BATTLE OF THE ALCHEMISTS COMPTON 281 



made to swin<if very high, even though each individual push would 

 lift him only a short distance. Similarly, a voltage of 10.000 volts, 

 applied 100 times in succession to an ion traveling around in a circle 

 under the influence of a magnetic field, will give it the same final 

 energy as if 1 million volts had been applied once. 



Van de GraafF has gone back to electrostatic principles and de- 

 veloped a d.c. generator in which electricity at low voltage is sprayed 

 onto a rapidl}' moving insulating belt, which carries it up into a 

 spherical terminal on which it is deposited. The charge and poten- 

 tial of the terminal thus rise up to the point at which further increase 

 is limited by the breakdown of the surrounding insulation. The 

 voltage limitation is therefore that inherently determined by the 

 geometry of the electrodes and the character of the surrounding in- 

 sulating medium, while the current is limited to the rate at whicli 

 electric charge is transported by the belts. After successful opera- 

 tion to 80,000 volts of a small generator made of tin cans, sealing 

 wax, and a silk ribbon, a larger generator was built to deliver 30 

 microamperes at 1,500,000 volts. It was successful, as have also been 

 similar and modified generators built during the past year in several 

 laboratories. 



The most ambitious of these generators is one designed to deliver 

 30 or 40 kilowatts at voltages calculated to be 15 million volts and 

 expected to reach at least 10 million. This is nearing completion in 

 the Massachusetts Institute of Technology experiment station on the 

 estate of Col. E. H. II. Green at Round Hill, Mass. The terminals 

 are 15-foot polished aluminum spheres, mounted on 30-foot textolite 

 insulating cylinders, inside of which run the belts that convey the 

 charge to the spheres. Each sphere is a laboratory room, within 

 which the experimenter can assemble and operate the apparatus that 

 bridges the gap between the positively and negatively charged 

 spheres. 



Although this Round Hill outfit is quite spectacular, it is ])robal)lo 

 that the most important developments of this apparatus Avill be not 

 in the open air but in some container filled with a medium of 

 superior electrical breakdown strength. Tlie voltage increases di- 

 rectly and the power output directly as tlie square of this break- 

 (h)wn strength. Two such modifications have already been success- 

 fully operated in small models, one operating in the best attainable 

 vacuum and the other in gas at about 30 atmospheres pressure. 



This is the story of the Battle of the Alchemists to date. They 

 have matched their skill, strength, and all the resources of science 

 against the dogged integrity of the atom for numy centuries. 

 Within the last 10 years, but mostly Avithin the last 2 years, it 

 begins to look as if the atom may succumh all along the battle front, 



