Nikola Tesla Books
Books written by or about Nikola Tesla
spark wire was taken off and ball with a rubber covered wire No. 10 specially prepared left alone, streamers formed on top of ball, but little as the wind was blowing. The ball being disconnected and rubber wire alone left, the streamers were very fierce reacting sometimes 16 - 18 feet. Best results were with 6 turns in coil in the last experiments.
A more careful tuning of extra coil without ball, only rubber covered wire or cord No. 10 (which was referred to before), the tip of cable being brought out about 2 feet and inclined to horizontal about 45°. This wire to prevent streamers was specially made and was covered with rubber. Composition Habirshaw, 40% pure Para. The tuning of the coil alone with the self-induction coil specially wound in series, gave:
| Capacity of primary | Turns in self-ind. regulating coil |
|---|---|
| 8 tanks on each side | 6 1/2 |
The coil used in series with the extra coil was one especially adjusted so as to give the same vibration to the system as when the extra coil was used alone and with ball on top at highest point. The coil has 160 turns and is wound on a drum 2 feet in diam. With wire No. 10, same as used in the secondary and extra coil.
Now the secondary with a ball on the end and elevated at a height of 2.66 feet from the ground gave also exactly, with 8 tanks in primary on each side and 6 1/2 turns in regulating coil, maximum effect. When the two were connected in series the display was magnificent, sparks flying to the ground a distance of over 16 feet. Their curved paths stretched out would be certainly 24 feet long. This was not the maximum of the power of the apparatus as the spark in the primary could have been still lengthened without difficulty.
Colorado Springs
Oct. 8, 1899
Experimental data in connection with tuning of extra coil and secondary as recorded yesterday.
| Capacity on each side in primary circuit | Turns in self-ind. Regulating coil | With ball 38.1 centim. on free end of secondary, the ball being 2.66 feet from a grounded zinc plate, the both had exactly the same period. |
|---|---|---|
| 8 tanks | 6.5 - 7 | |
Now the length of wire in the secondary was 803 meters, namely 17 turns each of a diameter of 15 meters.
213
October 7-8
He adjusts the "additional coil" with the intention of adjusting to the same resonant frequencies of the secondary circuit and the new coil. Coil resonant frequency is adjusted by the variation of the metal globe position which is connected to the coils. When he achieves the longer sparks on the "additional coil"; he considers that the coil is in resonance but he does not say how the "additional coil" was connected at this test. From further tests it could be seen that he connected the "additional coil" to the open secondary terminal and he continued experiments with a system of free resonant circuits. By repeated regulating coil inductance adjustments he achieved better oscillator operation and he obtained the current streamers of approximately 5 meters in length. When he removed the sphere, he put on one special coil in order to maintain the same resonant condition in the oscillator. As he did in the past, Tesla determines the oscillator wavelength according to the primary circuit (see for instance June 20). The quarter wavelength he compares with the total secondary wire length, special coil and additional coil (when there are no other coils, than just the secondary coil, he considers that the wire length in the secondary has to amount to a quarter wavelength). Because there is no complete agreement, it is thought that this could eliminate due to errors at measurement of the inductance capacitance and length.
