US1806100A

US1806100A - Intermittent motion sprinkler

Info

Publication number: US1806100A
Application number: US194923A
Authority: US
Inventors: Walter Van E Thompson
Original assignee: Thompson Manufacturing Co
Current assignee: Thompson Manufacturing Co
Priority date: 1927-05-28
Filing date: 1927-05-28
Publication date: 1931-05-19
Anticipated expiration: 1948-05-19

Description

May 195 1931. w. VAN E. THOMPSON- y 1,806,100

INTERMITTENT MOTION SPRINKLER Filed May 28,. 1927 2 sheets-sheet 1 l w, VAN E. THOMPSON I NTERMITTENT MOTION SRINKLER May 19, 1931;

Filed may 28q i927 sheets-sneer 2 Patented May 19, 1931 Y UTE STATES PATEN oriCE i` WALTER VAN E. THOMPSON, OF LOS ANGELES, CALIFORNIA, ASSIGNOR T THOMPSON MANUFACTURING COMPANY, OF LOS ANGELES, CALIFORNIA, A CORPORATION 0F CALIFORNIA INTERMITTENT MOTION SPRINKLER Application filed Majy 28, 1927. Serial No. 194,923.

This invention relates to irrigation sprinklers and particularly to types having movable or revolving nozzle-units.

Sprinklers having revolving nozzle-units are superior to stationary ones due to their ability to irrigate much larger areas than the sprinklers having stationary nozzle-units.

A common type of sprinkler comprises a body and a revolvable nozzle-unit. This nozzle-unit has radially extending arms, at the outer ends of which are secured non-A radial nozzles. The water passes from the body through the nozzle-units, egressing from the non-radial nozzles. There is a. reaction of the water on the nozzle-unit which causes it to revolve.` Streams ofwater flow from the nozzles and irrigate a circular area around the sprinkler. Inthe common type of sprinkler the nozzle-unit rotates comparatively fast, which rotation produces awhippingaction, this whipping action reducing the throw of the water and consequently reducing the area which is irrigated thereby.

It is an object ofthis invention to provide a sprinkler of the character mentioned' which will irrigate a comparatively large circular area.

It is another object of the invention to provide a sprinkler of this character Vin which the nozzle-unitV moves slowlyA through small arcs, pausing for a short interval of time'between each movement. t Y

A further object of the invention is to provide a sprinkler of the characterv mentioned in which thle nozzle-unit moves intermittently through a portion Y of its path and continuously through another portion of'its path.

A still further object of the invention is to provide a sprinkler which is adapted for irrigating parts of a circular area. A sprinkler having this feature is adapted for placement near the boundary of an area to be irrigated.

Other objects and advantages will be made evident hereinafter. v Y

Referring to the accompanying drawings in which the invention is illustrated:

Figfl is a diagrammatic View illustrating its utility. Y

AFig. 2 is an elevational sectional View through the mvent1on. Fig. 3 1s a sectlon taken on the une 343 of Fig. 2.

Fig. 4 is a section taken on the line 4-4 of Fig. 2. v

Fig. 5 is a perspective view of a portion of the operating-unit of the invention. Y

Fig. 6 is a plan view of Fig. 5 showing the mechanism in one position. Y

Fig. 7 is a view similar to Fig. 6, but showing the mechanism in another position. y

Fig. 8 is a section taken on the line 8 8 of Fig. 2. y y

Fig. 9 is a section taken on the line 9-9 of Fig. 2. l

The form of the invention shown in the drawings provides a shell 11 which includes a cylindrical member 12 having an upper head y13 and a lower head 14 whichv are threadedly secured to the member 12, as shown. A casing 20 is extended around the shell 11 so that it encloses the shell and so' that an annular shoulder 22 enga-ges the upper head 13. A radial wall 23 is formed at the upper end of the casing 20 which has a central opening 24.

