Colorado Springs Notes - September 1-30, 1899

The following items, partly worked out, omitted for want of time:

  • Sept. 9. Experiments to be made with st. waves. Exact distance measured to point from ground plate 1938 ft.

  • Sept. 10. Completed text on ways of producing electric oscillations for wireless telephoning etc. by

    • a) insulation impairment

    • b) change of pressure

    • c) condenser shunt.


  • Sept. 30. Completed text on

    • a) gass battery

    • b) voltameter as detector


  • From 1—30, Sept. Method of increasing magnifying factor of res. circuits by cooling.





Colorado Springs
Sept. 1, 1899

Various ways of connecting instruments on receiving station experimented with and considered as to their merits:

Diagram 1. illustrates one of the earlier dispositions involving the principle, before described, of exciting by means of energy stored in the condenser. This principle has proved itself highly effective as it secures self-excitation and great magnification of an initial feeble effect.


In Fig. 1 the defect is that no initial excitation of the condenser is provided for, which makes it difficult to employ a sensitive device of very high resistance which, for other reasons, is desirable. This fault is overcome in Fig. 2. by providing an additional battery B{ for charging initially the condenser and thereby exciting device a to the point of breaking down.


Still in the latter diagram there is the inconvenience that the relay is traversed by a pulsating current during the time when device a is not excited.

The improvement illustrated in Diagram 3. does away with this drawback and this makes it possible to adjust the relay much better. Still the relay by its self-induction is apt to interfere with the vibration of the tuned secondary s. This consideration led to the modification illustrated in Diagram 4.

In this case the battery was placed either near sensitive device a, as shown, or in series with the other end of secondary s and the rest of the apparatus.

To work best, however, it was recognized, that: there should be no capacity to speak of on the free end of the secondary which is connected to the sensitive device, and on the other end of the sensitive device there should be as much capacity as practicable. Various other considerations finally led to the adoption of the connection shown in Fig. 5 as the best suited so far.

In this plan all the advantages so far aimed at are successfully realized. The secondary is free on one end towards device a and the potential rise can freely take place; the earth and air connections are both very advantageously situated; the condenser is excited exactly to the degree desired by adjusting resistance r. The vibration of the secondary is not sensibly affected by attaching the air line and capacity C, and the current through the relay is made small by opposing batteries B and B1.

Colorado Springs
Sept. 2, 1899

The plan of connections of the receiving apparatus, which was last described, was modified as shown in the present diagram. The battery B1 instead of being in branch including resistance r was included in the other branch circuit containing the condenser. Furthermore the batteries B and B1 were disposed in a number of ways and graduated with reference to each other to study the best conditions of working with the plan.


The device a was here chiefly strained through the induced currents in J .the strength of these being graduated by adjusting resistance r. Therefore the strain by the batteries themselves was insignificant.

Now these batteries were connected either so as to add together in charging the condenser when device a was diminished in resistance, or they were made to oppose each other. In the former case a small diminution of the resistance of a tended to produce a change in the same sense and the apparatus possessed the feature of self-excitation, while in the latter instance when device fell in resistance, the condenser charge was diminished and the excitation ceased automatically.


This secured small current through the sensitive device. Any condition could however be readily secured graduating, the batteries.

Colorado Springs
Sept. 3, 1899

Experiments were resumed with oscillator the connection being as illustrated in diagram. The extra coil and secondary were both connected to ground and on top of each a bail was placed of 38 cm. capacity. On extra coil, to facilitate the pumping of the spark and thereby enable the balls to be placed at great distance, a wire was fastened to the ball.


The spark gap being about 8 feet. As both oscillator secondary and extra coil vibrated the same period but were displaced in phase sparks passed readily and the vibration was that due to each separately, the harmonics being practically prevented to pass to earth.

