Abstract:
The present invention is directed to environmentally friendly levels. Through the use of renewable resource or environmentally friendly liquids in the transparent tubes of a level, it is possible to provide a level that will not harm the environment if the liquid escapes from the tubes as well as reduce the use of petroleum based fluids. In one embodiment, the level contains non-petroleum based hydrocarbons and a water-based solution of dissolved ionic solids. In other embodiments, the level contains non-petroleum based hydrocarbons and water-based solutions of dissolved ionic solids with increased boiling points and lowered freezing points. In other embodiments the level contains arced tubes, standard tubes and combinations of both wherein the liquid in the tubes may be the same or different.

Description:
[0001]    This application claims priority to provisional application 61/016,188 filed on Dec. 21, 2007 which is incorporated by reference herein in its entirety for all purposes. 
     
    
     BACKGROUND 
       [0002]    In construction, determining the slope of a surface is an important skill in ensuring that the apparatus, item or structure being built is meeting proper specifications. For example, builders and carpenters often have to determine the slopes of surfaces for constructing houses, installing flooring, or the like. If a surface that is supposed to be sloped does not meet the specification set forth, then the structure may not meet proper codes and can lead to faulty construction. For example, determining the pitch of a roof is crucial in determining the shape and size of the roof as well as the amount of material to be used. On the other hand, other surfaces must be horizontally or vertically level. 
         [0003]    Spirit levels have been developed to meet some or all of the above-identified needs. For instance, a spirit level can include one or more sealed tubes partially filled with fluid so as to define a bubble in the tube. The position of the bubble in the tube can be used to determine whether the surface is level. If one or more appropriately-configured arced tubes are used, the position of the bubble in the tube can be used to determine the slope or pitch of the surface. 
         [0004]    Currently, commercially available levels use petroleum products such as alcohol or kerosene as the fluid in the tubes of the spirit levels. These fluids resist freezing yet have significant environmental and commercial drawbacks when the fluid is released from the tubes. These drawbacks include problems such as staining the areas where they are released, toxicity and creating potential fire hazards. Further, when a level is damaged or disposed of, it is sent to a landfill or other waste disposal area where the level is eventually broken and the fluid released into the environment. 
         [0005]    Petroleum based fluids also have use limitations when temperatures vary at worksites due to expansion and contraction of the petroleum based fluids. At 37.78° C. for instance, the bubble in a petroleum fluid filled level is very small due to expansion of the fluid. This makes determining the slope measurement difficult as well as places additional stress on the seams and/or seals of the tube due to the expansion of the petroleum fluid. Additionally, lower temperatures, such as −7.0° C., result in petroleum based fluids contracting and creating a large bubble that is far to large to provide accurate slope measurements. Moreover, finding substitute fluids requires walking a fine line between introducing fluids that are too viscous, which results in the bubble moving slowly or not at all, or fluids that are not viscous enough which cause the bubble to “splinter” into smaller bubbles when the level is jarred thereby hampering the users ability to obtain reliable measurements. 
         [0006]    Further, with the fluctuating price of petroleum products, using these as fluids in spirit levels can dramatically increase production costs in addition to the aforementioned drawbacks. 
         [0007]    Accordingly, the need exists for an environmentally friendly yet renewable fluid that overcomes the drawbacks associated with using petroleum fluids in spirit levels. 
       SUMMARY 
       [0008]    According to certain aspects of the present subject matter, a level is provided for indicating the slope of a surface. The level may be of any suitable construction, and may be configured to indicate the slope of a surface and/or may be configured to indicate only whether a surface is level or not. In some embodiments, the level includes a body having a top side and a bottom side. The body can have any suitable shape, has a front face and a back face disposed between the top side and the bottom side. The bottom side defines a first planar measurement surface. 
         [0009]    In some embodiments, a transparent arced tube is disposed on the body. The arced tube has a first end and a second end and defines a pinnacle point between the first end and the second end. The first and second ends of the arced tube are in closer proximity to the first planar measurement surface than the pinnacle point. The arced tube defines an inner space containing a liquid therein with the arced tube also having a bubble of gaseous fluid disposed in the inner space within the liquid. A template is positioned proximal to the arced tube. The template includes measurement indicia disposed thereon to indicate the measurement of the slope. 