Resting on an annular face 26 of the lower head 14 is a strainer 27 having a multiplicity of openings 28 formed therein. Water which issupplied tothe shell 11 Vthrough a pipe 30 threaded to the head 14 at 81 is deprived of particles of foreign matter by the strainer 27. A sleeve 33 which I'its snugly in the shell ll is placed above the strainer 27, and an impeller- Vplate 34 is placed in the shell -11 so that it rests .on anupper face of the slceveBB. As

shown best in Figs. 2, 8 and 9, the impeller-y plate 34 has depressions 36 which'provide water passages 37. The passages 37 are so constructed that water flowing therethrough is caused to flow in the direction indicated by the arrow 38 of Fig. 9. A cylindrical spacer 40is insertedv inthe shell' 11 above the impeller-plate 34. e

. Placed above the spacer 40 is an operatingunit 41 of the invention. A'boX which forms a part of the operating-unit 4l is composed of a cup-shaped member 42 anda cover 48. The` cup-shaped member 42 has a radial wall ico 44 from which there projects an annular flange 45 which contacts the inner face of the cylindrical member 12 and which has openings 46 provided therein. Extending upward from the peripheral part of the radial wall Y44 is a cylindrical wall 48. AsV

clearly shown in Fig. 2, the cylindrical wall 48 is substantially smaller in diameter thanthe inner face of the cylindrical lmember 12 of the shell 11, thus `providi-I'ig a substantially annular space 49. The cover v43 has a radial wall 51, the periphery of which engages the inner face of the member 12, and has openings 52 positioned in the outer annular areathereof which communicate with the A"sp'ace '49. The kcup-shaped member 42 and1 the cover 43 are 'secu-red together by screws "56, as shown in Fig. 4, which project through the cover and throughy lugs 57 formed on the cup-shaped member 42.

, In a rotor chamber 60 provided between the "operating-unit 41 and the im'peller-plate 34 is a roto-rl which has a web 63. Extending r-rcm an `outer annular radial portion 0In the web 63 are non-radial depending vanes 66. rThe rotor is secured to the lower end of a rotor-'shaft 68, which rotor-shaft extends through va `bearing 69 of the cup-shaped member 42. The upper end of the rotor-shaft 68 extends inside the box and has a small lgear 70 secured thereto. rIhe gear 70 meshes with a ,gear 71` which is rotatable on a shaft 72. s illustrated in Fig. 2 the lower end of the shaft 72 is supported by the radial wall 44 of the cup-shaped member 42 and the yupper end thereof is supported by a cross-web 73. The gear 71 is 'formed integrally with or attached to a Gear 74 which rotates therewith.v The gear 74 which is a small gear meshes wit-h and drives Va gear 75 which is rotatably supported on a shaft 76. The shaft 7 6 is 4supported at its lower end by the radi-al wall 44 and at its upper end by the web73. The gear 75 is adapted to rotate a pinion-gear 77'which is secured to a crank-shaft 78. The upper and lower ends of the crank-shafts are supported in sockets formed in the radiallwall 44 and the radial wall 51 of the cup-member and cover.

The crank-shaft 78 has an upper or pri-v mary crank 79 and a lower or secondary crank 80. Pivoted on a shaft 82 which exten-ds vertically in one side'of the interior of the box is a primary pawl 83 and a secondary pawl 84. The end of the primary pawl 83 has a slot 85 in which the primary crank 79 operfates, and the secondary pawl 84 has a slot 86 in which the secondary crank 80 operates. As the crank-shaft is rotated, the primary and secondary pawls move from the positions illustrated in Fig. A6 into the positions illustrated in Fig. 7. o

Extending through a bearing 89 of the cover 43, as shown in Fig. 2, is a drive-shaft 90.` The vlower e'nd of the drive-'shaft 90 extends into the interior of the box and has a primary ratchet-wheel 91 and a secondary ratchet-wheel 92 attached thereto. The ratchet-wheel 91 has teeth or projections 94 which are spaced a distance apart which is greater than their width, and the'ratchetwheel 92 has teeth or projections 95 which arespaced apart a distance equal to that of the teeth 94. The teeth 94 and the teeth 95, however, are offset in vertical planes as illustrated in Figs. 5, 6 and 7. The primary ratchet-wheel 91 is in the same horizontal plane as the'primary pawl 83, and the secondary ratchet-wheel 91 is in the same horizontal plane as the secondary pawl 84. As

