Nikola Tesla: Colorado Springs Notes, 1899-1900 Page 363

and

P = !$ {3000 \over \sqrt{214}} !$ = !$ {3000 \over 14.63} !$ = 205 volts only!

We see that with such an extreme frequency the voltage of the ordinary incandescent lamp supply circuit would be sufficient to pass enough current through the lamp. Under the above conditions the current would be

I = ECω = !$ {{205 \times 500 \times 2 \pi \times 214 \times 10^{4}} \over {9 \times 10^{11}}} !$ = 1.5313 amp. approx.

In the experiment illustrated in Plate XXIX. it will be seen that while the inductance of the "extra coil" was greatly reduced by shunting the same with the lamp, yet the coil was still effective, as is evidenced from the streamers visible on the wire leading from the lower end of the coil to the lamp, which is the wire marked w' in the corresponding diagram.

Passing now to the experiment illustrated in plate designated number XXX., the connections in this case are shown in diagram below.

Here the lamp was lighted only by induction from the primary circuit, the ground connection being omitted. In this case the capacity was 3 tanks on each side or 1 1/2 tanks total = 54 bottles = 54 x 0.0009 = 0.0486 mfd and the inductance 41,000 + 3 turns of the regulating coil = 41,000 + 10,000 = 51,000 cm, or !$ {51 \over 10^{6}} !$ H approx. This gives

!$ {T_{p} = {{2 \pi \over 10^{3}} \sqrt{0.0486 \times {51 \over 10^{6}}}} = {{2 \pi \times 1.37} \over 10^{6}} = {8.6 \over 10^{6}}} !$

and n = 116,300 approx.

Note: Here the excitation of the primary circuit had to be strong, showing that the inductive action was feeble in comparison with action through the ground. The tuning was not quite exact in all these experiments described as time was pressing. In the last experiment n ought to have been just twice the value found in case XXVIII.

XXXI. This is a Roentgen photograph taken in a peculiar manner. It so happened that a workman who thought he had injured one of his figures desired to have a photograph taken and a tube was inserted between the ground plate and a coil, as illustrated in the diagram under XXII. It was doubtful whether the tube could be energized in this manner but the experiment proved that it could and a photograph was taken by flashing the tube a few times, after the adjustment of the vibration in the primary and excited circuit was completed and resonating condition in the latter secured. Nothing peculiarly interesting beyond the manner of taking the photograph was contemplated, nevertheless an inspection revealed that this photograph, probably owing to the high economy of the oscillating systems used in these experiments, or possibly on account of the frequency, was distinctly different from many others taken with different apparatus. The tube was not strongly excited and the exposure was scarcely more than a few seconds, yet much of detail was recorded. It is quite curious how plainly the nails are shown, much as in an ordinary photograph.

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