THE INVENTION* OF DR. C. FRAUCI <* JEHKIHS
A The«i" prepared by
William -Hart ge Fifer
a = part of hi" initiation into the Maryland Beta Chap-
ter of the Tau Beta Fi Association, the Honorary En^in-
rering Fraternity of the University of Maryland.
Dr. Charles Francis Jenkins of Washington, D.G. has pro-
duced some of the io"t remarkable discoveries of this raechani-
cal age. He i« the father of the motion ricture industry .hav-
ing invented the prototype of the motion ricture projector now
u^ed in every theater in the world- He invented the apparatus
which ^ent and received the first radio photographs an d a "hort
while later produced an apparatus for viewing distant scenes by
radio directly, and radio movie° for hone entertainment. Devel-
oping the spiral wound all rarer container used the world over
for the transportation of liquids in "mall quantities i» to
also credited to him. He has been granted over four hundred
patent and maintain a private laboratory in Washington. He
owns 8 ,nd operate radio station W3XK where r^dio movie* 5 are
broadcast at a regular schedule. He has made several important
invention pertaining to aviation. Here truly is a man that
the world can give its thanks to for many of the luxuries ^nd
comforts that peorle tod^y enjoy.
DR. C. FRAHCI* JEHKIH**
Dr. C. Francis Jenkir. i w** born in the country near
Day ten, Ohio in 1B68. His* parent* were Quakers. He "pent his
"boyhood on a farm near Richmond, Indiana where he attended the
county grade and high school . On graduation from high school
he attended Earlham College from which he was* graduated in
1PP7. After graduation he explored wheatfield* and timber re-
gion" of the Northwest and cattle range" and mining camp«! of
the Southwest T, nited states. He came to Wa^hington.D.C* in
1B90 a° "ecretary to dinner I. Kimball of the TT nited ^ate"
Life ^ving ^rvice.the forerunner of the present TT nited "States.
Coast Guard. He resigned from the notation in 1^95 to take ut>
inventing as* a profession. To d--<te he ha" been granted over
four hundred patent most of which are on motion ri ctu re <*, rad-
io photograph e , and radio movie". He i" a member of the Frank-
lin Institute, the American Association for the Advancement of
^cience, the National Aeronautical Association, and is founder
of the "ociety of Votion Picture Engineers. TTe ha* v P pn awar-
ded the Elliot tQresson "old Medal by the Franklin Institute
and also the John <*cott Medal by the City of Philadelphia for
his motion ricture machine. He has a commercial airnlane pi-
lots license and ovn" and operates hi° own plane*
In June 1929 he was awarded the honorary degree of
Doctor of Science by Earlham College of Indiana.
Dr. Jenkin* Fome at 5502 <*ixteenth <*t. ,N.W. ,
Ur. Jenkins maintain* a private laboratory at 1519
Connecticut Ave. ,N.W. , Washington, D.C. where he employ* *even
a*«l*tpnt*. He own* and operate* radio station W3XK at Wheaton
Md. wher* r^dio movie* are broadcast on a regular schedule.
THE INVENTION" OF DR. C. FRANCI" JENKINS
In hi* rrivate l^borntory on the second floor o r
1519 Connecticut Ave. , Washington ,D.C -Dr. Jenkins and hi"
*ts.ff of a""i»tant" have produced *ome of the most rermrknble
invention of t i ~ ^cienti^ic age* It i* due to the keen in-
ventive brain of Dr. Jenkin* that we have many of our -present
day luxuries =<nd comfort".
PR0T0T v TE MOTION PICTURE PROJECTOR
The mo*t notable of hi* early work* de^l with photo-
graphy ^nd motion ricture machine*. He invented the r ir"t
printer* and devploper* used by the Eastman Kodak Co. of Roch-
ester, N.Y. and it i* due to the^e early di*coverie" that the
motion ricture inn chine was developed. Dr. Jenkin* made the
fir«t long mtrip film motion ricture mchine by fastening to-
gether roll* of Kodnk film ^nd cutting them in thin strip". The
pre*ent type projector u"ed the world ov<=r and which ha* made
the modern motion ricture ^o*«ible i" entirely due to him.
HIGH "(PEED CAMERA
Thi* camera wa* de*igned for the "tudy of high veloc-
ities or high *reed motion*, "uch a* the 'light of a projectile.