vshown in Figs. 3 'and 5,'p'orti`ons of the-primary fand secondary ratchet-

wheels

91 and 92 are smooth, as indicated-at 96. The mechanism vdescribed in this paragraph 'constitutes the operating-unit of the invention. The operating-unit is divided into a 'controlledmeans which includes the primary and secondary ratchet-wheels 91 Pand. 92 and -a controlling-means which includes the other mechanism olf the operating-unit The parts of the invention located inside the shelly 11 are clamped in place kby clamppins y98 which thread through the upper head 13, the lower ends of the clamp-'pins engaging the-cover 43 of the box. I For the purpose olf lubrication, I :desire to 'till the box witha soft grease.` l 'K The upper 1end of the `drive-shaft 90 is provided with la drive-member 100 having a drive-to'nguer 101. The drive-tong'ue 101 extends into a slot 102 formed in a head 103 of 'a tube 104, this tube 104 forming a part of the nozzle-unit of the invention. The tube 104 extends through 'an vopening 105 provided in the t'opof the shell 11. A shoulder Vof the head 103 prevents the tube 104r'om being forced from the position shown i'n Fig. 2. rlhe upper end :of the tube has a radial arm 113 connected thereto. The outer end 'of the radial 'arm 113 is provided with a nozzle 115 which extends tangenti-ally'with a circle generated around the center of the tube 104. This Yconstruction justv described comprises the nozzle-unit 'of the invention.

Water supplied' to the sprinkler flows into the shell :through the pipe 30, passing throughthe strainer 27. rl`he'water passes through the passages 37 and the impellerplate 34, being caused to flow in the direction indicated-by the arrow 38v of Fig. 9.l The waterpasses into the rotor chamber 60 and strikes the vane 66 of the rotor 61 and causes it to rotate. The water passes from therotor chamber 60 through the openings l 46 `and through the annular space 49 into the vcharnber .in the shell 11l above the :operating-unit 41. The water passes. from this chamber into the lower end of the tube 104 and is directed to a noz'Zl'e'll. In view oit the fact that the nozzleV 115 is non-radial, the stream ot water gears 70, 71, 74, 7 5 and 7 7 which operate theV crank 78. l/Vhen the crank is rotated, the primary and

secondary pawls

83 and 84 are alternately moved fromthe position-s shown in Fig. 6 into the positions shown in Fig. 7. When the primary and secondary pawls are in the position shown in Fig. 6, the primary pawl 83 is in position to be engaged by one of the teeth 94 of the primary ratchet-wheel 91. The secondary pawl 83 at this time is in a retracted position and is out of the pathof the teeth 95 of the secondary ratchet-wheel 92. At this time the primary pawl 83, due to its engagement with one of the teeth 94, prevents the nozzle-unit from being rotated by the reaction torque produced by the stream of water issuing from the nozzle 115. As the rotor 61 is turned, the interconnecting chain of gears moves the crank 78 so that the primary and secondary pawls 83 and84 move into the positions shown in Fig. 7. rI`he primary pawl 84 at this time moves into a retracted position out of the path of travel of the teeth 94, whereas the secondary pawl 83 moves into a position in the path of travel of the teeth 95 and is engaged by one of the teeth 95 as shown in Fig. 7. Referring particularly to Figs. 6 and 7, I will designate the tooth 94 engaged by the primary pawl 83 in Fig. 6 by the numeral 120, and I will designate the tooth 95 engaged by the secondary pawl 84 in Fig. 7 by the numeral 121. It will be readily seen from Figs. 6 and 7 that the secondary pawl 84 moves into the path of travel of the teeth 95 before the primary pawl 83 moves out of the path of travel of the teeth 94. The instant that the tooth.120 is disengaged, the nozzle-unit isfree to rotate and it will rotate in a Vdirection indicated by the arrow 122 of Figs. 6 and 7 until the tooth 121 has moved into engagement with the secondary pawl 84. Itwillbe seen that the nozzle-unit and the ratchet-

wheels

91 and 92 have moved through that fraction of a revolution represented by the ratio of one-half the circular pitch of the

teeth

94 or 95 to the pitch circle of the

ratchetwheels

91 or 92. This action repeats'itself during the operation of the sprinkler Vso that the nozzle-unit is permitted to intermittently move through small arcs. The result of this is that the stream of water issuing Vfrom the nozzle 115 will spray on one place for a short time, preferably about a second, and thenl the nozzle-unit will move a-,small distance so that the stream will spray on an adjacent area. This is a desirable feature in view of the fact that it permits the largest possible area to be irrigated. By utilizing small intermittent movements of the nozzle-unit, it is possible to eliminate all whipping of-theA streams of water'and thus increasetheir throw.

