Nikola Tesla: Colorado Springs Notes, 1899-1900 Page 319

and n = 70,000 approx. The coil connected in series with the extra coil was wound on a drum used before. In one case this drum was wound with wire No. 10, 346 turns and in this case it had an inductance of 6,040,000 cm. The new “extra coil" latest having 18,000,000 cm approximately, the total inductance may be placed closely enough at 18,000,000 + $! {\left({283 \over 346}\right)^{2}} $! x 6,000,000 cm, the coil in series with the extra coil here used having 283 turns. This gives inductance total 18,000,000 + 4,000,000 approx. = 22,000,000 cm. Now if the latter coil of 283 turns would have been omitted then the system would have vibrated quicker in proportion

$! {\sqrt{{22 \times 10^{6}} \over {18 \times 10^{6}}}} $! = $! {\sqrt{22 \over 18}} $! = $! {\sqrt{11} \over 3} $! = 1.106

times or since n in the first case was = 78,500, the extra coil alone will vibrate 1.106 x 78,500 = 86,800 approx. If the inductance in primary be left the same as in the first case then the number of bottles will be reduced by a ratio of $! {18 \over 22} $! = $! {9 \over 11} $! or instead of 90 bottles total we shall want $! {{90 \times 9} \over 11} $! = $! {810 \over 11} $! = 74 bottles or nearly so; this means 148 bottles on each side or about 4 tanks. This is only an approximate estimate for first guidance. Perhaps the reaction of the secondary is somewhat overestimated in this case as it was not resonating in these tests or near the resonating condition.

* With figures taken from second test the results are very nearly the same.

Colorado Springs

Dec. 15, 1899

List, for future reference, of some coils used in the experiments up to present.

* Exp. resonance

319