PLANT CONTAINER

Field of the Invention

The invention generally relates to plant containers, plant boxes, pots, hanging baskets and the like. More particularly, the invention relates to plant containers that are adapted to provide improved growing conditions for the plant contained therein.

Background to the Invention

A commonly experienced difficulty when growing plants in containers is the challenge of supplying optimal quantities of water to the plant for its consumption and survival. Warm and/or dry climates make this more difficult as moisture from the growing medium is more rapidly lost. This heightened rate of water loss results from a combination of increased rate of evaporation and, due to the more demanding environmental conditions, a greater consumption of water by the plant in order to sustain a healthy level of hydration.

As the presence of water is an essential requirement of any plant, a variety of plant containers which have been designed in an attempt to overcome the difficulty of maintaining optimal water supply, by utilizing a "self watering" principle are in the public domain. Such containers aim to retain water at the bottom of the container in a reservoir. One form of container, having at least one hole or aperture located in its base, has a reservoir, tray or the like positioned therebeneath. When water is poured into the container, it disperses throughout the growing medium contained therein. The growing medium, having only a limited capacity to retain the water, will become saturated and excess water will flow through the holes in the base of the container. The reservoir or tray located therebeneath, captures the excess water and retains it therein. This water may be accessible to the plant, provided its root system

extends deep enough to protrude through the holes in the base of the container, thereby reaching the stored water. Alternatively, if the water level in the reservoir or tray is sufficiently high such that it is above the hole in the base of the container, the water may translocate up through the holes in the base and into the growing medium.

Global warming has seen an increase in heightened environmental temperatures and drought conditions throughout the world. Governments commonly impose restrictions on household and industrial water consumption during these times. Such restrictions may prohibit, or at least reduce, the amount of water allowed for horticultural purposes. Therefore, plant containers possessing "self-watering" capabilities are of little benefit during these times, when water is not available and is rapidly lost from the growing medium through evaporation.

Planting/growing medium such as soil attracts and retains heat therein, causing the root system of the plant to experience and be damaged by high temperatures of the surrounding growing medium. These high temperatures, further contributing to dehydration of the plant, promote evaporation of moisture from the growing medium. "Self-watering" plant containers do not provide protection against heat While they can, for a limited time, provide water to the media located in lower extremities of the container, the vast majority of the growing area has no means of hydration or insulation from the heat

Thus, by being able to reduce the temperature of the planting/growing medium within the plant container, there is a consequential reduction in the rate of evaporation and thus better retention of the available water/moisture in the medium

for the plant Therefore, insulation of the plant results in less watering being required. Further, insulation can sustain or improve the plant's optimal growing parameters resulting in better quality or stronger plants, which are better able to cope with disease.

In another aspect, "self-watering" plant containers can also result in the significant problem of water-logging of the roots, when excess water is retained within the container. Water-logging is detrimental to plant growth, as it leads to rotting of the root system and/or preventing oxygen from reaching the roots. Water- logging is most likely to occur when the weather is cool and when the plant is already sufficiently hydrated and there is no way for water to escape or exit from the reservoir. Furthermore, many plant containers lack a way of visual determination as to whether water-logging, or over-watering of a plant has in feet occurred, or alternatively, determination as to whether the growing medium is dehydrated.

There is a need therefore to provide a plant container which is adapted to insulate the growing medium contained therein, thereby at least substantially lowering its temperature, thereby promoting more optimal conditions for the plant's root system. A further advantage would be to at least substantially reduce the rate of moisture lost through evaporation. Furthermore, it would be advantageous to provide a Container, which is capable of substantially conserving moisture within the growing medium for an increased length of time, while allowing the plant to access water on an as-needs basis wherein the risk of water-logging is at least substantially reduced.

The present invention therefore aims to improve on or at least substantially ameliorate the downfalls in the prior art.

Summary of the Invention According to the present invention, there is provided a plant container comprising an outer container and an inner container locatable in spaced apart relation forming a cavity therebetween and in which cavity thermal insulating means is housed, the inner container adapted to bouse plant(s) and planting/growing medium therein, having at least one opening therethrough to permit access to the cavity, wherein in use the thermal insulating means is a source of water/moisture.