It has a normal rate of exro*ure*.of from 1000 to 3000 pictures
per second, and a* high a* 4000 Pictures per -econd have been
It U"es standard "nrer-"peed motion picture negative
film and i« developed in the u"ual manner. The film i° pro-
jected in the standard projecting machine which give" a reduc-
tion of 100 to 200 in the apnarant speed of the photographed
object, which make" it" motion and reaction" irmch easier to
The camera u»e» 48 Zei"" Te^ar len"e s, "ize F«3*5
and of 2" focu°. The camera i * operated by an ordinary auto-
mobile starting motor and a 12 volt storage battery. tannine
or illumination equivalent to "un<-»hine i" sufficient ^or it*
The "ecret of this camera lie* in It* len*» system as
each len" may work g* much a." 150 rer cent of the time, that i *••
to say, the exposure* overlap.
TIRAL-WOUHD FAR ALINED ALL PAPER CONTAINER
Thi« i * the familiar round wrer container which i°
used in many confectionery "tore" a« a container for ice cream
or other liquids which require a cheap practical method of
transporting liquid". "Prom a monetary "tandroint thi<* wa" one
of hi" met «ucce""ful invention".
RADIO PHOTOGRAPH ^
Dr. Jenkins rrodueed the fir<*t photographs ever "ent
by radio and produced the fir«t aimaratu" for viewing distant
"cene" by rauio. TT i" first work on thi" mbject began in 1913
and wa° continuously -pursued *^il he was inter runted by the
World War to which he gave all hi" aid. After the termination
of the War he developed a prismatic ring, a new contribution
to the optical science. Tt i" comparable to a "olid gla«*"
rri*m which change" the angle between it" °ide",giving to a
beam of light x>a«"ing through an oscillating action on one
"ide of the ^ri a m while holding a fixed axis of the beam on the
other "ide of the rri«m. The prismatic ring "ection i" ground
into the face of a gla"" di«c. From one end to a point half
way around it ha« it° ba"e outward and from thi". noint around
to the other end hsvin^ it« ba"e inward.
PftiSMft Tt C /?//V g
It wa" with the development of the prismatic ring
that the fir"t real «ucce"" w»« obt^inpd in the tran"ni""ion of
picture" and virion by rriio,for it i » by the u"e of the"e
prismatic ring" and a light «en"itive cell at the "ending sta-
tion that the light value* which make up the ^icture htp conv-
erted into eletrical current" -mi broadcast 'i 9 i" nccom-
pli"hed by "weering the picture aero"" the light sensitive
cell hy mean" of the*e rotating prismatic ring". With each
downward "weec the picture i*? mov^d one one-hundredth of an
inch to the right until the whole picture ha" osc'ed the light
«»en o itive cell which convert" the light strength of the differ-
ent ps.rt" of each •'lice into corresponding electrical current*.
It i « immaterial whether the current modulation i" taken from
a flnt photogfaph.a <=olid object or an out-door <*cene at w'::ich
the transmitter i " directed.
At the distant receiving end it i° onl - " nece'^ary to
rut the a e light value" back again by revpr^ing the froce"".
Thi* i " accomplished by having a -noint of light to draw line"
aero " the photographic rlace, which i* done by the i-ri^matic
ring" and by varying the strength of the different of the "ucc-
e° p ive line" correTonding to the light" and "hadow* of the
-ricture at the transmitter which i« done by the vary init *trf>n-
gth of the incoming r^dio "iiTn^l which cau^f* corrp "bonding
change" in the intensity of the light.
The "puree of light i*> obtained from a filament lamp
which con^i^t" of => "inglp turn coil ^nclo^pd in an atr.o-'phere
of hydrogen. The variation of light i * caused by imvre«"ing
the incoming raaio signal* an thi« Lamp c'fter the filament hae
been brought to a dull red by a battery.
J. •=!. Montgomery
PHOEOffRAFH <3 «ENT AND RECEIVED BY APPARA'^r ^
I SVM TE D BY DR . C . FRAHCI 5 JBHK IS <*. June, 15 , 1 9 24 .
In/order thnt pending machine ^nd receiving machine will
run/exact synchronism a control fork was perfected. The con-
trol of the sending and receiving motors i« maintained by the
vibration of a rather heavy fork at each station and are ad-
justed to beat together, with a slight automatic conection by
fcadio as may be required td keep the folk* irt all of the re-
dETfing station" in synchronism with that of the transmi Uer.