An experimental coil was then fastened to the water pipe with one end and the adjustment for the same period was made. The coil was so placed as to exclude any inductive effect from the vibrating system so that the vibration in the coil was due only to that transmitted through the water pipe. The wire on the coil was previously wound upon a drum approximately 25 1/4 inches in diameter, there being 516 turns of wire No. 21, res. 45 ohms all wound in a single layer.


This coil gave on the free end — with induction from vibrating system aiding the vibration — a spark of 3/4"; with the induction eliminated the spark was fully 3/8" long. The spark on the water pipe itself was scarcely visible, say 1/64" long, so that the coil increased the pressure many times.

Now it was of importance to increase the magnifying factor Lp/R and for the purpose of investigating the best conditions the same wire was wound on a form 22 1 /2" diam., 1" wide, 1 1 /2" deep. 18 layers were made there being 28 turns in each.


The self-induction was now nearly 20 times greater, and as the resistance was the same Lp/R was to be much greater. It was feared though that the effect of distributed capacity which was largely increased would be detrimental to the rise of potential on the end. This proved to be the case so that it appears again imperative to overcome also in the receiving circuit the distributed capacity. Various ways are now to be experimented upon with this object in view.

Colorado Springs
Sept. 4, 1899

Experimental coil wound on frame made of bicycle hoop 25 1/4" diam., 16 layers, 28 turns in each, 448 turns total, self-induction about 1 /2 henry. This coil was wound very close to study effect of distributed capacity. It was connected for purposes of tuning to water pipe on one end the other being left free. From free end and water pipe short wires were run to a spark gap.


The sparking distance was observed from free end to body of experimenter, next from water-main to body, next between the two wires and finally with body of experimenter connected to free end, the spark between the same points. As it was sure that the vibration of coil was too slow for the impressed vibration of approximately 50,000, wire was gradually taken off.

Indications up to present confirm detrimental effect of capacity. A coil was now added in series. This coil was one used often in New York and was wound on a drum 30" diam. There were about 150 turns total length of wire 1125 feet.


To this added the 266 turns of experimental coil giving length of 6.5 feet per turn made length 2100 feet for exp. coil or total 3225 feet. This was very near quarter wave length as it ought to be. Now results were

To observe better the end of coil which was before connected to earth (or water pipe) was now connected to a wire run from one turn of secondary, that is from the turn which was nearest to earth connection of secondary.

The connection was in the previous experiments as illustrated in one, then it was changed to the connection shown in 2. Nothing was, in principle, changed by this connection, only a higher e.m.f. (initial) was obtained and the tuning was made easier. This I have found to be an excellent way to adopt in tuning coils. The results were as follows:

The general conclusions already arrived at before were still further confirmed by-these experiments.

They were:

1) distributed capacity must be done away with at any price;

2) the wire should have one quarter of wave length;

3) the last plan of tuning is the best;

4) harmonics appear prominently even under the conditions of these experiments (in the experimental coil the greatest spark between both ends of the coil was obtained when the wire was 200 feet long, this was just 1/16 of the length of secondary);

5) it is most important to tune secondary and extra coil so that they are of the same period exactly, to avoid beats.

Colorado Springs
Sept. 5, 1899

Experimental coil freshly wound on old drum 4 ft. high. Wire No. 18 and a small part of No. 20 covered with wax.

Plan of connections:

The coil had nearly 1/4 wave length and the response was at once good, a 6" spark being obtained from the free end, also between both ends of coil. The spark would have been probably longer but this was the limit to which the gap could be adjusted.

Measuring carefully the spark length to body of experimenter it was found that from the oscillator end (connection being made to 3d turn) the spark was 1 1/8" long, while from the free end of the coil the spark was 5" long giving more than 4 times the former value.

As it was thought that the body of experimenter was of too large a capacity and affected therefore the vibration of the experimental coil — diminishing the potential, while it did not sensibly affect the powerful oscillator
potential - a ball was fastened to an insulating stand and spark length tried in this way. With a ball of 4" diam. the spark from the oscillator end was 1 /2" while from the free end of the exp. coil it was A".