The outer and inner containers may be of any suitable peripheral or internal shape, for example, circular, cup-shaped, rectangular, square, frusto or truncated pyramidal, etc provided that a cavity is formed therebetween when the inner container nests or sits substantially within the outer container

However, as will be appreciated, the outer container may be a decorative container, which has a different exterior shape to the inner container locatable therein. Accordingly the outer container could be of a square exterior shape, while the inner container exterior is circular or cup-shaped, providing that a cavity is formed therebetween, when the inner container is placed within the outer container.

For convenience a substantially frusto-pyramidal plant container will hereinafter be described. In a preferred construction, each of the outer and inner containers comprises a substantially frusto-pyramidal body member, wherein the

outer container is larger in overall size or diameter compared to the smaller inner container, which is adapted to be locatable substantially within the outer container. In one embodiment, the body member of each container has a base, a first set of opposed side walls and a second set of opposed side wails and an open top. Preferably, the base is a substantially flat-bottomed wall with both sets of opposed side walls extending and diverging substantially upwardly and outwardly from the flat bottom wall and terminating in a rim to provide the open top.

Through the open top of the outer container, the inner container can be placed therein. The open top of the inner container enables placement of the planting/growing medium and plant(s), and if required nutrients, fertilizers and water therein.

The inner container can be maintained in a spaced-apart relation to the outer container by any appropriate means including spacing means, which can be positioned where required between the inner and outer containers. The spacing means may be one or more spacers as are known or used in the Art, for example, timber or plastic wedges or blocks, floral foam, filtration media, such as pebbles, charcoal and the like and/or blends of spacing means. As an alternative or additional thereto, the rims of the inner and outer container may be integrally or releasably joined in a spaced-apart relation. In a simple form, the inner container may be kept separated from the inside of the outer container by resting upon a spacing means, such as a charcoal block or pad positioned on the inside bottom wall of the outer container and on which the exterior of the bottom wall of the inner container sits. The inner container may be suspended from or relative to the outer container by

spacing means that protrude from the inner walls, base and/or rim of the outer container wherein the inner container hangs from the outer container.

The rims of the inner and outer containers are preferably aligned with one another, such that the collective rims form a substantially even open top region of the plant container. The cavity formed between the inner and outer containers is therefore capable of being at least substantially covered or closed via a closure means engaging or resting upon the collective rims. The closure means is preferably a cover or lid which may itself contain a removable cap that sits over an inspection opening within the cover or lid. Preferably, the cover or lid is removable to allow access to the cavity and thus to the insulating means positioned therein. The insulating means, preferably an insulating material is substantially accommodated within the cavity between the inner wall surface of the outer container and the outer wall surface of the inner container to provide a thermal insulation between the outer wall surface of the outer container and the planting/growing medium and plant(s) located within the inner container.

Into the base of the inner container, there is preferably provided at least one aperture. The aperture(s) allows a communication pathway or passageway between the contents within the inner container and the cavity. In a preferred form, the at least one opening of the inner container is positioned in at least one side wall thereof and more preferably in at least one side wall of the first set of opposed side walls, which oρening(s) is communicable with the cavity. Preferably, there is at least one opening in both sets of walls of the first set of opposed side walls. Where there are two or more openings in a wall of the first set of opposed side walls, those openings may

align vertically relative to the open top of the inner container. The size and/or shape and location of the openings can be the same or different.

In a preferred embodiment, the outer container further comprises at least one drain aperture therethrough extending between the cavity to the outer surface or exposed outer face of the outer container. Preferably, the or each drain aperture is located in one or more of the outer container's side walls. The drain aρerture(s) of the outer container, as with the aperture(s) and opening(s) in the inner container, may take the form of a slot, hole or any other suitable opening. Preferably, there are at least two drain apertures in the outer container, with one aperture in each of the second set of opposed side walls. The drain aperture(s) of the outer container is preferably positioned in the side wall(s) and at a location between the base and the rim of the outer container. A suitable distance may be approximately 1/4 to 1/3 along the height of the side wall extending between the base and the rim as measured from the base of the outer container.

Preferably further, the arrangement of the openings located in the inner container and the drain aρerture(s) of the outer container portions are such that the openings in the inner container wall(s) are positioned at about 90* offset relative to those drain aperture(s) in the outer container side wall(s). Such an arrangement thereby prevents a direct straight-line path from outside of the outer container to the planting/growing medium and plants) sitting inside the inner container. Therefore, the opening(s) in the inner container is(are) not in direct alignment with the drain aperture(s) of the outer container.