         [0010]    In some embodiments, one or more standard levels comprising standard tubes (i.e. one or more generally non-arced tubes) are disposed on the body. The standard tube(s) may be positioned parallel to the bottom side and/or may be positioned perpendicular to the bottom side so that vertical surfaces can be evaluated. The standard tube(s) also define an inner space containing a liquid therein and a bubble of gaseous fluid disposed in the inner space within the liquid. A template can be positioned proximal to the standard tube(s) for use in identifying the position of the bubble relative to the center of each tube. The term “standard tube” is used in contrast to “arced tube.” A “standard tube” may be straight. In some embodiments, though, it may feature a slight curve. Thus, the term “standard tube” thus is intended to include those tube shapes which are suitable for use in standard horizontal and/or vertical levels (also referred to as “conventional” levels). 
         [0011]    In some embodiments, the arced and standard tubes may be removable or replaceable. The tubes may be secured to the body of the level via conventional means such as fasteners, screws, bolts, VELCRO, gheko feet, brackets, friction, or other means known to one skilled in the art. In some embodiments, the tubes are not secured to the body but are secured to other parts of the level such as the cover or apertures which in turn may be removed and are held in place with the above-mentioned devices or other means known to one skilled in the art. 
         [0012]    In embodiments of the present subject matter, the fluid in at least one of the tubes comprises 1,3 Propanediol, also referred to as propane-1,3-diol or trimethylene glycol. In certain embodiments, the 1,3 Propanediol may be renewably sourced, such as 1,3 Propanediol derived from corn, rather than petroleum products. In one embodiment, the source of the fluid is capable of being replenished, for instance, the fluid can be made from plant material. Such a fluid is considered “renewably sourced” or a renewable resource fluid. In other embodiments, the fluid is a renewable resource hydrocarbon based fluid. A renewable resource hydrocarbon based fluid is a fluid with a hydrocarbon backbone such as methane, ethane, propane, butane, pentane, etc., wherein the hydrocarbon backbone may be substituted with various substituents including alcohols and other similar substituents. The hydrocarbon based fluid is obtained from renewable sources such as the conversion of corn by bacteria or other “green” or environmentally friendly processes. In other embodiments, the liquid may comprise an environmentally friendly liquid meaning that it has a limited impact on the environment. In other embodiments, the liquid may be an environmentally friendly renewable resource liquid. This fluid has a low impact on the environment and is derived from a source that can be replenished, e.g., plant material. 
         [0013]    According to further aspects of the present subject matter, a slope level for measuring the slope of a surface is provided. The slope level includes an elongated body having a top side and a bottom side. The body has a length great enough to neutralize minor variations of slope on the surface being measured. Further, the body has a front face and a back face disposed between the top side and the bottom side. The bottom side defines a first planar measurement surface. At least one transparent arced tube is disposed on the body. The arced tube has a first end and a second end and defines a pinnacle point between the first end and the second end. The arced tube also defines an inner space having a slope indicator disposed therein. The slope indicator is movable within the inner space. A template is positioned proximal to the arced tube. The template includes measurement indicia disposed thereon to indicate the measurement of the slope based on the position of the slope indicator within the inner space of the arced tube. 
         [0014]    In some embodiments, a slope level can comprise at least one transparent arced tube, the tube defining an inner space containing a liquid therein and a bubble of gaseous fluid disposed in the inner space within the liquid and a frame. The frame can comprise a top side and a bottom side, the bottom side defining a first planar measurement surface. The frame may further comprise a front face and a back face disposed between the top side and the bottom side. The frame may include one or more apertures in the frame at the front face and/or the back face. The apertures may correspond to the arced tube. For instance, the apertures may be shaped so that some or all of the arced tube is visible through the aperture(s). The frame may comprise any suitable material, may be formed in any shape, and may be formed from a single component or multiple components. 
         [0015]    The level can comprise one or more fill members positioned between the front face and the back face of the frame, with the fill member forming a groove shaped to accommodate the arced tube. The groove in the fill members may further be fully or partially open at one or more sides to allow for viewing of the arced tube from at least the front face or the back face through the corresponding aperture or apertures in the frame. 
         [0016]    The level can further comprise one or more clear covers comprising transparent material positioned between the fill member and a side of frame comprising an aperture. The clear cover(s) can be configured to extend across the aperture to protect the arced tube. 
         [0017]    The arced tube can have a first end and a second end and define a pinnacle point between the first end and the second end, with the first and second ends of the arced tube are in closer proximity to the first planar measurement surface than the pinnacle point. 
