US638236A

US638236A - Electric heater.

Info

Publication number: US638236A
Application number: US68224898A
Authority: US
Inventors: Edward E Gold
Original assignee: Individual
Current assignee: Individual
Priority date: 1898-06-01
Filing date: 1898-06-01
Publication date: 1899-12-05
Anticipated expiration: 1916-12-05

Description

No. 638,236. Patented Dec. 5, |899. E. E. GOLD.

ELECTRIC HEATER.

l (Application led June 1, 1898.)

(No Model.)

4 Sheets-Sheet l.

-WITNESSES ffm N0. 638,236. Patented Dec. 5, |899. E. E. GOLD.

ELECTRIC HEATER.

(Application led June 1, 1898.) (N0 MOMI.) 4 Sheets-Sheet 2l WITNESSES; INVENTOR:

m0 ma@ @uw i@ @a /y/ By /zis fforneys.

m. Damn fg, A'

No. 638,236. Patented Dec. 5, |899.

E. E. GOLD.

ELECTRIC HEATER.

(Appl cat nldJun 1 1898) 4 Sheeis--Shest 3.

(No Model.)

FIG. 34.

FIG. 33.

2. Zww F INVENTOR:

By his ,/lfiorneys. m. @kann f@ WgNESSES -Y .M/ /f/ff/Z/ |s mtas 00. Punto-mwa.. wam;

No. 638,236. Patented Dec. 5, |899. E. E. GOLD.

ELECTRIC HEATER. (Application med .nm 1,` 189s.)

` 4 shem-shet 4.

(No Model.)

FIG. 25.

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FIG. 26.

INVENTOR: www 22%,

By his Attorneys. Mhw fc5v UNITED STATES PATENT EDVARD E. GOLD, OF NEIV YORK, N. Y.

ELECTRIC HEATER.

SPECIFICATION forming part of Letters Patent No. 638,236, dated December 5, 1899. Application iiled .Tune 1, 1898. Serial No. 682,248. (No model.)

To ctZZ wiz/0m 'it may concern.-

Beit known that I, EDWARD E. GOLD, a citizen of the United States, residing in the city, county, and State of New York, have invented certain new and useful Improvements in Electric Heaters', of which the fol-l lowing is a specification.

This invention relates to electric heaters of that type in which the heating element is a resistant wire coiled into an open helix and so mounted as to afford free circulation of air through the helix, the wire being preferably naked and its support insulated. According to my present invention the support is a rod, preferably of insulating material or of metal coated with insulating material, such as enamel, this rod being of materialiysmailer diameter than the interior of the helix and passing through the helix, so that the latter is interiorly supported on the rod, but can touch the rod only at intervals, leaving the greater portion of the circumference of each loop or convolution out of contact with the support and surrounded on all sides by the circulating air. The helix is of Wire having sulicient stiffness or resilience to retain its helical forni. The helix is coniined on the rod by heads or plates at the opposite ends. The lrod is straight, or approximately so, in contradistinction to a rod which is bent into a helix. To avoid rattling of the wire helix upon the support and to seat the resistant wire firmly against the support, I put the wire under stress in such manner that it is thrust eccentrically against the support. In practice I buildup a heater, ordinarily, by assembling several suoli substantially straight helices and their supports in parallel order adjacent to one another between suitable end supports or heads, and usually within a suitable casing.

Having thus indicated the nature of my invention, I will proceed to describe thesame in detail with reference to the accompanying drawings, wherein- Figure l is a side elevation of an elemental heater comprising a single helix and its interior supporting-rod, Fig. 2 being a trans verse section thereof. Fig. 3 includes three transverse sections of the rod, showing at a, h, and o the position thereon of the convolution ofthe coil nearest to the lines 3a, 3b, and 3C,