In yet a further preferred embodiment, the aperture(s)/opening(s) in the inner container are screened by a screening means or fashioned to substantially prevent planting/growing medium contained therein from entering the cavity. Similarly, a screening means can be located above and/or below the interna! bottom wall of the inner container. The or each screening means can be formed by any suitable material known or used in the Art, preferably one that allows for liquids to penetrate therethrough. A suitable screening means is a mesh-structured material or cloth, which can be replaceably located above and/or over the aperture or opening or be integrally formed within the base and/or walls of the inner container. The drain aperture(s) in the outer container may optionally also be similarly fashioned or screened.

While not essential for the working of the invention, it has been found to be advantageous to position an absorbent material between the mesh-structured material and the inside surface of the base of the inner container, such that it overlays the aρerture(s) in the base thereof. Due to gravitational force, when water is added to the inside of the inner container it can flow rapidly downwardly through the planting/growing medium therein and through the aperture(s) in the base, thereby reducing the transit time and thus the allowable take-up time of the water by the planting/growing medium. This means that the water's ability to translocate outwardly through the planting/growing medium to those areas not directly in the line of the flow path of the added water within the inner container can be reduced. This absorbent material has a tendency to slow or retard the flow of water out of the inner container through the aperture(s) in the base of the inner container and into the cavity. Thus, the absorbent material can thereby increase the throughput time in

which water may reside within the inner container. As a consequence of the slower transit time for the water, this allows greater opportunity for translocation of the water through the planting/growing medium prior to any entry into the cavity.

The insulating means is preferably selected such that, when in use within the plant container, it will provide a cooler planting/growing medium temperature in summer compared to the hotter ambient temperature surrounding the plant container, thereby decreasing the watering requirements of the planting/growing medium and thus the ρlant(s) growing therein. Preferably, the insulating means is also water absorbent and as a result, it can also provide a temporary water/moisture source if needed for the plant growing within the plant container.

Further, the insulating material is one that can be housed within the cavity. The insulating material is preferably selected from a synthetic material, a naturally occurring material or a blend of both. A material that has thermal insulation and water absorbent, and if required, moisture-release properties is preferably desired. The preferred naturally occurring material is selected from an organic and/or an inorganic material. For example, sphagnum, Spanish, peat or bog moss, coconut fiber, paper/pulp mache, sisal or similar grass are preferred. It has been found that the properties of sphagnum moss suit this invention most effectively. As sphagnum moss is living plant matter, it has the capacity to draw water and move and retain it throughout its entire area. Therefore, it is adapted to effectively retain water in its upper extremities, rather than experiencing the gravitational effect that other water absorbent materials experience, where the water gradually sinks toward the lower regions of the absorbent material. Thus, sphagnum moss can translocate

water/moisture in which, it is sitting throughout substantially its entire mass/volume. acting like a capillary spreading water/moisture in direct contact with it to the rest of the moss which is not in direct contact with the water/moisture source.

When the cavity is filled with the sphagnum moss, the moss extends from the well in the base of the plant container to substantially the rim of the plant container. The well can be formed between the underside of the bottom wall of the inner container and the upper-side of the bottom of the outer container. Due to the moss's ability to translocate water, the water and that portion of the moss sitting in the well of the plant container is drawn away toward the moss located at the rim of the plant container and thereby moistens the moss that is not in direct contact with the water.

By removing the cover or lid or the removable cap therein, the user is able to visually inspect the condition of the insulating material. For example, the user can look at or even feel the moss sitting in the cavity and determine if it is dry or wet. The result of that inspection is that, if required, water may or may not have to be added to the inner container of the plant container. Further, the presence of the cover or lid means that moisture within the cavity is substantially retained therein and substantially prevents the moss (insulating means) from drying out due to evaporation.

