FIELD OF THE INVENTION 
   A gas lamp which utilizes combustible gas burned as a linear vortex to produce light along a substantial flame length for illumination, comfort, mood, decoration and large scale art. 
   BACKGROUND OF THE INVENTION 
   Combustion flames have historically been used for their radiant and convective heating effects, and for illumination. Hearth fires, campfires, and fire rings are classical examples. The combustion of wood, coal, natural gas and bottled gas is generally the source of the flame. 
   The shape of the flame is rarely of interest in most applications where warmth, mood and “coziness” are the principal objectives. The flame itself usually will be in a confined (but vented) region, and much of the heat from the reverse side of the flame will be re-radiated by surrounding surfaces. However, much of the light and some of the radiant heat will be dissipated or hidden from view. In addition, the height of the flame may be quite low, and its illumination effect will be minimized. Gas lamps are not usually tall enough to provide effective illumination. As a consequence, most gas lamps, lanterns, or “tiki torches” are mounted on poles or suspended from an overhanging support, which limits their placement. 
   This invention provides an attractive, surprisingly tall disciplined flame as a generally cylindrical vortex, providing an extended light source useful for decoration and for illumination and heating. It is a safe structure. The flame is inside a transparent shield which remains surprisingly cool to the touch. Furthermore the inside of the shield is kept clean by the flame and the air flow. 
   The lamp of this invention is very inexpensive. It comprises sections of curved plastic material that can even be folded neatly for storage or shipment, but which springs back to its curved shape. It is elegantly simple, does not require a blower to create the swirling flame, and needs no side support. 
   BRIEF DESCRIPTION OF THE INVENTION 
   A gas lamp according to this invention comprises a plurality of axially-extending curved channel-like sections that are mounted parallel to one another to form a shield. Each section has an axially extending edge that overlaps the wall of its neighbor so as to form ports between them which extend axially along the sections and open tangentially into the combustion region inside of their assembly (the shield). 
   At one end of the assembly of the sections, a gas orifice is disposed which faces axially into the chamber. It need not be a classical burner, because air is supplied through the ports. A simple orifice or a perforated plate will usually suffice 
   As the flame burns and rises, air is drawn into the chamber through the ports with a tangential movement. This results in a rotary swirling motion of the gases in the chamber. As the flame rises, air is brought into the chamber along the axis to feed the uncombusted material, thereby generating a flame that extends for a considerable axial length. It is this extended flame that is the objective of this invention. 
   The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which: 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevation showing the presently-preferred embodiment of a gas lamp according the invention. 
       FIG. 2  is a cross-section taken at line  2 — 2  in  FIG. 1 ; 
       FIG. 3  is a cross-section taken at line  3 — 3  in  FIG. 2 , and 
       FIG. 4  is a cross-section taken at line  4 — 4  in  FIG. 2 . 
   


   DETAILED DESCRIPTION OF THE INVENTION 
   The presently preferred embodiment of this invention is shown in  FIG. 1 . A gas lamp  10  rests on any suitable support  11  such as a table, fireplace, or wall. A source  15  of combustible gas is supplied under pressure through a conduit  16 . A control valve  17  admits or prevents the admission of gas, and controls its rate of flow. A mixing burner or mixing nozzle is not needed. The air is supplied through the gaps in the wall structure. 
   The lamp is shown in an upright position, with its central axis  18  vertically oriented. Exact upright orientation is not necessary. It may be slanted downwardly, up to about 45 degrees from the vertical. Beyond that, the advantages of improved convection are lost, and the lamp is not as reliable. 
   This lamp is characterized by its elegant simplicity. It may be formed by as few as two parts, and usually will be. It is possible to use three or more, but there is no particular advantage in doing so, although it is within the scope of this invention. 
   The shield  20  of this invention is formed by two axially extending channel-like sections  21 , 22 . These sections are preferably identical, and are arcuate in cross-section. They may be supported in grooves (not shown) in the support, or may be otherwise held in position together as preferred. 
   It is convenient for the sections to be identical. Then only one size and shape needs to be manufactured and kept in inventory. In the most convenient arrangement, both of them are axial sections of a cylinder. 