         [0018]    In some embodiments, the frame comprises at least one aperture in the front face and the back face corresponding to the arced tube so that the tube is visible from both the front face and the back face of the level. In some embodiments, one or more of the clear covers can extend outward to fill the aperture in the frame so that the exterior of the clear cover is substantially flush with a face of the frame at the aperture. 
         [0019]    In some embodiments, the liquid comprises a potassium salt, such as a solution comprising potassium formate. For instance, the liquid may comprise a solution comprising potassium formate and water at a percentage concentration between about ten percent and about seventy percent. 
         [0020]    The arced tube can comprise a sealed glass tube, and the glass may filter UV (ultraviolet) radiation. In some embodiments, the level can comprise an end cap at one or both ends of the arced tube, with each end cap comprising a pliable material configured to cushion the ends of the arced tube. For instance, the pliable material may comprise rubber, silicone, and in some embodiments may be transparent. 
         [0021]    The level may comprise one or more measurement templates, for instance, a plurality of indicia formed on the portion of the clear cover corresponding to an aperture. In some embodiments, the plurality of indicia are formed on the side of the clear cover facing the arced tube. For example, degrees or pitch indications may be formed on the clear cover so that the indications are visible while the tube (and bubble position) are viewed through the cover. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    A full and enabling disclosure of the present subject matter including the best mode thereof directed to one of ordinary skill in the art is set forth more particularly in the remainder of the specification, including references to the accompanying figures in which: 
           [0023]      FIG. 1  illustrates a perspective view of an embodiment of a slope level according to the present subject matter; 
           [0024]      FIG. 2  illustrates a back view of an embodiment of a slope level according to the present subject matter; 
           [0025]      FIG. 3A  illustrates a partial front view of a further embodiment of a slope level according to the present subject matter that is residing on a level surface; 
           [0026]      FIG. 3B  illustrates a partial front view of the embodiment of the slope level depicted in  FIG. 3A  residing on a slope surface; 
           [0027]      FIG. 4  illustrates a partial front view of a further embodiment of a slope level according to the present subject matter; 
           [0028]      FIG. 5  illustrates a partial front view of another embodiment of a slope level according to the present subject matter; 
           [0029]      FIG. 6  illustrates a schematic cross-sectional view of another embodiment of a slope level according to the present subject matter; 
           [0030]      FIG. 7  is a front view of another exemplary embodiment of a slope level; 
           [0031]      FIG. 8  is a partial side view of the interior of the slope level shown in  FIG. 7 ; 
           [0032]      FIG. 9  is a cross-sectional view of the slope level shown in  FIG. 7 ; 
           [0033]      FIG. 10  is another cross-sectional view of the slope level shown in  FIG. 7 ; and 
           [0034]      FIG. 11  is a partial perspective view of a level comprising two standard tubes. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    Reference will now be made in detail to the presently preferred embodiments of the invention, one or more examples of which are shown in the Figures. Each example is provided to explain the invention and not as a limitation of the invention. In fact, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a further embodiment. It is intended that the present subject matter cover such alternative combinations, modifications and variations. 
         [0036]    “Slope level” as defined herein means an instrument that is placed upon a surface to determine the angle or pitch of a slope of that surface. 
         [0037]    “Horizontal ground axis” is defined herein as a theoretical horizontal axis that is a tangent to the surface of the earth, and thus generally corresponding to the generic ground surface thereof. 
         [0038]    “Arced tube” is defined herein as having the walls of the tube curved in generally the same direction. For example, the arced tube may have walls that are substantially parallel to the outer circumference of radius of curvature of the arced tube. 
         [0039]      FIG. 1  illustrates a slope level, generally  10 , in use on a roof support structure  24 . The slope level  10  is used to determine the angle or pitch of a slope of a surface relative to a horizontal ground axis. The slope level  10  includes a body  11  with a slope measuring device  30  embedded within the body  11 . The body  11  of the slope level  10  may have a front face  14  and a back face (not shown). The back face may be identical or similar to the front face, as illustrated, or may provide different slope measuring devices as will be described below. The body may be constructed from metal, wood, plastic, a composite material or a combination thereof. For example, the body may include a metal I-beam with a composite material disposed between the wings of the I-beam. As another example, the body may include a box or other frame with a filler material disposed inside the body, with an aperture such as a groove through at least one side of the body with the slope measuring device therein. 