A still smaller capacity was now used in the belief that perhaps the 4" ball was too large but the experiments showed a contrary result. It was thought that the wave length being estimated from that of the oscillator and extra coil must be longer than that of the wire on experimental coil. This led to consideration of certain advantages of long waves allowing a great length of wire to be wound up on the experimental coil, this in certain instances overbalancing the advantages of the larger magnifying factor which the short waves offer.

The connection was now made to the second and then again to the first turn of oscillator secondary and, as even in this case the effects were inconveniently strong, connection was made to the water pipe to diminish impressed e.m.f. But even now the streamers would go over the spark gap. Several balls were now experimented with. Results were as follows:

It was now important to get an idea of the magnifying ratio and the spark was tried on the water pipe and on the free end of coil and the lengths compared. On the water pipe it was 1 /64" and on the free end 1 1 /2". This was fair but the coil was not yet quite well tuned. Completing the adjustment with more care the spark on the pipe was found 1 /100" and on the free end of the coil 2". This was quite satisfactory but not the best by far.

Further efforts to tune still more closely resulted in producing a spark between rods 2 1/4" and with the capacity of the experimenter on free rod, the same being disconnected from everything, 3 3/4". The capacity in the primary oscillating circuit was now 5 tanks on each side and the self-ind. box 7 turns in.


This capacity did not secure the best vibration of the sender which was a little slower but was suitable for the coil and no further attempt was made to tune still more advantageously by winding up more turns on the experimental coil. An important fact not to be forgotten is that the experimental coil responded without any spark passing between the oscillator balls.


Obviously it was seen that, although the experimental coil during the tuning was placed so as to avoid induction of the primary system, the same still existed to some extent. To ascertain how much induced e.m.f. was set up spark was first tried between the terminals of the coil without ground connection and the spark obtained was about 1 /64".


Now the coil was reversed so that the induced e.m.f. was against the directly communicated e.m.f. through the water pipe and it was found still that a spark of 1" between the rods was obtained. The same would have been probably longer had it not been for the fact that the end of the coil was influenced by the metal of the sink which was near. As this could not be helped the effect could only be approximately estimated. All this showed that the induced e.m.f. from the primary system was not to any considerable degree responsible for the rise of pressure on free end of experimental coil.

The coil {experimented with) was now taken outside the building and one end connected to a water pipe running across the field. At a distance of 250 feet from shop or rather from the connection of secondary to ground a spark between the reds 1/4" long was obtained and when the body of the experimenter was connected to the insulated sparkrod the spark was 1".


At a distance of 400 feet the spark without capacity was still 1/8" and with capacity of experimenter 1 /2" although at one place the pipe was buried for 30 feet in the ground. Strong shocks were obtained at that distance before the point of connection.

The experiments having shown the effects of distributed capacity to be very hurtful if not fatal to success with tuned coils, for convenience a winding was adopted to give very small capacity and thus the greatest possible length of wire and highest potential on the free end without any capacity.


Capacity on the end was not needed since the free end is connected to a sensitive device practically without capacity. Since it was desirable to get the greatest possible rise of pressure on this device, it was much better to tune for a condition without capacity on the free end, for any capacity would cause diminution of pressure since the amount of energy was fixed.


But wound in this way the tuned coil was not quite suitable to serve at the same time as secondary of the induction coil and, to utilize older apparatus, finally the connection shown in diagram on the left was adopted, which was found to be best.

Colorado Springs
Sept. 6, 1899

Experimental coil for receiving apparatus with short waves. These were produced in the following manner: the extra coil, repeatedly described, was connected in series with the secondary of oscillator, both being first tuned to the same period so that there was a nodal point on the place of connection.


The tension on extra coil terminal ( a ball of 38 cm. capacity) was over 3 million volts, as was evident from streamers from ball. At a distance from the extra coil (8 feet) another ball 38 cm. capacity was supported, and this ball was joined by a heavy cable 400,000 circular mills section to the ground.

