,the ,thompson-,houston                 
,system of ,electric                    
,lighting4                       ,thesis
 submitted for the degree of            
,bachelor of ,science in ,mechanical    
,engineering1                      to   
the ,faculty of ,purdue ,university     
,june #ahhg                             
----------------------------------------
--------------------------------        
8,in its power to assume always that    
form of energy which happens to be  the 
most useful lies the great importance of
 electricity40 ,this  importance has    
been brought to the notice of the public
 by means of the  many recent           
exhibitions4 ,public interest has been  
roused and there is  everywhere a desire
 for information and a guide through    
this far  reaching field for discovery  
and invention4 ,and1 although there are 
many  works treating on electricity and 
electric light1 people specially want  a
 short and concise though thorough      
description of the various schemes  by  

which electric light is produced4 ,in   
this thesis the object is to  give a    
brief treatise on one of the many       
schemes of producing light by  electric 
currents viz--,the ,thomson-,houston    
,system4    ,in pursuing the subject of 
electricity1 the first thing noticed is 
the  analogy and difference between the 
dynamo and its older and more  powerful 
rival the steam engine4 ,the            
resemblances are1 ,first as in the      
development of the steam engine1 but few
 of the improvements and  inventions in 
electrical machines were made by        
mathematical leaders4  ,watt ran across 
the idea of the seperate condenser while
 repairing the  ,newcomen model and     
applied the expansion of steam to the   
steam engine by  a mechanical accident  
rather than by his own ingenuity1 and so
 we find  the first designers of the    
dynamo were mechanics rather than       
philosophers4 ,secondly the tendency to 
disregard old methods and  instruments  
because of new discoveries and          

inventions has1 as in the  steam engine1
 hindered the advancement in electrical 
science4 ,as an  example it has become  
customary to regard frictional and      
statical  electric machines1 for        
practical purposes1 as obsolete1 but    
recent  discoveries seem to hint that   
they may yet be utilized4 ,lately ,prof4
  ,dodge has shown that dust and vapor  
whirling in the air may be settled  by a
 discharge of electricity consisting of 
a continuous series of  electric sparks4
 ,this has been utilized to clear the   
atmosphere in lead  smelting works from 
the fumes of volatized lead and with its
 application  comes the invention of    
,wimhurst which produces with a minimum 
of  mechanical labor a continuous series
 of electric sparks and works           
admirably4    ,the differences between  
the engine's and dynamo's developement  
are3  ,first the marvelously rapid      
developement of the dynamo as compared  
with that of the steam engine4 ,since   
#ahfg when the term 8dynamo electric    

machinery0 even to scientific men had   
but little signification1 the  dynamo   
has been brought to a very high degree  
of perfection4 ,secondly1  the          
development of the dynamo has reached a 
much higher degree of  perfection than  
that of the steam engine4 ,among the    
best steam engines  twenty per cent     
effeciency is considered as very good   
while a good  dynamo gives out in the   
form of electricity1 ninety per cent of 
the  mechanical energy put in it4 ,but  
the class of people who improved and    
made the steam engine what it is were as
 well educated in one sense as  were the
 men who brought out the dynamo4 ,while 
it is true that in ,watt's  time the    
knowledge concerning steam was very     
meagre1 yet the practical  men who made 
the dynamo1 did it by themselves as     
nearly all the  teachers of electricity 
knew nothing except what may be called  
electrical tricks4 ,as has been said#a  
8,the teachers and writers of           
textbooks1 practically did not know that

 there was anything in common  between  
the electricity from a rubbed glass     
machine and voltaic  electricity1 or to 
be brief1 that there was a science of   
electricity as  distinguished from mere 
natural history40 ,in fact as late as   
#ahgj there  were really no textbooks on
 electricity4 ,even now electrical      
knowledge  is so meagre as to warrant   
the same writer's expression1 8,we can  
not  imagine a mechanical engineer      
mistaking a few inches for a few miles  
or  a grocer compounding an ounce of    
sugar with a carload1 but this gives    
too truthful an idea of the vagueness   
that still exists40    ,in the distant  
future1 electricity will be used for    
electric lighting  only as subordinate  
to other uses to which it may be applied
 such as  heating houses1 taking place  
of stoves for cooking1 being used as a  
substitute for the steam engine4 ,in    
fact the motor is rapidly becoming  of  
as much practical use as the electric   
light4 ,the principle of the  motor is  

just this2 a certain amount of          
mechanical energy say thirty  four      
horsepower per minute into the form of  
electric currents1 which by  the way    
gives enough current to run #de1 #bjjj  
candle power lamps1 send  the current   
and distance through suitable conductors
 and attach them to  similar dynamo or  
dynamos but in such a manner that the   
current in the  second set of dynamos   
flows in the reverse direction to that  
of the  first2 when1 the armature of the
 second dynamo or dynamos will revolve  
and at the pulley or pulleys of the     
dynamos1 aside from friction1 will  be  
given out #ie of the thirty-four        
horsepower1 the loss being due to  the  
resistance of the conductors4 ,now in   
practice a motor is placed on  the arc  
light circuit the same as a lamp1 for   
energy less than twelve  horsepower4 ,it
 does not affect the lights and is a    
clean1 neat way of  obtaining energy4   
,but however true the foregoing may be1 
the greatest present use of  electricity

