Sherlock Holmes and the Adventure of the
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                          Cathode Ray Tube
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                         Timothy Paul Smith
                       Department of Physics
                     University of New Hampshire
                         tim.smith@unh.edu
 
                      (received May 20, 1997)
 
	In glancing through my somewhat stochastic memoirs of case which I 
have had the good fortune to be involved in, a few of which I have been able 
to put before the public, I came across one case what was trivial at the time, 
 but later opened doors on a most singular and interesting investigation.  In 
the original case Holmes had sent the authorities after the critical evidence 
and the miscreant with in twenty minutes of hear the story,  but the threads 
which emanated from that case reached far beyond the scope of these little 
monograms.  The case also presented a side of my worth colleague which I had 
not full appreciated before.  I thought that he had no use for the sciences if 
there were not the science of criminology.  The readers of these chronicles 
may recall an adventure in which I tried to enlighten Holmes about the 
distance to the moon.  He had told me thanks,  but no thanks -- and explained 
that the brain was like an attic in which,  if cluttered with worthless 
information,  all was lost.  After this, I assumed that he had a most limited 
interest in science.
 
	It was a boisterous evening in the very early spring of 1897.  Mrs. 
Hudson had brought a cold supper into our chambers on Baker Street, and I had 
no desire to go out and prayed that all of my patients had the good sense to 
stay healthy and avoid my attendance.  At St. Jame's Hall the orchestra was 
perform some heavy and tedious piece by Wagner which I was happy to miss. But 
I had expected my friend,  who has an ear for the German muses, to brave the 
elements and be in attendance of the teutonic giant.  However my colleague had 
taken upon himself the task of updating his vast catalogue of the activities 
of criminal world of London,  pasting newspaper report and private letters 
into one of his numerous leather bound notebooks.  Perhaps it was the 
suggestive powers of seeing my friend at work,  for soon I found myself at my 
writing desk pouring over the notes I had kept concerning some cases we had 
recently drawn to a satisfactory conclusions.  I was working through my notes 
on a case concerning a glass blower when I come to a point in my companions 
reasoning what I did not fully understand.
 
	I pushed my chair back and turned to watched Sherlock, who was bent 
over some newspaper spread in front of the fireplace.  "My dear Holmes",  I 
broke the long silences of our chambers,  "there are one or two points of our 
recent case which I do not think I completely understand."
 
	Holmes cast aside the copy of "The Times" which he had just started to 
cut up.  The evening had been a long one for him too,  filled with only 
necessary, but menial labor.  He rose from the floor and settled himself into 
the corner of our sofa then turned to me with a suggestion of a smile.  
"Please Watson,  ask away -- I am all ears."
 
	I paused to form my question,  and then realized that it was truly 
part of a more general question about the way he performed all of his 
investigations.  "Holmes,  I like to think that I can divide our cases into 
two categories.  There are cases,  like the one last month,  where an 
examination of the scene of the event was, in itself, enough to lay bare all 
the mystery to you."
 
	"You are eluding to the ladies bag in St. Regent Park?"
 
	"That was such a small case", I replied,  "no I was thinking about the 
murder of the tugboat captain along the promenade."
 
	"That murder really was a trivial case -- the only mystery there was 
why Inspector Lestrade could mistake that handkerchief as belonging to a rowdy 
fan of Queen's Park Rangers when it was clear from its deep hue,  that it 
belong to the uniform of the S. S. Athena."
 
	"Perhaps he has not had the opportunity to move in the same circle of 
ocean liners and world travels that you have had?" I defended our friend from 
Scotland Yards.
 
	"Actually it was my hours spent around those fields where 
championships are contested which gave me the necessary particulars",  Holmes 
let a little smile escape for but an instance.  "Now the case of the ladies 
handbag was a hundred times more interesting.  For as you stated,  all the 
necessary information to identify the owner was contained with the bag itself. 
 The return ticket to Wimbledon,  the handbill from one of Lipton's 
representatives,  the telltale hand cream with but a whiff of aloe and the 
bent silver spoon.  Each clue pointed to several hundred candidates,  but the 
convolution of the data uniquely identified Miss Jamie White."
	