respectively, in Fig. l. Fig. el is a diagram matic cross-section. Fig. 5 is an elevation of one form of helix before placing it upon' the rod. Fig. 6 is an elevation of another form of helix. Fig. 7 isa sectional elevation of a complete electric heater constructed according to inyinvention. Fig. S is a transverse section thereof. Fig. 9 is a transverse section of the coils and supports therefor, showing the inode of connecting the coils together serially. Fig. l0 is a fragment 01' one of the supporting-rods, on which are marked the contact-points at which the helical convolutions tangent the support. Fig. ll is an oblique elevation of a fragment ofthe helix, showing the preferred inode of applying stress thereto. Fig. 12 is an end elevation ot the helix after having been twisted in the manner shown in Fig. l1. Fig. lis a side elevation cfa modiiied construction, of which Fig. lli is a crosssection,Fig. l5 including three cross-seetions in different planes analogous to those shown in Fig. o. Fig. lo shows a fragment of the su pporting-rod of Fig. l,wirh the contactpoints indicated asin Fig. lO. Fig. 17 isan elevation of a further inodiiication, of which Fig. I8 isa diagrammatic cross-section. Figs. 19 and 2O are cross-sections of the helix of Fig. 17 before placing it on the support. Fig 2l shows afraginent of the rod of Fig. 17, showing the contact-points of the helix. Fig. 22 is atransverse section of a rod and coil, showing a modiiied construction. Fig. 2S is a transverse section of the type ot' heater shown in Figs. 7, 8, and 9, showing six helices connected in two series ot' three each for giving two gradations of heat; Fig. 24C is a similar cross-section showing a six-coil heater subdivided into three series of two coils each for giving three gradations of heat. Fig. 25 is a sectional plan and Fig. 2G a transverse section showing a modified type ot heater compounded from the simple types first shown to form a horizontal heater. Fig. 27 is a vertical transverse section of a vertical type of heater. Figs. 2S and 29 are respectively a cross-section and side elevation of a modified helix and its supporting-rod. Fig. 3() is a Fig. 33 is a cross-section of IOO 2 esaase a heater with two helices of this type. Figs. Se and 35 are cross-sections showing a further modification of helix. Figs. 36 and 37 are respectively a plan and cross section showing a still further modification.

In all the figures, A designates a helix of resistant wire having sufficient stiffness to retain itself in helical form and wound openly so as to leave ample space for air circulation between its successive convolutions and avoid any possibility of their touchilnli and short-circuiting.

B is asupporting-rod, preferably round or cylindrical, although this shape may be departed from, and of a diameter considerably smaller than the internal diameter of the helix, so as to be able to touch the latter tangentially at onlyone point. The supportingrod B might be of glass or porcelain or other insulating materialof sufficient strength; but l prefer a rod of stiff wire or metal coated with a vitreous enamel.

C C are heads or stops which serve to confine the opposite ends of the helix and hold them on the rod.

The helix A and supporting-rod B are relatively conformed in such manner as to cause the convolufions of the helix to press elas ticallyinto firm contact. with the rod, so as to touch the latter only at intervals, the helix being thus caused to cling upon the rod. This cling` of the helix upon the rod to such extent that the weight of the helix is supported on the rod and is held against undue vibration is effected by a relative conformation of the rod and helix in such manner that the rod may be straight, or approximately so, in contradistinction to the cling of the helix upon the rod being caused by the rod being itself curved or helical in shape. The helix has in each convolution a length of wire materially in excess of the circumference of the rod, so that the greater portion of its wire is out of contact with the rod and exposed to circulation of air.