 is to start and maintain light4 ,there 
are several so-called  systems1         
embracing dynamos1 lamps1 regulators1   
etc1 from which ,i select  the          
,thomson-,houston as the one for the    
purpose of describing for several       
reasons1 first1 it is at least as good  
as the average system of which  there is
 a mushroom growth2 second1 valuble     
information was kindly  offered by the  
parent ,company2 third1 a good plant is 
near to which  free acess was given1 and
 fourth1 we have at the ,mechanical     
,hall of  this ,university1 a dynamo1   
loaned by the parent ,company1 which    
affords  information without any        
inconvenience4 ,as each part of the     
system comes  up to be described a      
little of its history will be given4 ,as
 the first  part of a system necessary  
to be produced is the current generator 
we  will first describe                 
,the ,thomson-,houston ,dynamo4      ,in
 considering the current generator the  
first thing to be decided upon  is the  

definition of the term dynamo4 ,the     
following is thought to be a  correct   
definition1--,a dynamo or dynamo        
electric machine is a machine  which is 
used to convert energy in the form of   
mechanical motion into  energy of       
electric currents1 or vica-versa4 ,those
 used to generate  currents of          
electricity are called dynamos1 those   
used to generate  mechanical motion are 
known as motors4    ,in attempting to   
make clear the theory of the dynamo1 we 
will recall  some simple experiments4   
,in ,fig4 #a1 send a current around ,b  
from right  to left4 ,now ,a being free 
to move vertically either up or down1   
connect  its binding posts to a         
galvanometer 7that is1 an instrument    
used to  tell the direction of a current
 and also used to test the relative     
strength of two or more currents7 and   
move ,a up suddenly when a current  will
 be generated in ,a whose direction will
 be the same as that of the  current in 
,b4 ,now this current is not created    

energy1 because in  lifting#b the coil  
,a1 work is expending against the       
attraction between  the coils1 as       
between two currents flowing in the same
 direction there  is an attraction4 ,if 
we pursue this experiment in its various
 forms we  will find the following      
statement known as ,lentz law is true1  
viz3 8,if  the relative positions of two
 conductors ,a and ,b be changed of     
which ,b  is traversed by a current1 a  
current is induced in ,a in such a      
direction  that by its electro dynamic  
action on the current in ,b it would    
have  imparted to the conductor a motion
 of the contrary kind to that by which  
the inducing action was produced40      
,the theory of this law is that around  
every wire carrying a current  there is 
a magnetic whirl 7,fig4 #c74 ,now if the
 conducting wire be passed  through a   
hole in a horizontal plate of glass and 
iron filings be sifted  upon the latter 
they will arrange themselves1 as shown  
in ,fig4 #b41 along  lines1 radial in   

this case1 known as lines of force1     
which arranging is  due to the magnetic 
attraction of the current in the wire   
upon the iron  filings4 ,now in ,b4     
,fig4 #a1 every portion of the wire has 
just such a  whirl and just such lines  
of force1 or magnetic field1 and when ,a
 is  moved each part of the wire of ,a  
cuts one or more lines of force of the  
many magnetic fields making up the      
magnetic field of the entire coil ,b4   
,now when the wire of coil ,a cuts      
magnetic field of ,b a current is       
generated in ,a acording to the         
following statement known as ,faraday's 
,law2 8,when a conductor in a field of  
force moves in any way so as to cut  the
 lines of force there is an             
electromotive force produced in the     
conductor in such a direction that      
supposing a figure swimming in the      
conductor to turn to look along the     
positive direction of the lines of      
force 7in ,fig4 #a1 toward axis of ,b71 
and the conductor be moved to his       

right1 he will be swimming with the     
current so induced40 ,hence in ,fig4    
#a1 the current generated in it will be 
from left to right4    ,practically     
,faraday's principle means just this3 by
 moving a wire across  a space where    
there are magnetic lines1 the motion of 
the wire as it  cuts the magnetic lines 
sets up around the cutting wire a       
magnetic whirl  or in other words sets  
up a current in that wire4    ,the      
foregoing laws are the 8principles of   
the dynamo10 yet after their  deduction1
 the progress of the evolution of the   
dynamo was slow and  attended by many   
dificulties4 ,between #ahfj and #ahgj   
however1 a working  knowledge of these  
laws became the property of thousands of
 mechanics1  and by comparing the number
 of inventions before and after that    
date  7#ahfj7 the present generous      
growth of systems1 dynamos and lamps1   
prove  that inventions were almost in   
proportion to the number of people who  
had any electrical knowledge4 ,in #ahff 

,wilde produced a toy  magneto-electric 
machine for giving shocks1 in which he  
used excited  electromagnets4 ,in the   
same years ,varley and others produced a
 machine  which excited its own field   
magnets the type of all machines used in
  practice4 ,with this principle of     
,varley's and ,pacinnotti's ring1       
,gramme  produced in #ahga his since    
famous continuous current generator1 one
 of  which the second dynamo electric   
machine ever brought to this country    
can now be seen at the engine house at  
,purdue ,university4 ,in #ahgg ,silas   
,brush brought out his famous dynamo and
 it may be interesting to know  that he 
designed and had one made without       
experimenting in the least4 ,in  the    
following year a patent was issued to   
,messrs4 ,elihu ,thomson and  ,edwin ,j4
 ,houston1 ,professors of electricity in
 ,philadelphia on the  present though   
much improved ,thomson ,houston ,dynamo4
    ,illustration3      ,fig4 #a4       
,fig4 #b4      ,fig4 #c4      ,fig4 #d4 

