Part 2

_Thomson Houston Dynamo Operates._

In the diagram Fig. 19 the rotation is as in practice against the hands of the watch when seen from the commutator end of shaft. The three coils of the armature are represented by three lines _A_, _B_, _C_, united at their inner extremities each being joined to a segment of the commutator. There are two positive brushes _P_ and _F_ and two negative ones _P´_ and _F´_. The current delivered to _P_ and _F_ goes round one of the field magnet coils, then to the outer circuit consisting of regulating gear, lamps, motors, etc., through the other field magnet coil to brushes P´ and F´. Now from Fig. 20, we observe that supposing the loop to be rotating against the hands of the watch in a magnetic field the diagram represents by arrows the direction of the electro-motive forces induced in those loops. The action is a maximum along the line of the resultant magnetic field m m´ and the minimum along the line n n´ which is at right angles to m m´. The reason that m m´ is not horizontal is that the induced poles of the armature is in advance of the poles of the field magnet and is constantly tending to be drawn back. Applying Fig. 20 to Fig. 19, we see that there will be an outward current in _B_, an inward one in _C_, _A_ generating no current for that moment.

Now the following pair of brushes _F F´_ are shifted backward three times as far as _P P´_ is shifted forwards. When the current is the greatest possible the brushes P and F and P´ and F´ are 60° apart thus leaving _P_ and _F´_ and _P´_ and _F´_ just 120° apart and since the segments of the commutator are each 120° in length[3] there will always be two coils in parralel with one another and in series with the third. Taking one sixth of a revolution and continuing all the way round we find the following tabulated statement showing brushes in contact with coils, to be true viz:—

{ P - C } { P´ } From external circuit { } B { } to external circuit { F - A } { F´ }

{ P } { P´ - B } ” “ ” { } A { } ” “ ” { F } { F´ - C }

{ P - A } { P´ } ” “ ” { } C { } ” “ ” { F - B } { F´ }

{ P } { P´ - C } ” “ ” { } B { } ” “ ” { F } { F´ - A }

{ P - B } { P´ } ” “ ” { } A { } ” “ ” { F - C } { F }

{ P } { P´ - A } ” “ ” { } C { } ” “ ” { F } { F´ - B }

Now suppose the current to become to strong owing to any cause, the following brushes are made to recede. This can but shorten the time that the brushes are in contact with the commutator when the coil is passing through that position in which it is generating the maximum amount of current and also hasten the time when it goes into parralel with a comparatively idle coil. If the current is to weak then the brushes are made to close up thus reducing the time that the most active coil is in parralel with one less active and also makes the brushes be longer in contact with the segment when the coil is generating its maximum amount of current. The motion of advance and retreat of the brushes is accomplished by the _Thomson Regulating Gear_ before described. On Fig. 23 can be seen all the dynamo’s details except the _Controller magnet_.

As regards the _Thomson-Houston Dynamo_ it will be found to produce the steadiest and most uniform current of any dynamo now in use. It regulating gear is the simplest and most natural one ever used. In its ability to reduce the current simaltaneously to one tenth of its former quantity inside of one or two minutes _without injury to itself and lamps_ it stands alone, in practice.

_Fig. 23._

Your engraving representing “_Dynamo Electric Machine with Thomsons Spherical Armature_”

—Taken from one of your catalogues, and pasted on a sheet of this paper—

In a system the most important thing next to the dynamo is the lamps. The first experimenter who produced an electric glow was Otto von Guericke. But neither the glow nor electric spark have been used to produce electric light for practical purposes, this was left to the voltaic arc on the one hand and the incandescent lamp on the other. Davy in 1800 mentions experiments in which electric light was obtained by electric sparks between two carbon points. He showed the arc[4] light for the first time in 1810 at the Royal Institute, which with Foucalt’s hand regulator (1844) Deleuil lit the Place de la Concorde, Paris. Thomas Wright in London (1845) devised the first apparatus which automatically adjusted the carbons. W. C. Staite used the electric current for the regulation of the carbons in 1848. In 1855 Serrin constructed a lamp which would have been used on a large scale had it not been for the cost of generating electricity. In 1876 Paul Jablochkoff invented his electric candles and in 1881 there were 4000 in use, but as their use increased their defects were found out. Regulated lamps were again brought into use and with them experimenters again endeavored to solve the problem of dividing the electric light. In 1877 Tschikoliff solved the problem in a very simple manner. He reasoned that, if the current be divided and part go through the carbons and make the arc and the rest go through an electromagnet and regulate the arc and the the current unite and when another light is wanted the current be again divided and reunited, the current may be divided any number of times and the scheme work nicely. When put in practice it worked very nicely and is used on most lamps at present. Suppose there be a lamp placed in the circuit. The current divides and the larger half goes through the carbons, as here there is no resistance as the carbons touche, while the remainder, going through a spiral of high resistance, is small. When the carbons burn away a little the arc is formed and the resistance increasing brings the regulating gear into operation. Now the strength of the current is the same after it has gone through the lamp as before because the current is going to get through either one way or the other, hence any number of lamps may go on in series, depending only upon the tension of the current.