   For example, section  21  has a center  25 , a curved body  26 , and a pair of end edges  27 , 28 . The ends are parallel to one another, and to axis  18 . Section  21  has a wall thickness  29 , which is quite thin, an outer wall  30  and an inner wall  31 . 
   Similarly, section  22  has a center  35 , a curved body  36 , and a pair of end edges  37 , 38 . The ends are parallel to one another and to axis  18 . Section  22  has a wall thickness  39 , which is quite thin, an outer wall  40  and an inner wall  41 . 
   Importantly to this invention, as shown in  FIG. 2 , the respective ends of both sections, for example end edges  27  and  28 , extend onto the same side of a diameter  42  that is to say, the arcuate dimension of each of the sections exceeds 180 degrees. 
   Again as will be seen in  FIG. 2 , centers  25  and  35  of sections  21  and  22  are offset from one another by a dimension  45 . This offset dimension is approximately aligned with the mid portions of the sections. 
   As a consequence, two axially-extending air ports  50 , 51  are formed between areas of the two sections. In  FIG. 2 , notice that end edges  27  and  38  of sections  21  and  22  have passed over one another and that a region  52  of sections  21  and region  53  of section  22  face one another to form the gap-like port. A similar port  54  is formed at the other end edges. It will be observed that the edge section which is outermost at one port is the inner-most at the other. 
   This arrangement establishes two ports for air which are tangentially directed in the same rotational sense. The heat of burning gases rising in the structure will draw air into the combustion chamber in a way that will create a rotationally swirling flow pattern. 
   Especially notice that the air is continuously supplied along the length of the structure, so the combustion occurs along the entire path. Importantly, the incoming air flows along the inner walls and cools them. Further, it tends to keep them clean, and avoids the formation of smoke which would reduce the clarity of the structure and visibility of the flame. 
   Should more than two sections be desired, perhaps because of a very large diameter, the overlaps at the edges will be similar in function, but more numerous than two. 
   The preferred material is transparent, stiffly flexible, and self-shape retaining, so that when released after bending it returns to its original shape. A polycarbonate is preferred, although other substantially non-combustible plastics may be used instead. This material in its bent form is self-shape restoring. It can be folded for storage and will return to its curved shape when released. Although this shield will contain a flame, the flame will not directly contact the shield. Still it is preferred to use one which will not combust should flame impinge directly on it for some reason. 
   A wall thickness of about 0.030 inches will generally suffice for a shield as tall as 6 feet, with diameters ranging up to about 12 inches. Thicker walled material may be required for taller or larger diameter shields. Thinner material may be used for shorter heights and smaller diameters. 
   Suitable dimensions for a useful gas lamp according to this invention are as follows: 
   For a 30 inch lamp radius about 1.5 inches. For a 6 foot tall lamp, radius about 12 inches. 
   The height of the structure will be taller than the flame so the flame is entirely contained. The width of the ports is adjustable and selectible. A minor amount of adjustment will determine the proper width. 
   Although there is a wide range of dimensions, including height diameter, and ports, there appears to be a relationship which presents a particularly well-organized flame with a maximized flame height. This ratio is: height/radius is about 6:1. 
   The material will be transparent or translucent. It usually will be clear and colorless, but may be tinted if desired. Plastic material is to be preferred, although glass or other materials having similar light transmission properties may be used, although they may not have the desirable flexibility. 
   There results an attractive, elegantly simple and safe gas lamp, made of inexpensive material, which produces maximum light from the amount of fuel burned. The flame  60  is illustrated in the drawings in a “corkscrew” manner to emphasize the swirling motion. However, as viewed it will appear nearly cylindrical. 
   This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of example and not of limitation, but only in accordance with the scope of the appended claims.
A vortex type gas lamp comprising a base and an axially extending-transparent shield. Gas is supplied near the bottom end of the shield. The shield is formed of a plurality (preferably two) axial curved sections which overlap one another at their axial edges to form tangentially directed port. Combustion of the gas with atmospheric oxygen admitted through the ports results in an axial vortex of burning gas useful for illumination, decoration and heat.