Prof. Francis E. NIPHER

Electro-Gravitic Experiments

NY Times (19 Sept. 1917)
Electrical Experimenter (March 1918)

Trans. Acad. Sci. St. Louis XXIII (4): 173-176 (July 28,1916)

Trans. Acad. Sci. of St. Louis XXIII (4): 177-193 (July 28, 1916)

Trans. Acad. Sci. of St. Louis XXVII: 383-387 (March 2, 1920)

New York Times (19 September 1917)

"Professor Tells of Electrical Tests Turning Attraction Into Repulsion."

A new theory as to gravitation will be announced soon before the St. Louis Academy of Sciences by Professor Francis E. Nipper, retired head of the Department of Physics of Washington University.

"It will be shown that gravitational attraction between masses of matter not only has been diminished into zero, but has been converted into repulsion which is more than twice as great as normal attraction."

New Gravitation Theory ~

Professor Nipper made his experiments with bodies suspended horizontally toward each other. By introducing electricity into the atmosphere he converted normal attraction into repulsion.

"If electricity can alter the gravitational attraction of the bodies used in my experiments," he said, "the same force can alter the earth's attraction. If the negative electricity could be drawn from the earth's surface, gravitational attraction suddenly would cease and the cohesion of the earth's surface would be disastrously affected."

Electrical Experimenter (March 1918)

"Can Electricity Destroy Gravitation?"

Is it possible to nullify, and further to even reverse, the effect of gravity by electricity? This scientific conundrum seems about to be solved, at least to a certain extent. To begin with, everybody is familiar with that law of physics which states that "all particles of matter attract each other with a force which is greater the nearer the particles are together", and to be still more definite, Newton's law says that bodies behave as if every particle of matter attracted every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them. It is the gravitational attraction between the earth and the bodies upon it which causes the latter to have weight.

This fact is often lost sight of and should be well understood by every student. To make the matter more clear let us imagine that a man's body is (as by flying, jumping, diving from a high point, etc.) for the moment separated from the surface of the earth. As soon as the mass of the body is separated from the earth, gravitational attraction is set up between the two masses. The earth pulls the man's body, and also his body pulls the earth, but as the mass of the earth is infinitely greater, its movement cannot be detected.

The scientists of today believe that in some mysterious way the minute electrical charges existing on the particles making up molecules and atoms are definitely linked up and concerned with such basic phenomena as gravitation. Since all bodies are made up of atoms it would seem to logically follow that the forces of gravity must depend in some way upon attractions which atoms exert upon each other, and due to the fact that the atoms are separated, at least in solids and liquids, by extremely small distances, we might expect these inter-atomic forces to be relatively more powerful than are those of ordinary gravitation.

Until recently, however, the mystery linking this inter-atomic activity with the force of gravitation baffled all attempts at solution, although many scientists had tackled it.

But at last experimental proof has been forthcoming through the untiring labors of Professor Francis E. Nipher, of the St. Louis Academy of Science. In a pamphlet issued November 8, 1917, Prof. Nipher supplies experimental evidence that gravitational attraction can not only be suspended or nullified by the electrical current, but it actually can be transformed into "gravitational repulsion"!

All during the summer of 1917, Prof. Nipher had his apparatus in almost continuous operation, and the experiments have been repeated time and again, always with the same result.

Prof. Nipher's mechanical apparatus resembled that used in the "Cavendish experiment", by which it was first experimentally proved that Newton's law of universal gravitational attraction applied to small bodies in their action upon each other at short distances, just as well as it did to small terrestrial bodies under the influence of the earth. This apparatus consists of a delicate torsion suspension fiber (Figure 3 & Figure 4), a light, rigid arm at the lower end of the fiber suspension, and at either end of this bar two small lead spheres of known mass. Two equal large balls of solid lead are placed close to the small suspended spheres in the manner shown. Now, remembering our law of physics stated above -- that every body in space attracts every other body proportionally to their respective masses and inversely as the distance between them -- then it is evident that when this apparatus is set up, that the small suspended spheres will be slightly attracted by the larger, stationary balls. This condition is represented in Figure 1.

Before connecting any form of electric current to the modified Cavendish apparatus, Prof. Nipher took special precaution to carefully screen the moving element from any electrostatic or electromagnetic effects. His apparatus briefly consists of two large lead spheres ten inches in diameter, resting upon heavy sheets of hard rubber. Two small lead balls, each one inch in diameter, were now suspended from two silk threads, stationed at the sides of the two large lead spheres, from which they were separated by a little distance. Moreover, the suspended balls were insulated elaborately from the large spheres by enclosing them first airtight in a long wooden box, which was also covered with tinned iron sheets as well as cardboard sheets. There was, furthermore, a metal shield between the box and the large metal spheres. The large metal lead spheres now exerted a certain gravitational pull upon the suspended small lead balls as indicated in Figure 1, and the small lead balls were slightly pulled over towards the large spheres.

In his first experiments Prof. Nipher applied a high tension current from a static machine to the large lead balls (Figure 2). No difference was noted whether the positive or negative terminals were applied. In one of these experiments the masses were "repelled" (normal gravitational attraction had been nullified and changed to repulsion) by a force nearly twice as great as the initial gravitational repulsion. The effect is shown in Figure 3.

In further experiments Prof. Nipher decided to check his results. To do this he replaced the large solid lead spheres with two metal boxes, each filled with loose cotton batting. These hollow boxes (having practically no mass) rested upon insulators. They were separated from the protective screen by sheets of glass and were grounded to it by heavy copper wires. The metal boxes were then charged in every way that the solid lead spheres had been, but not the slightest change in the position of the lead balls could be detected. This would seem to prove conclusively that the "repulsion" and "gravitational nullification" effects that he had produced when the solid balls were electrically charged were genuine and based undoubtedly on a true inter-atomic electrical reaction, and not upon any form of electrostatic or electromagnetic effects between the large and small masses. If they had been, the metal boxes, with no mass, would have served as well as the solid balls.