         [0040]    The slope measuring device  30  may be viewed from the front face  14  or the back face or both the front and back faces. The slope level  10  includes a slope measuring device  30  that will indicate the angle of the slope or the pitch of the slope of the surface on which the slope level  10  is placed. For example, the slope level  10  is placed upon a surface  26  of a roof support structure  24  to determine the slope of the surface. 
         [0041]    The slope measuring device  30  includes a transparent arced tube  32  and a slope indicator  34  which resides in the arced tube  32 . In the embodiment shown in  FIG. 1 , the slope indicator  34  is a gaseous fluid-filled bead which resides in a liquid within an inner space of the arced tube  32 . The gaseous fluid-filled bead that comprises the slope indicator  34  is less dense than the liquid within the inner space of the arced tube  32 . When the slope level  10  is placed upon the surface  26  in the manner shown in  FIG. 1 , the slope indicator  34  floats on the liquid within the arced tube  32  along an outer wall of the arced tube  32  to a point of equilibrium. The point of equilibrium on the slope indicator  34  indicates the angle of the surface on which the slope level  10  resides relative to the horizontal ground axis. The body  11  of the slope level  10  may also include horizontal and vertical levels  82 ,  84 . The horizontal level  82  determines the horizontal condition of the surface on which the slope level is placed, while vertical levels  84  can be used to determine the vertical condition of such surfaces. In particular, the horizontal level  82  may be used to determine if the surface on which the slope level  10  is placed is level in a horizontal direction. The vertical levels  84  may be used by placing the slope level  10  on a surface to determine if that surface is level in a vertical direction. Conventional spirit levels may be used as the horizontal level  82  and the vertical levels  84 . 
         [0042]      FIG. 2  illustrates another embodiment of a slope level  10 . The slope level  10  includes a body  11  with a measuring device  30  embedded in a back face  18  of the body  11 . In such an embodiment, a second measuring device may be placed on the front face (not shown) of the body  11 . The measuring device  30  includes a transparent arced tube  32  having a first end  36  and a second end  38 . The arced tube  32  defines an inner space  39  in which a liquid  35  resides. A slope indicator  34  that comprises a bubble of gaseous fluid  33  resides within the liquid  35  of the slope measuring device  30 . In the embodiment shown, a template  40  comprising measurement indicia  42  is marked on the body  11  along an outer edge  41  of the arced tube  32 . The bubble of gaseous fluid  33  rises along an inner portion of the wall that defines the outer edge  41  of the arced tube  32 . 
         [0043]    The measurement indicia  42  of the template  40  may be used to indicate the slope in degrees or pitch. The pitch measurements are commonly used measurements for carpenters and builders. Pitch is defined by a unit of rise for every 12 units of horizontal length. For example, if over a 12 inch horizontal length, a slope rises 1 inch, then the pitch for this surface would be equal to 1. Similarly, if over a 12 inch horizontal length, a slope rises 6 inches then the pitch would be equal to 6. 
         [0044]    The placement of the measurement indicia  42  along the outer edge  41  of the arced tube  32  corresponds to the positioning of the slope indicator  34  when the body  11  is placed at specific angles relative to a ground position. Each indicator  42  reflects the angle at which the body  11  is positioned relative to the horizontal ground axis when the slope indicator is below that specific measurement indicator  42 . The measurement indicia  42  of the template  40  may be marked or engraved on the body  11  of the slope level  10 . Alternatively, the template  40  may be a sticker placed along the outer edge  41  of the arced tube  32 . The measurement indicia  42  may be marked on the sticker. In other embodiments, the template may be on or behind the arced tube  32 . 
         [0045]    The body  11  of the slope level  10  has a top side  12  and a bottom side  16  with the top side  12  having a planar measurement surface  22  and the bottom side  16  having a planar measurement surface  20 . In the embodiment shown in  FIG. 2 , a second slope measuring device may reside on the front face (not shown) on the opposite wall from back face  18 . The slope measuring device on the front face may be inverted as compared to the slope measuring device  30  on the back face  18 . In this manner, when the planar measurement surface  20  is placed on a surface to be measured, the slope measuring device on the front face can be used to indicate the measurement of the slope of the surface. In contrast, when the planar measurement surface  22  is placed upon a surface to be measured, the slope measuring device  30  on the back face  18  will indicate the slope of that surface. In this manner, both the top side  12  and the bottom side  16  of the body  11  may be used as a planar measurement surface thereby increasing the versatility of the slope level  10 . 