The cable was 120 feet long and was not straight but made 3 small turns about 4 feet diam. The rest was practically straight. As the ball connected to the thick cable could not be elevated as high as the other ball of equal size on top of the extra coil a spark-gap was established as indicated in sketch.


A small ball was joined to the cable leading up this ball being placed at about the height of the large ball connected to the thick cable. In estimating the vibration of the system comprising the large ball and thick cable leading to ground it was assumed for the present that the large cable was straight and self-induction calculated on this basis would, of course, give a smaller value, but this was thought sufficient to give the first idea as to how much wire should be placed on receiving coil.


Assuming the cable straight we have

This wire is to be wound on a drum 10" diam. Therefore, we want 328 turns at least.

Colorado Springs
Sept. 7, 1899

A new experimental coil wound with 400 turns on same drum 10" diam. 66" long.

The coil when attached to a water pipe gave on free end spark 5/8". To test whether the wave length is greater 72 turns were added and sparks were decidedly stronger. But adding 50 more turns the effect was weaker. The self-induction was now calculated to get a better idea of the probable wave length and L was 2,000,000 cm. approx.


As with this L the capacity would have to be extremely small, far less than the coil evidently had, it was safe to proceed in taking wire off. Gradually shortening the wire increased the spark length until at 405 turns and a capacity of 15 sq. inches tinfoil the longest spark was obtained about 1". Calculating from wire length λ/4 was 1010 feet approx. giving n =245,500 per sec. approx.

As there was a possibility of confounding the true vibration with a harmonic, wire in definite lengths was taken off. With 270 turns and small capacity on end the effect was still good. From that point on the diminution was steady.

The wire No. 20 was now taken off and wire No. 18 wound in place to study the effect of diminished resistance. New exp. coil wound on drum 10" diam. used before. It was estimated that for the vibrating system before described, comprising ball 38 cm. capacity and 120 feet cable 400,000 c. mills, about 400—420 turns would be needed. There was wire enough for 495 turns.

The spark was taken to the body of the experimenter, the length being at once read off by a simple arrangement comprising a small rule of insulating material and a metal strip, the position of which was adjustable relative to end of the insulating rule.


The metal strip was held in hand and the end of the insulating rule was maintained almost in touch with the wire forming the free terminal of the coil which was carefully placed in the proper position such that there was no induced e.m.f. from the primary but only through the ground connection could the coil be excited.


The connection of coil and manner of reading off spark-length is indicated in the above diagram.


With 405 turns the limit was nearly approached. With 400 turns the spark without capacity was 1 1/4" and with tinfoil on wire 5/8"; with 395 turns the former was 1 1/4" the latter 5/8" and with 390 the same also, with 385 practically the same. The system still needed a small capacity for when a hand was held at a distance of about a foot a spark of 1 3/8" could be obtained.

These data give wave length.

Colorado Springs
Sept. 8, 1899

In some previous experiments coils were used wound on a drum 10" diam. but the inductances were not measured as the changes were made too often. The following data of a new coil built for similar purposes will be useful in connection with the preceding experiments.


The coil was wound on a new drum 10 5/16" diam. and 41 1/4" length. There were 550 turns of No. 18 wax-covered wire.

Data for calculating inductance

Colorado Springs
Sept. 11, 1899

Experiments were continued with apparatus before described and the effects outside at a distance investigated, the chief object being to establish nodal points on earth's surface. The transmitting apparatus was one giving more rapid vibrations and was improvised as indicated in the left sketch.

The apparatus for investigation comprised the ten" drum, before referred to, wound with 395 turns wire No. 18 B. & S. and to increase magnifying factor another layer was wound on top, thus doubling the section. It was found that the scheme of double windings is not a good one because the e.m.f. in both wires are apt to be unequal and it is more difficult to make adjustment. The connections of apparatus were as indicated in

The secondary of the induction coil was connected between the two legs of the receiver, this being convenient for eventually reversing. A high self-induction L was provided to give initial excitation but the apparatus worked also without it. The batteries B and B' were connected both in the same way and opposite, the former giving best results.