It is a simrle and very dependable method.
Another method of keening the motors in "ten is to
have a small synchronous radio suitor controlled by rower radia-
ted from the broadcasting station. It is rotated partly by
thi° rndiated -rower and partly y -~' a local current jn^t as n
a loudspeaker is orprated. These small motor" regulate the
rotation of a larger motor nnd thus kenr> t v *=m in step with the
tren smiting station.
Thi° method to the present time i« the ao«t practical and
give* the he c t reeults in "ending ^icturp-* by r'Hdio.
RADIO VISION AND MOVIES
After obtaining ouch wonderful results in rndio photo-
graph « Dr. Jenkins '■ mediately began to develop some practi-
cal mean e of transmitting picture" of moving object'' and mot-
When transmitted and received by th<= flat rlate method
radio virion in identical in principle to the method by which
radio photograph" are broadcast with the only difference being
in the speed of transmission.
A" in radio photographs the Picture is formed by a small
srot of light moving over the picture in 'uccp'^ive parallel
lines, with the light value controlled by the incoming rsdio
signals. The whole -picture is covered in one- sixteenth of a
second and the r^r^i stenc* 3 of vision of the human pye enables
us to see the whole picture- Tn order to get this great in-
crpase in speed a lens di«c i e substituted for the pair of nri-
L?.H" DIX TAilNPIR
The rotation of the di"c carrying the len«e" arranged in a
priral cau^e" 9 the light to "weer aero" 9 the screen. A "need
of one- «ixtpenth of a second v&r revolution of the di <*c will
give a motion picture screen effect.
The Radio Virion receiving 9 et a" designed by Dr.
Jenkin* 1« very =imrle and all the a v ^arat-ii* may "be -placed in
a ^mall box beside the radio "et ^nd one may ^ee a distant
football game or inaugural cerera^nv or my <*ee a motion picture
transmitted from a film.
Simple Standard Four Tube Radio Vision Receiver
■ ' 'I'M
230 TO 300 V.
- C j U to 45V.
CI — 2 pieces 1} 2 " square copperplates spaced
C2- -.01 M.F.D. Mica coupling condensers
C3— At least 1 M.F.D.
C4 — At least 4 M.F.D,
CS— .00025 M.F.D.
C6— .00014 M.F.D. Variable condensers
C7— .001 M.F.D.
SW — Speaker and Neon Lamp cut-out switch
All resistors must be non-inductive
R— 2 to 7 megohms
Rl — .025 megohms ,
Rp .25 megohms
Rg — 1 megohms
Rgl — .5 megohms
LI— 5 turns 3" dia. Wo. 18 D.C.C. Wire
L2 -6 turns 3" dia. No. 18 D.C.C. Wire
LI and LZ — Spaced 'i"
Antenna— 50 to 100 feet total length
Dr. Jenkiri" made hi* fir«t fcfeboratory demonstration
of Radio Virion and Radio Movie" on June 14,1923 before a very
distinguished gathering of gue^t^f^ee visitors li<*t).
^ jL&rA*. fUi
^0^>~v *"* <&*-~, -,
hi, f H-i .^1 U/WW
^.^*^-* *"-^r- <Jl—-c. t* t
<3^ o i_J
HELICAL i3RUl£ BANNER
With the dice "Conner the minimum ~e~nration of the
aperature c determine 1 " the width of the picture and &<» the pic-
ture i " -square the aperture *eparation al «so determine* the off-
set of the end" of the spiral. Tn order to have a Picture 2
ir.che" square a 36 inch diameter di^c i«» required and 6 foot dia-
meter di*c for a 4 inch picture* In order to have a picture of
reasonable "izp with apparatus of "mall dimension* hp dpvplo^
the Helical Drum Scanner.
f?BUR Tf>RGE7 CATHODE GlO*
HELICAL DRHM "CA^JPTO
In the peripheral wall of the drum 48 hole-> are drilled.
There are four helicnl turn 1 ' of 12 hole= each. Each hole being
"T-ced 2 inche" apart circumferentially and the helical turn a
being £ inch apart. In the middle of the drum there i* 5 placed
a 4 target c nth ode- glow neon lamp. Between the lamu and thp rer-
phery of the drum are small quartz rod®, each rod ending
it* particular minute aperture in the peripheral wall. The p e
qusrtz rod" a^ei a« they have the property of conducting li
through it with a very small lo«i. The cathode target* are
placed one under each of the row* of quartz rod« and are light-
ed in «ucce i »^ion through b commutator, '~v the ^late current of
the power tube of the receivpr. Each helicil turn of the «ean-
ning aperture i° lighted inderendentlv "by its own particular
glowing target, which result*, in a great economy of current re-
quired for lighting the entire Picture.