,fig4 #e4      ,fig4 #f4      ,fig4 #g4 
,to go back to ,lentz and ,faraday's    
laws and carefully consider them we  can
 but assent to ,s4 ,p4 ,thompson's      
8fifteen propositions on the dynamo0    
which are3--#a4 ,a part of the energy of
 an electric current exists in the  form
 of a magnetic whirl surrounding the    
wire4    #b4 ,currents may be generated 
in a wire by setting up these whirls4   
#c4 ,we can set up these whirls by      
increasing or decreasing the relative   
distance between magnets and wires4     
#d4 ,to set up and maintain these whirls
 consumes power4    #e4 ,to induce      
currents in a conductor there must be   
motion between them  so as to alter the 
number of lines of force 7,fig4 #d to   
#g74    #f4 ,increase in the number of  
lines of force in the circuit produces a
  current of the opposite sense to      
decrease 7,fig4 #g74    #g4 ,approach   
induces electromotive force in the      
opposite direction to  that induced by  
retreat4    #h4 ,the stronger the       

magnetic field the stronger the current4
    #i4 ,the more rapid the motion the  
stronger the current4    #aj4 ,the      
greater the length of the conductor     
which cuts lines of force  the stronger 
the current4    #aa4 ,the shorter the   
conductor not so employed the stronger  
the current4    #ab4 ,approach being a  
finite process the approaching and      
receeding must  give alternating        
directions to the current4    #ac4 ,by  
the use of a commutator all the currents
 can be turned in the  same direction4  
#ad4 ,in a steady circuit it makes no   
difference what kind of magnets are     
used to procure the requisite magnetic  
field whether permanent or              
electromagnets4    #ae4 ,hence the      
current of the generator may be used to 
excite the  magnetism of field magnets4 
,now the ,thomson-,houston dynamo comes 
under that class of dynamos in  which   
there is a rotation of coils in a       
uniform field of force1 such  rotation  
7,fig4 #f47 being affected round an axis

 in the plane of the  coil4 ,of course  
this dynamo is made like all others of  
its class to have  first1 as powerful   
field-magnets as possible1 second1 the  
armature  or rotating coil has as great 
a lenght of wire in it as possible the  
wire being thick to offer little        
resistance and third1 built to stand    
high rotative speed4    ,the simple     
theoretical dynamo is shown at ,fig4 #h1
 consisting of a single  rectangular    
loop of wire rotating in the magnetic   
field formed by large  magnets1 and in  
order to take the current so generated  
from the loop so  as to give a          
continuous current1 we use a two part   
commutator 7,fig4 #i7  consisting of a  
metal tube split in two and mounted on  
wood1 each half  connected to one end of
 the loop4 ,the current is taken off by 
brushes  which lead to the main circuit4
 ,but manifestly this dynamo would give 
no  appreciable current becase it has a 
very small length of wire on the        
armature1 so a great number of loops    

were used which at present  constitute  
the so-called drum armature4    ,we may 
rotate the loops of wire in ,fig4 #h1 on
 one of its sides as an  axis or even   
push it farther from the center of      
revolution than that4 ,to  do this1 wrap
 the wire around a ring and connect both
 ends to a two part  commutator 7,fig4  
#aj74 ,if instead of the ring in ,fig4  
#aj1 being solid it  be a number of     
coils of wire and if instead of there   
being one coil  around the ring there be
 thirty we will have ,pacinnotti's ring 
before  spoken of4 ,if we used four to  
ten coils or 8bobbins0 of large size    
which  is shown diagramatically at ,fig4
 #aa1 we would have the ,brush dynamo4  
,so with exceptions we may say that     
there are practically two types of      
dynamos as regards armatures1 the ring  
type as ,brush1 ,pacinnotti's  ,gramme1 
and the drum armature 7page #bj74       
,the ,thomson-,houston dynamo is like   
the rest of that dynamo1 unique4 ,to    
quote ,s4 ,p4 ,thompson2 8,the          

,thomson-,houston spherical armature is 
unique  among armatures1 its cup shaped 
field magnets are unique among field    
magnets1 its three part commutator is   
unique commutators40    ,illustration3  
,fig4 #h4    ,simple ,dynamo4      ,fig4
 #i4      ,fig4 #aj4      ,fig4 #aa4    
,fig4 #ab4      ,fig4 #ac4    ,an       
armature of a dynamo is the rotating    
coil or coils which generates  currents 
of electricity by moving in a magnetic  
field of force4 ,it is  the most        
important part of a dynamo as it is     
literally the current  generator4 ,so we
 first consider the ,thomson-,houston   
,armature      ,it is spheroidal in     
shape as is noted for the fact of its   
very seldom  burning out1 i4 e41 the    
electricity heating the wires of the    
armature  to such an extent as to       
destroy the insulation or fuse the      
wires1 either  rendering the armature   
useless4 ,it is made by keying two      
dish-shaped  iron disks ,,ss ,fig4 #ab1 
to the shaft x and putting ribs dd about

 ten  in number in the twenty-five light
 machine1 and over the whole putting    
varnished paper4 ,then at stated        
intervals1 pegs ,,jjj are driven into   
suitable holes in the disks and ribs to 
help in winding wire on the  shell4     
,next three insulated wires of equal    
length are joined together at  h ,fig4  
#ac1 and the three wires are then wound 
over the shell in the  following        
peculiar manner3 one half of ,no4 #a is 
wound so as to form a  zone of a sphere 
of which the shaft is in the same plane 
as the center  circumference of the     
zone4 ,the armature is then turned on   
the shaft as  an axis #abj and one half 
of ,no4 #b is wound in the same manner  
as the  first half of ,no4 #a4 ,the     
armature is moved #abj more and all of  
,no4 #c is  wound4 ,the armature is then
 turned back1 #abj on the shaft as an   
axis  and the remainder of ,no4 #b is   
wound4 ,lastly the armature is turned   
back  #abj more and the rest of ,no4 #a 
is wound4 ,they are bound by wires gg   

