September 21, 1917] 



SCIENCE 



293 



understanding and solution of the milk prob- 

 lem." Leo F. Eettger 

 SHEFriELD Scientific School, 

 Yale IlNrvERSiTT 



SPECIAL ARTICLES 

 GRAVITATIONAL REPULSION' 



In a paper entitled " Gravitation and Elec- 

 trical Action " published by The Academy of 

 Science of St. Louis, on July 28, 1916,2 the 

 following passage may be found : 



These results seem to indicate clearly that gravi- 

 tational attraction between masses of matter de- 

 pends upon their electrical potential due to elec- 

 trical charges upon them. 



Every working day of the present college 

 year has been devoted to testing the validity 

 of the above statement. All of the experi- 

 mental results confirm this conclusion. "No 

 discordant results have been obtained. Not 

 only was gravitational attraction diminished 

 by charges of electricity upon the attracting 

 bodies, when direct electrical action was wholly 

 cut oil by a metal shield, but gravitational 

 attraction was converted into a repulsion 

 which was greater than the normal attraction. 

 On two days, when the influence machine, 

 driven by a single-phase motor, was most 

 highly efficient, the value of the gravitation 

 constant was reduced by 250 and 300 per cent. 

 of its maximum value. The maximum value 

 of the gravitational attraction was evidently 

 exerted when the potential of the attracting 

 masses was zero absolute. The suspended 

 masses were two spheres of lead, having a di- 

 ameter of one inch, and distant from each 

 other 91.5 cm. They were suspended on two 

 untwisted threads of silk fibers, about 3.4 

 millimeters apart, and having a length of 179 

 cm. These silk threads were tied together at 

 the top and hung around a pulley one inch 

 in diameter. Below were two movable pul- 

 leys by means of which the distance between 

 the silk threads could be adjusted to a par- 

 allel position. The large masses were spheres 



1 Abstract of a paper to be published by the 

 Academy of Science of St. Louis. 



= Trans. Acad, of Sc. of St. Louis, XSIII., 4, p. 

 173. 



of lead having a diameter of 10 inches. They 

 were mounted on blocks of wood having caster- 

 wheels provided with roller bearings, which 

 rested upon heavy sheets of hard rubber. The 

 screen around the suspended masses was in 

 part composed of wood, forming the top, bot- 

 tom, and ends. The sides which faced the 

 large masses each consisted of two sheets of 

 heavy cardboard, outside of which was a sheet 

 of metal. They were securely clamped to the 

 top, bottom and ends of the enclosing shield 

 by means of bars of wood and the joints were 

 sealed by means of bees-wax, which was melted 

 and run into the joints by means of a hot iron. 

 The entire screen was then surrounded by 

 another shield of metal. A layer of air about 

 1.5 cm. in thickness was thus formed between 

 the two metal sheets on either side. A sheet 

 of glass was also placed between each of the 

 large masses and the metal sides of the shield. 

 A box of metal filled with loose cotton-batting 

 was placed in contact with the metal shield, 

 alternating in position with the large masses. 

 This was done in order to prevent as far as 

 possible radiation from the northern sky from 

 producing unbalanced convection currents in 

 the air within the screen. 



The large masses, the metal boxes contain- 

 the cotton, and the metal screen were all in 

 metallic connection with each other. All heat 

 from the heating system of the building was 

 cut off. The change in the position of the 

 suspended masses was determined by means 

 of a mirror, telescope and scale, observation 

 being made through a narrow slit in the screen 

 which was covered by a plate of photographic 

 glass, sealed to the inner sheet of metal. 



Three feet distant from the ends of the 

 screen and the side opposite to the observing 

 telescope was a line of insulated metal rods 

 upon which was hiuig metal strips armed with 

 800 pins. At one end of this line of rods was 

 a metal disc armed with 150 pins. Facing 

 this disc was a duplicate disc attached to a 

 line of rods hung upon silk cords, and leading 

 to the influence machine in an adjoining room. 

 There was no gap in the line of rods excepting 

 between the two discs having 150 pins soldered 

 to them. The rods carrying the 800 pins were 