A "even inch diameter drum of this type will give a Pic-
ture 3" X 3" which may be magnified to 6" X 6" and from four to
five neo-rle mav watch it. A 10£ inch drum "ill -^ive a Picture
four inches square which ma" be magnified to a ricture 10 in-
ches Square. The photograph shows how the drum receiver may
be u-^ed in the home.
Dr. Jenkins operate? radio station W3XF* at Wheaton.Md.
which operate s on a wavelength of 46.7 meter". He broadest i
rr^dio movie" from this station on a regular schedule.
^mmtSK*-'- i £-; ^'^ ;
JE^KIS 6 * RADIO. MOVII TRAtf'VTTTER W3XK, AT
The di «c- "canning receiver, with 48 aperature^ in the
^riral on the dJ e c,ha« a current-to-eye efficiency of le^** than
one fifty thousinth of one percent. Thi* low effiency i« due
to the fact that each elementary area light "ource should "be
a" large a" the whole ricture and that persistence of virion of
the eye i« not defended u^on for an assembly o f the element! ;
area" of the ricture.
Theoretically there should be no more light current
than is needed to light a single elementary area at the time
considered and a real nlcture should <=ri«t in the receiver
whether there i« a human eye to "pe it or not; that is, it "hould
he T-o^'-iW to photograph the received picture with a <»nap shot
camera which cannot he done with the lens Ji'^e scanner.
The rlate receiver satisfies both of these conditic
and ocn^iet" of a ricture ""l«te divided into 2,304 elementary
areap. This may be built by having 48 horizontal row™ of
flash light bulb* with 48 bulb" in each row. The "e lamps are
divided, electri clly into four groups and each lamp is indivi-
dually wired to it* 5 rarticul3r contact of the "witching gear.
All the lamp" in each group have a common return.
The "witohin/* p.paf §fm"i*t* 0? n ooramatotor having
four separate sections, one for each group of lamps, a 3,600
RIM J-B-P* synchronomous motor i» used to drive the commutst-ftf
In orierati en, the incoming radio signals are distri-
buted to the several lsmr* in <mcce <s< *ion and the lamp* are
lighted according to the inten^it" "■ c ' the signals. The result
i ° a r-icture 2 feet square made up in li^ht* and halftone and
"hadow. The ricture i° made up of the glowing lamp*! which
Tr e i=t in light value for the a^rreciable time of about one
tenth of a °econd. A" the impulse to each lamp is every one-
fifteenth of a *econd the lamp i ° glowing for the whole time
the corresponding elementary aref> o^ the ^cene at the broadcas-
ting station is alight. That i° to iny , rer e i ■>t< a nce of light
i<* u e ed in^teau of per Ki^tenoe of vision a? in the len^-di^c
and dr'irr. receiver. Another advantage of the --ytem i 9 that the
light cr.lor is white and net the pinkish color of a npon light.
A* nearly all "uch *y stems are reversible, an excellent
transmitter may be made by reversing the «y«tem,u*ing light »en<
= itive cpII 15 in place of the lamps.
Virion by Radio, Radio Photograph* and Radio photogram*.
published by Jenkin* Laboratories, Inc. in 19P.5.
Radiorccvie*, Radiovi=ion and Television. Published by
Jenkine Laboratories, Inc. , in Feb 1929.
Varioi:<» rtaort articles and sketches from tine to tine in
the Electrical Engineer, Hot ion Picture Hew*, Popular Radio,
Radio Hew*, Newspaper article*, etc», "beginning in 1B94.
Department of Commerce
OFFICE OF THE SECRETARY
Mr .G .Francis Jenkins ,
1519 Connecticut Avenue,
Washington ,D .0 .
Dear Mr .Jenkins:
£ wish to express my
appreciation for the photograph which
you so kindly sent me. It represents
a very startling development in radio
and sometime when I hare some leisure
I would be interested in discussing
the method with you .