' As previously pointed out, the portions 96 of the primary and secondary ratchet-

wheels

91 and 92 are left smooth. When these smooth portions 96 of theratchet-wheels come into the positions adjacent to the pawls 83v and84, the nozzle-unit will rotate until vone of the

teeth

94 or 95 is engaged. VIt will be obvious then that during a portion of the revolution of the nozzle-unit the movement of the nozzle-unit will be intermittent, and during another portion of the revolution the motion will be continuous. This construction is adapted for use when it is desired to irrigate one portion of the area much more than another portion thereof, and is very valuable where a portion of a circle is to be irrigated and another portion is not to be irrigated; for' example, when large areas are to be irrigated, certain of the sprinklers are placedY away from the boundary of the areas and may irrigate an entire circular area, and other sprinklers are placedfnear the boundary so that they cannot irrigate an entire circular area but only a segment thereof.

Referring to Fig. 1, the numeral 130 represents a sprinkler ofthe invention which may irrigate a circular area defined.- by the dotted line 131. In this figure the numeral 133 indicates a sprinkler of a slightly different type which is placed near the boundary 134 of the area'to be irrigated and which can irrigate only a portion of a circular area 1nydicated by the dotted line 135. The sprinkler 133 includes the mechanism shown in the sprinkler in which the nozzle-unit will revolve intermittently during the entire revolu tion.

The sprinkler-unit 133 is provided with a flow-arrester which is in the form of a screen 140, the screen 140 being supported by a suitable bracket 112. .The screen 140 is preferably arcuated and is placed on the side of the sprinkler 133 adjacent to the boundary134. The smooth parts 96 of the ratchet-wheels'91 and 92 are arranged on the same side of the tube 104 of the nozzle-unit as the arm 113. When the arm 113 reaches the position indicated by dotted lines 143, the smoothy parts 96 come into adjacency with the primary and

secondary pawls

83 and 84, and the nozzle-unit will swing quicklyl and continu` ously until the arm reaches the position indicated by dotted lines 144 of Fig. 1, at which time the nozzle-unit will again move intermittently. It will be seen, therefore, that the arm 113, when it moves so that the stream issuing from the vnozzle 115 will engage the screen, will move very quickly so that there will not be an excess of waterdropping from the screen 140 at the boundary 134. When the arm 113 moves fromthe'position indicated by dotted lines 144 into the position indicated by dotted lines 143 in Fig. 1, itsl movementV Willbe intermittent and the proper amount of Wfater Will be supplied to the portion of the circular area indicated by dotted lines 135.V

I claim as my invention:

1. In asprinkler, the combination of: a reaction nozzle-unit adapted to move so as to supply Water to an area to beirrigated means for supplying Water to said nozzle-unit; and an operating-unit actuated by the Water supplied to said nozzle-unit adapted to stop the rotation of said nozzle-unit Jfor periods of timeto render the motion of said nozzle-unit intermittent.

2. In a sprinkler, the combination of: a nozzle-unitadapted to move so as to supply Water to an area to be irrigated, said nozzleunit being moved by the reaction of thewater issuing therefrom; means for supplying Water toV said nozzle-unit; and geared operatingunit actuated by the Water supplied to said nozzle-unit adapted to stop the rotation of said nozzle-unit for periods of time to render the motion of said nozzle-unit intermittent.

v3. In a sprinkler, the combination of: av

nozzle-unit; and an operating-unit adapted.

to stop the rotation of saidV nozzle-unit for periods of time to render the motion of said nozzle-unit intermittent, said operating-unit Y including controlled-means connected to and adapted to move in synchronism With said nozzle-unit, and controlhng-means for governing the movement of said controlled-V means. n

5. In a sprinkler, the combination of: a rotatable sprinkler-unit, said sprinkler-unit being moved by the reaction of the Water passing therethrough; means for supplying Water to said sprinkler-unit; and an operating-unit adapted to stop the rotationof said nozzlenozzle-unit, said nozzle-unit being moved by the reaction of the lWater passing there-` throughlso as to supply Water to an area to be nozzle-unit; and an operating-unit Vadapted to stop the rotation of said nozzle-unit for periods of time to renderthe motion of'said nozzle-unit intermittent, said operating-unit including controlled-means connected to and adapted to move synchronism with said nozzle-unit, and controlling means operated by the Water passing through said nozzle-unitk for governing the movement of said controlled-means.