,fig4 #ac to hold them when rotating4   
,the object of this rather  complicated 
winding is to get the three coils equi  
distant from the  shaft in order that   
each coil will generate practically the 
same  current4 ,now as will be seen the 
overlapping wires will form a nearly    
spherical armature4 ,the armature is    
mounted on the shaft x as an axis  which
 extends far enough out from its        
bearings to put a pulley on the  end ,h 
and a commutator on the other end to the
 three parts of which  are fastened the 
three wires marked one1 two1 three1     
,fig4 #ac4    ,it has been urged that   
the repairs of this armature will be    
larger than  on any other armature4 ,if 
there should be a 8burnout0 it would    
necessitate the taking apart of the     
dynamo and sending the armature to  the 
factory to be rewound4 ,but it never    
burns out except through  positive      
carelessness and it will be found that  
the repairs on this  armature is less   
than on the armatures of its several    

powerful rivals  taken separately even  
though they be of simpler construction4 
,when the ,thomson-,houston armature is 
rotated between the cup-shaped          
fieldmagnets alternate currents are     
generated in each coil in turn and  now 
the next point to be considered is the  
,commutator      which incites the      
alternate currents so formed into one   
continuous  current4 ,the commutator as 
before stated is fastened on the shaft  
at the  end one1 two1 three ,fig4 #ac4  
,it consists of three copper plates in  
the  form of a cylinder each segment    
,a,a,a covering #aae of the dotted      
circle ,fig4 #ad4 ,they are screwed to  
rod ,,ccc and ,,ddd which are  insulated
 by wood and gutta-percha plates ,,ee   
from the iron mounting  ,e which is in  
turnescrewed to shaft by set screws     
shown4 ,the wires  one1 two1 three1 have
 respectively red1 white and blue       
insulation and  are put in binding posts
 ,,ddd marked one1 two1 three at the    
factory and  if not so placed may work  

badly4 ,the current enters ,d goes to   
,b,b  which there have direct contact   
with ,a4    ,illustration3      ,fig4   
#ad4    ,half ,sec4 ,a4,b4      ,fig4   
#ae4 ,air blast ,nozzles4      ,fig4    
#af4 ,air blast ,mechanism4      ,fig4  
#ag4 ,section of ,dynamos4    ,spherical
 ,armature in ,fig4 #ac4    ,now in a   
three-part commutator the spark         
occurring as the segments pass  under   
the brushes would very quickly destroy  
the surface and interfere  with the     
currents in the coil4 ,this difficulty  
is overcome by blowing  out the spark by
 an air blast given at just the right   
place and time4  ,the manner in which   
the blast is delivered is as follows3   
the segments  of the commutator    are  
separated by gaps of about #e and in    
front of each of the leading  brushes   
there projects a nozzle1 ,fig4 #ae1     
which discharges an air blast           
alternately three times in each         
revolution4 ,the blast itself is        
supplied  by an ingenious piece of      

mechanism known as the                  
,thomson ,air ,blast4      ,it consists 
of an elliptical box ,,ii whose sides   
have perforations ,,ii  where air can   
enter while inside of this rotates a    
steel disk keyed to  the armature shaft 
and having radial slots in which slide  
three wings  ,,rrr of ebonite which as  
they fly around drives air into the     
holes ,,jj  leading to the nozzles ,fig4
 #ae4 ,the result is that1 since the    
spark is  done away with1 oil can be    
supplied to the commutator in limited   
quantities but still amply sufficient to
 reduce the wear on the  commutator to  
such an extent that the life of a       
segment is greatly  increased4 ,the air 
blast is fastened to the dynamo frame   
just behind the  commutator and can be  
see in ,fig4 #bc4                       
,the ,field-,magnets1      as may be    
seen from ,fig4 #ag1 consists of two    
flanged iron tubes ,,aa  whose end      
consists of a convex segment of a sphere
 accurately turned to  recieve the      

armature4 ,coils of wire ,,cc which are 
in the outside  circuit and through     
which the entire current flows are wound
 upon the  tubes4 ,after the armature is
 placed between them the two tubes are  
bolted together by heavy wrought iron   
bars ,,bb and the whole carried on  the 
frame work ,,pn shown also at ,,pn ,fig4
 #bc4 ,now a little magnetism  only     
remains in the wrought iron bars and    
iron frame works when the  armature     
first revolves1 but the current even    
though slight1 going  through the coils 
makes an electromagnet out of each tube 
and heavily  magnetizes the wrought iron
 bars and in two or three seconds after 
the  armature first rotates it is       
entirely surrounded by a heavy magnetic 
field4 ,one of the good points of these 
field magnets is that but very  little  
magnetism is lost as compared with most 
other dynamos and since  it takes power 
to maintain a heavy magnetic field1 this
 dynamo is in  this respect very        
economical4                             