The tests showed that without any capacity or wire the disturbances were recorded about one mile away; only the ground connection was essential as the waves were still fairly long, about 4000 feet (approx.)


Colorado Springs
Sept. 12, 1899

Experiments were again resumed after some changes for the better had been made. The secondary was reduced to 26 turns and the adjustment was so made that but little self-induction remained in the self-ind. box and all tanks were used. The best condition was obtained with 8 tanks on each side and self-ind. on sixth turn.


The extra coil was now adjusted to the same vibration. As with the ball lifted up the vibration was somewhat too slow for the secondary, the ball was lowered to about half the height when resonance was secured with nearly the same capacity and self-induction in primary circuit as corresponded to the vibration of the secondary. Although the agreement was not quite close, the effects were remarkable.


The streamers went from ball 38 cm. capacity on top as freely as though it were a small one, this showing that the e.m.f. was far in excess, possibly many times the 3 million volts which theoretically are necessary to produce streamers from a ball of this radius of curvature.

Colorado Springs
Sept. 13, 1899

On Westinghouse Transformer the following change was made. The wire was cut in the middle and the two parts connected as shown in diagram: the end of the first half was connected to the tank which as before remained connected to the ground. The second half was left intact. This mode of connecting afforded the advantage of connecting the two parts in multiple arc for 22,500 volts or 30,000 volts —thus providing double current capacity.


This was recognized as necessary as the one half previously used did not load 2 the jars quite fast enough as was evident from the measurement and calculation of constants. When the parts are used in multiple arc the 1i connection is as illustrated by -------- lines. When the old connection was desirable the dotted connections were taken off and the connection indicated by —.. —.. line.

A further change was made today by n substituting for the 5" pulley on the alternating motor another pulley of 6". This gives now breaks per sec. The tests showed best results with secondary of oscillator, 8 tanks on each side self-ind., 6 turns in. Streamers were all along on the top wire which was raised today, very strong, more so than before.

Colorado Springs
Sept. 14, 1899

Experiments continued with the object of completing adjustments of secondary and extra coil with ball elevated to the highest position.

It was found that the capacity necessary in primary for resonance with extra coil was increased-25% when ball was lifted about half way. This gave the basis for the calculation showing that about 10 turns from the extra coil had to be taken off to give the same vibration with ball elevated to top position. All in all nearly eleven turns were taken off and it was found that the vibration came out very closely as estimated.


The resonance of secondary was obtained with all jars or tanks (8 on each side) and 6 turns self-induction, while resonance of extra coil with ball elevated took place with all tanks likewise and 4 turns self-induction. The coil was still a little faster than the secondary. When both were connected in series the effects were magnificent, streamers up to 12 feet from the ball. To get best effect a middle value of self-induction had to be inserted, but although with this number of turns (about 4) both the secondary and extra coil were weakened individually, their joint effect was much stronger.


This showed importance of very close tuning.

Colorado Springs
Sept. 15, 1899

As it was impracticable in the form of apparatus used in some of these experiments to insulate the sensitive device from the break, a number of arrangements were adopted to dispense with this necessity. Some are illustrated below:

These diagrams are self-explanatory. In all of them both the secondary coil and synchronized coil have their ends free for the purpose of enabling great size of pressure. This has been found a great advantage as has also the construction of a resonating coil in which distributed capacity is reduced to minimum.

In some of the above arrangements the secondary coil was dispensed with and a part of the synchronized coil utilized to give initial excitation. It was found in these experiments that the primary must be for the best results always on the side near the ground connection as otherwise the influence of the primary is detrimental to a great rise. In one instance results were remarkably good with ratio of transformation 1 :250, that is two turns of primary and 500 turns in synchr. coil.