Another interesting experiment was conducted with low frequency alternating current applied to the large lead spheres. Spring contact brushes were fastened to the wooden blocks supporting the large spheres as shown in Figure 4, one brush on either side of the ball. This permitted sending current through the ball from one side to the other. First, a direct current of 20 amperes as sent through the two large masses, but no effect on the suspended masses could be detected. Next, an alternating current of 20 amperes was sent through the two masses (See Figure 4), with the result that the gravitational attraction was quickly reduced to zero, and not only that but in 15 to 20 minutes the small lead spheres had moved over one-half as much to the opposite direction as the distance they had been attracted originally towards the large masses. Thus gravitation had not only been completely nullified, but it was actually reversed.

Figure 1: "Attractive" effect of gravity between large & small masses. No current.

Figure 2: Gravitational repulsion caused between large & small masses. Current on.

Figure 3: Nipher's experiment with two metal boxes filled with cotton (no mass). No gravitational change with or without current.

Figure 4: When 20 amps AC was passed through the large balls, the gravitational attraction was reduced to zero and made negative. This repulsion was 50% of the normal attraction.

Trans. Acad. Sci. St. Louis, pp. 163-175 (July 1916)

"Gravitation & Electrical Action"

Francis E. Nipher

In former publications the present writer has suggested an intimate relation between gravitation and electrical action. (*1)

(*1: Proc. Amer. Phil. Soc. Philadelphia 52: 283-6; Science (Sept. 1, 1911), pp. 282-3; Experimental Studies in Electricity & Magnetism, pp. 19-24.

There can be no doubt of the truth of the statement, that the attraction between any two masses of matter, depends not only upon the amount of matter in the two masses, and their distance from each other, but also upon their electrical condition.

Assume that two spheres, having radii R1 and r2, composed of metal having a density p, and distant from each other r, have electrical charges Q1 and Q2, the spheres having a common potential V. their attraction for each other will be:


Here K is the Newton constant of gravitation as it would be determined if electrical action were eliminated, or if V were zero absolute.  The absolute zero in V would be the common potential of the two bodies, under the condition assumed in Eq. (1), when their attraction for each other is a maximum.

The gravitation constant has been determined by methods, which it was assumed made it unnecessary to consider the electrical condition of the two bodies. Nevertheless the results have been very unsatisfactory. In his presidential address before the American Mathematical Society in December 1899, R.S. Woodward (*2) referred to this constant as being one of the constants of the solar system whose determination was in a most unsatisfactory condition, as regards precision.

(*2: Bulletin Amer. Math. Soc. II 6: 153)

If the masses are capable of acting upon each other electrically, and the final term in Eq. (1) is omitted, that equation might be written:


In this equation an error of x per cent in the value of K would result. By (1) and (2):

If V is measured in volts:


For purposes of illustration, assume that K = 6.6576 x 10-8 and that of R1 = 101, R2 = 1 and p = 11.35; then:

V = 3.68 square root of x

If the common potential of the two spheres differs from absolute zero by 3.68 volts, the value of K would be in error by one per cent of the above value, which is that of Boys, unless adequate means are taken to eliminate the effects represented by the final term of Eq. (1)

If V were 8.23 volts an error of 5% would result. If V were 36.8 volts, the two spheres would have no attraction for each other, although both would be attracted by the earth, even if it had the same potential. The attraction of the earth for a gram of lead would then be by (1):

A = 981 - 0.000,000,000,006.

The acceleration of a falling body would be practically unchanged, and would not depend upon the density of the matter of which it is composed, as it would apparently be under the conditions assumed in Eq. (1).

Rainbows falling through an overcharged thundercloud (*3) would repel each other. After the diverging branches of a flash of lightning have penetrated the cloud a new condition has arisen. Overcharged drops of water along the lines of the intricate system of branches of the discharge, have delivered their overcharge to the cloud at the other end of the long flash. These drops are intimately commingled with drops which are outside of the drainage lines. The value of V for these two groups of drops now have opposite signs. The final term in equation (1) then becomes positive, as applied to these groups, and it is much greater than the gravitation term. These drops coalesce as they fall to earth and a brief dash of unusually large drops of rain follows.

(*3: The word overcharged, or super-charged, was in common use more than a century ago, when the one-fluid theory was in general favor.)

(*4: See Nipher: "A Flash of Lightning", Popular Science Monthly, Jan. 1912: p. 76; Nipher: Experimental Studies in Electricity & Magnetism, pp. 16-17))

In former papers above referred to, an experimental study of explosive effects due to a discharge from a large condenser through a small lead wire was discussed. The wire was sealed within a glass tube filled with coal oil. This work has been continued in a modified form. Four quarter ampere wire fuses of lead were placed in multiple across a gap, 5 cm in length in a line leading from either terminal of an influence machine to a water-pipe system. The other terminal was grounded on a gas pipe. The lead wires were clamped between the leaves of two small brass door hinges, one lead of each hinge being soldered to one of the ends of the rods at the gap. Between the gap in which the leaves were mounted and the ground was placed a large battery jar filled with 4 liters of a solution of common salt. The wire was parted at this point, and the ends were immersed in this solution which thus formed part of the ground circuit. One of the wires penetrated the liquid to a depth of about half a cm. Between the gap in which the wires were mounted and the machine was a spark gap, between knobs of equal radius. The condenser consisted of 40 large sheets of glass (36 x 36") having upon them 2 x 40 sq ft of tinfoil. The machine was driven by a single-phase electric motor. Below the lead wires a sheet of white paper was laid upon a plate of glass.

It was found that there was a marked difference between the effect of the positive and the negative discharge, or the compression wave, would cause the lead wire to fuse and drop in hot globules upon the paper below. The effect upon the paper is shown in Plate XLIV, Figure 1. [Not available]

With the same adjustment, the positive discharge3 causes the lead wires to rise in a cloud of dust. If the paper were placed 3 cm below the wires, it would usually be practically unaffected when the positive discharge was used. In a few cases, as in Figure 2, it was slightly discolored by the lead fumes.

Of course the discharge could be made greater, so that either discharge would cause the lead to be dissipated in a cloud. It could be made less, so that fused metal would fall upon the paper when the positive terminal was connected with the ground containing the wire. In all cases the cloud effect was the more marked in the case of the positive discharge, and the fused metal falling upon the paper was less marked.

In case of the positive discharge there is of course a heat effect. Part of the result is due to this cause. But if we are to consider the positive terminal as an exhaust terminal, into which the negative electrons are suddenly drained and thence into the positive sheets of the condenser, we may explain the result as an explosive condition which is suddenly impressed upon the lead. When deprived of negative corpuscles, each atom repels every other. The negative term in question (1) has become very much greater than positive, when applied to inter-atomic attraction under these conditions.