Incandescent lamps were produced as early as 1859 but not till 1879 when Swan, Edison, Sawyer and others were they ever in a practical form. The first glow lamp Edison constructed had platinum wire to be heated. He however examined the properties of organic substances and finally fixed on bamboo fibre. The bamboo is divided into fibres one millimeter in diameter and twelve millimeters long. These fibres are pressed in U-shaped moulds and baked in ovens where they are allowed to become carbonized. The carbonized filament is attached to platinum wires which are fused in a glass vessel from which the air has been exhausted. We will speak more fully of the incandescent lamp when describing the Thomson Houston System’s incandescent lamp.

The Thomson Arc lamps was used by the Thomson Houston System since its begining till about two years ago when they stopped manufacturing them, only furnishing broken parts. The arc lamps at present used is

_The Thomson Rice Arc Lamp._

They are manufactured in two styles the single lamp used for stores, buildings etc., and the double lamp used for street service, all night work, etc. The light is produced by the voltaic arc between two carbons, the negative pole or lower carbon burning away about half as fast as the positive pole or upper carbon. The outside view of the single lamp is seen in Fig. 21 and of the double lamp in Fig. 22.

The regulation of the double lamp is diagramatically shown in Fig. 24, which is a plan of the lamp with cover removed, showing only a plan of cylindrical part of the lamp. The wires marked _a b c d_ run along the top in order to be out of the way. In Fig. 24 the current comes in at the binding post and is at _A_ divided into three currents _A_, _B_, and _C_. The current _a_ goes to the yoke _I_ of the electromagnets _h_ and _i_ and when the yoke is not held down by magnets _h_ and _i_, it goes out wire _a_ to binding post _B_. This only continues a moment until the current _b_ which goes through the carbons and at the start has almost no resistance offered it, attracts the yoke _I_ thus breaking contact of curcuit _a_ until the current ceases or till both carbons burn away, when in the latter case the resistance of _b_ becoming very high as compared to _j_ and _k_ but little current goes through _h_ and _i_ and _I_ is raised by a weak spring not shown, thus making contact of circuit _a_, and since current _a_ has little resistance as compared to _b_ or _c_ most of the current goes through it, thus practically making a cut-out. The current _b_ goes round the electro-magnets _h_ and _i_, then to the “bed” through screw J, the “bed” being a cast iron bottom of the cylinder _E_ Fig. 22. From the bed it goes down carbon holder _C_ (or _H_) through carbons and arc to frame bed _A_ Fig. 22. From there it comes up a wire by the side of frame _C_ Fig. 22 and joins other currents at _B_. The third current _a_ goes through electromagnets _j_ and _k_ and joins other currents at _B_.

This is when switch F Fig. 22 and _M_ Fig. 24, is turned _on_. Now since the dynamo will regulate all differences in current the lamps can be turned _on_ or _off_ at will by any one. This is accomplished at the lamp by turning _off_ the switch. When the switch is turned _off_, the current goes through _d_ to screw _K_ which is then touched by metal L (in contact with binding post B and worked by _M_).

It will be perceived that any disorder in a lamp cannot affect other lamps in the circuit and will right itself or if not the lamp can immediately be switched out of circuit.

Now as to the regulating gear. The two carbon holders are held up, _H_, by clutch operated by springs (not shown) till end _N_ of lever _ON_ is permanently held down, and _C_, by the raising and falling of yoke _D_. There is only _one_ arc burning at a time in a double lamp and the so-called positive carbon _C_ burns first. When the lamps are trimmed the switch is first turned _off_ the carbons put in and the switch turned _on_. This will draw the upper carbons up about a quarter of an inch.