         [0046]    In such an embodiment, one slope measuring device on one face may include a template of the measurement indicia representing degrees, while a template on the slope measuring device on the other face may have measuring indicia that represent pitch. In this manner, the slope level can give measurements of a slope in two different measurement metrics that are both useful to carpenters and builders. 
         [0047]    In other embodiments, slope measuring device may have the same orientation on the front face and the back face so as to permit measurements based off the same planar measurement surface. For example, slope measuring device  30  may be positioned on the back face  18  and the front face so as to take measurements when the top side  12  with its planar measurement surface  22  is placed upon a surface to be measured. Again, with such embodiments, the measurement indicia  42  for the templates  40  may measure angles in degrees or pitch. Alternatively, one slope measuring device may have measuring indicia that measure angles in degrees on one face, while the measuring indicia of the template of the slope measuring device on the other face may measure pitch. In the embodiment shown in  FIG. 2 , the ends  36 ,  38  of the arced tube  32  are positioned along the same plane P that runs parallel to the planar measurement surface  22 . The arced tube  32  has a pinnacle point  37  that is positioned halfway between the first end  36  and the second end  38 . The pinnacle point  37  is located at a point on the arced tube  32  where a tangential plane T of the arced tube  32  runs parallel to the planar measurement surface  22 . In the shown embodiment, the first and second ends  36 ,  38  are closer in proximity to the planar measurement surface  22  than the pinnacle point  37 . When the slope indicator  34  resides at the pinnacle point  37 , then the measurement planar surface  22  resides on a surface which has no slope and the tangential plane T is parallel with the horizontal ground axis. The measurement indicator  42  at the pinnacle point  37  would read zero (“0”) for both pitch and degrees since the surface being measured has no slope whereas a measurement of 45 degrees would equate to a slope of 100%. 
         [0048]    The portion of the arced tube  32  on either side of the pinnacle point  37  can be used to measure the slope depending on the orientations of the surface and the slope level  10 . The measurement indicia  42  on the left side  45  of the arced tube  32  would indicate a downward slope of the surface being measured (as measured from left to right) with the left side  13  of the body  11  being in a higher position than the right side  15  of the body  11 . Alternatively, the measurement indicia  42  on the right side  46  of the arced tube  32  would indicate an upward slope of the surface being measured with the left side  13  being in a lower position than the right side  15  of the body  11 . Since the first end  36  and the second end  38  are positioned at equal distances from the pinnacle point  37  along a plane P that is parallel to the tangential plane T, an equal number of measurement indicia  42  may be placed on either side of the pinnacle point  37 . In this manner, angles of a downward slope or an upward slope may be measured to the same degree in such an embodiment without having to flip the body  11  of the slope level  10  around. However, such equal measurement indicia or equal lengths of the arced tube  32  on either side of the pinnacle point  37  are not required. 
         [0049]    The body  11  has a length L that is long enough to provide an adequate planar measurement surface  20 ,  22  to provide an adequate base for measuring the slope of the surface that is being measured. The length L should be great enough to neutralize minor variations of slope on the surface being measured. In other words, the length L should also be long enough to minimize the effects of minor variations on the surface of the structure being measured. For example, a rough surface may have undulations within the surface that would create erroneous readings of the slope for a slope level having an inadequate length. In certain embodiments, the length L of the body  11  may be between about 1 and about 5 feet. For example, the length may be 4 feet. For certain uses, other embodiments may employ a smaller length such as for laying tile flooring. The body  11  of the slope level  10  also has a width W. The width W should be such so as to accommodate the arced tube  32  within at least one of the front or back face  14 ,  18  of the body  11 . The size of the arced tube  32  will depend on the range of angles or pitch to be measured by the slope measuring device and the radius of curvature of the arced tube  32 . The length and width of the body  11  of the slope level  10  should be such that the slope level  10  is easy to use in various locations and accurate measurements of the slope may be taken. 
         [0050]      FIGS. 3A and 3B  illustrate a portion of slope level  10  that includes a body  11  and a slope measuring device  30 .  FIG. 3A  shows the slope level  10  on a surface  29  having zero (“0”) slope.  FIG. 3B  shows the slope level  10  on a surface having a slope at an angle α. The slope measuring device  30  includes an arced tube  32  having a wall  31 . The wall  31  may be constructed of one single continuous wall or may be constructed of a series of connected sides depending on the cross-sectional shape of the arced tube  32 . The arced tube  32  is capped at a first end  36  by a cap  56  and a second end  38  by a cap  58 . The wall  31  of the arced tube  32  defines an inner space  39  between the two capped ends  36 ,  38 . The inner space  39  contains a liquid  35  in which a bubble of gaseous fluid  33  resides that serves as a slope indicator  34 . The slope measuring device  30  also includes a template  40  of measurement indicia  42 . 