Ideal Radio Vision Receiver Using Standard Parts
ZSO TO 3»¥W,
1^1—2 pieces \}4" square copper plates spaced
C2 — .01 M.F.D. Mica coupling condensers
C3— At least 1 M.F.D,
C4— At least 4 M.F.D.
CS— .0002S M.F.D.
C6 -.00014 M.F.D. Variable Condensers
C7— .00014 M.F.D. Variable Condensers
CS— At least .01 M.F.D.
CS> — .001 M.F.D. Mica Condenser
Antenna -SO to 100 feet total length
SW — Speaker and Neon Lamp cut-out switch
"All resistors must be non-inductive"
R — 2 to 7 megohms
Rl -.025 megohms
Rp — .25 megohms
Rg — 1 megohms
Rgl — .S megohms
L —6 turns 3" dia. No. 18 D.C.C.
LI 5 turns 3" dia. No. 18 D.C.C.
L2 — f> turns 3" dia. No. 18 D.C.C.
LI — and L2 —Spaced I ., "
UX-222 — Requires only 3.3 volts on filament
iuly 31, 1928.
C. F. JENKINS
SPIRAL MOUNTED LENS DISK
Filed Jan. 2, 1925
$usu V*. OLSu~^i^,
Patented July 31, 1928,
UNITED STATES PATENT OFFICE.
CHABX.ES FBANCIS JENKINS. OF WASHINGTON, DISTRICT OF COLUMBIA.
SFIBAL-MOU NTED LENS DISK.
Application filed January 2. 1925. Serial Ho. 323.
This invention relates to apparatus for
the transmission of pictures by radio, in
which the picture is made up of lines across
an approximately itat surface, said lines
having varying values.
The principal object of this invention is
the design of a simple device which permits
of a speed which will cover the entire pic-
ture surface within the time of persistence
of vision, say. one-twelfth or one-sixteenth
of a second.
With these and other objects in view the
invention consists of the novel details of
construction and combination of parts mom
fully hereinafter disclosed and particularly
pointed out in the claims.
Referring to the accompanying drawing
forming a part of this specification, Figure
1 is a front view of the lens-carrier disk, and
Figure -2 a schematic drawing showing how
it is employed
Tn the drawing A is a disk with a plural-
ity of spirally arranged holes therein, over
each of which a lens is mounted, as B, B\
B", etc. The dUk is intended to be rotated
between a spot-source of light L, and a pic-
ture surf nee or screen M, shown edge on.
When the lens 15 is in front id the light
the image of the source strikes the screen
near the top, as shown in full line; when the
lens li" i ition to project, the image
will appear on the picture surface near the
bottom, as indicated by the dotted line;
when other lenses come into pnsiti m to pro-
ject, the images fall in successively differ-
ent positio is between these extremes.
It will-readily be understood that the ro-
tation of tiie disk would cause the lenses lo
travel across the screen from side to side;
while I lie location of the lenses at different
radial distances from the a.\is makes the
lateral trips of each lens at different levels,
so that the whole picture surface is scanned.
It will also lie understood that the disk-
mounted lenses could just as well scan a *&•.
picture surface to he sent as they scan a
screen upon which (he picture is put, with-
out departing from (he spirit of my inven-
What I claim, is— W
1. "In combination, a stationary picture
surface, a stationary Jjghf translating ele-
ment, a lotatahle disk interposed between
said surface and said element, said disk lift-
ing provided with a v plurality of apertures M
of huge dimensions as compared with an
elementary area of the picture surface, and
a spherical lens mounted in each aperture
For imaging the picture surface and the light
translating element each upon the other, M
-aid apertures ami lenses being so arranged
that upon rotation of the disk the lenses
pass successively between said surface and
said element, and successive images of the
light translating element traverse the pic- 65
lure surface by adjacent parallel paths.
2. In continuation, a stationary light
translating element, and a scanning device
consisting of a rotatahle disk interposed be-
tween the said element and a plane to be 70
scanned, said disk being provided with a
plurality of apertures of large dimensions
as compared with an elementary area of the
scanned plane, and a lens mounted in each
aperture, said apertures and lenses being so TS
arranged that upon rotation of the disk
the lenses will pass between said plane and
said element and successive images of the
light translating element traverse the plane
by adjacent parallel paths, 80
In testimony whereof 1 have affixed my
CHARLES FRANCIS JENKINS.
Oct. 8, 1929.