,the ,thomson ,regulating ,gear         
,later on we will show that pushing the 
brushes together or pulling them  apart 
alter the strength of the current1 but  
for the present just accept  the fact   
and we will show how the brushes are    
varied4 ,it is accomplished  by the     
mechanism shown in ,fig4 #ah4 ,the      
brushes are fixed to the levers  ,,yy   
and ,y#b,y#b united by the lever l4 ,the
 automatic movement is  obtained by the 
electromagnet ,r while a dashpot ,j     
prevents too  sudden motion4 ,suppose   
the brushes to be in the position shown 
when the  current would get too strong  
owing to lights being cut out4 ,the     
electromagnet ,r getting stronger would 
raise ,a and reduce the current  taken  
off until current came to normal4 ,if1  
instead1 some lamps were  thrown in the 
current would become weak and the       
electromagnet ,r would  become weak1    
drop ,a which would increase current and
 this will continue  till current       
reaches normal4    ,the foregoing       

regulating gear is used on small dynamos
 and old style  large ones4 ,on the     
large new style dynamo a more delicate  
regulating  gear is used1 the current   
which operates it being shown at ,fig4  
#ai4  ,normally the electromagnet ,r is 
short circuited by the wire r and  only 
acts when this circuit is broken4 ,at   
some point in the main circuit  is a    
wall controller or controller magnet    
shown in ,fig4 #ai1 at ,,st1  consisting
 of two electro magnet1 ,their yoke     
supported by a spring and  the yoke     
operating the contact lever ,s4 ,if the 
current becomes too  strong the         
controller magnet circuit is broken and 
all the current of  the main circuit    
goes through the electromagnet ,r which 
by its sudden  increase of strength     
quickly raises ,a and thus alters the   
brushes4  ,this only exists for a moment
 until the yoke of the controller magets
  fall because of their decrease of     
magnets strength1 when current again    
flows through wire r because when yoke  

drops contact is made4 ,this  decreases 
the strength of electro magnet ,r thus  
dropping ,a and  increasing current4    
,hence ,s will again raise and break    
contact and ,r  again rais ,a4 ,this is 
continually repeated4                   
,the ,brushes1      of which there are  
four in use on all machines1 are made of
 a broad  strip of springy copper having
 six slits two thirds the distance up1  
and  thus touching at several points4   
,they are held by clamps shown at ,fig4 
#bc which also shows the brushes4 ,the  
brushes are held to the commutator  by  
their own springiness and the variation 
of position due to strength  of current4
 ,the brushes are set by a gauge sent   
with each dynamo which  shows length    
from the end of brush to the holder4    
,the holders are set at  the correct    
angle by a gauge of brass of the shape  
of a right angled  triangle the short   
side having a wide flange curved to fit 
the  commutator for which it is sent1   
while the second side as regards length 

must fit to the holder when swung to it 
on the commutator as an axis4    ,after 
describing the details of the dynamo1 we
 will at once proceed to  find how the  
,thomson ,houston ,dynamo ,operates4    
,in the diagram ,fig4 #ai the rotation  
is as in practice against the hands  of 
the watch when seen from the commutator 
end of shaft4 ,the three coils  of the  
armature are represented by three lines 
,a1 ,b1 ,c1 united at  their inner      
extremities each being joined to a      
segment of the  commutator4 ,there are  
two positive brushes ,p and ,f and two  
negative  ones ,p and ,f4 ,the current  
delivered to ,p and ,f goes round one   
of the field magnet coils1 then to the  
outer circuit consisting of  regulating 
gear1 lamps1 motors1 etc41 through the  
other field magnet  coil to brushes ,p  
and ,f4 ,now from ,fig4 #bj1 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  
loops4 ,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 m4 ,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 back4 ,applying ,fig4 #bj to ,fig4
 #ai1 we see that there will be an      
outward current in ,b1 an inward one in 
,c1 ,a generating no current  for that  
moment4    ,now the following pair of   
brushes ,f ,f are shifted backward three
  times as far as ,p ,p is shifted      
forwards4 ,when the current is the      
greatest possible the brushes ,p and ,f 
and ,p and ,f are #fj apart thus        
leaving ,p and ,f and ,p and ,f just    
#abj apart and since the  segments of   
the commutator are each #abj in length#c
 there will always  be two coils in     
parralel with one another and in series 
with the third4  ,taking one sixth of a 

revolution and continuing all the way   
round we  find the following tabulated  
statement showing brushes in contact    
with  coils1 to be true viz3--          
,p - ,c     ,p    ,from external circuit
             ,b       to external       
circuit                              ,f 
- ,a     ,f                             
,p      ,p - ,b     0      8        0   
,a            0    8         0          
,f      ,f - ,c                         
,p - ,a     ,p     0      8        0    
,c        0    8         0              
,f - ,b     ,f                          
,p     ,p - ,c     0      8        0    
,b            0    8         0          
,f     ,f - ,a                          
,p - ,b     ,p     0      8        0    
,a        0    8         0              
,f - ,c     ,f                          
,p     ,p - ,a     0      8        0    
,c            0    8         0          
,f     ,f - ,b       ,now suppose the   
current to become to strong owing to any
 cause1 the  following brushes are made 

to recede4 ,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 coil4 ,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 current4 ,the motion 
of advance and retreat of the brushes is
  accomplished by the ,thomson          
,regulating ,gear before described4 ,on 
,fig4  #bc can be seen all the dynamo's 
details except the ,controller magnet4  
,illustration3      ,fig4 #ah4          
,fig4 #ai4      ,fig4 #bj4      ,fig4   
#ba4      ,fig4 #bb4    ,as regards the 
,thomson-,houston ,dynamo it will be    
found to produce the  steadiest and most

