Benjamin Wakefield provides a history of the death ray:
The concept of the modern death ray was forged in the 1920s and 1930s, when various individuals theorized the application of a particle beam or electromagnetic weapon. The American inventor Edwin R. Scott claimed to have developed a “lightning device” that could “bring down planes at a distance” (NYT, 1924). Prior to this, Harry Grindell-Matthews had tried to sell an energy weapon to the British Air Ministry. In 1923 he claimed to have invented a device that could “put magnetos out of action,” which with enough power could operate to a distance of up to four miles (Ibid.). However, despite demonstrating the weapon to journalists he was unable, or unwilling, to produce a working model for the military. Over a decade later, Antonio Longoria produced one of the more bizarre claims. Apparently he had constructed a device that could kill a mouse that had been encased in a “thick walled metal chamber” by dissolving its red blood corpuscles (Popular Science, 1940). The then president of the Inventor’s Congress, Albert Burns, said that he had witnessed dogs, cats, pigeons and rabbits being killed at a distance by this weapon (Time, 1936).Longoria’s wanton abuse of pigeons would have angered the noted eccentric Nikola Tesla, who harbored a deep fondness for the bird. No discussion on the history of the death ray would be complete without mentioning the pioneering work of Tesla. He worked on his “teleforce” weapon from the early 1900s until his death in 1943, but because he was unable to secure any governmental funding, the project was left undeveloped. His ideas concerning the creation of the energy weapon seem to be the most viable when compared with those of Longoria, Scott, and Grindell-Matthews. His theory was that a narrow stream of particles, perhaps mercury or tungsten, could be accelerated by a high-voltage current to produce a concentrated beam of minute projectiles. Tesla believed (some would say wildly exaggerated) that this would produce enough energy to destroy “a fleet of 10,000 enemy airplanes at a distance of 250 miles” (NYT, 1934). He boasted that his weapon would have the effect of surrounding every country that used it with an impenetrable barrier, capable of destroying invading armies before they could even cross the border (Ibid.). In fact, all four of these pioneers made similar claims.
Indeed, the one thing that these men all had in common was their singular belief that their death rays could put a stop to armed conflict. Tesla optimistically referred to his weapon as a “peace-ray”—”a machine to end war” (Tesla, 1937). Similarly, Grindell-Matthews believed that “the death-ray will sweep whole armies into oblivion, whole cities into bleak, smoldering ruins, explode bombs in midair, blow up ammunition dumps from great distances [and so] end war” (Time, 1924). Fundamentally, they desired to create a weapon that was so powerful that it would act as the ultimate deterrent against war. It is no surprise, then, that when such a weapon was finally developed, public interest in the death ray dwindled. The atomic bomb took its place as the superweapon of unimaginable annihilation, surpassing the destructive capability of any of the proposed energy weapons. Although the United States National Inventors Council would continue to list the death ray as a much needed military invention until 1957 (NYT, 1957), the golden age of the concept was over by the late 1940s.
(Hat tip to Nyrath.)