Nikola Tesla Books
Books written by or about Nikola Tesla
whereas before it was found to be so with 18 3/8 turns. When the different value 18 3/4 turns was observed the wind was blowing hard and it would seem as if this would have had the effect of increasing the apparent capacity of the aerial vertical conductor. This is to be followed up.
The experiments seemed to demonstrate clearly that the augmentation of the capacity as the ball was elevated was in a simple proportion to the height, for at the middle position the value found was very nearly the arithmetic mean of the values in the extreme positions.
Colorado Springs
Oct. 24, 1899
Tests continued on the effect of elevation upon the capacity of a body connected to earth.
The same coil was used as in the tests just before recorded, but the ball of 18" diam. was substituted for by one of 30" diam.
These readings were in all probability closer as an improvement in the procedure was made.
The results were as follows:
First set of readings.
| Capacity in primary circuit | Self-inductance of primary: Turns of reg. coil + connections | Height of ball above ground from center | Analyzing spark on terminals of excited coil | |
|---|---|---|---|---|
| Bottles total | mfd. | |||
| !$ {{(8 \times 36) - 2} \over 2} !$ = 143 | = 0.1287 | 10 3/8 + connections | 9' 11" | 4 1/2" |
| !$ {{(8 \times 36) - 2} \over 2} !$ = 143 | = 0.1287 | 10 3/4 + " | 34' 3" | 4 3/4" |
| !$ {{(8 \times 36) - 2} \over 2} !$ = 143 | = 0.1287 | 11 1/8 + " | 58' 6" | 5 1/8" |
Second set of readings. Capacity reduced in primary to get greater variation on regul. coil.
| Capacity in primary circuit | Self-inductance of primary: Turns of reg. coil + connections | Height of ball above ground from center | Analyzing spark on terminals of excited coil | |
|---|---|---|---|---|
| Bottles total | mfd. | |||
| !$ {{(4 \times 36) - 2} \over 2} !$ = 71 | = 0.0639 | 19 3/4 + " | 19' 11" | 4 3/8" |
239
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.