	In that case my friend had exhibited a more human side then I was 
aware of him possessing.  He had spent nearly a whole day tracking down a 
child to return an old, wore, two shilling handbag.
 
	Holmes eyed me as if he read my mind.  "It wasn't the importance or 
value of the handbag.  It was the challenge of seeking out of this city of a 
million souls, one who had left a seemingly unidentifiable trinket."
 
	"And to be repaid by the undying gratitude of a small child?" Holmes 
let my question pass.
 
	"But what is the other category of cases?" he asked me.
 
	"I am thinking of cases where the evidence at the scene doesn't 
completely identify the culprit.  The cases where even after a detailed 
inspection of all available data we still need something more to solve the 
case."
 
	"Ah yes,  the more scientific cases," said Holmes and he rose up to 
search for his tobacco and pipe on the mantle piece.  While he hunted for the 
slipper where he stowed his special blend I puzzled over what he meant by 
`Scientific'.  "As you have aptly pointed out, in these cases we many know 
many things about the crime,  and perhaps even the criminal,  but we are not 
at an end."
 
	"So, the crux of my question -- the one which prompted me to interrupt 
you ten minutes ago -- is this.  When the deductive process,  for which you 
are so famous,  comes to an end,  logically speaking,  what takes over in the 
reasoning of the investigator?"
 
	Holmes eyes twinkled, "Science my dear Doctor, science.  As a medical 
man you know the methods -- but refuse to see criminal investigation in the 
same terms as the tools of your own practice.  Tell me Watson,  when a patient 
arrives with a mysterious aliment and a preliminary examination can not reveal 
the true cause,   think of a case where a variety of conditions would give 
rise to the same symptoms,  what do you do?"
 
	"Well", I begun,  "that of course depends on the particular symptoms 
and the relative risk involved, but I would try to perform some type of test."
 
	"Yes,  that is the scientific method, at least in part.  The aliment 
might be the Tasmanian flu,  or too much Turkish delight.  Starting with the 
flu hypothesis,  you realize that the such-and-such blood test will confirm 
the hypothesis.
 
	"It is the same in my criminal investigations.  I will construct 
several working hypothesis about the events which may have lead up to the 
crime and the physical evidence which we are presented with.  It is then my 
task to reason what additional evidence each hypothesis might also generate.  
But this is the key to constructing a test.  An arbitrary piece of evidence 
may not distinguish between two hypothesis.  A good test looks for the 
evidence which can eliminate or promote a hypothesis."
 
	I thought about this,  then raised the case of the glass blower.  "Now 
in our recent case with regards to the glass blower and the cathode ray tube 
-- I think it was called -- there were two hypothesis.  First that the 
laboratory assistant,  Mr. Giles,  had made off with this unique apparatus.  
Second that the glass blower, a Mr. Goseberg,  had never produced the device.  
I believe that I was ready to search the room of Mr. Giles,  whereas you 
guided us to the glass furnace and pronounced that Professor Thomson had been 
swindled by the blower,  and not that his confidant had betrayed him."
 
	Holmes nodded, "That is a perfect example, for if we had founded Mr. 
Gile's room empty we would only have tested the hypothesis that he had stolen 
the apparatus _and_ hidden it in his own chambers.  True, if we had found it 
things would have gone hard with the young assistant.  But by examining the 
glass furnace, which Mr. Goseberg assured us had been fired at great expense 
and inconvenience for the sole purpose of this cathode ray tube,  we could 
distinguish between the rival hypothesis."
 
	After a few moments contemplation I added, "It seems somehow 
impossible that Mr. Goseberg is held at Her Majesties Goals on the evidence of 
a thin layer of dust on the portal of a furnace."
 
	Holmes smiled, "Do not underestimate the weight of the evidence merely 
because the mass of it substance."
 