The negative discharge, which is to be regarded as a compression wave could not give a super-charge to atoms within the wire, causing them to repel each other. The super-charge is on the outside of the wire. The one-fluid theory seems to furnish a more rational explanation of these phenomena than the two-fluid theory, as in the case in the phenomena of the Crookes tube.

Some work has been done in the examination of the effect of the electrification of air within a glass vessel, upon the pressure of the air on the walls of the containing vessel. A large 3-necked Wolff's bottle was used, the 3 openings being provided with rubber stoppers which had been treated with vacuum wax. The bottle had a volume of 9.6 liters. Through the central stopper was passed a copper wire to which were attached 150 pins whose heads were soldered to one of its faces. This many pointed terminal could be placed directly in front of either of the large knobs of the machine, at a distance of 10 cm, the other knob, or terminal, being grounded.

A U-shaped water gauge was mounted in another stopper of the flask. In the third stopper of the flask a tube with a bulb containing calcium chloride was mounted, this tube being provided with means for connecting the confined air with the outer air. The condensers were wholly removed from the machine. The glass bottle was placed upon a sheet of heavy plate glass.

When the discharge-knobs of the machine were near enough together so that the brush discharge between them was accompanied by faint disruptive effects, the pressure within the flask could be increased by about 2 gr-wt per sq cm, the effect of the negative electrification being somewhat greater than that of the positive.  When the knobs were far enough apart to prevent disruptive discharges, no luminous effects being observed within the flask, the change in pressure due to either terminal was reduced to 1 and 2 mm as shown by the water gauge. After the pressure due to electrification of the air had reached a final limit, a transfer of the may pointed collector of the front of the other terminal, would result for a time in a slow decrease in pressure, and then in a slow increase to the former limit. The decrease in pressure did not begin until the discharge from the other terminal had begun. Heat effects had been practically eliminated.

If the gas contains moisture a permanent decrease in pressure at once results, due to condensation of vapor upon the sides of the vessel.

These results seem to indicate that there is an electrical condition of the gas, for which the Boyle-Gay-Lussac constant is at a minimum. When this condition is reached, the second term of equation (1) is zero, as applied to molecules of gas.

An attempt has been made to determine whether or not the value of the gravitational term of Eq. (1) can be affected by electrical action, when the effect represented by the final term is eliminated. The apparatus used was a modified form of that used by Cavendish. The suspended masses consisted of 2 lead tubes, each being about 15 cm length, each having a mass of 50 grams. They were mounted around the ends of a bras tube 91 cm in length, and having a mass of 30 gr. This tube was suspended upon 2 loosely twisted threads of silk fibers, 180 cm length, whose distance apart was approximately 0.4 cm, the twist was removed from these threads by hanging upon each a mass of 65 grams. This formed a very sensitive bifilar suspension. The suspended masses were wholly surrounded by a metal shield of rectangular form 10 x 12.5 cm in cross section. The suspension fibers were enclosed in a metal tube, having a torsion head at the top, thus providing means for properly adjusting the position of the brass tube. The ends of the rectangular shield were provided with metal caps, fitting closely into its ends. They entered the shield a distance of 2.5 cm. An opening at the middle of the shield, in front of a mirror mounted upon the suspension wire, served for observation of position by means of a telescope and scale. This opening was covered by a sheet of glass which was sealed to the shield by means of sealing wax. The window was covered with a metal wire screen having about 5 wires per running cm. The mirror was observed through this wire screen, the telescope being focused upon the scale at the telescope. A change of one scale division represented a change of 2.36 minutes of arc in the position of the suspended tube. The suspended masses and the brass tube on which they were mounted were surrounded by sheets of asbestos paper, which fitted into the caps at the ends of the shield, and fitted loosely the interior of the shield. These two linings formed extensions of the end caps and were intended to prevent a convection of the air within the shield.

The larger masses each consisted of two 50-pound weights placed one upon the other and mounted upon heavy columns of rubber. They were separated from the metal shield by a space of about 2 cm. In this space was placed a sheet of paper and 3 layers of asbestos paper.

The shield was mounted upon a heavy piece of timber and rested directly upon a sheet of glass. It was also wrapped with asbestos paper. The long suspension tube was held in stable position by 3 heavy silk cords attached to surrounding cases, and loaded with a series of distributed masses varying from 50 to 100 grams each. The metal shield was loaded with two 10-pound masses of iron and its sides were clamped with wooden clamps in order to quiet any vibrations in the shield. The large iron masses and the metal shield were connected with each other by large copper wires, leading to a spark-knob mounted upon a massive table. The floor of the room was of reinforced concrete. The discharge terminal was connected with the influence machine in an adjoining room, by means of brass rods hung upon silk cords. The machine was operated by a synchronous electric motor. The discharge knobs at the machine were separated so that no disruptive discharges were possible. One terminal of the machine was grounded. There were no condensers on the machine terminals.

The time interval of a to and from vibration of the suspended masses was 485 seconds. When at rest there appeared to be no disturbance of any kind. The reading would sometimes remain constant for hours. At other times the reading slowly changed. It often varied throughout a day through 20 scale divisions. It was found that the large masses appeared to attract the suspended masses with a varying force, even when the former were hung from the ceiling above. Sometimes they appeared to repel the suspended masses. These varying effects were finally traced to very moderate changes in the temperature of the room. It was found that the flame of a wax candle, placed 14 inches from either of the suspended masses, exerted a marked apparent attraction for them. When a sheet of glass and two sheets of asbestos paper were placed between the candle flame and the metal shield, it being provided with a wrapping of asbestos paper in addition to the inside lining of the same material, an apparent attraction resulted. Fluctuations in the flame of the candle due to the condition of the wick produced observable effects. When the outer wall of the screen was rising in temperature more rapidly on one side of the suspended mass than on the opposite side, this mass moved towards the warmer side. This was apparently due to the convection effect of air within the lining of the metal screen.

The suspended rod bearing the small masses was below the central axis of the enclosing shield. If one side of the shield was warmer than the opposite side the suspended rod would be in a slowly drifting current of air, which would urge it towards the warmer side of the screen, or away from the colder side. The temperature of the large masses lagged behind that of the screen in the small daily changed in the temperature of the room.