I will first describe the preferred construction with reference to Figs. l to l2, inclusive. The wire helix is wound, preferably, of about the degree of openness shown at the left in Fig. 6 and has a diameter which should be at least fifty per cent. greater than that of the supporting-rod. The helix, being cut to a suitable length, is thrust over the rod. Preferably the helix is wound on a straight mandrel, so that it tends to retain a straight form and is of sufficient stiffness to hold itself straight unless forcibly bent or deflected. The helix is then put under stress by bending it torsionally, as shown by the arrows in Fig. 1l. rlheresult of thisbendingis to cause the helix to tend to assume the Vform of a compound helix, so that viewed endwise it would appear as in Fig. l, or viewed silewise somewhat as in Fig. 5; but if confined on the rod its spiral deflection is limited by the rod itself, so that it assumes the form shown in Figs. l and 2. The torsional stress imparted to the wire throws each convolution of the helix eccentrically against the rod in the manner shown in Fig. 3, where three separate sections are shown pressing in three different directions. Fach successive convolution is thrust against the rod in a different direction, so that the successive thrusts being each in advance of the preceding progress spirally around the rod, thus pressing the convolutions into con tact with the rod at points which equally progress spirally, as shown in Fig. l0. In this figure the contact-points ou the near side are shown by black dots a, and those on the far side by light dots 0f course the area of the contact-points is in this figure greatly exaggerated, .li ,\"colifact being tangential and forming` an actual surface in contact amounting to little more than a geometrical point. Hence practically all the wire of the helix is out of contact with the support and is exposed to circulation of air. in Fig. l I have shown the heads C C as being` disks placed over the ends of the rod, fastened thereto by pins d, for example, and having holes at c c through which to thrust the ends of the wire in order to retain it under torsional strain. The same result of deflecting the helix into tangential and spirally-progressive contact with the rod can be accomplished by origin ally winding the wire openly, for example, as shown at A' at the right hand of Fig. G and compressing it on the rod without necessarily any torsional strain whatever. This compression tends to force the helix into a bowed form, which distributes itself from one convolution to the next, fhrowingeach laterally int-o tangential contact with the rod and producing the same effect as shown in Figs. l and 2. The torsional stress,however,is preferable, for the reason that it avoids anyliability of the pitch of the helix becoming unequal owing to the wire varying in strength. It is found that the best wire varies somewhat in strength or in electrical resistance in different portions of its length, so that if the helix is confined compressively upon the rod and an elecf ric current is passed through it that heats it somewhat above the normal temperature of an electric heater, the weaker or more resistant portions of the wire yield first or in greater proportion than the others to the stress, and the con volutions formed by these portions of wire are crowded closer together than the convolutions of stronger wire, so that they may in an extreme case actually be forced into contact with one another, thereby short-circuiting them and impairing the valuel of the heater. This result, however, is due to the stress being in direction perpendicular to the planes of the convolutions, and by avoiding stress in this direction this disadvantageous effect is avoided. By applying the stress torsionally if any portion of the wire becomes weaker than the remainder this portion will not have itsl convolutions forced closer together, but will yield in a rotative direction in obedience to IIO the superior twisting stress of the remaining convolutions. I have subjected coils thus under torsion to a sufficient electrical current to heat the Wire to a red heat, and hence (the wire being of iron or steel) to anneal it, whereby it lhas been .deprived of nearly all elasticity, but without perceptibly varying the spacing of the convolutions and Without causing the wire helix to lose its spiral cling upon the rod. Tire thus treated acquires a permanent set in the spirally-distorted form of the helix, its resistance to bending being sufficient to retain the convolutions in their original eccentric contact with the rod. These results are of great importance when is is desired to wind the maximum length of wire in the minimum space.

In some of my previous inventions in electric heaters I have formed the supporting rod or wire preferably in helical form, so as to force the resistant-helix into a compound helix, which is a highly advantageous construction from many points of view; but the amount of wire that can be arranged in a given space is limited by the minimum spacing apart of the minor convolutions on the inner side of the major helix, this being the point of greatest approach of the successive minor convolutions, while exteriorly they are separated more widely than is necessary for safe insulation.

In my present construction the successive convolutions are substantially parallel instead of being mutually divergent, and hence they need be spaced apart only sufficiently to insure safe insulation and enable the air to freely circulate around the wires. The practical result of this difference is that considerably more wire can be concentrated in a given cubical space (or given heater-casing) than when the wire is formed into a compound helix. My present invention therefore is characterized lby the extending of the resistant coil or helix and its support in substantially straight direction, as contradistinguished from bending them into a spiral or helix, the stress which causes the resistant helix to bear tangentially against or cling to the supporting-rod being imparted otherwise than by the tendency of the helix to straighten out to its original shape when conned on a curved spiral or helical rod.

My invention may be worked out and applied in various ways, as will be described hereinafter with reference to the modifications illustrated.

