The controversial Tom Bearden  has this to say:
(1) Maxwell's theory, which was worked out in quaternions rather than vectors, had actually not been completely captured by its translation into Heaviside's vectors by none other than Heaviside himself. [Heaviside was the cofounder of modern vector analysis and almost single-handedly produced what today is the recognized vector form of Maxwell's equations. He also nearly single-handedly transformed Maxwell's theory into its modem form.].
(2) The effects of stresses in the vacuum medium had been eliminated by Heaviside, while Maxwell certainly had pointed out additional terms required to address this issue. [A Soviet team addressing this omission, would have inevitably connected it to Whittaker and Kaluza-Klein theories, revealing electrogravitation (scalar electromagnetics).].
(3) A quaternion, which contains a scalar part in addition to a vector part, could maintain** its non-zero scalar part when the vector was zeroed, whereas in vector analysis, when the vector is zeroed, it is assumed that no residue exists. [This is also directly connected with the mistaken assumption that an abstract vector space itself can have no substructure.]
**and even vary and oscillate, its internal EM stress.
(4) The direct connection could be made with Whittaker theory to produce scalar vacuum stress gravitation when the EM vector fields were zeroed.
(5) The West had missed this unified theory because of its total aversion to quaternions, and its elevation of the curtailed Maxwell's theory to cult status.
(6) Investigative experiments to explore bucking EM force fields which neatly zero sum would have almost immediately revealed highly anomalous behavior of materials and circuits. [Such simple investigations of zero-vector EM force field summation do not seem to appear in the Western literature at all, so far as can yet be established.]***
***with the single exception of the Aharonov-Bohm effect, which has finally been proved after 27 years of controversy, and Hooper's work which was obscurely published. 
Marc Seifer notes “Tesla researcher Tom Bearden has gone so far as to say that the Hertzian decision to eliminate scalar waves and vector potentials from Maxwell’s equations created a flaw in the next theoretical development calledquantum mechanics. I was for thei reason Bearden speculates, that Einstein could not create a unified field theory. .. He further suggests that by using Tesla transmitters to produce converging powerfully pumped scalar waves, spinners and twisters can be created, hat is, local space/time can be curved, and large amounts of power can be transmitted wirelessly over long distances.
Can Bearden be taken seriously?
 For critical review of Bearden, see: http://www.phact.org/e/z/BeardenReview.htm; http://quantumfuture.net/quantum_future/bearden.htm
 Mark Seifer The Life and Times of Nikola Tesla: Biography of a Genius Citadel Press 1998.
Note 60. Bearden presented the paper Scalar Waves and Tesla Technology at the International Tesla Society Symposium,