Colorado Springs
Sept. 16, 1899

Further experimentation led to adopting one of the two arrangements illustrated according to whether an independent induction coil was used or not. The induction coil secures the advantage that the synchronized coil need not be touched and the apparatus is made suitable for any coil. On the other hand to use the synchronized coil itself has the chief advantage of having the coil entirely open.


This latter advantage is secured to a large extent also when an independent induction coil is used, as in following diagram (1): The lettering is as in previous diagrams. A small condenser C, is connected to secondary to allow easy passage to the high frequency currents from the ground through the synchronized coil to the sensitive device and wire or capacity in the air.

Diagram two shows manner of connecting when the synchronized coil itself is used as the secondary of the induction coil. In this case the primary consisting from 1—5 turns or so is placed near the ground and the tuning is effected with all apparatus mounted together except sensitive device.

This seems best so far judging from tests.

Remark: Another battery is sometimes placed in synchr. coil circuit (this is not shown).

Colorado Springs
Sept. 17, 1899

To suit the two boxes which were made some time ago for the reception of the receiving instruments in easily portable form a number of connections were adopted. These boxes are 9" wide, 14" long and 10" high overall. In the lower part was placed the induction coil, batteries, condenser, resistances and cell.


A board was provided to close up this part and on the board was mounted: sensitive relay, clockwork driving break and sensitive device, also a special circuit interrupting device.

These boxes were merely made for the investigation outside and such use. The synchronized coil was wound in one instance' around a drum 10" in diam. and about 4 feet high from the ground and carrying on top a board for placing the box with the instruments and supporting a light rod for air or capacity wire. In another form of apparatus the synchronized coil was wound on drum of 2 foot diam. and 18" high, which was supported on a tripod of photographic outfit.

These two connections illustrated in Diagrams 1. and 2. were found best suit;;; The small condenser around secondary s comprised only a few sheets of mica a-sufficient to let the currents of a frequency of 50,000 per sec. pass through cut

Colorado Springs
Sept. 18, 1899

Experiments were resumed with all transformers in place, high speed.break and connection in multiple arc of West. Transformer. The object was to further test the intensity of the vibrations produced particularly without spark. The connection was as in diagram. It was though that in this arrangement, which was dwelt upon before, the disturbances were produced more economically than when using a spark discharge.

The experiments fully confirm this. In the tests the capacity of the two balls of 18" diam. did not very materially derange the adjustment and period of the circuit. This is to be expected; as for the secondary the capacity was far too small and on the other hand the independent vibration of the extra coil could not be materially interfered with since the condenser formed by the two balls and zinc plate allowed free passage of currents to earth. Now the important thing was to decide whether it is better to make length of extra coil one half or one quarter of wave as before. This to be thoroughly investigated. The working

Colorado Springs
Sept. 19, 1899

Various arrangements with oscillator and extra coil for production of most powerful disturbances.

All of these arrangements have been experimented with and described before, and so far the plan illustrated in Diagram 4. seems to be best. In Fig. 1. the extra coil is merely a means of increasing pressure on the end.

In Figs. 2. and 3. the vibrations through the ground are intensified by the extra coil working directly on the ground either through a gap with capacity or without same. In all cases it has been found important to have the two systems vibrate in synchronism. The same considerations apply to Diagrams 4, 5 and 6. The plan in Fig. 1 being found best, the question is what is the best give to the wires.

With each secondary and extra coil having one quarter of a wave length the action on the condenser is not most intense.

With the extra coil 1/2 wave length and the secondary 1/4, they both cooperate on the condenser producing on the ball a much greater pressure. This appears the best relation in Fig. 4. In Fig. 5. and 6. it is found best to make extra coil 3/4 wave length and the secondary 1/4 for obvious reasons.

Colorado Springs
Sept. 20, 1899

Consider a form of oscillator of great simplicity particularly adapted for telegraphy similar to type exhibited before Am. Ac. of Science. A coil of high self-induction is connected in series with a condenser and across the condenser is placed a break generally in series with the primary of the coil. Very sudden discharges are produced when using a fine stream of electrolyte or mercury to effect short-circuit.