Figs. 7, 8, and 9 show the preferred construction of a complete or commercial electric heater embodying my invention. The supporting-rods B B and coils A A are the saine as already described. The rods are supported at their ends by being thrust into holes or sockets in end heads or caps C C, preferably of porcelain, bushings of asbestos ff being interposed as apacliing around the rods to prevent rattling. Ihave shown seven rods, one being arranged in the center and the other six arranged in hexagonal order around it. The center rod (lettered B) is longer than the others and has its ends screwthreaded and passing through the head C or into a recess g formed in thehead, and having nuts 7i h screwed on its threaded ends in order to draw the heads together. The other six rods have their ends simply seated in sockets in the heads. rlhe ends may abut against the bottoms of these sockets, as shown at the left in Fig.7; but preferably at least one end of each rod is cushioned against a spring, which may be formed as shown at ,in order to compensate for varying expansion and contraction of the rods. For the same purpose itis preferable to introduce a spring between one or both of the nuts h and the heads, which may take the form of a spring-washer j, as shown at the right in Fig. 7. It is usually preferable to provide a foraminous or openwork casing for the heater, which may be made of a perforated sheet-metal tube, as shown at D, the ends of which it over bosses 7c Z; on the porcelain heads. The heads are drawn into firm contact with the opposite ends of this tubular casing by the nuts 7i 7L on the central rod B', and it is chiefly to allow for differences in expansion and contraction between this tube and the rods B B that the latter are provided with springs or yielding cushions t' j. If a casing is used which is longitudinally yielding-such as a helical wire, as set forth in my pending application Serial No. 668,528-such cushions or springs may be dispensed with. The resistant helices A A are all formed in the construction here shown of one length of wire, a single long helix being placed over one rod, twisted to put it under stress, uncoiled sufficiently to extend to the next rod, twisted on that, uncoiled and extended to the next one, and so on, the opposite ends of the wire being carried to binding-posts E E', respectively, which pass through holes in the opposite end heads and have nuts screwed on them in the recesses g for clamping the circuit-wires 'zu lw. The recesses gin the heads are preferably closed and covered by caps F F, fastened by screws l Z, which may be slackened to turn aside the caps to get access to the recesses. In Figs. S and 9 I have for clearness shown the cross-section of the helices A at only a single point in each to avoid the confusion incident to illustrating them in the manner indicated in Figs. 2 and l2; but I have in Fig. S indicated the extreme outward displacement of each coil by the dotted circles g/ y. This form of heater is very compact, and, while affording most perfect ventilation and exposing practically all portions of the wire on all sides to the air, enables the maximum length of wire to be assembled in a given space.

My invention readily lends itself to the provision of means for graduating the heat being generated. In Fig. 23 I have shown six coils or helices connected in two circuits or branches w' 102, which by means of a switch IOO IIO

ceases (indicated elementally at o) can be connected with the main circuit, so as to throw in either one or both. XVhen the switch is connected with circuit w', the current passes serially through coils numbered 1, 2, and 3, and when the switch is carried also into connection with circuit 102 the current also traverses coils d, 5, and G, thus giving two degrees of heat. If three degrees of heat are required, the arrangement shown in Fig. 2st is adopted,where in there are three circuits w' to2 w3, the first of which when in circuit carries the current serially through coils numbered 1 and 2, the second of which through coils 3 and 4, and the third through coils 5 and G. With either arrangement either the entire resistance required to be introduced between the circuitterminals may be arranged in one heater by making the heater of suiiicient length to contain in the two or three helices the necessary length of wire, or it may be divided between two or more heaters arranged serially, so that each branch circuit wl cu2, the., traverses tirst the two (or three or more) coils of the iirst heater, then the corresponding coils of the second heater, and so on through the entire series. In this way in heating a railwaycar, for example, a single switch may control all the heaters in the car, causing each h eater to give out one or two (or one, two, or three) degrees of heat, so that the heat is equally moderated in all portions of the car, which practically is of great advantage compared with the customary mode ot' cutting out certain heaters, leaving the others generating the full degree or" heat.