              *    *    *    *    *    *    *
 
	The next morning I preceded Sherlock to the breakfast table.  While 
sipping my coffee I sorted through the pile of letters Mrs. Hudson had brought 
up from the early post.  Most of the letters were of the most ordinary type.  
But one letter struck me as most singular.  It was address to Holmes in a very 
strong hand.  It was postmarked Cambridge,  and made of a ridged,  but smooth 
paper stock.  My curiosity was aroused and I set upon the ways of my friend.  
The was no return address,  which could have meant someone was trying to 
conceal their identity,  or perhaps was too busy for such a detail.  I knew 
that Holmes was a Cambridge man,  but I was quite certain that if the old 
college was calling upon him there would have been a proud crest and return 
address.  But the writing of Baker Street itself was so strong,  there had 
clearly been no attempt to disguise the handwriting.
 
	At that moment Holmes walked into the room.  I held the letter up to 
him and said,  "I believe Professor Thomson for you."
 
	Holmes took the letter,  turned it over and examined it carefully,  
then looked back at me,  "I think perhaps my little methods have rubbed off on 
you."
 
	"They're contagious", I replied.
 
	He torn open the letter and quickly read its content.  "The good 
professor would like to show us his apparatus now that it is fully functional. 
 I believe it is meant as some type of gratitude for the odd consultation we 
were able to render to him."
 
	My patients had all maintained their health that day and I was without 
obligations.  Holme's practice was also experiencing a lull,  so a hour later 
we found ourselves passing through the arches of that wedding cake-like folly 
of a train station - St. Pancras.  Ten minutes later we were northbound on a 
train to Cambridge.
 
	As we left London the sun came out and the agricultural expanse of 
Green England glided by the window of our carriage.
 
	"My dear Doctor",  said my companion without looking away from the 
rising and failing telegraph wire which stretched from pole to pole just 
outside our window,  "I must confess that I am more then unusually ignorant 
about the research of Professor Thomson.  Now I have noticed you thumbing the 
pages of "Nature".  Perchance can you relieve my ignorance before our 
forthcoming interview?"
 
	I closed my eye and tried to compose a reply.  "The chief point of 
Thomson research his been geared towards answering the question as to what a 
cathode ray is."
 
	"Oh but isn't that old stuff?",  exclaimed Holmes. "In one of these 
glass chambers the voltage between two probes is increased to the point of 
discharge.  At that stage there appears some sort of greenish-yellow glow on 
the glass.  But we have all known about this a quarter of a century or more."
 
	"We have known how to make this `glow' for a long time.  But we still 
do not really know what causes that glow.  Which is not to say people don't 
have ideas,  and haven't leaned a great deal about them.  For instance, they 
can cast shadows,  which makes one think that they might be some type of 
special charged molecules which travel or steam in a straight line.  That 
seems to be the British point of view."
 
	"I take it that the case is not conclusive?" asked Holmes.
 
	"Well,  the case has a great many problems.  For starters the cathode 
rays travel further through air then anything so large should travel,  even if 
it was as small as those most fundamental of particles -- the atoms.  So the 
Germans have proposed some sort of wave explanation.  Light waves,  which we 
are familiar with,  travel essentially in straight lines,  but I do not 
understand this wave-theory beyond that."
 
	I thought I had exhausted the subject but Holmes continued to probe 
me.  "Let us return to this `charged molecule theory',  surely we could 
construct a test of such a theory."  I could see him thinking hard.  Perhaps 
there are non-criminal puzzles which could amuse my companion?  "For explain,  
and perhaps I reach beyond by specialty,  but if you coil up a wire which has 
a charge passing though it you get a magnet.  Undoubtedly you could do 
something like that with cathode rays?"
 
	"These scientist are nearly as clever as you,  and they have made this 
area their specialty",  I smiled.  "Actually what they ended up doing was 
passing the cathode ray through a magnetic field and seeing how it coils up or 
is deflected.  But here the results only add confusion.  First the deflections 
they measure are consistent with cathode rays having a mass more then a 
thousand time smaller then a lightest atom.  But the really nemesis is that 
one should also expect a deflection due to an electric field -- and none is 
seen."
 