         [0051]    The caps  56 ,  58  used to seal the liquid  35  in the inner space  39  of the arced tube  32  prevents leakage of the liquid  35  that would cause the bubble  33  to grow in size, thereby lessening the accuracy of the slope measuring device  30 . Also, the caps  56 ,  58  may be useful in preventing or minimizing the changing of the size of the bubble  33  due to temperature or other environmental changes affecting the slope level  10 . For example, the caps  56 ,  58  may be pressure caps that expand and contract as the liquid expands and contracts to allow the air bubble  33  in the liquid  35  to remain generally a constant size. In this manner, temperature changes would have less effect on the slope measuring device  30 . 
         [0052]    In some embodiments, arced tube  32  may comprise a tube that is sealed at one or both ends. In such embodiments, end caps  56 ,  58  may not be needed to prevent leakage or address expansion/contraction of the liquid. Instead, end caps  56 ,  58  may be used to cushion arced tube  32  against motion imparted to the level due to vibration, impact shocks (such as when the level is dropped), and/or other sources of physical stress. Cushioning the arced tube  32  may result in a more durable product. The end caps  56 ,  58  may comprise rubber, silicone, and/or other suitable materials selected to achieve the cushioning effect. In some embodiments, as will be discussed in further detail below, the end caps may be adapted to properly seat the arced tube  32  in a groove in the body of the slope level. Of course, in other embodiments, the end caps  56 ,  58  may be configured to provide a cushioning effect as well as sealing one or more ends of arced tube  32 . 
         [0053]    Between the first end  36  and the second end  38  of the arced tube  32 , is a pinnacle point  37  that coincides with the point where a tangential plane T touches an outer edge  41  of the arced tube  32 . The tangential plane T runs parallel to a planar measurement surface  20  on the bottom side  16  of the body  11 . At the pinnacle point  37 , the template  40  has a measurement indicator of “0” pitch, thereby indicating that the surface on which the planar measurement surface  20  resides has no slope when the slope indicator is positioned there.  FIG. 3A  illustrates the slope level  10  on the surface  29  that has a pitch of zero (“0”) meaning the surface  29  has no slope. 
         [0054]    The measurement indicia  42  also provide measurement of pitch from 1 to 12 on either side of the pinnacle point. The range of pitch or angle measured by the slope measuring device  30  can vary depending on the end use. In the embodiment shown, the pitch can be measured up to 12, which correlates to an angle of about 45 degrees. The arced tube has a radius of curvature R that is measured from an axis  45  to a center line  44  that runs through the middle of the arced tube  32 . The radius of curvature R is uniform across the arced tube  32 . The range of angles to be measured by the slope measuring device and fineness of the degree of measurement indicia  42  effects the width of the body  11  as well as the radius of curvature R of the arced tube  32 . The larger the radius of curvature R is, the more accurate the measurements of the slope measuring device  30  can be. At the same time, the width W of the body  11  must be taken into consideration to ensure that the width is manageable for easy use of the slope level  10 . 
         [0055]    Depending on the range of the angles capable of being measured by the slope level  10  and on the level of accuracy that is needed, the radius of curvature R may be larger or smaller, while still providing a width W of the body  11  that provides for easy use of the slope level  10 . For example, to provide a measurement for a pitch of up to 12 on either side, a radius of curvature R of about 5 and ⅛ inches may be used on a body  11  having a width of about 2½ inches. Such a width allows for easy use by builders or carpenters who are working on roofs or in other precarious positions. 
