% of fibrillating sheep

Using electrodes placed externally on the chest of sheep already put into ventricular fibrillation, the same Columbia-led experimental program tested whether a second, deliberately applied shock could reverse the condition it studies elsewhere in the paper as an injury. The result: "Such counter-shocks were found to be effective in recovering coordinate heart action in about 60 per cent of the cases." This sits fourteen years before the Johns Hopkins program's closed-chest defibrillator reached a practical device, and demonstrates the reversal mechanism working external to the chest — not yet a portable instrument, but a documented, quantified success rate for the underlying physiological effect.

The paper's own account of where this experiment sits historically — crediting earlier work rather than claiming originality for the reversal effect itself — is recorded separately in claim-ferris-1936-priority-credited-to-prevost-battelli-1899-not-kouwenhoven.