The effect of a noiseless discharge from the pin-point terminal into the air around the knob connected with the screen and the large masses, was to produce an apparent decrease in the attraction of the large masses for the suspended masses. This result was obtained when no trace of disruptive discharge could be detected. After the extreme displacement thus produced had been reached, the distance between the pin-point terminal, and the knob connected with the shield and the large masses, was increased from 15 to about 90 cm, the charged bodies being then grounded. This was done by means of a fine wire attached to an insulated rod, which could be laid upon the floor of the room, or lifted into contact with a rod, one end of which rested upon one of the large masses. The pin-point terminal was meantime made to face another grounded conductor. The suspended masses then swayed to the other extreme position during the next four minutes. By a repetition of this operation, the arc of vibration could be increased from 1 or 2 scale divisions to 26 in the interval of an hour. The average of the extreme readings of consecutive vibrations, usually showed slow progressive changes of 2 to 5 scale divisions per hour. Sometimes the average reading showed a decrease and sometimes an increase. The results were of the same order of magnitude whether the masses were connected with the negative or with the positive terminal of the machine, although most of this work has been done by the positive "discharge".

It was suspected that this result might be due to a slight rise in the temperature of the walls of the metal shield. If this were the case it must be assumed that while the gap at the pin-point terminals was least, the rise in temperature was least in that part of the sides of the metal screen facing the large external masses.

In order to examine this influence, a delicate air thermometer was extemporized. The bulb consisted of an oil-can having a capacity of 4.5 liters (1 gal). Connected by a rubber hose with the nozzle of the can was a horizontal tube of glass, having a length of 75 cm and an internal diameter of 0.76 mm. Within this tube was a short column of water, serving as an index. The entire device was insulated upon glass supports. A candle flame 20 inches distant from the can was electrified and in electrified contact with the large masses and shield, no change in the position of the index column could be detected when observed by means of a telescope.

The large masses were then wholly enclosed in two metal boxes, from which the masses were insulated. The masses rested upon rubber blocks placed upon the bottom of the boxes, and each box was mounted upon rubber blocks which rested upon plates of glass. The masses were in the same position as in the work described above. The boxes were separated from the shield, enclosing the suspended masses by the plates of glass and the asbestos paper.

The two metal boxes and the metal shield were then electrified precisely as has been done before. It was then found impossible to increase the arc of vibration of the suspended masses, although the operation was continued for several hours. If the former results had been due to heat effects, they should have produced the same results in this case. The large masses were removed from the enclosing boxes. The empty boxes and screen were then electrified as before.

No change in the amplitude of vibration could be produced.

These results seem to indicate clearly that gravitational attraction between masses of matter depends upon their electrical potential due to electrical charges upon them. To assume a special case, such as exists when the gravitation constant is being determined, Newton's law holds only when the common potential of the two bodies is such that their gravitational attraction for each other is at a maximum. If the two masses are not separated by a metal shield and their common potential is that of the earth, these masses and their common potential is that of the earth, these masses will repel each other by a force represented by the final term in Eq. (1) and the value of K will also be diminished, if the above conclusions are correct. If the two masses are separated by a metal shield, this final term will be eliminated, but the value of K will be diminished and may seem to be variable, if there are local variations in the potential of the earth. By adjusting the potential of the attracting masses by well known means we may hope that the real value of K and the absolute potential of the earth may be determined. This is a problem for the future to solve.

In the work discussed in this paper an effort has been made to eliminate heat effects from all sources. It may be that alternating discharges from a high potential transformer would produce more marked effects than have been observed by the methods above described. The surging of negative electrons within the large attracting masses would be greatly increased. This would also involve heat disturbances, the effect of which would cast a doubt upon the results. Under the conditions in which this work was done the amplitude of vibration of the suspended masses sometimes changed in a way that seemed to discredit the above conclusions. It was finally found that variations in the illumination of clouds in the northern sky produced marked effects upon the position of the suspended masses. The apparatus was fifteen feet distant from five large windows in the north wall of the room. The variation in radiation from such clouds was occasionally followed by a marked change in the amplitude of consecutive vibrations. After such disturbances and others not here referred to had been eliminated, there still remained distinct evidence that the value of the gravitation constant as it has been determined, is dependent upon the electrical potential of the attracting masses, when the effect represented by the final term in equation (1) is wholly eliminated by a metal screen.

Plans are now being prepared which will, it is hoped, result in a determination of the change which can be produced in the value of the gravitation constant, by electrification of the larger masses.

Figure 1: Fusion of lead wire by negative discharge. [Not available]

Figure 2: Explosion effects due to positive "discharge". [EV's ? Not available]

Trans. Acad. Sci. of St. Louis XXIII (4): 177-193 (July 28, 1916)

Gravitational Repulsion

Francis E. Nipher

In a former paper published by the Academy on July the following passage may be found: (*1)

(*1: Trans. Acad. of Sci. of St. Louis, XXIII (4): 173-176; July 28, 1916)

"These results seem to indicate clearly that gravitational attraction between masses of matter depends upon electrical potential due to electrical charges upon them."

Every working day of the following college year has been devoted to testing the validity of the above statement. No results in conflict with it have been obtained. Not only has gravitational attraction been diminished by electrification of the attracting bodies when direct electrical action has been wholly cut off by a metal shield, but it has been made negative. It has been converted into a repulsion. This result has been obtained many times throughout the year. On one occasion during the latter part of the year, this repulsion was made somewhat more than twice as great as normal attraction.

