Palmer H. Craig

Palmer H. Craig was an American physicist, head of the physics department at Mercer University in Macon, Georgia, and the claimant behind a 1920s bismuth-based "Hall Effect Device" promoted as a replacement for vacuum tubes and batteries in radio receivers.

Biography as reported by the source

• Ph.D., University of Cincinnati, June 1926. His doctoral thesis was "The Hall effect with low magnetic fields" (8 pages; DP15709).
• Head of the physics department at Mercer University, Macon, Georgia.
• Described in the 1927 press as "not yet thirty."
• Author of "The Hall Effect in Bismuth with Low Magnetic Fields," Physical Review 27:772–778 (June 1926), and Physical Review 30:964 (1927).
• Author of U.S. Patent 1,822,129 (granted September 8, 1931) and of a long list of further U.S. and Canadian patents.

The claim

Craig reported an anomalously large Hall coefficient in thin bismuth films at very low magnetic fields (0.07–1.0 gauss), with -R ≈ 171 at 0.07 gauss falling to about 12–13 by 0.3–1.0 gauss. He found that stacking films in series adds their Hall potentials, and proposed using this additive behavior to rectify alternating current in radio circuits. The 1927 press account went further, reporting that the plates "generate the energy necessary to operate the radio" and that Westinghouse had offered $100,000 for the invention.

Rebuttals

• C. W. Heaps (Physical Review 29:332, 1927) measured a bismuth plate over the same low-field range and found R essentially constant at about 11.5, with variations below experimental error, concluding Craig's data were erroneous — probably from insulation leakage or uncompensated thermomagnetic effects.
• Harry F. Breckel (U.S. Naval Institute Proceedings, August 1927) tested the device at Craig's Macon laboratory and at a commercial laboratory and found the apparent rectification to be a thermal junction effect from lead–copper contacts, with meter readings dominated by inductive pickup and radio reception results of zero.
• Alfred N. Goldsmith of RCA denied the reported Westinghouse offer and rejected the premise that bismuth's Hall property could serve the claimed purpose.

Patents

The archive lists Craig's U.S. patents as US1778795, US1778796, US1792001, US1798658, US1825855, US1935738, US1956121, US1981583, US1992146, US2001836, US2001837, US2001838, US2296269, US2310304, US2327622, US2357727, US2393890, US2405089, US2414636, US2435202, US2444221, US2444222, US2463249, US2465202, US2520383, US2615062, US2937351, US3008882, plus CA386489, CA296979, CA456916, and US3197651A. The central Hall-effect patent is US1822129 — System & Apparatus Employing the Hall Effect.

See also

Hall Effect, Hall-Effect Rectification, Additive Principle (Series Hall Potentials), Anomalous Low-Field Hall Coefficient in Bismuth, comparisons/comparison-craig-hall-effect-claims-vs-evidence.