Nikola Tesla Books
Books written by or about Nikola Tesla
Colorado Springs
Aug. 28, 1899
Experiments with oscillator, secondary 29 t. in series with extra coil before used (160 t) were continued today and showed the following:
Capacity in primary being from 5 2/3 - 8 tanks on each side, varied to observe shifting of nodal point, play on arresters and behaviour of streamers and spark discharges.
A half circle of bare wire on top of extra coil was left and in addition a larger half circle of bare copper wire (No. 14) was supported on wooden strips 4 feet below the former half circle. Both the bare wires were connected to the free end of an extra spool. The lower half circle was 9 1/2 feet away from a circle of the same bare wire which was supported on oscillator secondary frame and formed the terminal of the secondary. Abundant sparks and streamers were produced. The play on arresters was also observed at each throw of the switch. The rain and lightning were just beginning. Magnificent intense white light witnessed below Pikeâs Peak, something very unusual. It resembled a white hot silver furnace. The lightning on the mountains was very frequent and the discharges of unusual brilliancy. Twice a curious phenomenon was noted. Lightning striking in one part of the mountains from cloud to earth, there was seen in another part a few miles away from a high peak a lightning discharge which to all appearances came from the peak to the cloud. The discharge was much thicker at the root and branched out towards the sky spattering itself in many branches and disappearing in fine streams. The astonishing phenomenon was witnessed a second time and subsequently, though there was much uncertainty about the direction in the latter cases; a few times a similar discharge took place from other peaks. Is it possible for a discharge to go from Earth to cloud? As far as the visual impression is concerned there can be no doubt. The discharge in all cases followed a preceding lightning discharge in another region, and apparently from cloud to earth. Perhaps it can be the effect of an intense vibration started by the first discharge which results in another discharge towards an oppositely charged cloud. The clouds were unusual in configuration and grouping. A large portion of the sky was quite clear. The wind at times was very strong. An instrument by its constant play indicated strong electrical disturbances through the earth, even when there was no display of lightning as far as could be seen or heard.
After some time the experiments were continued and presently it was observed that the usual sparking on the arresters was no longer to be seen when the switch was thrown in. The only change made was to take the upper half circle off leaving only the lower one. This gave a smaller streamer surface and consequently longer streamers. The display was fine. In order to see whether the upper half circle of bare wire was responsible for sparks on arresters the wire was replaced but still no result. Then it was thought that other causes for the sparks not appearing were responsible and everything that could have the slightest bearing upon this was investigated. Still nothing was arrived at. The sparks did not appear no matter what change was made in the adjustment of the vibratory circuits. What could be the cause? The only explanation at present is that the roof was rendered slightly conducting (although there was little rain in this locality) and that this produced the change. Important to find out. Observation: The lightning lighted two houses about two miles away.
165
August 28
Tesla's idea of the Earth as a perfectly conducting sphere lead him to a mistaken hypothesis about the general behaviour of the electromagnetic field around the grounding of the transmitter. What he expected at frequencies of the order of 10 kHz in fact occurs at much lower frequencies(72), at which, as far as can be seen from his notes, he did not work in Colorado Springs. He correctly observed that the decisive factor determining whether predominantly waves of the âHertzian typeâ or the waves which he thought to be propagated through the earth (in fact waves in the spherical condenser constituted by the Earth and the ionosphere) would be excited was the excitation of the âEarthâ. Tesla was also certainly in error when he tried to make generalizations concerning the wave frequency, and in his conviction that he needed extremely high voltages to âcreateâ the second conductor for a system of wireless power transmission. He could not know that this conductor already existed permitting transmission at very low loss of very low frequency waves, and that it would not matter whether the energy transmitted was high or low.
August 28
He continues with experiments with transmitter with small changes to secondary circuit. He changes the primary frequency for the purpose of changing the node points (for the explanation, see patent(42)), sparking on lightning protector and generally sparks and current lines. In the meantime, a change of weather occurred and Tesla devoted himself to electrical discharge observations and the receiver's reaction to the electrical discharges. Continuing the experiment with the oscillator, it was shown that after a disturbance, some operating conditions were changed. When the oscillator was switched on, the sparks on lightning protector didn't occur. His first assumption regarding the influence of a wet roof proved wrong the next day. The sparks didn't appear any more, although the weather was nice, and the humidity evaporated from the roof.