The large masses used in this work were spheres of lead ten inches in diameter. They were mounted upon blocks of dry wood, which were mounted upon caster-roller bearings. The wheels rested upon heavy sheets of hard rubber. The suspended masses were two spheres of lead, having a diameter of one inch, mounted upon the ends of a brass tube. Their distance apart, from center to center, was 91.5 cm. They hung upon two untwisted threads of silk fibers, forming a bifilar suspension. The length of the threads was 179 cm, and the distance between them was about 3.4 mm. Near the top of the long metal cylinder enclosing these suspension fibers, was a lateral brace formed of two bars of hard rubber, about 30 cm in length. The ends of these bars formed a right angle against which the vertical suspension cylinder was pulled. These rubber bars formed the ends of two long bars of wood attached to the tops of instrument cases along adjoining sides of the room. The bars were also supported by a framed structure. Silk cords attached to the cases ran along the two bars and were tied to the suspension cylinder. Weights distributed along these cords served to hold the cylinder against the ends of the rubber bars. Vibrations of the suspension cylinder were thus wholly eliminated. The torsion head forming the top of the cylinder was provided with a rod which extended radially outward to a distance of about 20 cm. By this means the torsion head could be turned in order to put the suspended masses into vibration. The top of the suspension cylinder had a similar rod clamped to it having an upward projecting stop, by means of which the torsion head could be returned to the original position. Change in the temperature of the air within the shield resulting in a change in volume was provided for by the outflow or inflow around the torsion head.

The enclosing case was of the general form used by Cavendish. In the early part of the year it was formed wholly of metal. It rested upon insulating blocks of rubber, which were mounted upon two long pieces of timber having a cross section of 4x4 inches. These timbers rested upon a massive table, which was on a floor of reinforced concrete within a building having granite walls. At the central part of the metal shield the dimensions were 5x5 inches. A narrow slit on one side covered by a small plate of glass sealed to the shield, served for observing the movement of the suspended masses by means of a telescope and scale. At the outer ends of the shield, the lateral dimension was about 15 inches. This form was chosen in order that the suspended masses and the brass tube upon which they were mounted could be inclosed by a cylinder of copper wire gauze, between which and the outer screen was very loosely packed cotton fiber. A thin layer of cotton was placed at the ends of the screen, being also held in place by wire netting. This was designed to diminish convection effects.

The body of the observer was wholly below the level of the table. Radiation of heat from the head to the screen was cut off by sheets of heavy cardboard.

The two rooms used for this work were wholly disconnected from the heating system of the building. During the day the temperature of the large masses was usually slightly lower than that of the shield around the suspended masses. This temperature difference never exceeded 1.5° C.

The large masses were placed at the ends of the screen or shield in line with the rod upon which the small masses were mounted, in order to determine their effect upon the time of vibration of this bifilar pendulum. The large masses and screen were in direct metallic connection, and the air around them was electrified by a discharge from pin-points. A disc armed with 150 pins was placed with the pin-points 4 cm. from each of the large masses. A noiseless discharge was delivered from the points of the pins.

Let T represent the time of vibration when the masses were away.

Let T1 represent the time of vibration when the masses are in place.

Let T2 = the time when the masses and screen are electrified. Then:


Here m is the suspended mass, 2d the distance between the two silk fibers on which it is suspended, and l their length. I is the moment of inertia.

When the large masses are in place:


Here D is the directive constant of Eq. (1), b the distance between the centers of the two suspended masses m', and, and r the distance between the suspended masses and the large masses M. The equivalent of the brass rod is included in m'.

When the large masses are electrified, if the time of vibration is increased to T2 and we assume that this is due to a decrease in the value of the gravitation constant G, then:


From these equations:


The time of vibration was determined by means of a chronograph belonging to the department of astronomy of the University. The key was snapped when the mean reading passed the cross-hair of the telescope. The mean reading was obtained from the reading of the four extremes of the two complete vibrations which immediately preceded. The values here given are the mean of six complete to and fro vibrations and the probable error does not in any case exceed 0.25 sec.

Observations March 10, 1916:

T = 623.0 sec.
T1 = 614.5 sec.
T2 = 625.0 sec.

By Eq. 4, n/100 = 1.23

When T was determined the temperature of the air the room was 15.5° C = ta.

The temperature of the screen was t8= 15.2° C.

When T1 was determined,

ta = 17.4° C
t8 = 17.4° C

The temperature of the two large masses was 16° and 16.6°.

These values were determined by means of four thermometers reading to tenths of a degree. The bulbs were placed in contact with the masses, and covered with a layer of cotton batting.

When the readings for T2 were finished,

Ta = 18.0° C
T8 = 17.9° C

The temperature of the large masses was 17.7°and 17.8°.

On a former occasion, when the bifilar suspension different, it was found that placing metal vessels containing a liter of water having a temperature of 28° C. at the beginning of the experiment, and 24° at the close, in positions occupied by the large masses, the temperature of the air and shield being 13°,8, the value of T was increased  from 644.2 sec. to 652.5. The warm vessels were in contact with the shield.

When the metal vessels contained water and ice, temperature of the air and shield being 12.0°, the value of T was decreased by 25 seconds.

These results seem to indicate clearly that convection of the air within the shield had no material effect upon the values of the quantities used in computing the value of n in Eq. 4.

It apparently follows that the value of the gravitational constant was made negative by the process described. Attraction was converted into a repulsion. The influence machine was unusually active by reason of fresh dry material in the case in which it was enclosed. On other days the value of G was decreased by 16, 23, 27, 69, 77, 134 and 184 per cent of its initial value. It is not claimed that these are results of any high degree of precision. During the first week while the bifiar method above described was being tested, the time of vibration during a period of two hours was found to be very constant. For example, in the first determination made on October 23, the mean position of the suspended masses was determined from readings of the extremes for several vibrations. The key was then snapped for six readings while the mean reading passed the cross-hair of the telescope. The mean reading was determined in each case by a computation from previous readings. It was found to be very constant. After lunch the same operation was repeated. This gave six readings of the time interval of 7 complete to and fro vibrations, with data for determining the probable error of the mean. The result was 653.45 +- 0.062 seconds. The probable error was sometimes three times as great as the above value and the mean value varied from the above value on other days by between one and two seconds. An error in the value of n might amount to three or four per cent. The cause for the variations proved to be a difficult problem. The silk threads were very loosely wound, and before they were put in place a weight equal to half the weight of the entire suspended mass was hung upon each of them for several days. They then seemed to be in permanent condition. The breaking stress was about five times that which was thus applied to them.

The causes for the variation in the time of vibration were thought to be possibly due to a breaking of some of the fibers in the threads which might result in an entanglement between the two threads, or which might result in an unequal division of the load between them. It  was sought to eliminate the former source of error by applying vaseline to the threads. This did not appreciably change the result. It was finally decided to check the results above described by placing the large masses on alternate sides of the suspended masses and observing the deflection doe to gravitational attraction.

