Nikola Tesla Books
Books written by or about Nikola Tesla
Coil L alone only with spark wires, no vertical wire:
| Capacity total in primary circuit | Total primary self-induction turns of regulating coil + conn. | Height of ball from center to ground | Analyzing spark at s |
|---|---|---|---|
| !$ {{142 \over 2} = 71} !$ bottles | 9 7/8 turns + connections | no ball, no wire | 3 3/4" |
Coil with vertical wire and spark wires:
| !$ {{142 \over 2} = 71} !$ bottles | 18 3/8 turns + connect. | no ball | 3 1/4" |
Coil with ball, vertical wire and spark wires:
| !$ {{142 \over 2} = 71} !$ bottles | 19 1/2 turns + conn. | 9 feet 5" | 4" |
| " " | 20 3/8 " + " | 33' 9" | 4 3/8" |
| " " | 21 1/4 " + " | 58' 9" | 4 1/8" |
Owing to the construction of the coil L which, as before stated, aimed at sharp tuning it was easy to detect a variation of 1/16 of one turn of the regulating primary coil R.
It was desirable to take some readings with all the bottles in and the results were nearly the same and could still be read off with fair exactness, although the variation on the regulating coil R was reduced to one half, the capacity in the primary being just double that used in the experiments the results of which were just given.
The readings with all the condensers were as follows:
| Capacity in primary total | Total self-induction in primary turns of reg. coil + connections | Height of ball from center to ground | Spark on terminals of L |
|---|---|---|---|
| 286 bottles | 10 1/8 + conn. | 9' 5" | 4 1/4" |
| " | 10 9/16+ " | 33' 9" | 4 1/2" |
| " | 11 + " | 58' 9" | 4 3/4" |
Note to above experiments:
The vibration of the coil L with vertical wire and spark wires was found to be in resonance with the primary in another series of observations with
| 142 bottles | 18 3/4 turns + connections |
238
October 23
In further experiments to determine change of capacity with height Tesla uses an apparatus similar to that of the previous day. As far as can be judged, the coupling between the oscillator and the measuring circuit (coil with elevated ball) was loose. The lower terminal of the latter was connected with a condenser of the oscillator circuit. Loose coupling is evidenced by the relatively weak sparks obtained across the air gap of coil L (see figure) in comparison with the sparks obtained when a similar coil was excited by the secondary of the oscillator, tightly coupled to the primary (as for example on October 4th and 5th). Under these conditions the spark oscillator would generate a single frequency, determined by the parameters of the oscillatory circuit with the spark gap.