               *    *    *    *    *    *    *
 
	By noon we had arrived in Cambridge and soon found ourselves at the 
great oak doors of the Cavendish Laboratories.  On the left hand side of the 
archway was carved the coat of arms of the Duke of Devonshire,  the crest of 
the Cavendish family.  On the right hand side the arms of the University,  and 
across the center, *Cavendo tutus*.
 
	"`Safe by being cautious'",  translated Holmes.  "I remember that it 
is the Cavendish family motto,  but I do hope our friend the Professor doesn't 
feel bound by it."
 
	A porter lead us through a hallway and up the central four-sided 
stairwell.  Just then a lecture was being dismissed and Holmes and I quickly 
stepped out of the way less a wave of undergraduates would wash us down the 
stairs and carry us back out into the street.  The porter left us in Professor 
Thomson's office,  and in a few minutes the great man himself joined us.  He 
surprised me as to how young he was,  a mere forty-one years old and already 
he had spent over a dozen years administering this University Laboratory.  He 
was a man of youthful energy,  despite his hairline receding around his 
temples.  He wore small wire-rimed glasses and a large bushy mustache.  Under 
his arm he carried  notes from his recent lecture,  and his hands were still 
white with chalk.  He smiled at us.
 
	"My dear Mr. Holmes and Dr. Watson!" holding out his chalk covered 
hand,  and then retrieving and cleaning it before shaking ours.  "I do hope 
that I have not brought you up from town on false pretenses."
 
	"Professor,  you merely mentioned your curious investigation with this 
glass apparatus," Holmes reminded him.
 
	"Please,  after what you have done for me call me J. J.  .  Of course 
my investigation is not in the criminal line.  However,  it really is most 
intriguing -- if you have a mind that is bent that way."
 
	Holmes smiled,  "Professor,  I was under no elusions as to your 
requiring our professional guidance.  It just so happened that the good Doctor 
and I needed some country air.  Also, on our way up from town Dr. Watson has 
been so good as to refresh my memory as to this particle-molecule vs. 
aether-wave cathode ray controversy. A most curious problem  -- the evidence 
has seemed to exclude all theories.  But of course it really mustn't."
 
	J. J. seemed to be on the verge of bursting with pride.  "Let me show 
you something new."  He lead us through a series of laboratories were students 
of variously levels were working with the most curious apparatuses.  I had 
been use to medical laboratories,  and even the apparatus of Holmes chemical 
analysis,  but these bristled with wires and pipes of every imaginable type.  
Throughout our walk J.  J. continuously paused to exchange a few brief 
comments with his students,  suggestion for the undergraduates,  question to 
the advance students and fellow scientist.  Finally he ushered us into his 
private laboratory.  On the beach was a round glass sphere with various glass 
bumps as well as numerous electrical probes and plates embedded in it.
 
	"The glass not blown by Mr. Goseberg", commented Holmes.
	
	"Yes,  that is right.  After you pointed to the problems with Mr. 
Goseberg we were eventually able to find a superior glass blower.  As you can 
see the requirements were most peculiar and exacting.  This little wire,  
which looks like the filament of a light bulb, is the cathode.  If my view of 
these particles or `corpuscles' as I like to call them, is correct,  we 
essentially boil the corpuscles off the wire."
 
	"Why do you call then `corpuscles'?" I asked.
 
	"It is just that the other popular term is `charged molecule',  and 
since we know what molecules are it sounds like we know more then we really 
do", answered the Professor.  "Here we have a plate towards which the 
corpuscles,  or waves, as Professor Hertz contends, move.  That part of the 
apparatus is essential the same on any cathode ray tube anywhere. [Editor's 
Note:  It is also essentially the same as the back of a television tube,  or 
the screen of a standard (not flat) computer monitor. - TPS] Beyond that 
section we start to do a few interesting things.  For instance,  if we let the 
cathode rays or corpuscles pass through a magnetic field they are deflected 
and we can determine the charge-to-mass.  Since we can also do this with ion,  
we know that the mass is over a thousand times smaller then that of an atom."
 