In order to maintain equality of stresses in the two threads, which had been hung around a hook attached to the torsion head, they were hung around a pulley, having a diameter of one inch. Below were two adjustable pulleys. The threads approached each other around these two pulleys, and their distance apart could be so varied as to make the threads parallel within the suspension cylinder. The metal shield before described was replaced by one having equal width from end to end. The top, bottom and ends were of wood 1/8 inch in thickness. A sketch of this wood frame is shown in vertical section in Figure 1.

Figure 1 ~

This wood frame was varnished with shellac and the points of contact of its parts were closed. The sides this frame were each closed by two layers of heavy cardboard outside of which was a sheet of flexible tinned iron. They were clamped to the wooden frame by means of wood bars screwed to the bottom, top and ends. The edges of the cardboard were then scaled by means of beeswax applied by means of a hot iron. The entire device as thus described was then enclosed by a metal shield. A cross section through one of the suspended masses is shown in Figure 2.

Figure 2 ~

This outside metal shield was not air-tight. It was formed of sheets of flexible tinned iron, the parts of which overlapped. They were tied in place by windings of twine. It was considered an advantage to allow convection currents which might form in the layer of air between the two sheets of metal forming the sides of the enclosing case some opportunity to escape into the outer air.

The large masses M were thus separated from the suspended masses m' by two superposed sheets of cardboard and a sheet of metal, which were clamped and sealed to the wood frame of Figure 1, a layer of air about 0/8 inch thickness, and the outer sheets of metal, forming part of the metal shield enclosing the entire device.

Both of the masses M, and the shield around the suspended masses, were insulated as before described. The large masses and the shield around the suspended masses were connected by means of large copper wires. Between the masses M, and the shield were sheets of glass, not shown in Figure 2.

In the work to be described, the air around the large masses and screen was electrified by a noiseless discharge from 800 pin points which were mounted in strips of metal hung upon insulated metal rods three feet from the large masses and screen. A sketch of this arrangement as shown in Figure 3. The sheets of metal which carried these pins were punched with small holes, through which the pins were inserted and the heads were then soldered to the sheets of metal, which were then hung upon the insulated rods by metal hooks. At one end this line of rods terminated in a disc of metal upon which 150 pins were mounted. Facing this disc was a duplicate, the points of the pins in the two discs being three or four inches apart. This last named disc was directly connected with one terminal of an influence machine in an adjoining room, the other terminal being grounded on a water pipe. There were no condensers attached to the machine, and the knobs were widely separated. There were no gaps in the line of conductors. The machine was enclosed in a glass case containing drying material, and it was driven by a single-phase motor. Placing the large masses in the position shown in Figure 3 at the time when the work to be described began, increased the scale reading by 0.40 cm.

Figure 3 ~

An illustration of the results obtained is shown Plate XLV. In each case the masses had been grounded during the preceding night. The scale was displaced in order that the two diagrams might be shown on the same plate, without interference. On the lower diagram the arrangement of apparatus was as shown in Figure 3. The hour of the day is laid off upon the horizontal axis. The scale reading in cm. is along the vertical axis. One mm represents an angle of 2.6 minutes of arc. The negative terminal was applied at 9:38 a.m. On the diagram the arrow indicates the time. At 10:12 a.m. the terminals were reversed, an operation which required a few seconds of time. At 11:30 the machine was disconnected. There was evidence shown in the drop in the reading at 11:20 that the reading would begin to decrease. The upper diagram of this plate shows results obtained on May 4. Here the positive terminal was first applied at 9:35  a.m. The terminals were reversed at 10:24 and the machine was stopped at 11 :20, the readings being continued to 12:05 p.m. In this work the conductors upon which the 800 pins were supported were directly connected with the large masses and shield.

When direct contact was made between the pin-conductors and the large masses, the changes took place more rapidly than when the air surrounding the masses was supercharged with negative corpuscles emitted from the pin points, or when the reverse action took place, this alone being depended upon to change the potential of the masses. The most interesting feature of this work is the complete elimination of the possibility that the apparent decrease in the attraction between these masses was due to the convection currents of air resulting from heat effects. Reversing the terminals would not reverse the heat effects.

The possibility that one terminal of the machine produced greater heat effects than the other, the deflecting effect being decreased when the terminal producing the lesser heating effect was applied is also eliminated. It matters not which terminal is first applied. The result is the same, and has been obtained many times.

During the afternoon of May 4 the operation represented in the upper curve of Plate XLV was repeated, the positive terminal being first applied. A result of precisely the same kind was obtained.

The upper curve of Plate XLV also means that the gravitational attraction between the masses at 9:35 a.m. had been decreased by about 110% at 10:10 a.m. Gravitational attraction had been decreased to zero, and had then been converted into a repulsion. An hour later it had regained its initial value. On the afternoon of June 1, 2:30 p.m., it was decided to change the electrical condition of the suspended masses. One of the end caps forming the outer metal shield of Figure 2 was removed. A hole which had been bored through the wood frame, and which had been closed by a rubber stopper, was opened. A glass tube was passed through the opening, about two centimeters beyond the inner surface of the wood frame. A copper wire to the end of which the head of a pin had been soldered, was passed through the tube, the point of the pin projecting slightly beyond the end of the tube.

The wire was about six inches in length. The apparatus was arranged as shown in Figure 3. The positive terminal of the machine was used in draining negative corpuscles from the air within the shield around the suspended masses. A slow change of 1.2 cm. or 12 scale divisions in the scale reading was produced. The terminal was disconnected when this deflection had been produced and the machine was stopped. The tube was removed, the end cap of metal was replaced and the large masses and shield and the pin-point conductors were grounded until the next day. The mean rending had not been appreciably changed.

At 10:25 a.m., June 2, readings were taken until 10:43 a.m. The suspended masses were at rest. The positive terminal was then applied. The result is shown in Plate XLVI. The arrangement of the apparatus was that shown in Figure 3. A sudden decrease in the attraction occurred. It was so sudden that forced vibrations were impressed upon the suspended masses. The vibrations were small, and only occasional readings of consecutive extremes were recorded. At 2:20 p.m. the terminals were reversed and at 2:32 p.m. direct contact of the pin-point conductors and the large masses and shield was made.