         [0056]    For measurements of smaller slopes which require a finer degree of accuracy, a larger radius of curvature R may be used that permit the use of measurement indicia at smaller intervals. For example, when leveling tile, a slope level  10  having a smaller range of measurement capabilities that allow for measurements of angles in tenths of degrees or fractions of pitch may be useful.  FIG. 3B  illustrates the portion of the slope level  10  of  FIG. 3A  having its planar measurement surface  20  residing against a surface  28  to be measured. The slope indicator  34  in the form of the bubble of gaseous fluid  33  moves along the outer edge  41  of the arced tube  32  as the liquid  35  in the inner space  39  of the arced tube  32  settles. Through use of the template  40  with its measurement indicia  42 , the position where the slope indicator  34  comes to reside indicates the angle α (as measured in pitch) at which the surface  28  extends in relation to a horizontal ground axis G. The point along the outer edge  41  of arced tube  32  at which the slope indicator  34  resides corresponds to the point where a tangential plane TI that runs parallel to the horizontal ground axis G passes through the outer edge  41  of the arced tube  32 . Again, this point can be correlated to the angle α at which the surface  28  extends in relation to the horizontal ground axis G. In the embodiment shown in  FIG. 3B , the slope indicator  34  indicates that the slope angle α has a pitch of around 5.33, which is around 20 degrees. 
         [0057]      FIG. 4  illustrates an exemplary embodiment of a portion of an alternate slope level  110 . The slope level  110  has a body  111  having a top side  112  and a bottom side  116  as well as a front face  114  and a back face. The bottom side  116  has a planar measurement surface  120  that may be placed against a surface to be measured. 
         [0058]    The slope level  110  also includes a slope measuring device  130 . The slope measuring device  130  has an arced tube  132  located on the front face  114  of the body  111  of the slope level  110 . The arced tube  132  has a first end  136  and a second end  138 . As described above, the arced tube  132  has a pinnacle point  137  located between the first end  136  and the second end  138 . The pinnacle point  137  corresponds to a point on the outer edge  141  of the arced tube  132  at which a tangential plane T 3  passes that is parallel to the planar measurement surface  120 . The arced tube  132  defines an inner space  139  in which a slope indicator  134  resides in the form of a solid spherical bead  160 . Preferably, the solid spherical bead  160  may be made out of a metal. For example, the bead may be made from aluminum, stainless steel, titanium, or the like. Alternatively, instead of a spherical bead, a drop of a heavy liquid such as mercury may be used. The arced tube  132  is positioned on the body  111  such that the arced tube  132  is visible from at least one of the front face  114  or the back face. The first and second ends  136  and  138  are further from the planar measurement surface  120  than the pinnacle point  137  such that the arced tube  132  is in an inverse position compared to the arced tube  32  shown in  FIGS. 3A and 3B . In some embodiments, the inner space  139  may contain a liquid with the spherical bead  160  being made of a material that has a greater density than the liquid. For example, the liquid may be a mineral oil. In such embodiments, the liquid may reduce rattle and dampen the movement of the bead  160 . When liquid is used in the arced tube  132 , a small air bubble may be included in the liquid to allow for contraction and expansion of the liquid due to temperature changes depending on the liquid used. 
         [0059]    A template  140  having measurement indicia  142  extends along the outer edge  141  of the arced tube  132 . Each measurement indicia  142  resides at a point where the spherical bead  160  comes to reside when the planar measurement surface  120  is placed upon a surface having a slope of an angle that corresponds to that specific measurement indicator  142 . 
         [0060]    The arced tube  132  may have a larger radius of curvature or a smaller radius of curvature. For example, the radius of curvature may be 12 inches or larger in some embodiments. In other embodiments, the radius of curvature may be as small as about an inch. The arced tube  132  has a uniform radius of curvature. When the slope level  110  is placed against the surface to be measured, the point where the slope indicator  134  comes to rest is at a point where a tangential plane passes that is parallel to the horizontal ground axis. Therefore, pinnacle point  137  occurs at a tangential plane parallel to the planar measurement surface  120  and this represents the point where no slope is indicated. For this reason, the measurement indicator  142  located at the pinnacle point  137  represents a pitch of zero (“0”). 
         [0061]    In the embodiment shown in  FIG. 4 , gravity works to pull the spherical bead  160  along the outer edge  141  of the arced tube  132  as the body  111  is tilted once the planar measurement surface  120  resides against the surface to be measured. Where the spherical bead  160  comes to reside will directly correlate to the angle of the surface being measured in relationship to a horizontal ground axis. As above, the length of the slope level is important to the operation of the slope level  110 . The length should be great enough to neutralize minor variations of slope on the surface being measured. For example, the length of the body  111  should be long enough to allow the carpenter or builder to use the level  110  on structures having a rough surface. For instance the length may range from about 1 foot to about 5 feet. The depth of the slope level should also be such that the slope level can rest against the surface to be measured without extra support. The depth (see the cross-sectional view of  FIG. 6 ) should be such that the slope level  110  will not tip over when placed on the surface to be measured. 