7 In a sprinkler, the combination of: a rotatable sprinkler-unit, A said sprinkler-unit being moved by the reaction of the Water passing therethrough; means for supplying Water to said sprinkler-unit; and an operating-unit adapted to stop lthe rotation of said nozzleunit for short periods of time so that said nozzle-unit' moves continuously during one part of its revolution and intermittently during another partot its revolution, said operating-unit including controlled-means oonirrigated; means for lsupplying Water to said Y nected to and adapted to move in synchronism f with said nozzle-unit, and controlling-means operated by the Water passing through said nozzle-unit for governing the movement of said controlled-means. i V Y 8. A combination as defined in claim 4- in which said controlled-means has projections, andY in VWhich said controlling-means has pawls adapted to engage said projections.

9. In a sprinkler, the combination of: a

yrotatable sprinkler-unit, said sprinkler-unit being adapted-to be rotated by the passage of Water therethrough; 'means for supp-lying Water tosaid sprinkler-unit; gears associated With said sprinkler-unit; a Water-Wheel; and paWls associated vWith said Water-Wheel, said paWls being adapted toengage said gears to stop the rotation of said sprinkler-unit for short periods of time. l,

10. In a sprinkler, the combination of: a rotatable sprinkler-unit, said sprinkler-unit being adapted to be rotated by the passage of Water therethrough; means for supplying Water to said sprinkler-unit; gears associated With said sprinkler-unit; a Water-Wheel; an eccentric associated with said Water-Wheel; and pawls operatably connected to said eccentric, saidpawls being ladapted to engage said gears to stop the rotation ort-said sprinklerunit for short periodsof time.

11. In a sprinkler, the. combination of: a shell; means for supplying Waterto said shell a Water-Wheel rotatablyl mounted in said shell; an impeller-plate .positioned in said shell, said impeller-plate being adapted to direct `the vWater tangentially against said water-Wheel; a shaft mounted in said Watervvheel; an eccentric geared to said shaft; a nozzle-unit` carried 'by said shell,.said nozzleunit being adapted to be rotated by there- ISO action of the Water passing therethrough; a second shaft associated with said nozzle-unit; ratchets mounted on said second shaft; and pawls associated With said eccentric, said paWls being adapted to alternate in engagement with their respective ratchets to stop the rotation of said nozzle-unit for short periods of time to make the motion of said nozzle-unit intermittent.

12. In a sprinkler, the combination of: a shell; means for supplying Water to said shell; a Water-Wheel rotatably mounted in said shell; an impeller-plate positioned in said shell, said impeller-plate being adapted to direct the Water tangentially against said Water-Wheel; a shaft mounted in said Water- Wheel; an eccentric geared to said shaft; a nozzle-unit carried by said shell, said nozzleunit being adapted to be rotated by the reaction of the Water passing therethrough; a second shaft associated with said nozzle-unit; ratchets mounted on said second shaft; paWls associated with said eccentric, said pawls being adapted to alternate. in engagement with their respective ratchets to stop the rotation of said nozzle-unit for short periods of time to make the motion of'said nozzle-unitintermittent; a box in said shell surrounding said eccentric, ratchets and paWls, said box journalling said shaft and said second shaft;

' and lubricant in said box.

13. In a sprinkler, the combination of: a nozzle-unit having means tending to rotate it continuously; means for supplying Water to said nozzle-unit; and means operated by the passage of Water to said nozzle-unit for interrupting the rotation of said nozzle-unit to make its motion intermittent.

14. In a sprinkler, the combination of: al

rotatable sprinkler-unit, said sprinkler-unit being adapted to be rotated by the passage of Water therethrough; means for supplying Water to said sprinkler-unit; a gear associated With said sprinkler-unit; a Water Wheel; and a paWl operatively connected With said Water Wheel, said paWl being adapted to engage and disengage said gear to intermittently interrupt the rotation of said sprinkler-unit.

15. In a sprinkler, the combination of: a rotatable sprinkler-unit, said sprinkler-unit being adapted to be rotated by the passage of Water therethrough; means forsupplying Water to said sprinkler-unit; a gear associated With said sprinkler-unit; a Water Wheel; an eccentric operatively connected with said Water Wheel; and a paWl operatively connected to said eccentric, said paWl being adapted to engage and disengage said gear to intermittently interrupt the rotation of said sprinkler-unit.