 uniform current of any dynamo now in   
use4 ,it  regulating gear is the        
simplest and most natural one ever used4
 ,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 alone1 in practice4     
,fig4 #bc4                     ,your    
engraving representing 8,dynamo         
,electric ,machine with ,thomsons       
,spherical                 ,armature0   
--,taken from one of your catalogues1   
and                 pasted on a sheet of
 this paper--    ,in a system the most  
important thing next to the dynamo is   
the lamps4  ,the first experimenter who 
produced an electric glow was ,otto von 
,guericke4 ,but neither the glow nor    
electric spark have been used to        
produce electric light for practical    
purposes1 this was left to the  voltaic 
arc on the one hand and the incandescent
 lamp on the other4 ,davy  in #ahjj     
mentions experiments in which electric  

light was obtained by  electric sparks  
between two carbon points4 ,he showed   
the arc#d light  for the first time in  
#ahaj at the ,royal ,institute1 which   
with ,foucalt's  hand regulator 7#ahdd7 
,deleuil lit the ,place de la ,concorde1
 ,paris4  ,thomas ,wright in ,london    
7#ahde7 devised the first apparatus     
which  automatically adjusted the       
carbons4 ,w4 ,c4 ,staite used the       
electric  current for the regulation of 
the carbons in #ahdh4 ,in #ahee ,serrin 
constructed a lamp which would have been
 used on a large scale had it  not been 
for the cost of generating electricity4 
,in #ahgf ,paul  ,jablochkoff invented  
his electric candles and in #ahha there 
were #djjj in  use1 but as their use    
increased their defects were found out4 
,regulated  lamps were again brought    
into use and with them experimenters    
again  endeavored to solve the problem  
of dividing the electric light4 ,in     
#ahgg  ,tschikoliff solved the problem  
in a very simple manner4 ,he reasoned   

that1 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 reunited1 the current may be
 divided any number of  times and the   
scheme work nicely4 ,when put in        
practice it worked very  nicely and is  
used on most lamps at present4 ,suppose 
there be a lamp  placed in the circuit4 
,the current divides and the larger half
 goes  through the carbons1 as here     
there is no resistance as the carbons   
touche1 while the remainder1 going      
through a spiral of high resistance1  is
 small4 ,when the carbons burn away a   
little the arc is formed and the        
resistance increasing brings the        
regulating gear into operation4 ,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      

other1 hence any number of lamps may go 
on in series1 depending only  upon the  
tension of the current4    ,incandescent
 lamps were produced as early as #ahei  
but not till #ahgi when  ,swan1 ,edison1
 ,sawyer and others were they ever in a 
practical form4 ,the  first glow lamp   
,edison constructed had platinum wire to
 be heated4 ,he  however examined the   
properties of organic substances and    
finally fixed  on bamboo fibre4 ,the    
bamboo is divided into fibres one       
millimeter in  diameter and twelve      
millimeters long4 ,these fibres are     
pressed in  ,u-shaped moulds and baked  
in ovens where they are allowed to      
become  carbonized4 ,the carbonized     
filament is attached to platinum wires  
which  are fused in a glass vessel from 
which the air has been exhausted4 ,we   
will speak more fully of the            
incandescent lamp when describing the   
,thomson ,houston ,system's incandescent
 lamp4    ,the ,thomson ,arc lamps was  
used by the ,thomson ,houston ,system   

since its  begining till about two years
 ago when they stopped manufacturing    
them1  only furnishing broken parts4    
,the arc lamps at present used is       
,the ,thomson ,rice ,arc ,lamp4         
,they are manufactured in two styles the
 single lamp used for stores1  buildings
 etc41 and the double lamp used for     
street service1 all night  work1 etc4   
,the light is produced by the voltaic   
arc between two carbons1  the negative  
pole or lower carbon burning away about 
half as fast as the  positive pole or   
upper carbon4 ,the outside view of the  
single lamp is  seen in ,fig4 #ba and of
 the double lamp in ,fig4 #bb4    ,the  
regulation of the double lamp is        
diagramatically shown in ,fig4 #bd1     
which is a plan of the lamp with cover  
removed1 showing only a plan of         
cylindrical part of the lamp4 ,the wires
 marked a b c d run along the  top in   
order to be out of the way4 ,in ,fig4   
#bd the current comes in at  the binding
 post and is at ,a divided into three   

currents ,a1 ,b1 and  ,c4 ,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  
i1 it goes  out wire a to binding post  
,b4 ,this only continues a moment until 
the  current b which goes through the   
carbons and at the start has almost  no 
resistance offered it1 attracts the yoke
 ,i thus breaking contact of  curcuit a 
until the current ceases or till both   
carbons burn away1  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 shown1 thus 
making contact of circuit  a1 and since 
current a has little resistance as      
compared to b or  c most of the current 
goes through it1 thus practically making
 a  cut-out4 ,the current b goes round  
the electro-magnets h and i1  then to   
the 8bed0 through screw ,j1 the 8bed0   
being a cast iron bottom of  the        
cylinder ,e ,fig4 #bb4 ,from the bed it 

goes down carbon holder ,c  7or ,h7     
through carbons and arc to frame bed ,a 
,fig4 #bb4 ,from there it  comes up a   
wire by the side of frame ,c ,fig4 #bb  
and joins other  currents at ,b4 ,the   
third current a goes through            
electromagnets j  and k and joins other 
currents at ,b4    ,this is when switch 
,f ,fig4 #bb and ,m ,fig4 #bd1 is turned
 on4 ,now since  the dynamo will        
regulate all differences in current the 
lamps can be  turned on or off at will  
by any one4 ,this is accomplished at the
  lamp by turning off the switch4 ,when 
the switch is turned off1 the  current  
goes through d to screw ,k which is then
 touched by metal ,l  7in contact with  
binding post ,b and worked by ,m74      
,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 circuit4    ,now as to  
the regulating gear4 ,the two carbon    
holders are held up1 ,h1  by clutch     