	"That is simply incredible!", I exclaimed.
 
	"This would explain why they can penetrate things so well", noted 
Holmes in a slightly more sober tone -- although he too seemed to be 
delighted.  "A most noteworthy discovery Professor!"
 
	"Alas I can take no credit for that.  Authur Schuster up in Manchester 
has known this for a decade.  Of course this is only true if cathode rays are 
matter and not waves.  But there has always been the objection that the rays 
are deflected in magnetic fields,  but not electric fields."
 
	"I see that your newest cathode ray tube has coils for a magnetic 
field,  as well as plates for an electric field", noted Holmes.
 
	"I didn't realize that you were so well versed in the ways of 
electricity", I commented.
 
	"You will remember the case of the telegraph operator and the arson,  
I made it a point to learn a few rudimentary points."
 
	J. J. smiled and continued,  "Yes,  our new tube not only has the 
potential for electric field studies,  but it has seen those predicted 
deflections!  It now seems ridiculously simple.  But all we did to improve 
things was to highly exhaust our tube,  to create a better vacuum in it."
 
	"So simple",  I muttered.
 
	"Do not take it too hard Professor,  after I have explained a case 
which appeared to have no solution to my companion he often retorts with those 
same word",  added Holmes.
 
	"Yes it really was so simple.  Apparently the passage of the cathode 
rays though a gas tended to ionize that gas and produce a flow of ions in the 
other direction which shielded the cathode ray from the effects of the 
electric field",  J. J. explained.  "That was probably the most significant 
innovation we made,  but now we can really start to measure the properties of 
these corpuscles.  For example we have used the fields to direct the cathode 
rays onto a metal receptacle and then we have measured the charge deposited.  
Not only that, but we have also measured heat deposited -- which tells us the 
energy of the rays.  We have also balanced the electric deflection against the 
deflection due to the magnetic field.  From this we can calculate the velocity 
of the particle.  They are traveling at 60,000 miles per second,  that's about 
1/3 of the speed of light!"
 
	We were interrupted by one of the younger scientist -- a Mr. 
Rutherford of New Zealand,  and reminded that tea was being served by Mrs. 
Thomson,  and the Cavendish Physical Society would soon be meeting.  J. J. 
begged us to stay,  and it was an event I would not have missed.  J. J. 
insisted on first hearing about all the other research projects going on in 
the laboratory,  but every one else wanted to talk about the cathode rays.  
The whole society,  from most junior to the masters tried to find flaws in the 
body of evidence which had been acquired.  But there just weren't any flaws or 
unexplained behavior left.
 
	Going home on the train that evening Holmes was in a quite mood for 
many miles.  As the train slowed down as it entered London he turned to me.  
"My dear Doctor,  do you remember how last night you commented that it seemed 
curious that Mr. Goseberg could be held on the evidence of a thin layer of 
dust?  I think today we have witnessed an even more amazing case,  where the 
aether-wave theories of Professor Hertz have been destroyed on the weight of 
the evidence of a particle millions and millions of times smaller then any 
dust particle."
 
                        _________________________
 
[Editor's Notes:  We generally date the discovery of the electron with J. J. 
Thomson's paper of April 1897 [1,2] at the same time as Holmes and Watson's 
visit. The term `electron' (Greek for `amber') came into use in 1905,  but J. 
J. Thomson continued to use the term `corpuscles' for more then another 
decade.  In 1906 J. J. Thomson received the Nobel prize for his work related 
to the electron.]
	
[1] Philosophical Magazine and Journal of Science, London, Edinburgh, and 
Dublin, ser. 5, vol. 44, n. 269, p. 293.
 
[2] Proceedings of the Royal Institution, vol. 15 (1897) 419.
 
[3] Great Experiments in Physics, ed. by M. H. Shamos, Henry Holt and Company, 
New York, (1960)