The attraction at once increased very rapidly. The absolute zero of potential was reached and passed in a less time than that of a semi-vibration. Forced vibrations were impressed upon the suspended masses as the attraction began to decrease. These vibrations were observed, and the extremes were read until 3:30 p.m. The masses were then being repelled by a force nearly twice as great as the initial gravitational attraction. Direct contact between the discharge points was removed, but the masses were not grounded. On Monday, June 4, at 9:20 a.m., the masses were vibrating over a very small arc (about one scale division). Readings were taken at some of the extremes of vibration, which were sufficient in number to show that the mean reading was constant until 11 a.m. These readings are represented in Plate XLVII. The masses were still repelling each other, with a force about 50 per cent greater than the initial attraction on the morning of June 2. This conclusion seemed beyond belief at the time but subsequent results on that day seemed to make it a necessary conclusion. At 11:03 a.m. the positive terminal was applied and direct contact between the large masses and the pin-point conductors of Figure 3 was made. The time is represented by the arrow marked +DC on Plate XLVII.

At once the attraction began to increase. The masses were swaying in the opposite direction at the time when contact was made. A maximum reading was obtained at 11:18 a.m. and the masses swayed in the opposite direction during the next 14 minutes. Forced vibrations were again impressed upon the suspended masses, but they were less violent in character than those at the close of the observations; represented in Plate XLVI. At 12 observations were discontinued until 12:48 p.m., when the reading showed only a slight decrease. At 1:00 p.m. the terminals were reversed and the direct contact was removed. The conditions then were as represented in Figure 3. At this time the apparent decrease in the initial attraction which existed at the beginning of the observations on June 2, was about 340 per cent. In other words the apparent repulsion was then more than twice the initial attraction. This conclusion seems to be fully justified by the amazing increase in the attraction which at once resulted. At 1:53 p.m. direct contact between the pin-point conductors and the shield and large masses was made by dropping a wire into position. It was removed at 2:02 p.m. Forced vibrations were again impressed upon the suspended masses. The machine was stopped at 2:19 p.m. and I was called away for an bour. A few readings taken between 3:12 and 3:22 p.m. shown at the close of Plate XLVII indicate that the attraction had then approached closely to the initial value on the morning of June 2.

It will of course be understood that no attempt has been made to secure results of precision in this work. The only aim has been to determine whether or not it would be justifiable to construct the much more expensive apparatus which will be required for such results. The suspended masses must be capable of being electrified independently and the enclosing walls must surround them in symmetrical form, so that their inductive action will not produce deflection of the surrounded masses. If they are suspended in highly rarefied air, it may be necessary to use a metal wire rather than a quartz fiber, which must then be attached to an insulated torsion beam. A modified form of the apparatus used by Boys will be required. The necessity for such a construction seems to be justified by the evidence already obtained, that if the potential of either of the attracting masses M and m' is zero absolute, gravitational attraction between them will not be affected by varying the potential of the other mass. The gravitation, constant as it has been determined by methods which made use of some form of the Mitchell-Cavendish apparatus, would have a maximum value when either or both of the masses had a potential of zero absolute.

Neglecting the inductive effect which electrified masses have upon each other, it is possible that the amended equation for gravitational attraction between them is:

It seems possible that the effect of the charges Q and Q' upon gravitational attraction between the masses m and m' may be a surface effect. If so the values of Q and Q' may be replaced by RV and R'V', where R and R' are the radii of the two masses and V and V' their potentials due to those charges.

The above equation may also be written:

Here it is assumed that the masses are so electrified as to diminish their normal attraction for each other by n per cent. From these two equations the values of m and m' being replaced by their values in terms of volume and density.

If this equation really represents the conditions imposed upon the masses, it appears that for any given decrease in gravitational attraction the potentials of the masses must be directly proportional to the surface areas of the masses. Small planets having high and perhaps varying potentials might not follow Newton's law. The value of n would be large and variable.

In the work represented in Plate XLVI, if we assume that when n was l00, the attraction between the masses being reduced to zero, the potential of the large masses was 30,000 volts, or 100 E.S.C.G.S. units, and that of the suspended masses was 10 volts or 1/30 E.S.C.G.S. unit, then the last equation would give for K':

K' = 165800 K

This result is based upon assumptions and estimates. One inference may be drawn from it. There is nothing here to indicate that the force whose action is represented by Newton's term, should not be the main factor in determining the motion of the masses in our planetary system.

The large masses represented in Figure 1 were replaced by boxes of metal, filled with loose cotton batting. They rested upon insulators. They were separated from the screen by sheets of glass, and were put in metallic contact ,vith it by means of copper wires. Precisely the same treatment was applied to this system as was given when the large masses were in place. No change in the position of the suspended masses could be detected.

The large masses being in position as before described, spring contact brushes were fastened to the blocks of wood upon which the large masses rested. They made contact with the large masses at points midway between the top and bottom of the spheres. A direct current of 20 amperes was sent through the two large masses. The axis of the line of flow was in one case practically coincident with the line through the centers of gravity of the two masses nearest to each other. The direction of flow was either from the outside contact, to the one nearest the screen, or the reverse, the direction of flow being reversible by means of a double switch. The screen was insulated from the two large spheres. No effect upon the suspended masses could be detected. If any effect was produced it was very small. The large masses were turned 90° in position, with a like result.

An alternating current of 20 amperes was applied. No effect could be detected when the masses were in the latter position. When the lines through the points of contact with the brushes with the large spheres was coincident practically with the line through the centers of gravity of the two masses nearest to each other, the gravitational attraction was quickly reduced to zero, and made negative. When the double switch was opened, so that the large masses were wholly separated from the source, and the masses were grounded it required between two and three hours for the large masses to recover from the shock which they had received. This has been repeated many times, with no discordant results. It may be that the parts of the large spheres which are most affected by the alternating current are those parts near the brushes. If there are heat effects, they tend to oppose the observed effect. Burning candles replacing the large masses cause a change in reading in the opposite direction from that of the alternating current, the glass plates being removed. This is due to convection currents within the screen.

The work here described has been done in a private laboratory in the second story of Eads Hall, now occupied by the physics department of Washington University.

My thanks are due to the Carnegie Institution of Washington for meeting the expense of this work.

