US2584591A

US2584591A - Radiant heating system

Info

Publication number: US2584591A
Application number: US746601A
Authority: US
Inventors: George F Keck
Original assignee: CLAY PRODUCTS ASS
Current assignee: CLAY PRODUCTS ASS; CLAY PRODUCTS ASSOCIATION
Priority date: 1947-05-07
Filing date: 1947-05-07
Publication date: 1952-02-05
Anticipated expiration: 1969-02-05

Description

Feb. 5, 1952 G. F. KECK RADIANT HEATING SYSTEM 4 Sheets$heet 1 Filed May 7, 1947 D PPPPDIDI IPDPPPPpDIPPPPD PPPPD D OIPPP 3 PPPPP P mmvroze. Geo/ye f ziec/z, BY

1952 s. F. KECK RADIANT HEATING SYSTEM 4 Sheets-Sheet 2 Filed May 7, 1947 INVENTOR.

660C963 [Ego/0, BY %MM /7W Feb. 5, 1952 ca. F. KECK RADIANT HEATING SYSTEM 4 Sheets-Sheet 3 Filed May 7, 1947 n u u I JNVENTORi Gemyef 1590/6 Feb. 5, 1952 s. F. KECK RADIANT HEATING SYSTEM 4 Sheets-Sheet 4 Filed May '7, 1947 INVENTOR. George ffzi s'c/c,

Patented F e13. 5,

Gdrge F; Keck, Chicago, I-l'Ii, a'seigzidr -itoi Clay Pi-b'duct's'= Associfltio'n; Chicagm Ill-2,; a. cal-purs tion of Illinois l The presentease is a ontiniitib in peft (if my co pending application serialflNd-a' 52gg 3tj4; filed March 27; 1944, new Patent Number 2,422,685, directed to impfovem'ent in R'adiant Heatingior Buildings; y I

This invention 52$ to do with ii'idian't neatmg for biiildings, 'and' isfiar'ti'eiflai ly eontgrnefi with the constiuet'ion and arrangement bifthe various ducts and headers einplojyed' handling the eirculitipn o'f tiie heated 'air'br Otheif fiiii'di One of the piifieiril objects dfthe invention Still anqther important objeqt is topr bjviiie in a panel heating system or the t e des iibea im eluding an assembly of tiles-an ndilel bridg'ifig eor cementing: means; ai'spo'ea" 'at'tiie tile joints 'i'nd dd pted t6 falcilit'a'te 'a'rid' expeuite iil's'talllatin'bf Y -HW A 4 u Andther specific object is'to p'i'bvide it proved tile briiijgi'n'g 'dr jcciiiiieating; element of the tyiie i f i red td iii the pi'be'diiigiipafagififihl Yeten'dthen afid more general pljeiit t0 pidir'i'tle various i pveiassqifibiies dr ti1es; sab:- aesembiies thereof and tiles? bi' 's'; ald'aiptti {to pidv id 311 1 impi'dired I circiflitibn" of lieifiinfi medium in a radiant panel heating system;

Other more s'pifib ObjeCtS' andwldvantaes will be apparent. tci those skilledin' the lart upon a full understanding of thetwoalternativeforins of the new radiant heating. layout hereiriillu; trjted;andthecdnstructibn and arrangement 16f the several speciai-tileziinits' entering: into-the same.

the-5113 fillet-the invention 35 l'liscebtibleaof line corporatidni "var iousubther zsfri'ictura'llx media fie'd for'ms' oming equan withinzthe scope-"of theappended c1aims.- v

Initheccemp"nyifikidrwinys'z v Fig. 1 is a pImzview-Of a, hblldwgtilexfloolratrufi ture constructed: in-f'acco'rdance withaone' "embodiment of theinvention; v .w t. t- N- Figpzzia petspective View 011 adhere-mailbox:- tion of the floorfstriictures shown: in; Fig. taken approximately:bnwtheiiinei 2i;2-"ofi;Eig.i Fig; 3 is ahhorizontalg.seetionnthrmigh; oneznf the tiles'rofa'. supifly .01: return headerg-tof the-floor structure;.takenointhe21inei3e3iofili'ig'elii Fig. 4 is a side iview iof the tilezshowniin'ifiig. 3.; Fig. 5 is'a'=perspctiveyiew1 of an; intermediate portion Of-the fior;;st1tue,ture;; showing; tWO'nQ thetiles" separated Ntome'xpose; the bridge ;,mem: bers .which are" insentedeih the{"a;1 ignedendsruof the .ducts'in the tiles when th'e latter are brought Fig; v.6 is: a;--,sectiomth-reugh',tl esiomtgbetween the end'sg ofgtwo; .of the" field fprmingqttileslnshow ing one-10f the; bridge; members in; position;