The stream is broken by condenser current. The plan followed for some time was to produce the stream automatically by a magnet worked by a key.

The connections are schematically indicated in the diagram. The question is to get the proper capacity of condenser, the amount of self-induction and other particulars. The secondary of the oscillator may be connected as shown to the ground and elevated object of capacity or else a spark gap may be used.

(This to be followed out.)

Colorado Springs
Sept. 21, 1899

Proposed structure to elevate terminal to a height of 140 feet from ground. On a telegraph post very strong and reaching nearly to the roof of the building is to be placed a cap consisting of a pipe 10" diam., a about 2 feet long with a coupling for a 6" pipe. The cap will widen out at the bottom so as to keep the wood safe against the streamers.

The pipes come in lengths of 20 feet. This will give roughly 120 feet of pipe plus cap and timber, at least 20 feet, all in all 140 feet.

The approximate area of pipe above the roof will be: π x 20 x 12 (6+5+4+3+3+ M + 2)= 17,332 sq. inches or 120 sq. feet. The ball having nearly 20 sq. feet. We shall have 140 sq. feet+cap. There may be possibly 150 sq. feet with all joints. The electrostatic capacity will reduce turns on coil to probably less than one half.

The wind pressure will be considerable but except for an unusually strong wind it will be fairly safe.

Colorado Springs
Sept. 22, 1899

The construction of new secondary for oscillator was begun this morning. The plan of tapering coil before used was abandoned as it was decided to obtain effects by the extra coil, this making it desirable to obtain better energy transfer from primary to secondary and if possible increased impressed e.m.f. on extra coil. The mutual induction will be much better and the oscillator more efficient.

The diameter of the new coil is to be exactly 15 meters inside of wire or about 49.25 feet. Two turns of primary are to be used as before, generally connected in multiple. Provision is made for 48 turns of secondary. Twenty two of the new turns will be equivalent to the 25 turns used last on tapering frame.


The frame is being built up as in sketch. The primary cables separated by pieces 1 1/8" thick. The secondary wire No. 10 used before to be wound in grooves provided in mouldings as shown. Two groovers were provided in each moulding this making the work simplest. Space was provided for two wires in each groove as it might be found later necessary to double copper. Primary and secondary are to have same amount.

Colorado Springs
Sept. 23, 1899

For best results the copper masses in primary and secondary of reconstructed oscillator should be equal.

There are two primary cables generally connected in multiple arc. These cables each have 37 wires No. 9 B. & S. The area in mills from table of wire No. 9 is 13,090, the total section of one cable being therefore

Taking one wire in each groove (No. 10 B. & S.) we have for 48 turns 10.380 mills being the section of wire No. 10 total section reduced to one turn

Therefore, if two primary cables are used there should be two wires in each groove of the secondary as provided for. The total section of primary will then be 490.82 sq. mm. and of secondary reduced to one turn: 504.92 sq. mm., but as the wirjfis slightly stretched the sections or masses respectively will be more equal.

Colorado Springs
Sept. 24, 1899

Note relative to Westinghouse Transformer.

The iron core is of dimensions indicated in sketch. The insulation from core 1" thick blocks of wood. Insulation between fibre paper about 1/2" thick.

There are three primary coils and 4 secondary coils. For a transformation to 60,000 volts a part y of primary is left out. Best way of working is to use smaller transformation ratio to 45,000 approx. The secondary coils are connected up alter natively, that is, beginning with the first on the left, then to third, then to second and from there to the fourth coil.

The transformer gives every evidence of hav.1 ing a high efficiency. The leakage current is remarkably small for so large a machine. The alternate connection and disposition of coils is evidently to reduce stray field and also for convenience to enable use of similarly wound coils, that is, coils wound on one form.

The tests of mineral seal oil 300° show it to be oil of excellent quality penetrative, of high flashing point and good insulating properties.