Sphagnum moss, like all absorbent materials has an absorption capacity whereby once saturated, excess or additional water cannot be retained within the material. Therefore, once absolute saturation is reached, any excess water presented to or present within the moss-filled cavity will accumulate in the well of the cavity

within the plant container. The drain aperture(s) in the side walls of the outer container are therefore preferably positioned a distance above the base of the outer container such that once the desired water level within the cavity is reached; excess water is able to drain out of the plant container. The location of the drain aperture(s) of the outer container can be located relative to the opening(s) in the inner container. Preferably, where there are two openings of the same wall on the inner container, the drain aperture of the outer container is positioned in the outer container's wall(s) at a mid-way point relative to the distance between the openings of the inner container. In another form, the drain apertures in the outer container are located below relative to the positioning of the openings in the inner container. Typically, the drain apertures are located below the uppermost openings of the inner container. As the drain aperture(s) in me side wall(s) of the outer container allow for release of excess water from the cavity, this aids in reducing water-logging of the planting/growing medium within the inner container. Ideally, maintaining the insulating material in its optimum thermal capacity condition produces the most favourable conditions within the planting/growing medium. It is the top layer(s) of the planting/growing medium that is most likely to dry out more rapidly than the regions far deeper within the inner container. Commonly it is in these susceptible layers that prized shallow-rooted plants grow and in an effort to protect them, gardeners cover the top lay with mulch and the like. To inspect whether the prized plants have sufficient water to feed on, one must disturb the mulch and dig into the top layer, hopefully while not injuring the plant's feeding roots. With the present invention, the user is better able to determine the health of these more susceptible layers without disturbing the mulch or digging into the planting/growing medium by way of actually feeling or looking at the insulating

material to see whether it is drying out. If so, this is a good indication that water within the planting/growing medium needs replenishing. Thus, the condition of the insulating material can also act as an indicator of the moisture/water levels within the planting/growing material.

The opeπing(s) within the inner container can provide a further means to the aperture(s) by which excess water can be removed from the planting/growing medium. This usual role of the aperture can be reversed to mimic the operdng(s) where it is found that the planting/growing medium is water/moisture deficient. The wet/moist moss within the cavity is able to act as a water/moisture supplier to the planting/growing medium. Thus, water/moisture captured by the moss can be fed back to or exchanged with the planting/growing medium, via the aperture(s) and/or opening(s) of the inner container to help the growing plant when under water stress.

The insulating capacity of the moss is dependent upon its moisture content.

Thus, when the moss acts as a water source to the drying planting/growing medium, it is found that there is a resultant drop off in the thermal insulating capacity of the moss.

Brief Description of the Drawings

Other features and advantages of one or more preferred embodiments of the present invention will be readily apparent to one of ordinary skill in the art from the following written description with reference to, and used in conjunction with, the accompanying drawings, in which:

Fig. 1 is a cross-sectional, partially cut-away view of an embodiment of the invention.

Fig. 2 is a second-cross sectional, partially cut-away view of an embodiment of the invention. Fig. 3 is a perspective; partially cut-away view of an embodiment of the invention. Fig.4 is an exploded perspective view of the embodiment of Fig. 3.

Detailed Description of the Preferred Embodiment of the Invention

Referring to all the drawings where like reference numerals represent like or corresponding parts throughout the several views.

Referring initially to Figs. 1 and 2 where views of the first embodiments of the plant container 10 are shown. The plant container 10 is made up of an outer container 20 with an inner container 30 situated within the outer container 20.

Within the inner container 30 there is a planting/growing medium 12 in which a plant 11 with roots 13 is growing therein. The planting/growing medium 12 is preferably soil or more preferably a selected soil, potting mix, with or without additional nutrients such as those appropriate for the type of plant to be grown therein. Mulch 14 is shown applied to the top of the soil 12, which can aid in reducing the growth of unwanted weeds while also assisting in reducing water evaporation from the soil.

The invention can be used with any standard type planter pots or containers wherein one is able to sit or nest within the other provided a cavity is formed between the two

containers. With this in mind, in the drawings, both the outer 20 and inner 30 containers are shown to have a substantially inverted frusto- or truncated- pyramidal body shaped member. The outer container 20 body member 21 has a base 22, a first set of opposed side walls 23a and 23b, a second set of opposed side walls 24a and 24b and an open top 25 which terminates in a rim 26. Likewise, the inner container 30 body member 31 includes a base 32, a first set of opposed side walls 33a and 33b, a second set of opposed side walls 34a and 34b and an open top 35 which terminates in a rim 36.

The bases 22 and 32 are both preferably substantially flat bottom walls 27 and 37 respectively, where the relevant opposed side walls extend and diverge substantially upwardly therefrom.