Fig. .7 .is; a: fragmentary seetiqnali View" of; an

' intermediate portioni'of theiflooristrubture,taken Fig. ,8 is-=-a:- diagrammatic .perspee ei v emnf alayout oftra ie tifloon .1h.ea ng--s stem in.-:,-a.cr eordance .;;with an alternative; modified form of thainventionzmm i. F st 9i isfl ;1sec ion: take i leng' .1ine;correspending ieral-lygitqilmei 9a-:3:.'i0f=F g-=-,8;-'

.Ei'e. 0 s.;at xa m ntary"ienlar slciiiiewi.ius rat n :a "tun-assembly e lezieiements x nde-a modified ,iq m; ofnbx deinei c0nn ct ng;..or .;ioinr ing element; associated therewith in accordance with theiinvention; \Figs 11- to 1,4- inqlusive are perspective; w,s of vai'ieiisztile"elements.of ttheetype jfierporatifl in-lthelayout represented-"by Figs; Bland 59';

,Fi'g.a.1.5 is: it perspectix i view ofithe bridge or a connector elementappearin'g inZFigW-IOJxaIidL V Fig.-. 7.16 isLaa fragmentary: sectional :YTGW r thr. .illiistiatifigz.ceftaindetailszof, the leydiit $313.; tearing it Figs? 8; arid 9" inctsho'wing themethod the latter.

of interconnecting the tile elements of the floor system in installing the latter.

The floor structure shown in the embodiment of Figs. 1 to 7 inclusive of the drawings is composed throughout practically its entire expanse of a large number of hollow fiat-topped tiles l6 (see Figs. 2, 5 6' and 'n which tilesare arranged in regular rows like-"ordinary floor surfacing tiles. The tiles H! are individually supported on a rigid sub-base I l of suitable material, and are set flush with each other on a relatively thin layer l2 of suitable bedding material. The edges of the tiles are separated slightly from each other and the spaces between such edges are filled inand pointed up with strip-like sections 13 of suitable jointing material, which material may be the same as the material used for the bedding layer [2.

Each of the tiles I is a vitrified clay unit of.

rectangular cross section which is closed at its top l4, bottom l and sides 16, is open at its ends l1, and is provided midway between its sides 16 with a vertical partition 18. The partition l8 reinforces the top I4 and divides the hollow interior into two open-ended passages [9 for directing the hot air used in the system. The under surface of the top [4 is arched at 20 between the sides 16 andthe partition [8, whereby to afford maximum loadesupporting strength with. minimum thickness over. the passages [9. The outer surfaces of the sides l6 arerecessed at 2| between their. upper and lower edges, whereby to provide keying spaces-v of substantial size between the opposed sides of adjacent tiles .forthe reception of the jointing material while still permitting the tiles to be brought fairly closetogether.

. In applying the present system to the floor of a building in which several rooms are to be located on the same flooras in the ordinary dwellingthe tiles Hi can be arranged advantageously in a number of separate groups, as for example the three rectangular groups included. within the areas indicated respectively by the crossed arrows A, B and C in Fig.1. Each of these groups can be individually supplie'd withthe hot air used in heating the tiles. It), thus enabling the temperature of the floor in any particular area to be controlled easily in accordance with requirements and independentlyof the proximity or remoteness of such area from the source. of the hot air.

Referring to the intermediate group B-.-the tiles H1 in that group are positioned in a number of transverse rows,.with the passages 19 in the tiles in each row all extending in the same direction as the transverse rows in endwise communication with each' other. The hot air used in heating the tops M of the tiles in group B is fed under pressure from a heater 'H or other suitable source up through a flue F into a supply conduit S. The conduit S extends horizontally at right angles to the rows of tiles in group B and opens laterally after the fashion'of-a header into-each of the passages l 9 in the tiles in that-group.

flush with the tops I4 of the tiles l0, and with each of the tiles 22 in lateral alignment with one of the rows of the tiles It], thus presenting a finished tile floor surface of the same regular tile pattern throughout.