operated by springs 7not shown7 till end
 ,n of lever ,,on is  permanently held  
down1 and ,c1 by the raising and falling
 of yoke ,d4  ,there is only one arc    
burning at a time in a double lamp and  
the  so-called positive carbon ,c burns 
first4 ,when the lamps are trimmed  the 
switch is first turned off the carbons  
put in and the switch  turned on4 ,this 
will draw the upper carbons up about a  
quarter of an  inch4    ,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           
resistance4 ,the electromagnets j an k  
attract ,d which lets loose  ,c1 which  
falls to lower carbon1 and the          
resistance being almost  nothing1 most  
of the current goes through b4 ,this    
weakens j and k  which lets ,d up while 
,d takes ,c up with it thus establishing
 the  arc4 ,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 
8bd10 which it was not in before4       
,after a short time the carbons burn    
away1 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 c4 ,this makes the          
electro-magnets j and  k strong enough  
to draw ,d to them in spite of spring   
,q4 ,when ,d  is attracted by j and k1  
,c 7or ,h7 falls and again the arc      
lengthens1 always being kept about      
#c_/cb inch long4 ,this is frequently   
and continually repeated1 the delicacy  
depending upon the strengh of the       
spring ,q as compared to the            
electromagnets strength4                
,illustration3 ,fig4 #bd4    ,when the  
carbon in carbon holder ,c burns to a   
length of about two  inches in          
attempting to fall to maintain arc's    
length1 an enlarged port  at the top of 

the carbon holder ,c strikes and holds  
down lever ,,on  pivoted at ,o 7and end 
,n held up by a spring ,p7 thus letting 
loose  a clutch by which electrical     
contact is made between ,h and 8bed0 and
  letting ,h fall till it touches lower 
carbon when an arc is established  and  
regulated just as for ,c4    ,the       
,thomson-,rice single lamp has the same 
gear with the exception of  having only 
carbon holder ,c1 ,h1 lever ,,on1 and   
spring clutch and  spring ,p being      
absent4 ,the single lamp will burn eight
 hours and the  double lamp fourteen    
hours continuous running4    ,these     
lamps are intended only for a steady    
current and will not cut out  of circuit
 if the current gets too strong4 ,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 better4 ,as   
the ,thomson-,rice lamp has  less       

functions and power consuming machinery1
 it can but be the most  economical1    
delicately adjusted and steadiest lamp  
extant4 ,they are made  to stand a      
current of five amperes above the normal
 current for a short  time1 as1 when    
forty lights are simultaneously cut out 
of a forty-five  light circuit1 the     
current runs up about four amperes above
 the normal  current for about one half 
a minute4    ,prof4 ,thomson has gotten 
out a divided arc lamp which supplies a 
light  of moderate candle power for     
locations where a #bjjj candle power    
lamp  gives more light than can be      
economically utilized4 ,it is specially 
suited for factory and mill use where   
looms or other tall machines are  liable
 to cast disadvantageous shadows4 ,it is
 said that these lights are  supplied   
cheaper per candle power than the       
standard lamp and up to date  is        
sucessful4    ,he has also arranged     
apparatus by which arc lamps are run in 
multiple  series1 series or multiple    

arc4 ,it is said that divisions1        
redivisions  and reunions are           
practicable4 ,this is also sucessful as 
far as we can  find out4                
,the ,sawyer-,man ,incandescent ,lamps4 
,as before stated ,edison fixed upon    
carbonized filament of bamboo4 ,the     
,sawyer-,man company however applied for
 a patent on carbonized filament  for   
incandescent lamps on ,january #aith    
#ahhj1 and after five years  litigation 
with ,thos4 ,a4 ,edison they were       
granted a patent ,no4 #cag1fgf1  on ,may
 first1 #ahhe1 covering their invention4
 ,the ,sawyer-,man lamp ,fig4  #be1     
consists of a carbonized connected to   
platinum wires fused in a  glass tube   
from which all the air possible had been
 extracted4 ,the light  is produced by  
the glow of the filament and heat of    
gases given from  filament4 ,the life of
 a lamp is from #ajjj to #aejj hrs4 and 
requires a  current of #a to #a4c       
amperes and give #bj to #be ,c4,p4 ,when
 the filament  becomes brittle and      

breaks the tube is unscrewed from the   
key ,fig4 #bf1  and a new one screwed   
in4 ,they are run on the arc light      
circuit by the  use of an individual    
distributor ,fig4 #bg 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 ,fig4 #bf4 ,the scheme of        
arranging lamps so as to get the right  
current is shown at ,fig4 #bh4 the      
number of lamps in a group depending on 
the current4    ,prof4 ,thomson has     
gotten out a lamp ,fig4 #bi in two      
styles one for #f4h  amperes current and
 one for #aj amperes current4 ,three    
lamps of different  candle power1 due to
 different potential differences at     
binding post of  lamp1 are use on the   
same current4 ,the method of connecting 
them is  shown in ,fig4 #cj4 ,it will be
 perceived that the lamps carry the full
  current yet have a life of #ajjj hrs4 
or more4 ,this is a great invention     

