[NM023095A], Technical Note, Arthur Edwin Kennelly, April 1889



[this is daily record of]; according to Time sheets and book of experiment numbers these are all related to Etheric Force] Experiments on Electric Oscillations April 1st Monday Used small induction coil for preliminary experiments. Itslength is 18 cms its diam 8.5 The res. Of its primary 0.14 its secondary 7500w. Actuated the primary and its automatic vibrator with the 6 volt dynamo. Connected the secondary terminal to an air condenser formed of two insulated brass disks each 17.4 cms in diam and sepaated by about 0.5 of air space. Next took a spark micrometer whose electrodes are tapering points and joined them bya wire of black covered copper some 160 cms long. Twisted this covered wire round the rods of the air condenser. Ascertained that the sparks passed easily between the points of the micrometer when the distance was perhaps 0.025 cms.##April 2nd Tuesday Repated this experiment with the large induction coil whose length is 51 cms and diam 20. Its primary res is 0.025w and its secondary 2100w. Activated it by a mercury contact breaker using the 110 volt circuit and some 10 to 20 ohms of resistance. Tried to obtain sparks fom the micrometer when shortcircuited as before, but without success. Many combinations were tried but een when considderable self induction was interposed I the shortcircuiting wire, the spark invariable failed to appear a the micrometer nor could any p.d. be detectyed by the tongue.##April 3rd Wednesday Tried experiment again with small coil. When its secondary terminals were connected direct to the terminals of the mircometer no device succeeded in obtaining sparks or p.d. evidences so soon as the micrometer was shortcircited by a wire of any convenient length. So soon however as the micrometer wires were insulated and laid upon the terminals of het air condenser, sparks were immediately visible, and continued to be distinguished even when shortcircuiting was effected through thick copper rod.They were however very faint and could noly be discerned by scraching the micrometer points. On making two coild in air round the condenser rods with the micrometer wires their effects were still visisble so that conduction under these circumstances were probably out of the question. By charging the exterior of two leyden jars direct from the secondary after shortcircuiting were distinctly increased.##Tried the same experiment with the large coil and succeeded in obtaining distinct sparks across an air break of very short length (not permitting a knife edge to intervene) when shortcircuit made with a wire and a 1/4" copper rod pressed above the micrometer pillars.##It was observed that when sparks were thus passing freely during this experiment between the micromter points short circuited by a bare wire 0.1 diam and some 10 long the interposition of an opaque substance such as paper or metal between the micrometer and jars caused them to cease, reappearing however on the removal of the substance. The same effect was produced by interposing a sheet of transparent glass but occasionally a spark would be observed in this case. Various colored glasses were tried and they all obstructed apparently the passage of the spark. Quartz however in the form of a thin section @ 45 [degree sign] to the axis seemed to offer very little obbstruction, but another section parallel to the axis seemed to offer some obstruction less than glass.##The micrometer was then fixed in a convenient dark box admitting a ray of light through a variable aperture to fall upon the points shortcircuited as above. By observing through an eyepiece on the same principle as the eteroscope, it was evident that rays passing through a metal aperture 0.5 in diam from the spark between the jars had influence on the passage of the apark at the micrometer when the intervening distance was 80cms. The closing of this aperture by a side screw instantly stopped the spark as did also the interposition of different kinds of glass, selenite, talc, mica, iceland spar and quartz section parallel to the axis. Some of these substances acted in different degrees, plain glass and talc being perhaps the most effective. An observer watching the sparks could tell the moment one of these substances divided the line between the two. It was noticed that whenever the spark occurrred, the tongue applied to the points could detect the electrical disturbance.##Tried whether an incandescent lamp could by its light restore the micromoeter sparks when this was extinguised by some opaque screen, but without success. On removing the screen the passage of the incandescent lamp across the spark connecting line extinguised that at the micrometer. Next tried an independent inductio coil spark with and without a leyden jar and tried to effect the reproduction of the extinguished micrometer spark by its aid without success.##Removed the micrometer and dark box to a distance of about 4 meters from the leyden jars spanning the distance by two cotton covered wires 0.1 diam. At this distance the mutual lrelation between the sparks was scarcely if at all evident.##Brought the micrometer back to its previous range and tried to substitute an arc light for the jar spark in restoring the lost micromtere spark but at a distance of some 2 meters between arc and micrometer this was not successful.##The only substances found which permitted the mutual action to pass unchecked were quartz section at 45 [degree sign] to axis and rock salt, the latter even 2 cms thick.##April 4th Thursday Insterted a powerful solenoid of 14 layers betweent eh two sparks so that the mutual influence took place through its axis. Excited this powerfully by an alternating current making some 230 complete periods per second. No effect from this alternating magnetic field could be discerned upon the sparking.##Made a small rock salt prism and tired to find at what particular angle of prism rotation the sparking at the micrometer was affected when all the light was cut off except through the rock salt. The prism was however too imperfect to be able to arrive at any conclusion but it certainly did interrupt the sparking contrary to the behavior of plane sections.##Arranged a plane mirror about 5 cms in diam in such a manner as to deflect the jar shock upon the micrometer points even when the direct spark was cut off from all influence. Unmistakeable evidence of the influence being exerted by the relfected ray, though it may have been a little less decided##Took a slip of mmicroscope=glass and 0.013" = 0.033 cms thick and found that even this thickness effectually stopped the influence, the mircometer sprk ceasing on the insertion of the polised slip in the line of action.##April 5h Friday Repeated last experiment with glass screens 0.005" = 0.011 cms thick Also tried to ascertain by thin slips of this glass arranged in different positions whether the effect observed was due to an influence on the dielectric or on the electrodes themselves. It seems from these trials that if the electrodes are screened, the influence is cut off but if the air space is screened, and the points left within view of the main spark the micrometer spark continues. On removing the shortcircuiting wire and replacing it by a seounder whose magnetic circuit was forcibly closed so that it possessed large self induction, the spark length was increased to 0.25 cm. At one time it seemed that the screenig of one point interrupted the spark more than the screening ofhte other, the difference reversing with the reversal of the wires from the jars, but other experiments did not always show this. Little or no influence could be obtained by reflection from a thick silvered glass mirror, in restoring the spark, but a simple sheet of steel seemed to reflect the influence. A small Bunsen burner flame was thrown round the secondary points after the spark had been interrupted by a screen but without success unless the flame were very close above or underneath them.##Took a second parabolic mirror similar to the above, and placed them facing one another at opposite ends of the galvanometer room some 23 metres apart. In the focus of one was set the primary spark, and at the forcus ofhte other the micrometer point, the distrance being spanned by two g.p. [Siemens?] wires rather in excess of length. The micrometer air apace was about 0.025 cm and the sounder formed the short circuit. The influence was plainly discernible but was not so complete as at short range. This may have been partly due to the variation of the primary spark from the focus. It appeared as though time were here required to stimulate the reproduction of the spark on removing a screen from the line of mirror action, just in the way a spring takes time to respond by increasing amplitude to a continous stimulus before a maximum is attained.##[CONT APR. 6]







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[NM023095A], Technical Note, Arthur Edwin Kennelly, April 1889

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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University