After the air supplied by the conduit S to the tiles H1 in group B has traveled the lengths of the passages 19 in the tiles 10 it enters a return.

as the tiles H), with main passages and side openings like those shown in Figs. 3 and 4, the latter being disposed in communication with the passages IB in the tiles ID. ;The tiles 21 are set into the floor in the same manner as the tiles I0, with.

their tops flush with the tops M of the tiles Hi. When setting the tiles ID in the bedding layer l2, and before bringing the tiles in each row to- I gether, inverted channel members 32 of thin sheet The supply conduit Sis composedof a single row of open-'ended-tiles 22 (see Figs. 2, 3 and 4) which have tops 23 of thesame shape and size as the tiles I0. The tiles 22 areof greater depth than the tiles I0 and each contains a main passage and two side openings 25. The openings 25 are of the same size as the passages I9 in the tiles l0 and are disposed in communication with The tiles 22 are provided interiorly with arcuate reinforcing portions 26 which serve to provide the-requisite load-supporting strength.

The tiles 22 are set in the bedding layer l2 in the same .manner as the tiles ID, with their tops 23 metal or other suitable material are telescoped into the confronting ends of the passages l9 (see Figs. 5 and 6), whereby to render such passages continuous throughout each row of tiles and prevent entry of the jointing material into the passages. The members 32 are provided intermediate their ends with out-turned positioning tongues -33 which limit the extent of insertion of the members into the ends of the passages. Similarly functioning bridge members 34 are inserted within the ends of the passages in the rows of tiles forming the supply and return headers and also in the side openings in those tiles.

The tiles forming groups A and C are laid out in the same general way as the tiles forming group B. i

The tiles In of group A are positioned in a number of transverse rows, with the passages IS in the tiles in each row all extending in the same transverse direction in endwise communication with each other. The hot air used in heating the tops [4 of the tiles in group 'A is fed under pressure from the heater H up through a flue F into a supply conduit S The conduit S extend horizontally at right angles to the rows of tiles ID in group A and opens laterally into each of the passages in the tiles in that group. The conduit S like the conduit S, is composed of a, single row of the tiles 22. The hot air which is fed into the tiles In of group A is discharged from the same into a return conduit R And the conduit R is composed of a single row of the tiles 2'! and emptying into the conduit R.

The tiles IU of group C are similarly fed with hot air from a supply conduit S the hot air upon leaving the tiles l0 discharging into a return conduit R 7 The return conduit R is connected in series withthe two other return conduits. It makesqa right angular turn at 35 at the far end of group 0; passes the closed end 36 of the supply conduit S makes another right angular turn at 31; and returns alongside the supply conduit S at 38 to an intake flue I leading back into the heater H.

In various supply and return conduits those tiles of the conduits which are perforated laterallyfor communication with the passages l9 in the tiles ID are marked with the letter P (see Fig. 1) in order to distinguish them from the unpgrforated tiles in other stretches of the condui Where theconduits sg-s and R traverse sec tion of the-fioor structure such conduits pass under the field tilesll -of= that section without interfering in" any way with the-circulation through such field*'ti1es,-thenecessary vertical jogging being effected ineach conduit through the introduction ofa special conduit tile 3 9- (see Fig. '7) having a-verticaldimension-equal -to the combined vertical-dimensions of thetiles liland Where -the-conduit R makes the rig-htangular. turn at 35 a specialconduit tile w containingan '--Sha.-ped -air passage; as illustrated inmy-copending application-identified above, maybe positioned in the 'reen'trant angleto prevent any diin'inishment inthe-flow through theconduit in turning the corner:

The--usual utilities such as pipes and wires. may-be advantageously placed in one ormore marginal conduits U (see Fig. 2) formed between upwardly opening-channel members i i: and. flat cover tiles 42 arranged-flush with theupper sure. face-of-the floor-structure.- The tilesdi; which can be removed-withoutdiilicultyat any point to give access to'theutilities, can be jointedin line with the joints between the various other tiles wherebyto present if desired an uninterrupted tile pattern over the entirefioor area.

Figs; 8- through'1'6- illustrate a further highly desirable-and alternative layout of a floor heating' system 'inaccordance with the invention and the various component tile and connector elements involved in that layout. Said components, which ar'epreferablyof a vitrified .claymaterial, are illustrated individually in Figs. 11. through 15-,- to-which attention is directed.

