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Full text of "The inventions of Dr. C. Francis Jenkins of Washington, D.C. / William Hartge Fifer"

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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. 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. , 
Washington, D.C» 

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. 



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". 

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. 


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 
successfully obtained. 


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. 


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". 


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. 


W.J. Brvan 

J. •=!. Montgomery 


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. 


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- 
ion picture^. 

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- 
smatic rings. 




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 

46.7 METERS 



■ ' '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). 


dkc^M 9Z^k 

- 0?T. 




^ jL&rA*. fUi 

■<z ■ 


^0^>~v *"* <&*-~, -, 

hi, f H-i .^1 U/WW 

/%. ^ 

to / 



^.^*^-* *"-^r- <Jl—-c. t* t 


<3^ o i_J 

ClTWK 4 

■^%^<-W i 

■ 11- 


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. 


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 £-; ^'^ ; 





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 



February 1,1924, 

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 . 

Yours faithfully 

Ideal Radio Vision Receiver Using Standard Parts 




ZSO TO 3ȴW, 

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. 



Filed Jan. 2, 1925 





fTcj 2. 





$usu V*. OLSu~^i^, 


Patented July 31, 1928, 





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 


Oct. 8, 1929. 


*T_D 1 


Filed June 13, 1938 



^pji^Ji^ ft. ex-g- " *-*^ ^ . gJSy 


@JL«sU<« «>U~_~^ W&-": 


Patented Oct. 8, 1929 





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 - 

■ picture. 

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- 
!ight target. 
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- 
lieved necessary. 

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.