Nikola Tesla Books
Books written by or about Nikola Tesla
Colorado Springs
Oct. 22, 1899
One of the upper terminals of the condenser (+) usually connected to the ground was joined to the lower end of the coil of 689 turns, the upper end remaining free. The ground was in this case omitted for the purpose of securing a higher initial excitation. The maximum rise was ascertained by an adjustable spark gap as shown. The results of the tests are given in the table below:
| Capacity in primary circuit expressed by the number of bottles used | Self-induct. of primary or exciting circuit Turns in regul. coil + connections | Spark length on terminals of the coil | Observation relating to spark |
|---|---|---|---|
| $! {{(8 \times 36) - 2} \over 2} $! | 1.125 + connections | 4 1/8 inch | The spark was continually increasing and the excitation was reduced as the capacity was getting smaller |
| $! {{(7 \times 36) - 2} \over 2} $! | 2.375 + " | 4 3/4 " | |
| $! {{(6 \times 36) - 2} \over 2} $! | 3.625 + " | 5 5/8 " | |
| $! {{(5 \times 36) - 2} \over 2} $! | 4.75 + " | 5 3/4 " | |
| $! {{(4 \times 36) - 2} \over 2} $! | 6.25 + " | 5 7/8 " | reduced |
| $! {{(3 \times 36) - 2} \over 2} $! | 8.25 + " | 6 1/4 " | still more |
| $! {{(2 \times 36) - 2} \over 2} $! | 11.625 + " | 7 " | still more |
| $! {{(1 \times 36) - 2} \over 2} $! | 22 + " | 9 " | still more |
| appr. $! {31 \over 2} $! | 24 + " | about same |
The spark was getting longer because the efficiency of the exciting circuit was increased, as the inductance of this circuit was increased and capacity diminished. There were smaller frictional losses and after each break the system vibrated longer and excited the coil better.
233
October 22
He applies the same measurement method as on the previous day and finds a number of values for the primary inductance and capacitance (for the purpose of determination of the inductance of the connections). The oscillator's frequency is determined on the basis of a maximum spark at the coil's terminals with 689 turns (please see the figure).
In continuing the measurements he adds a high power transformer primary coil in the oscillator's arcing circuit. He uses only some measurement data for finding the inductance of connections.