Referring to Fig. 11,- the 1 block-like surfacing and distributing or field-tile 50 shown therein is generally similarto thetile It of the earlier embodiment, although it is divided into three parallel=heat distributing passages 51, instead of two, and is provided along its-bottomwith the longitudinally extending rib- 52' adapted to be em.- beddedin and to interlock with cementitious grout or other suitable bedding material 53-. in which the tiles are supported on a sub-base 5.4, asillustrated in Figs. 10 and 16. The passagesor. ducts extend from end to end through the tile, whichis otherwiseimporforate. Its upper sur.-' face serves as a=finish:andload-supporting sur: face, in the same manner as .contemplated'inthe first embodiment: of the invention described above. The passages. are arched for 'strength, as illustrated in Fig. 11.

Fig; 12 illustrates a fragment of a standard, elongated and hollow, single conduittile, desig nated by the referencenumeral 55. This conduit is generally rectangular in shape and is employed with like conduits, all disposedbeneath the level of the field tiles 58, in supplying hot air from the furnace manifold or other heat source M shown in Fig. 8, and for returning the cooler air thereto after circulation through-the fieldof the system. A'special floor surfacingand feedjand return manifold tile 56 is illustrated'in Fig; 13, which issomewhat similar to the field tile 50. Its exposed upper surface is identical in shape and area: tothat of tile 50:, with the further feature that the bottom thereof is medially and transversely recessed or cut away to provide distributing recesses 51 in the opposite side walls 58 of said tile and in the parallelintermediate partitions 59, thereby placing the three tile pa'ssagesincommunication at said recesses.

In accordance with the invention-a series. of

the: manifold theses are associated :with the sizedopenings B2. in.header .tilezfi I as .shown :in. Fig, 16, itlfollows that. its transversely extending bottom recess shouldbe of substantiallygreaten width-- than any. of its longitudinal. passages-.111- order to' avoidan objectionable back. pressure.v

I Fig. .15..illustrates details of. a. special. sheet metal bridging. element .or. shield adaptedfor. the

2G same purpose as the

members

32, 34. of the first modification, but formed in a somewhat different fashion. Said shield elements are generally des.-.

I ignated by the. reference numeral 63, being stamped and shaped in an inverted U .outlinegfrom a .fiexible steel sheet. The form of the element Git-is such asto provide a main body portion. of: substantial length, and externally projecting, transverse, continuous locating beadtS formed in theelement adjoining said..body,.por.tion, and a forwardly projecting guidetongue fifiwhich is cut away. rearwardly at 61 adjacentthe lower. ends thereof for a purpose to. be described- In so far as it concerns the. general principles of circulation of hot air'in aloop duct system, in accordance with the invention, the layout 11-, lustrated in Figs. 8, 9 and 16 correspondsclosely to that shown in Figs. 1, 2 and? of the drawing; It differs therefrom in they types, of specialtiles employed and the methodof arrangement of the component tiles, in the manner now described.

Referring to Fig. 8, which represents a stand ard and relatively simple installation contemplated by the invention, av number of the plain vitrified tile supply conduits 55 are. associated end to end, employing asuitable cementitious bonding material at the joints in a well known manner, and preferably laying said tile on insulating material supported by sub-base 54, to pro vide a plurality of outgoing supply ducts D, D which are connected at their intake end with the manifold heat source M; The, number of these supplyducts may obviously by varied in accordance' with the, number of rooms'or areas to be heated. These ducts are arranged towextend in parallel side-by-side relation along one direction of; the area involved and, as illustrated in Fig. 9, are insulatingly supported on the sub-base 54 in substantially. spaced relation beneath the intended fioor' surface.

It is to be understood that the ducts D, D are constituted by the imperforate tile members 55 and'serve merely as supply conduits which, after an appropriate run, depending on the lengths of the respectivefieldareas serviced thereby, empty into an aligned series of the perforated header or distributing tiles 6|, arranged in end-to-end communication in the fashion illustrated in Fig. 8. The tiles 5! are of course laid on the same level as ducts D, D and are joined to one another at their ends, using bridge members similar to the

members

32, 36 or 63', to constitute continuousheader'or distributor ducts E, E in endcommunication with the respective supply ducts D, D Each line of: distributor tiles 6.1, constituting. the respective ducts. E, E S81,V%t0.

supply hot air to its corresponding section of the floor surface in the identical fashion served by the supply conduits S, S S of the first form of the invention described above.