The rims 26 and 36 can be covered or closed by a closure means 60, preferably in the form of a removable cover or lid. Although not shown, the cover or Hd may contain an inspection opening therein which is sealed by a removable cap.

A cavity 40 is formed between the inside surfaces of the outer container 20 and the outside surface of the inner container 30. When assembled, with the inner container 30 sitting or nesting inside the outer container 20, a cavity well 41 is formed in the cavity area designated A. The well 41 is formed fully or in part in the area between the inside face of the bottom wall 27 of the outer container 20 and the outside face of the bottom wall 37 of the inner container 30.

Access to the cavity well 41 from inside the inner container 30 is via at least one aperture 38. Thus, water applied to the soil and not taken up by the soil is able to drain out of the inner container 30 via the aperture 38 to collect in the cavity well 41.

To the second set of the opposed side walls 24a and 24b of the outer container 20, there are provided drain apertures 28a and 28b. The placement of these drain apertures 28a and 28b in the outer container 20 determine the overall depth of the cavity well 41, such that when the water level within the cavity well reaches drain apertures 28a and 28b, any additional water is able to drain away out of the plant container 10. Accordingly, placement of the drain apertures 28a and 28b higher or lower in the side walls of the outer container 20, can prc-determine the extent/volume of water that can remain in the cavity well 41.

Insulating means 50, preferably in the form of a naturally-occurring product such as moss or plant fiber is housed within the cavity 40 of the plant container 10. In the embodiment shown in the drawings, particularly Fig.4, sphagnum moss in the form of pre-formed panels or infills 51, is arranged/placed within the outer container 20 and, if desired, within the inner container 30 at its base 32, prior to final assembly. Alternatively, the moss 50 may be sprayed or blown into the cavity 40.

In the drawings, a panel 51 of moss 50 sits on the base 32 of the inner container 30. This panel 51 also covers aperture 38. A screening means, such as mesh-structured material 52, is then preferably placed on top of the moss panel 51 and thus, it also sits above and over aperture 38. The mesh-structed material 52 and the panel 51 act as filters for the liquid passing into the cavity 40. In addition, the

mesh-structured material 52 and the panel 51 substantially prevent or limit the soil 12 and, if desired, the roots 13 from actually entering into the cavity well 41. Preferably the mesh-structured material can be made of any suitable material such a metal or plastics materials or a combination of both.

To the first set of opposed side walls 33a and 33b of the inner container 30, there are provided openings 39a and 39b which act as passage means between the inside of the inner container 30 and the cavity 40. Preferably, these openings 39a and 39b are either screened or fashioned, such that water/moisture released by the moss in proximity to these openings 39a and 39b can be translocated into the soil 12. In this way, the released water/moisture from the moss can assist in replenishing required moisture to the soil 12.

As shown, the drain apertures 28a and 28b of the outer container 20 are positioned about 90 degrees out of alignment with openings 39a and 39b of the inner container 30. Additionally, the drain apertures 28a and 28b are positioned out-of- plane with openings 39a and 39b.

In Fig. 1, the moss 50 is shown where it is all in a moist/wet state, whereas in Fig. 2, the moss 50 is in a partially moist/wet state where the upper region of moss

50' is in a dehydrated condition relative to the lower region of the moss 50. (The dots in the cavity show the show the concentration of water/moisture.) The moss 50 provides its maximum thermal insulating ability for the soil when in the condition shown in Fig. 1. The thermal insulating ability of the moss is lower when part of the moss is partially dried compared to the remainder as illustrated in Fig. 2.

In another form, Fig. 1 shows the insulating material, moss 50, in a fully charged condition, whereas in Fig. 2, some of the moss 50' in the region marked B has lost moisture by supplying that moisture to the soil via openings 39a and 39b in the inner container 30.

Lid or cover 60 is removable so that the user upon inspecting the moss 50 or 50* within the top of the cavity 40 is able to ascertain whether watering of the moss is necessary. For example, when inspecting the moss 50 following removal of the cover 60 and noting the drier appearance of the moss 50' as shown in Fig. 2, the user can evaluate whether watering is required to restore the wet condition of the moss to that as shown in Fig. 1. The condition of the moss 50 gives a good indication as to the level of dehydration of the soil 12 in the plant container 10 and thus one can decide whether or not to water the plant and soil. Any excess water added at this time will pass into the cavity 40 and thus commences rehydration of the moss and restoration of the thermal insulating capacity of the plant container.