C. F. JENKINS
HELICAL. DRUM SCANNER
Filed June 13, 1938
^pji^Ji^ ft. ex-g- " *-*^ ^ . gJSy
@JL«sU<« «>U~_~^ W&-":
Patented Oct. 8, 1929
UNITED STATES PATENT OFFICE
CHARLES FRANCIS JENKINS, OF WASHINGTON, DISTRICT OF COLUMBIA. ASSIGNOR TO
JENKINS LABORATORIES, OF WASHINGTON, DISTRICT OF COLUMBIA, A COHi'ORA--
TION OF THE DISTRICT OF COLUMBIA
HELICAL DRUM SCANNER
Application filed June 13, 1928. Serial No. 255.015.
This Invention relates to radiovisors, i. e.,
ratus for the reception of motion pic-
■ ; i : ' ■ I l ■ - dio, and has for its prin-
cipal object simple, inexpensive apparati
tana!] size, and producing a relatively large
i :>f superior quality.
■etofore the generally employed method
for the ■ n of radio vision, radio
mo\ re of a large
with a plurality of scanning
holes therein arranged in a spiral. Such a
mechanism i'-- limited by the dimensions of the
apparatus itself, for example —
liming 48 lines to the pid scan-
15 ning disc two feet in diameter produces a
pic inch square. For a picture
two inches square with the same number of
lines pei* picture, requires a disc four feet in
iameter, and an enormous increase in the
power cf J he motor required to drive it at
speed, an increase equal to the ninth power of
se in speed. Reduced to merchan-
dising terms, this means a device impractical
use in (he average home.
A still further limitation of the disc method
ofsc that the whole picture an
the surface scanned is lighted simultaneously,
and, therefore, requires a radio power ampli-
fier (many times greater than a method
so which consists of hut a small glow area).
Thi >■ amplifier required still further
limits Hie ;i ility of the apparatus for
the average home, Eor it can id be atta e
l' the usual two-stage amplifier radio
The employment of a drum as (he scanning
ided in the present invention, is
without the limitations cited above, for ex-
ample, the picture may be increased by (1)
an meres e to the speed of rotation; and/or
(2) an increase in the diameter oft! ' urn;
and/or (3) a lesser increase in both.
Among its further advantages, incident to
the above, is that the scanning means is very
ht, with moderate peripheral speed, and.
45 therefore, requires but a small motor.
The scanning apertures, in the drum
I, are all equi-distant from each other,
and, therefore, distortion due to varying
spa apertures in the di e method, is en-
50 tirely eliminated.
Also, with this drum method of scanning,
"in of the scanning apertures
lighted independently by its own par-
r glowing target, which results in a
lonomy of current required for light -
With this and other objects in view, the
invention consist- of the novel combination
lements herein described, illustrated in
the. drawings, and pari icularly pointed out in eo
i he drawings, Figure 1 is a top view of
the drum : Figure 2 an end view thereof; and
Figure 8 : sectional view of the lamp eni-
In the figures, A is the scanning drum; B
auning apertures therein arranged in a
irn helix; C the lamp which encloses
the glowing targets 1 , C 2 , C 3 . and C*.
Between the lamp and the inner periphery
of the drum lies a funnel structure V, divided
hin part'' ' into four parts oi
tions. The small end of. each section of this
multiple funnel structure lies over its particu-
The larger end has an opening in length
equal to the circumferential separation of the
scanning apertures, and a width equal to the
helical separation of (he holes beginning and
ending the helical turn.
•■eft > re. the light from each target is
confined to the illumination of bill a single
helical turn of the scanning apertures.
Again, as the mouth of the funnel is only as
wide as the circumferential separation be-
i ween any two scanning apertures, the result
is that but a single aperture is illuminated at
any one moment
As the generally accepted method of scan-
ning in receiving instruments is so well known 90
to those skilled in this art, a description of
ation in meticulous detail is not be-
In general, however, the method consists,
first, in turning the scanning drum as many
times per picture as there are helical turns
of the circumferential line of scanning aper-
tures; second, lighting the glow targets or
light sources one at a time in synchronism
with each rotation of the drum, for example ioo
wOTE: The material wed in this the«i=>
wa" obtained from Dr. C. Franc i 6 * Jenkin« himself; hi*>
"pcrpt'iry, •'vteil Almnnd Windridge and the intent Offi-
ce* of P. q ingpr. The writer greatly RT>rreciate*
their kind help and a^netance.