While the construction of heater shown in Figs. Tand 8 is preferable forinost purposes, yet it is sometimes desirable to arrange the heating elements in different forms. Figs. 25 and 2G show a ilat heater, which may he arranged horizontally or otherwise. The opposite heads (here lettered C C') instead of being in the form of disks are formed as longitudinal bars having sockets for receiving the ends of the rods B B. I have shown the end rod B' passing through the heads or side bars and having screw-threaded ends for receiving nuts h 7i to clamp them together. I have shown certain of the rods B B united integrally in the form of a zigzag rod, a form which may be used in this or in any other arrangement of my improved heater in which a plurality of parallel supporting-rods is desired.

In Fig. 27 I have shown a vertical arrangement of heater adapted to be set into a panel or opening in the riser of a car-seat, for example. The front plate G has a perforated or grated air-inlet opening m below and a similar opening m above and is provided with a curved back plate Gr, forming between them a flue traversed by the air which is circulated by the heater, and in which 'llue is arranged aseries of supporting-rods B B and coils A A, extended across it horizontally from side to side between suitable side or end plates or heads C2. I have shown these heating elements as arranged in oblique order in order most perfectly to subdivide and heat the ascending air.

I will now describe some further modifications of which the heating element constituting the gist of my invention is susceptible, referring for that purpose to Figs. 13 to 22, inclusive, and Figs. 28 to 37, inclusive,

In Figs. 13 to 16 I have shown a construction constituting a reversal of that shown in Figs. 1 to Ll-. In the latter' figures the supporting-rod is straight and the resistant helix is forced into a sinuous or spiral shape in eccentric contact with the rod. In Figs. 13 to 16 this arrangement is reversed, the helix remaining straight and the rod being slightly twisted in spiral manner, as clearly shown. By comparing the three sections shown in Fig. 15 with the corresponding seotions shown in Fig. 3 the equivalence of these two methods will be obvious. Fig. 1G shows the contact-points of the convolutions with the supporting-rod by dots :t n3 in the same manner as in Fig. 10.

Figs. 17 to 2l, inclusive, showafurther modification. Here the resistant helix A is slightly bent laterally at intervals ot a few convolutions, so as to bringits successive sections out of alinement with one another in the manner shown with reference to two sections only in Fig. 19 and developed with reference to i'our sections in Fig. 20. rIhe deliection of the sections should be sufficient to make the central space common to all, which is lettered u in Fig. 20 of smaller diameter than the supporting-rod B, so that when the rod is thrust through the helix it will bend the successive sections into positions more nearly in alinement with one another, thereby causing them by their mutual reactions to press elastically against the rod. The resulting structure is shown by the diagrammatic end view in Fig. 1S. Fig. 21 shows the touch-points of the convolutions upon the rod by dots x 02'. This modification may be further modiiied by bending each successive convolution slightly out of alinement with the preceding one, which would produce a helix having an initial spiral set, and appearing in end view exactly the same as the helix shown in Fig. 12, with its central space u smaller than the diameter of the supporting-rod, and which when placed upon such rod would produce exactly the heater of Figs. 1 and 2, only that its shape to exert stress against the rod is produced by an initial bending of the helix instead of by twisting a straight helix, so as to give it a torsional stress.

Figs. 2Sand29showa modification in which successive convolutions or groups of convolutions of the helix are displaced laterally in such manner that every alternate group encircles the rod, while the intervening groups are exterior to the rod, the directions of pressure against the rod being shown by the small arrows in Fig. 2S.

lOO

IOS

The word helix as used in this specification is not to be construed in a limited sense, as the helix may be more or less distorted from a true helix without, however, departing from its essential nature. One example of such distorted helix is shown in Fig. 30. This modified helix consists of a simple helix with its diametrically opposite sides forced in at r r, so as to approach each other. Such a helix can be readily mounted upon the supporting-rod by further forcingin the portions r r in the direction of the arrows in Fig. SO until they have crossed each other and thrusting the rod through the new loop thus formed in the manner shown in Fig. 3l. Fig. 32 is a plan of the heater thus formed. This modification provides a great length of wire supported by a single rod and pressing against vit at diametrically opposite points, as indicated by the small arrows in Fig. 3l. Instead oi' each convolution touching the rod at one point it touches it at two points; but as the length of wire in each convolution is approximately doubled the result'is much the same as in the previously-described constructions. There it is desired to avoid any possible tilting of the distorted helices thus formed, the rod may be made oval, as shown in Fig. 33.