Heated gaseous medium discharged into the respective distributor ducts E, E is vented upwardly through the opening 62 in the constituent tiles thereof and passes through the recessed bottom and into the interior of the aligned series of manifold tiles 56 immediately thereabove, in the manner illustrated in Figs. 9 and 16. The recesses 5'! in the walls and partitions of said manifold tiles serve to distribute and equalize the discharge of gas passing thereto from respective adjacent tiles SI of header ducts -E, E The manifold tiles 56 are laid coplanar with the floor surfacing tiles and, like said last named tiles, constitute a continuous floor surfacing area on the margins of the field area. Heating medium travels from the tiles 56 through the respective aligned passages 5| of the parallel rows of field tiles 50 and across the respective areas serviced by the respective headers E, E in a manner which will be apparent, discharging from the tiles 50 into discharge manifold tiles which are identical with the tiles 55, though being arranged over the continuous receiving and return header H, as shown in Fig. 8. The header H is constituted by aligned perforated tiles 6! and receives the discharge from all tile units of the area serviced by the supply ducts D, D and headers E, E It empties into the continuous, imperforate return duct H through which it is circulated in the direction illustrated by the arrows in Fig. 8 to a manifold of the heat source.

As illustrated in Fig. 8, special corner tile 10 may be employed at the end of the section at the corners of the respective supply and return ducts or headers. Likewise, it will be appreciated that the end tile of the header ducts E, E is suitably closed by a plate, or plug or like provision H.

Ducts H, H are laid with their tops flush with the tops of the respective ducts D, D and E, E as shown in Fig. 9, the tops of the floor surfacing and distributing

tiles

50, 56 disposed thereabove also being mutually coplanar as shown.

Further extended discussion of the arrangement and advantages of the system illustrated in Figs. 8, 9 and 16 appears unnecessary, in View of the description set forth in connection with layout of Fig. l. The modification of Figs. 8 to 16 has all the advantages of the earlier modification and, moreover, represents a considerably greater standardization of the tile elements which go to make up the same. Furthermore, the method of laying the tile is simplified and the installation expedited generally.

With reference to the shield or connector 63 illustrated in Fig. 15, the novel outline thereof contributes substantially to increased ease and speed in laying the system. As illustrated in Fig. 10, this element 63 is disposed in telescoped and connecting relation to two

adjacent tiles

50, 56, the bead 65 positioning the shield relative to the tile and also locating the tiles-relative to one another. Naturally, the element is associated similarly with two adjacent tiles 56. In employing this shield it is first inserted fully into the tile being laid, in the manner shown in Fig, 16, and the forwardly projecting, overhanging lip 66 is then inserted into the

tile

56 or 50. The relieving at 61 of the legs of the forward guide tongue 66 of the shield considerably facilitates use of the device, since it enables swinging insertion thereof into a previously laid tile,

8. rather than by a purelyhorizontal, sliding or translational movement in the grout 53. The tile in which the shield is inserted may be tipped upwardly, as shown in Fig. 16, the lip initially inserted and thetile and connector swung downwardly and forwardly toward and into the adjacent tile in a very simple and expeditious manner. Fig. 16 indicates the gas return section of an installation; however, it is to be understoodthat the same relationship of

tiles

50, 56 and 6|, which is shown to best advantage in that figure, exists atthe supply or outgoing section.

The duct H through which the air is returned to the source is preferably of somewhat larger cross-sectional area than the individual supply ducts, inasmuch as it handles the entire volume of air circulating in the system. M

It is evident that any given area of a building serviced by any of the ducts D, D of the system may be heated to any degree desired by merely dampering said supply ducts, without in any way sacrificing the uniformity of heating at any point in said area. This is an important advantage of the multiple loop duct arrangement, whether as shown in Fig. 8 or in Fig. 1. In both forms the tiles constitute the exposed load and wearing surface, the outstanding diiference being that the supply and return conduit means of the Fig. 8 layout are positioned lower than the field and manifold tiles, involving an improved and simplified method of supplying and exhausting the latter.

I claim:

1. A panel heating system comprising a plurality of parallel heating and surfacing units extending across an area to be heated and provided with internal communicating passages, and means for the circulation of fluid heating medium through said passages, comprising a hollow header duct disposed at a level beneath said units and apertured for the flow of heating medium, and a row of hollow manifold tiles disposed over said duct, said last named tiles having an upper surface substantially flush with the upper surface of said surfacing units and being provided with end openings communicating the interior of the tiles with the internal passages of said surfacing units, said manifold tiles. having means for the communication of the tile interior with the interior of said header duct through said duct aperturing, whereby to con.- nect said first named units and duct for the circulation of said heating medium.