16. In a sprinkler, the combination of: a rotatable sprinkler-unit, said sprinkler-unit being adapted tobe rotated by the passage or Water therethrough; means for supplying Water to said sprinkler-unit; gears` associated With said sprinkler-unit, said gears having teeth formed only on one portion of thepe ripheries thereof; a Water Wheel; and lpaWls of Water therethrough; means for.y supplying Water to said sprinkler-unit; gears associated with said sprinklerunit, said gears having teeth formed'only on a portion of the peripheries thereof; a Water Wheel; an eccentric associated With said Water Wheel and pawls operatively connected toVV said eccentric, said pawls being adapted` to engage teeth of said gearsto stop the-rotation of said sprinkler-unit for short periods oftime during a portion ofthe revolutionpol vsaid sprinkler-unit. Y Y j i .18. In a sprinkler, the combinationof:Y a rotatable sprinkler-unit, said sprinkler-unit being adapted to be rotated by the passage of Water therethrough;means for supplying Water to said sprinkler-unit.; a'gear 'associated with said sprinkler-unit, said gear having teeth formed only on one portion of the periphery thereof; a Water Wheel; andv a paWl associated With said Water Wheel, said paWl being adapt-ed to engage the teeth formed on said gear to stopv the rotation of said sprinkler-unit for short periods of time during one kportionofthe rotation ofthe sprinkler-unit. f

19. In a sprinkler, thecombination of: a rotatable sprinkler-unit, said springlerfumt being adapted tobe rotated by the passage of Water therethrough ;V means for supplying Water to said Vsprinkler-unit; a gear4 associated With said sprinkler-unit, said gear having teeth formed only on a portion of the to an-area'to be Virrigated;means'ffor supplying Water to said noz/zlelunit; Vand an operating-unit adapted to stop the rotation of said nozzle-unit for periods of time during a portion of its rotation to render the motion of said nozzle-unit intermittent during part 'neueren of its Ivtravel and continuous during another part of 'its travel. A

21. In la sprinkler, the combination of: a

v"rotatable sprinkler-unit havingl means ftend- Q55 ing to cause its continuous rotation; means ffor supplying Water to said sprinkler-unit; *and an operating-unit adapted to stop the rotation of said nozzle-unit for short periods of time during la portion of the rotation 'of 'am said nozzle-unit so that said nozzle-unit moves continuously during one part of its revolution and intermittently during another part of its revolution.

22. In a sprinkler, the combination of: la

rotatable sprinkler-unit Zhaving "means tending to cause its continuous "rotation'; means 'for supplying Water :to said sprinkler-unit; and an operating-unit adapted to stop 'the rotation of said nozzle-unit for short periods :20 Of'time during a portion of the rotation 4of said nozzle-unit so that said nozzle-unit moves continuously duringv one part of its revolution and intermittently through small arcs during another part ofits revolution.

425 23. In a sprinkler, the combination of: a

rotatable :sprinkler-'unit having 'means tending to cause 'its Econtinuous rotation; means 'for supplying Water tosaid sprinkler-unit; an operating-unit'adapted to stop the -rota- 30 tion'oisaid nozzle-'unit for short periods of Y time duringa portion oftherotaition of said nozzle-unit so that said knozzle-unit moves continuously during one part of its revo'lu tion and intermittently during another part 35 of its revolution; andan arcuated Tflow-arrester against which said Water issuing from said nozzle-'unit strikes When said nozzleunitis moving continuously.

24. In a sprinkler, the combination of: "a

' 40 rotatable -sprinklerlunit having means tending to cause its continuous rotation; 'means for supplying Water to said sprinkler-unit; an operating-unit adapted to stop the '-'rotation 'of said nozzle-unit for short periods of 45 time during a vportion ofthe 'rotation of said nozzle-unit so `-thatsaid nozzle-unitfmoves continuously during one part of its revolulutin and intermittently through small ares during another part of its -revolution;fand

lio an arcuated flow-arrester againstwhich said Water issuingfrom said vnozzle-unit strikes when said nozzle-unit is moving continuously. e

25. A combination as defined in claim523 in VWhich said flow-arrester isprovided inthe 'form of an arcuated screen. y In testimony whereof, I have hereunto set my hand at'Los Angeles,'California,`this' 21st day of May, 1927. Y

e@ 1 ALTERvAN'n. THOMPSON.