When the current is turned on the circuit _aa_ is almost instantly broken and most of the current goes through _c_ as the distance between carbons being a quarter of an inch the arc has a _very_ large resistance. The electromagnets _j_ an _k_ attract _D_ which lets loose _C_, which falls to lower carbon, and the resistance being almost nothing, most of the current goes through _b_. This weakens _j_ and _k_ which lets _D_ up while _D_ takes _C_ up with it thus establishing the arc. The current _all_ goes down _C_ till the enlarged end of _C_ strikes lever _ON_ thus letting _H_ drop and also putting it in electrical contact with “bd,” which it was not in before. After a short time the carbons burn away, the arc becomes longer and establishes itself and the resistance becoming greater in passing from carbon to carbon and a correspondingly less current flows through _b_ and a greater one through _c_. This makes the electro-magnets _j_ and _k_ strong enough to draw _D_ to them in spite of spring _Q_. When _D_ is attracted by _j_ and _k_, _C_ (or _H_) falls and again the arc lengthens, always being kept about 3/32 inch long. This is frequently and continually repeated, the delicacy depending upon the strengh of the spring _Q_ as compared to the electromagnets strength.

When the carbon in carbon holder _C_ burns to a length of about two inches in attempting to fall to maintain arc’s length, an enlarged port at the top of the carbon holder _C_ strikes and holds down lever _ON_ pivoted at _O_ (and end _N_ held up by a spring _P_) thus letting loose a clutch by which electrical contact is made between _H_ and “bed” and letting _H_ fall till it touches lower carbon when an arc is established and regulated just as for _C_.

The Thomson-Rice single lamp has the same gear with the exception of having only carbon holder _C_, _H_, lever _ON_, and spring clutch and spring _P_ being absent. The single lamp will burn eight hours and the double lamp fourteen hours continuous running.

These lamps are intended only for a steady current and will not cut out of circuit if the current gets too strong. But with the Thomson Houston dynamo the current never gets too strong and because of this there are less power absorbing mechanism and as anything’s functions decrease the remaining functions are increasedly better. As the Thomson-Rice lamp has less functions and power consuming machinery, it can but be the most economical, delicately adjusted and steadiest lamp extant. They are made to stand a current of five amperes above the normal current for a short time, as, when forty lights are simultaneously cut out of a forty-five light circuit, the current runs up about four amperes above the normal current for about one half a minute.

Prof. Thomson has gotten out a divided arc lamp which supplies a light of moderate candle power for locations where a 2000 candle power lamp gives more light than can be economically utilized. It is specially suited for factory and mill use where looms or other tall machines are liable to cast disadvantageous shadows. It is said that these lights are supplied cheaper per candle power than the standard lamp and up to date is sucessful.

He has also arranged apparatus by which arc lamps are run in multiple series, series or multiple arc. It is said that divisions, redivisions and reunions are practicable. This is also sucessful as far as we can find out.

_The Sawyer-Man Incandescent Lamps._

As before stated Edison fixed upon carbonized filament of bamboo. The Sawyer-Man company however applied for a patent on carbonized filament for incandescent lamps on January 19^{th} 1880, and after five years litigation with Thos. A. Edison they were granted a patent No. 317,676, on May first, 1885, covering their invention. The Sawyer-Man lamp Fig. 25, consists of a carbonized connected to platinum wires fused in a glass tube from which all the air possible had been extracted. The light is produced by the glow of the filament and heat of gases given from filament. The life of a lamp is from 1000 to 1500 hrs. and requires a current of 1¼ to 1.3 amperes and give 20 to 25 C.P. When the filament becomes brittle and breaks the tube is unscrewed from the key Fig. 26, and a new one screwed in. They are run on the arc light circuit by the use of an individual distributor Fig. 27 which consists of a brass case containing a magnet in the circuit of the lamps and a resistance coil automatically substituted in case the lamp should break or is turned off by key Fig. 26. The scheme of arranging lamps so as to get the right current is shown at Fig. 28. the number of lamps in a group depending on the current.

Prof. Thomson has gotten out a lamp Fig. 29 in two styles one for 6.8 amperes current and one for 10 amperes current. Three lamps of different candle power, due to different potential differences at binding post of lamp, are use on the same current. The method of connecting them is shown in Fig. 30. It will be perceived that the lamps carry the full current yet have a life of 1000 hrs. or more. This is a great invention indeed doing away with a great loss of power due to high resistance coils. It will be noticed however that a 125 C.P. incandescent lamp uses as much energy as a 2000 C.P. arc light, the 65 C.P. lamp one half as much and the 32 C.P. lamp one fourth as much.