Fig. 34E shows another construction of distorted helix, the diametrically opposite portions of a simple helix being forced toward each other, each approaching portion, however, being formed with an outward hump s, between which humps the supporting-rod Bis embraced7 the helix being` under such stress as to press against the rod in the direction of the small arrows.

Fig. 35 shows a further slight modification in which the portions s s are bent to arcs of smaller radius than that of the rod B, so that they make contact with the latter only at opposite sides or corners s2. In this latter construction the helix touches the rod at four points in each complete convolution.

A further modiiication is shown in 22, which differs from that shown in Fig. 34, for example, only in the shape of the coil or helix in cross-section, its convolutions being flattened, as shown.

The last-described constructions may be modified by bending the wire into a curved zig- Zag in the manner indicated, for example, in Figs. 36 and 37,where the loops of wire, viewed in plan, as in Fig. 36, extend in zigzag form and are carried alternately under and over the rod, as there clearly shown, the arrangement of the wire as viewed endwise being indicated in Fig. 87. The wire clings upon the rod by pressure in diametrically opposite directions to each complete loop or convolution in essentially the same manner as in Figs. 34; and 85. Hence within the scope of my invention the Word helix7 must be understood as covering any arrangement of wire in successive loops or convolutions extending around and around or back and forth and progressing continually in longitudinal direction, so that the successive loops thereof may touch the supporting-rod at successive points progressing along the rod from end to end.

It is common to all the modifications of my invention thatwhiletheheaterelements-that is to say, the combined coil and supporting rod-extend as a whole in substantially straight direction they are so conformed relatively to one another as to cause the loops or convolu tions of the coils which encircle or substantially inclose the rod to press elastically into firm contact with the rod, so as to cause the coil to cling upon the rod, touching the rod at one point in each convolution, (or it may be at more than one point,) the portion of wire of each convolution which is in contact with the rod being minute, so that by far the greater proportion of the wire is wholly out of contact with the support and is wholly surrounded by air, so as to expose to the air the greatest possible amount of wire that is consistent with affording the wire a firm and suit-- able support upon the rod. In other words, the wire constitutes a spring' which is so bent that it repeatedly touches the rod, the portions between its points of contact therewith being bent away from the rod, so as to be immersed in air, the successive loops or portions of wire pressing against the rod in different directions, so that each portion serves as the reaction for receiving the tension of the neighboring portions in such manner that the algebraio sum of the directions of pressure against the rod relatively to the central axis of the rod equals Zero.

The term rod as used herein is not necessarily to be understood as limited to a rigid material, since any material which is given the proper shape and direction being straight, orapproxi mately so,and which has or to which is impart-ed by putting under strain or otherwise the requisite rigidity to support the coil in the manner described may serve as the rod 0r as its mechanical equivalent.

I claim as my invention the following defined novel features, substantially as hereinbefore specified, namely:

l. An electric heater comprising asupporting-rod, combined with a coil of resilient resistant wire, the combined rod and coil extended in substantially straight direction,and the coil having loops encircling the rod, the wire thereof touching the rod at intervals and looped through the air out of contact with the rod between its touch-points, and shaped to press elastically against the rod in different directions against different sides of the rod so that the wire clings to the rod, while its greater portion is free therefrom and exposed to circulation of air around it.

2. An electric heater comprising a supporting-rod combined with a resilient resistant wire formed into successive loops constituting a coil, the combined rod and coil extended in substantially straight direction, the rod passing through loops of said coil, and the wire touching said rod at intervals, looped IOO IIO

through the air out of contact with the rod between its touch-points, and shaped to press elastically against the rod on different sides thereof so that the wire clings to the rod while its greater portion is free therefrom and exposed to circulation of air around it.

An electric heater comprising an open helix of resilient resistant wire combined with a substantially straight supporting-rod extending within it, the helix conformed relatively to the red to press elastically against the rod on different sides thereof so that it clings thereon, and having in each loop or convolution a length of wire exceeding the circumference of the rod, so that the greater portion ot its wire is out of contact with the rod and exposed to circulation of air.