Example

Using a standard single-skinned, plastic garden pot sitting within a larger single-skinned, plastic garden pot separated from each other by a layer of moist sphagnum moss ('test pot'), soil temperatures in a planting/growing medium within the inner pot were monitored.

A control, using the same smaller sized standard single-skinned, plastic garden pot and the same planting/growing medium ('control pot'), was also monitored under the same environmental conditions.

Soil temperatures of the test and control pots were taken at six hourly intervals over a 14-day period during the hot summer months. The temperatures within the control pot were found to be between 6 and 8 degrees C higher at any time than in the test pot. Minimal temperature fluctuations and substantially constant moisture content were achieved with the test pot compared to the control pot.

The control pot exhibited higher temperature rises and these higher temperatures were maintained for longer periods, which resulted in a drier planting/growing medium, compared to the test poL

It was found that the control pot required a greater volume of additional water to maintain suitable growing conditions therein.

Over 14 days, the control pot received approximately an additional 0.1 liters of water every second day and thus in total 0.7 liters. The test pot received 0.1 liters every three days and thus in total 0.4 liters of water. In addition, enhanced plant growth was noted in the test pot compared to the control pot.

The test shows an approximate 40% saving in water usage coupled with enhanced growth of the plants contained within the test pot compared to the control pot.

The plant container of the present invention can be made from any suitable materials or even blends of materials as are known in the Art. Preferably, both the

inner aad outer containers are manufactured from the same materials. The preferred materials being plastic and/or fiberglass.

Either or both the outer and inner containers may be treated with UV protection and/or barrier materials. It is preferred that the inner container, in particular, is treated to ensure protection from the light to allow improved root development for the plant growing within.

The moisture that flows to the insulation cavity is preferably only provided from the excess water that the soil/plant does not require. Thus, when the insulating means becomes "dehydrated" this provides a reliable indicator that the soil/plant is not receiving enough water and as a consequence has been forced to draw upon water retained in the insulation cavity for survival.

The planting/growing medium can be a blend of growing mixtures such as soil, potting mixes, manures, etc necessary to maintain plant growth-

High temperature in the surrounding planting/growing medium may adversely affect plant roots thereby stunting growth. The present invention is advantageous in that the insulating means contained within the cavity can act as an insulating barrier from the external heat prevailing upon the outer container and thus at least substantially reduces the temperature of the planting/growing medium contained within the inner container thereby providing more suitable conditions for the plant roots growing within the medium.

Further, reducing the temperature of the planting/growing medium by even a few degrees, substantially reduces the rate of moisture lost from the planting/growing medium through evaporation, which in turn maintains cooler temperatures within the planting/growing medium for a longer period of time. It is often the case with plant containers of the prior Art that in order to retain moisture within planting/growing medium, water-retaining chemicals are added or mixed with the planting/growing medium. The present invention therefore offers the advantage of possibly eliminating or minimizing the need for the addition of such chemicals, thereby hopefully providing a natural and chemical-free solution to water retention in plant containers.

A further advantage of this invention is that water retained in the cavity is available for uptake by a thirsty plant, through osmotic translocation of the water from the insulating material to the planting/growing medium. As the equilibrium shifts and the planting/growing medium become drier, water from the insulating material is drawn or translocated into the planting/growing medium through the oρening(s) and/or aperture(s) of the inner container. This slow-release method for providing water to a growing plant is beneficial in that there is a reduced likelihood of the planting/growing medium drying out completely. It also therefore decreases the chances of the plant becoming significantly dehydrated and limp, which damage to the plant structure adversely affects the quality and subsequent growth of the plant

The present invention can be classified as a water saving device in that through its use, the volume of water required to applied to a plant during its lifetime to sustain it will be lower.

As the present invention may be embodied in several forms without departing from the spirit of the essential characteristics of the invention, it should be understood that the above-described embodiments are not to limit the present invention unless otherwise specified, but rather should be construed broadly within the spirit and scope of the invention. Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the invention. Therefore, the specific embodiments are to be understood to be illustrative of the many ways in which the principles of the present invention may be practiced.

Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification, they are to be interpreted as specifying the presence of the stated features, integers, steps or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component or group thereof.