_General Remarks_

The Thomson Houston system also furnish lightning arresters, ammeters, hanging boards, switchboards, hoods, insulators, lamp arms, etc, but, though in some respects many of these miscellaneous articles are ingenious and novel, yet they are not distinctive of the Thomson Houston or any other system. Be it said however that all these articles fill their proper places. The company also furnish a motor to go on their circuits but for the double reason that of the motor not being strictly related to electric lighting and of being unable to obtain a description of it, it must remain undescribed as far as this thesis is concerned.

After describing all the parts of the system it may be interesting to know how a plant is arranged. The last plate is a photograph of the LaFayette Gas Company’s Plant of the Thomson Houston System taken at ten oclock one night. It shows the engine, dynamos, the wall controller on the left wall, and a view of the lamps which had hoods put before them to prevent the polarization of the negative.

On the accompanying page will be found a table showing experiments with an old style dynamo given Purdue University by the Thomson Houston Company, which dynamo is now in the engine house of the Mechanical Hall.

_Experiments with Three Light T-H. Dynamo No. 79_

The dynamo was run by a large pulley (about four and one half feet in diameter) on the same shaft as the fly wheel and beside the latter. Two lamps were put in circuit with a Deprez-Carpentier ammeter and a volt meter of the same make was put in between the brushes. First one lamp (old Thomson style) was switched out of circuit, the dynamo started and when speed was reached the circuit made. The following readings were taken when the engine made 139 & the dynamo 1122 revolutions per minute.

+-----------+----------+----------+---------------+----------------+ | | One Lamp | Two | When 2^{nd} | When 2^{nd} | | | | Lamps | lamp was | Lamp was | | Readings | | | switched in | switched out | | At End of +----+-----+----+-----+-------+-------+-------+--------+ | |Amp.|Volts|Amp.|Volts| Amp. | Volts | Amp. | Volts | |-----------+----+-----+----+-----+-------+-------+-------+--------+ | 1 second | 10 | 55 | 10 | 110 | 6.7 | 55 | 14 | 110 | | 30 ” | 10 | 55 | 10 | 110 | 10 | 75 | 10 | 85 | | 2 Min | 10 | 55 | 10 | 110 | 10 | 109 | 10 | 60 | | 3 ” | 10 | 55 | 10 | 110 | 10 | 110 | 10 | 55 | +-----------+----+-----+----+-----+-------+-------+-------+--------+

_Fig. 25_

consisting of drawing of Sawyer Man lamp cut from catalogue, and trimmed to contour of drawing

_Fig. 26_

a drawing showing action of key in Sawyer Man lamp, cut to contour

_Fig. 27_

a drawing of the Thomson Rice Individual distributor cut from cataloug and pasted in.

_Fig. 28_

a drawing cut from pamphlet showing “Method of using Thomson Rice Individual distributor”

_Fig. 29_

a drawing cut from pamphlet showing “Prof. Thomsons incandescent lamp—series incandescent lamp”

_Fig. 30_

Drawing showing “method of using the Series Incandescent Lamp manufactured by the Thomson-Houston Elec. Co.” cut from your pamphlet and pasted on a similar sheet.

A photographer of La Fayette photoed the Gas Company’s plant of T & H in this city one evening at 10 o’clock when several lights were burning in room. I had a large one printed and pasted on a piece of bristol board of the same size as this sheet, and put in my original copy.

_Footnotes_

Footnote 1:

The foregoing statement is quoted from Dr Urbitzkany’s work “Electricity in the Service of Man.”

Footnote 2:

Gravity does not enter, as a current is generated in lowering A.

Footnote 3:

Each segment is really only 115° in length but the brushes are set at a distance from the holder far enough to just reach over the five degree gap by the gauge above described.

Footnote 4:

An arc light is a light produced by the use of the voltaic arc, which is made by the sparks passing between two poles of a powerful battery which are brought together and then seperated a little.

_Transcriber’s Note_

The source for this e-book was a hand-written thesis.

Footnotes have been moved to the end of the book.

The captions for Figures 23, 25, 26, 27, 28, 29 and 30 are reproduced, however, the original drawings were not bound with the published thesis and are therefore not part of this e-book.

The author’s spelling has been maintained, Some standardization of punctuation was done to improve readability.

The following proper names as used by the author are reproduced here with their more commonly used spelling:

Author Standard

Thompson Thomson Wimhurst Wimshurst Dr Urbitzkany’s Alfred von Urbanitzsky Lentz Lenz Pacinnotti Pacinotti Foucalt’s Foucault’s

Phrases which the author portrayed as underlined are presented by surrounding the text with _underscores_. Some standardization of these was also done particularly with regard to the presentation of illustration captions.