4. An electric heater comprising a coil of resilient resistant wire combined with a substantially straight supporting-rod therefor, the coil wound with its convolutions of the degree of openness required in the heater, and applied upon the rod under stress laterally thereagainst to make firm contact therewith, but without longitudinal stress so that its convolutions are free from any tendency to Vary their relative spacing, to the effect set forth.

5. An electric heater comprising an open helix of resilient resistant wire,combined with a supporting-rod within said helix of materially smaller diamet r than the interior of the helix, the combined rod and helix extended in substantially straight direction,and the helix tending to assume a direction different from that of the rod so that it presses eccentrically against the roth-successive portions of the helix touching the rod at different points and pressing against it in different directions so that the helix clings upon the rod.

6. An electric heater comprising' an open helix of resilient resistant wire, combin ed with a supporting rod within it, of materially smaller diameter than the interior of the helix so as to be capable of making only tangential contact with the helix at one point in the circumference of the latter, the combined rod and helix extended in substantially straight direction, and the helix being under stress forcing it into sinuous form so that its successive loops touch the rod at points which progress spirally around the rod.

7. An electric heater comprisinga supporting-rod combined with a resilient resistant wire formed into successive loops constituting a coil, said coil extendingin the same general direction as the rod, the rod passing through loops of said coil, the wire touching said rod at intervals, looped through the air out of contact with the rod between its touchpoints, and shaped to press elastically against the rod in different directions, its successive loops touching the rod at points which progress spirally around the rod.

8. An electric heater comprising an open helix of resilient resistant wire, combined with a straight supporting-rod within it, of materially smaller diameter than the interior of the helix so as to be capable of touching it tangentially only, at one point in the circumference of the helix, the helix being normally straight and being put under stress on the rod so as to distort it into sinuous form and force its loops eccentrically against the rod so as to press against the latter in different directions, so that the helix clings upon the rod.

S). An electric heater com prising an open helix of resilient resistant wire, combined with a supporting-rod within it, ci materially smaller diameter than the interior of the helix so as to be capable of touching it tangentially only, at one point in the circumference of the helix, the helix being under torsional stress on the rod so as to distort it into sinuous form so that its successive loops touch the rod at points which progress spirally around the rod.

10. An electric heater comprising an open helix of resilient resistant wire, combined with a supporting-rod within it of materially smaller diameter so as to touch it tangentially only, and heads at opposite ends of said rod between which the helix is confined, the helix being under stress between said heads to cause it to press elastically into eccentric contact with the rod.

ll. An electric heater comprising opposite heads or supports, a plurality of supportingrods extended between said supports, a coil of resilient resistant wire carried on each rod, each such combined rod and coil extending in substantially straight direction, with the rod passing through loops of such coil, and the wire thereof touching the rod at intervals, looped through the air out of contact with the rod between its touch-points, and shaped to press elastically against the rod on different sides thereof so as to cling thereto.

l2. An electric heater comprising opposite end heads, a group of parallel supporting-rods extended between said heads, one of said rods passing through the heads and constructed as a bolt for connecting the heads together, and the remaining rods having their ends sccketed in said heads, coils of resistant wire mounted on said rods, and a tubular open-work casing extending between said heads and inclosing said rods and coils.

13. ln an electric heater, the combination of insulating end heads C C having a central hole and sockets around it, a central rod B having threaded ends passing through the central holes in said heads, and nuts thereon for drawing the heads together, a group of supporting-rods B B arranged around said central rod with their ends seated in the sockets in said heads, and coils A A of resilient resistant wire mounted on said supportingrods, the loops of wire making only tangential contact therewith and clinging thereto.

le. ln an electric heater, the combination of end heads C C, a tubular open-work casing D extended between said heads and fitting thereto, a central rod B passing through said IOO IIO

In witness whereof I have hereunto signed my nmne in the presence of two subscribing lo witnesses.

EDVARD E. GOLD.

Witnesses:

FRED WHITE, THoMAs F. WALLACE.