indeed doing away with a great loss of  
power due to high resistance  coils4 ,it
 will be noticed however that a #abe    
,c4,p4 incandescent lamp uses  as much  
energy as a #bjjj ,c4,p4 arc light1 the 
#fe ,c4,p4 lamp one half as  much and   
the #cb ,c4,p4 lamp one fourth as much4 
,general ,remarks      ,the ,thomson    
,houston system also furnish lightning  
arresters1 ammeters1  hanging boards1   
switchboards1 hoods1 insulators1 lamp   
arms1 etc1 but1  though in some respects
 many of these miscellaneous articles   
are  ingenious and novel1 yet they are  
not distinctive of the ,thomson ,houston
  or any other system4 ,be it said      
however that all these articles fill    
their proper places4 ,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 it1 it must   
remain undescribed as far as this thesis
 is concerned4    ,after describing all 

the parts of the system it may be       
interesting to  know how a plant is     
arranged4 ,the last plate is a          
photograph of the  ,la,fayette ,gas     
,company's ,plant of the ,thomson       
,houston ,system taken at ten  oclock   
one night4 ,it shows the engine1        
dynamos1 the wall controller on  the    
left wall1 and a view of the lamps which
 had hoods put before them  to prevent  
the polarization of the negative4    ,on
 the accompanying page will be found a  
table showing experiments with  an old  
style dynamo given ,purdue ,university  
by the ,thomson ,houston  ,company1     
which dynamo is now in the engine house 
of the ,mechanical ,hall4               
,experiments with ,three ,light ,t-,h4  
,dynamo ,no4 #gi      ,the dynamo was   
run by a large pulley 7about four and   
one half feet in  diameter7 on the same 
shaft as the fly wheel and beside the   
latter4 ,two  lamps were put in circuit 
with a ,deprez-,carpentier ammeter and a
 volt  meter of the same make was put in

 between the brushes4 ,first one lamp   
7old ,thomson style7 was switched out of
 circuit1 the dynamo started and  when  
speed was reached the circuit made4 ,the
 following readings were  taken when the
 engine made #aci  the dynamo #aabb     
revolutions per minute4                 
----------------------------------------
----------------------                  
,one ,lamp  ,two       ,when #bnd       
,when #bnd                              
,lamps     lamp was       ,lamp was     
,readings                       switched
 in    switched out       ,at ,end of   
----------------------------------------
-------                                 
,amp4,volts,amp4,volts ,amp4   ,volts   
,amp4  ,volts                           
----------------------------------------
------------------    #a second   #aj   
#ee   #aj  #aaj   #f4g    #ee      #ad  
#aaj       #cj  0      #aj  #ee   #aj   
#aaj   #aj     #ge      #aj     #he     
#b ,min      #aj  #ee   #aj  #aaj   #aj 
#aji      #aj     #fj       #c   0      

#aj  #ee   #aj  #aaj   #aj    #aaj      
#aj     #ee                             
----------------------------------------
------------------                      
,fig4 #be                consisting of  
drawing of ,sawyer ,man lamp cut from   
catalogue1 and trimmed to contour of    
drawing                                 
,fig4 #bf                a drawing      
showing action of key in ,sawyer ,man   
lamp1            cut to contour         
,fig4 #bg                a drawing of   
the ,thomson ,rice ,individual          
distributor            cut from cataloug
 and pasted in4                         
,fig4 #bh                a drawing cut  
from pamphlet showing 8,method of using 
,thomson ,rice ,individual distributor0 
,fig4 #bi                a drawing cut  
from pamphlet showing 8,prof4 ,thomsons 
incandescent lamp--series incandescent  
lamp0                                   
,fig4 #cj                ,drawing       
showing 8method of using the ,series    
,incandescent ,lamp manufactured by the 

,thomson-,houston ,elec4 ,co40 cut from 
your pamphlet            and pasted on a
 similar sheet4                         
------------------------------------    
,a photographer of ,la ,fayette photoed 
the ,gas            ,company's plant of 
,t  ,h in this city one evening at      
#aj o'clock when several lights were    
burning in room4            ,i had a    
large one printed and pasted on a piece 
of            bristol board of the same 
size as this sheet1 and            put  
in my original copy4                    
,footnotes      -----    ,footnote #a3  
,the foregoing statement is quoted from 
,dr ,urbitzkany's work    8,electricity 
in the ,service of ,man40    ,footnote  
#b3      ,gravity does not enter1 as a  
current is generated in lowering ,a4    
,footnote #c3      ,each segment is     
really only #aae 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 described4    ,footnote #d3       

,an arc light is a light produced by the
 use of the voltaic arc1 which    is    
made by the sparks passing between two  
poles of a powerful battery    which are
 brought together and then seperated a  
little4                                 
----------------------------------------
--------------------------------        
,transcriber's ,note      ,the source   
for this e-book was a hand-written      
thesis4    ,footnotes have been moved to
 the end of the book4    ,the captions  
for ,figures #bc1 #be1 #bf1 #bg1 #bh1   
#bi and #cj are reproduced1  however1   
the original drawings were not bound    
with the published thesis  and are      
therefore not part of this e-book4      
,the author's spelling has been         
maintained1 ,some standardization of    
punctuation was done to improve         
readability4    ,the following proper   
names as used by the author are         
reproduced here  with their more        
commonly used spelling3                 
,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           
underscores4 ,some standardization of   
these  was also done particularly with  
regard to the presentation of           
illustration captions4