Colorado Springs
Sept. 25, 1899


Measurement of self-induction of primary of oscillator and regulating self-in. coil.

Of the above readings the one showing 58.9 amp. was taken repeatedly and is very probably closer than the other reading with smaller current. Taking this as the-basis I find, neglecting resistance of both primaries and self-in. coil being very small L2p of two primaries:

As there are 24 turns we may take as a rough approximation when quickly computing: 3600 cm. per turn when there are a considerable number in.


Colorado Springs
Sept. 26, 1899

Following method for determining period of vibration, inductances and capacities is simple and convenient. The vibrating system is formed by a continuously variable and exactly determinable inductance and a capacity standard, or by an inductance standard and continuously adjustable condenser or by a system in which both these elements are continuously adjustable and can be exactly determined in one way or another.


This system is then excited by a primary vibrating system in a convenient manner and one or both of the elements of the excited system is varied until resonance is obtained. This gives the period of the primary system and if in this only one more element is known all the others can be easily determined.


The excitation is conveniently secured and graduated by connecting the wire leading to the system to be excited to the ground through an adjustable spark gap, which is generally very small.


This method was applied to determining the period of the primary system used in these experiments in the following manner: a standard self-induction coil made long ago and used in experiments in N.Y. about 1560 turns wound on a drum 3 1/2" diam. was shunted by the adjustable condenser, also frequently used and consisting of two brass plates 20" diam., and this system was connected to one of the terminals of the Westinghouse transformer as illustrated in diagram below.


By varying the length of spark at b the degree of excitation was varied to any value desired, the spark at a serving to determine maximum rise of potential on terminals of excited system.

Colorado Springs
Sept. 27, 1899

Determination of inductance of coil used in series with extra coil when no ball was used on latter, with old secondary. 160 turns No. 10 B. & S. wire rubber-covered Habirshaw, drum 2 feet diam.

First measurement average of readings:

The difference must be due to the internal capacity of the coil or possibly inexactness of the dimensions above.

Colorado Springs
Sept. 28, 1899

One of the difficulties in telegraphy and a drawback in practical introduction is the elevated terminal of capacity as proposed by me. It is difficult to elevate a structure to the desired height and keep the same insulated from the ground and with very powerful vibrations, as here produced even an insulated wire leading up offers difficulties because of streamers which reduce the force and the effect at a distance.

I propose to overcome this by the following plan. A structure is to be elevated from the ground up to the desired height and an insulated wire from the oscillator is to be brought up to a point on the structure and connected to same or else brought into proximity, as for instance when a spark is used.


This point should now be so located that there is at the same moment, say, a position maximum on top and a negative on the bottom or ground, that is the top and bottom should be one half of the wave apart or a multiple thereof.

When secondary is grounded as usual it will probably be advantageous to make the wave length in both systems so that they work in unison on the ground.

Colorado Springs
Sept. 29, 1899

Various advantageous arrangements of oscillating circuits for producing disturbances in the natural media.

The object of these arrangements is to produce especially in conjunction with an "extra coil", as before explained, disturbances in the most effective and economical manner. In such a coil the e.m.f. is raised to an extremely high value by the "magnifying ratio".


The arrangements furthermore contemplate doing away with the spark which consumes energy, although in many respects it possesses advantages giving, in particular, a very high rate of energy delivery. In the diagrams three such arrangements which have been experimented with are illustrated.

In Fig. I. the form of connection is shown most frequently experimented with here. The primary p energizes secondary s shunted by condenser c, the secondary exciting extra coils e e with their capacities € C, at the free terminals, one of which, C1, is at some distance from the ground or groundplate E forming a condenser with same. All the three systems, primary, secondary and extra coil have the same period of vibration.


Fig. 2. illustrates a simplified way; in this instance the extra coils are partially influenced by induction from the primary p. In Fig. 3. again the extra coil e may be only electrically or also inductively excited. The upper terminal is here a very large capacity as the roof of a building and the terminal of high potential is C1.

This seems to be very effective.


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