2. A panel heating system comprising a plurality of parallel heating and surfacing units extending across an area to be heated and provided with internal communicating passages, and means for the circulation of fluid heating medium through said passages, comprising a hol-' low header duct disposed at a level beneath said units and apertured on an upper surface thereof for the flow of heating medium, and a row of hollow manifold tiles disposed over and resting on said duct, said last named tiles having an upper surface substantially flush with the upper surface of said surfacing units and being provided with end openings communicating the interior of the tiles with the internal passages of said surfacing units, said manifold tiles having an opening the surface thereof adjoining said duct for the communication of the tile interior with the interior of said header duct through said duct aperturing, whereby to connect said first named units and duct for the circulation of said heating medium. i

3. A panel heating and circulatory system comprising a plurality of parallel adjacent rows of aligned field tiles defining a floor surface, the tiles of said rows extending across an area to be heated and being provided with aligned, internal communicating passages, and means for the circulation of fluid heating medium through said passages, comprising a hollow header duct disposed at a level beneath said tiles and provided with openings in an upper surface thereof for the distribution of heating medium, and a transversely extending row of hollow manifold tiles resting on said header duct, said last named tiles having an upper surface substantially flush with the upper surface of said field tiles and being provided with lateral openings communicating the interiors thereof with the internal passages of said field tiles, said manifold tiles having an opening on a lower surface thereof adjoining said duct in communication with said duct aperturing whereby to connect said field tiles and duct for the circulation of said heating medium.

4. A panel heating and circulatory system comprising a plurality of parallel adjacentrows of aligned field tiles defining a floor surface, the tiles of said rows extending across an area to be heated and being provided with aligned, internal communicating passages, and means for the circulation of fluid heating medium through said passages, comprising a hollow header duct disposed at a level beneath said tiles and provided with openings in an upper surface thereof for the distribution of heating medium, and a transversely extending row of hollow manifold tiles resting on said header duct, said last named tiles having an upper surface substantially flush with the upper surface of said field tiles and being provided with lateral openings communicating the interiors thereof with the internal passages of said field tiles, said manifold tiles having an opening on a lower surface thereof adjoining said duct in communication with said duct aperturing whereby to connect said field tiles and duct for the circulation of said heating medium, said manifold tiles being recessed on the sides thereof to communicate the interiors of adjacent tiles of said row with one another.

5. In combination, a header du'ct adapted to circulate a fluid medium, said duct being apertured on the upper surface thereof, and a series of hollow manifold tiles arranged in a row along I 10 said duct and supported thereby, said tiles each having a recess on the lower portion thereof for internal communication with said duct through said aperturing, and being provided with a lateral opening for the flow of said medium.

6. In combination, a header duct adapted to circulate a fluid medium, said duct being apertured on the upper surface thereof, a series of hollow manifold tiles arranged in a row along said duct and supported thereby, said tiles each having a recess on the lower portion thereof for internal communication with said duct through said aperturing, and being provided with a lateral opening for the flow of said medium, and a plurality of rows of floor surfacing tiles provided with aligned internal passages in communication with the openings in said respective manifold tiles.

7. In combination, a header duct adapted to circulate a fluid medium, said duct having a plurality of fiuid flow openings on the upper surface thereof, and a series of hollow manifold tiles arranged in a row along said distributor duct and supported thereby in covering relation thereto, said tiles having a lower portion thereof recessed for communication of their respective interiors with the interior of said duct through the openings in the latter, and being provided with lateral openings in the sides thereof for flow of said medium in a direction at an angle to said row.

GEORGE F. KECK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,086,031 Davis Feb. 8, 1909 1,302,667 Jones 1 May 6, 1919 1,800,951 Miller Apr. 14, 1931 1,968,680 Grothaus July 31, 1934 2,029,876 Klein Feb. 4, 1936 2,086,744 Seelye July 13, 1937 2,105,106 Bridgman et al Jan. 11, 1938 2,294,776 Freeman Sept. 1, 1942 2,422,685 Keck June 24, 1947 FOREIGN PATENTS Number Country Date 151,896 Switzerland Mar. 16, 1932