Plate XLV: Variation in Gravitational Attraction

Plate XLVI: Variation in Gravitational Attraction [Not available]

Plate XLVII: Variation in Gravitational Attraction [Not available]

Trans. Acad. Sci. of St. Louis XXVII: 383-387 (March 2, 1920)

New Evidence of a Relation Between Gravitation & Eelctrical Action, & of Local Changes in the Electrical Potential of the Earth.

Francis E. Nipher

In the work to be here described, the apparatus used was a modified form of that used by Cavendish, as shown in the former paper, published by the Academy of Science of St. Louis, Vol. XXIII, pp. 183-185.

The wood frame was in this case covered with tin-foil, within and without. The sheet metal forming the sides of the shield were clamped to the wood frame, by bars of wood which were also covered with tin-foil. All joints were sealed with wax before the tin-foil was put in place.

The whole shield was then surrounded by two end caps of metal which meet at the middle or the shield and are scaled together by means of tin-foil. A layer of air was thus formed between the two metal shields surrounding the suspended masses. Either of these two metal shields was considered ample protection to prevent the suspended masses from being acted upon electrically by the large masses. The layer of air between the two shields was designed to diminish convection effects within the shield due to changes in the temperature of the room, and changes in the temperature of the air within the room were made as small as possible by cutting off all sources of artificial heat. It did not usually vary more than 1.5 degrees C. during the day. The temperature was determined by means of a thermometer placed near the large masses. The reading was by means of a telescope. The reading could be made accurately to tenths of a degree C and hundredths of a degree could be estimated with fair precision. The air within the shield was electrically charged by means of a wire armed with a pin which was thrust through the end of the shield about an inch above the level of the suspended masses, and was sealed in place. The inner end of the tube was drawn to a small diameter, being only large enough to admit the end of the pin. This could be withdrawn at any time and the outer end of the tube could be covered with a metal tube which was closed with a metal plug at its outer end.

Convection effects, due to changes in temperature, have been very carefully studied. When the masses have not been electrically charged for several days, the rise in the temperature of the room during the day caused a very slow increase in the scale reading which determined the position of the suspended masses. This change in position decreases the distance between the suspended masses and the large masses. When a door opening into the hallway was opened for four minutes this change is larger and more abrupt. When an outside window was opened, admitting cold air, a sudden decrease in the reading results.

The room containing the apparatus was always entered from an adjoining room, from which heat from the heating system was wholly cut off.

In order to decrease convection effects, the large masses and shield were covered on all sides with a pile of cotton batting, forming a layer of about 6 to 8 inches thickness. This was permissible by reason of the fact that the electric machine in the adjoining room was discarded as a source of electricity. It was replaced by the earth, which had been found to be equally effective, and which has a much greater capacity. The large masses and shield, and when necessary, the injection pin were connected by wire with a copper lightning rod on the outside of the building. This rod formed the ground connection for a steel tower used for wireless. Its top was 100 feet above the ground. This tower is mounted upon the roof of the physics building, the walls of which are red granite. The room containing the apparatus is on the second floor of this building, and below the tower.

Twelve copper wires about ten feet in length were soldered to the lower part of the lightning rod, and spread over the ground, their ends being injected a few inches into the soil. The wire leading from the masses within the building to the rod was also soldered to it. Connected with this wire within the room containing the gravitating masses were metal rods surrounding the apparatus which were hung sheets of metal to which were attached about one thousand pins. Small holes were punched through the metal, the pins were inserted, and the heads were soldered to the metal, This was intended as a means to put all of the air in the room in an electrical condition as near uniform as possible.

With such an apparatus a determination of the gravitation constant would be utterly impossible, the position of the suspended masses changes from day to day and from night to day by greater amounts than was at any time possible when the plate glass machine was used for the electrification of the masses. Their position depends upon the weather and upon the moisture in the surface of the earth. The changes were often greater than was ever caused by the removal or replacing of the large masses. Results obtained on December 12 last are alone sufficient to establish the fact that enormous local changes in the earth's potential are constantly occurring, and that these changes produce variations in gravitational attraction between the large masses and the suspended masses.

On December 5 and 6 over an inch of rain and sleet fell, and on December 8 and 9 there was a light fall of sleet. The minimum temperature gradually fell from 28° on the 5th to 1° on the 10th. The ground was covered with a thin layer of ice and snow on the 12th. On that day the morning temperature was 20° but rose to 56°. The ground around the lightning rod between the building and a walk about 12 feet from the building was very dry, having been shielded by the building. During the forenoon the large masses and the injection pin for electrification of the air within the shield were connected with the lightning rod. Between 8:50 a.m. and 11:45 p.m. the scale reading decreased very slightly but with no vibrations. The temperature of the air around the shield increased by 1.5° C. The injection pin was then withdrawn and the glass tube was covered with the metal cap. Vibrations of the suspended masses at once began. The scale reading varied through about three divisions of the scale. This amplitude had diminished to about two divisions of the scale at 1:20 p.m. The time of a complete vibration was about 9 minutes. The frozen ground outside of the walk was then covered with a thin layer of water. Eight buckets of water were splashed over the ground around the lightning rod, covering the area over which the copper wires were spread, this wet area thus formed being finally connected with the wet ground beyond the walk. The scale reading abruptly diminished during the next three vibrations. The change in the average reading was about 80% of the change formerly produced by the removal of the large masses to a position of no deviation in the position of the suspended masses.

This determination of the deviation, due to the large masses, was obtained before electrification of the mass was begun. They were, however, then above the surface of the earth, and subject to the inductive action of the atmosphere.

The results described in this paper indicate that the disturbances here discussed would be greatest if the work were done on a barren island, in a building above the level of the surrounding water. It is under such conditions that the phenomenon known as St. Elmo's fire is commonly observed. On land each blade of grass and the leaves of trees have a function similar to that of the masts of ships provided with lightning protection. They are individually less effective, but they are far more numerous.

In order to eliminate these disturbing effects the work should be done in a room below the surface of the earth the walls, ceiling and floor being of metal. Insulate copper wires within copper tubes should be connected with the masses. Those connected with the suspended masses should terminate in a cup of mercury. A flexible chain of metal attached to the middle of the bar carrying the suspended masses, should be provided at its lower end with a fine platinum wire, making contact with the mercury surface. These protected copper wires should be grounded in a well of water. The water in this well must be protected from any inductive action of the atmosphere.