         [0062]      FIG. 5  illustrates a further exemplary embodiment of a slope level  210 . The slope level  210  includes a body  211  having a front face  214  and a back face (not shown) as well as a top side  212  and a bottom side  216 . The bottom side  216  has a planar measurement surface  220  that may be placed against a surface to be measured. 
         [0063]    A slope level  210  includes a slope measuring device  230  having an arced tube  232  and a template  240  of measurement indicia  242 . In the embodiment shown, the measurement indicia  42  indicate the angle of slope in degrees. The arc of the tube  232  has a large radius of curvature and provides an outer edge  241  that allows measurement of only a limited range of slope angles. Since the radius of curvature is larger, the degree of measurement details of the measurement indicia  242  template  240  may increase. For example, angle may be measured to tenths of a degree. In this manner, small changes in grade or slope within the range of slope angles that are capable of being measured can be more accurately determined by such a device. 
         [0064]    In the embodiment shown, the arced tube  232  has a wall  231  that defines an inner space  239 . The inner space  239  is filled with a liquid  235  and contains a slope indicator  234  that is a hollow bead  262  filled with a gaseous fluid. The hollow bead  262  has a density less than the fluid  235 . The arced tube  232  has a first end  236  and a second end  238  and a pinnacle point  237  that corresponds to a point through which a tangential plane passes that is parallel to the planar measurement surface  222 . The pinnacle point  237  corresponds to a zero (“0”) slope indicated by the “0°” slope measurement indicator  242 . As the body  211  and its measurement planar surface  222  is placed against a surface to be measured the hollow, spherical bead  262  moves on the outer edge  241  to a resting position. The resting position correlates to the angle of the slope of the surface that is being measured. The slope angle can be deciphered based on the closest measurement indicator  242  at which the hollow, spherical bead  262  resides. 
         [0065]      FIG. 6  illustrates a schematic cross-sectional view of another embodiment of a slope level  310 . The slope level  310  includes a body  311 . In the shown embodiment, the body  311  is constructed of a metal I-beam  352  forming a base. A filler material  350  fills the voids formed on either side of the I-beam  352  between the I-beam&#39;s wings to give the body  311   a  generally rectangular cross-section. The filler material  350  may be wood, a composite resin, plastic, or the like. The body  11  has a top side  312  and a bottom side  316 . A planar measurement surface  320  is formed on the bottom side  316 . The body  311  has a depth D that allows it to easily rest against the surface to be measured without fear of being tipped over. The depth D allows the slope level to stand in its measurement position without extra support. Thus, the user does not have to stand and hold the slope level  310  upright. 
         [0066]    The body has a measuring device  330  embedded in a front face  314  and a second measuring device  330 ′ is embedded on a back face  318  of the body  311 . Each measuring device  330 ,  330 ′ includes a transparent arced tube  332 ,  332 ′ and a template (not shown) as described above. Each arced tube  332 ,  332 ′ is embedded in a groove  329 ,  329 ′ cut into the filler material  350 . A transparent coating  354  surrounds the arced tubes  332 ,  332 ′ inside the respective grooves  329 ,  329 ′. The coating  354  can be a clear transparent epoxy, an acrylic, or the like. The coating  354  protects the arced tubes  332 ,  332 ′ from physical abuse and also thermal changes to a certain degree. 
         [0067]    Each arced tube  332 ,  332 ′ defines a respective inner space  339 ,  339 ′ in which a liquid  335 ,  335 ′ resides. Within each arced tube  332 ,  332 ′, a slope indicator  334 ,  334 ′ that comprises a bubble of gaseous liquid  333 ,  333 ′ resides within the fluid  335 ,  335 ′, respectively. In the embodiment shown, the templates (not shown) for each measuring device  330 ,  330 ′ with their measurement indicia may be marked on the arced tube  332 ,  332 ′ or on filler material  354 . Alternatively, the template of measurement indicia may be on the body  311 . For example, the measurement indicia may be marked along outer edges  326 ,  326 ′, of the respective grooves  329 ,  329 ′. In other embodiments, the measurement indicia may be marked along back walls  328 ,  328 ′ of the respective grooves  329 ,  329 ′. 
         [0068]    A slope measuring device of the slope level may be in the front face or back face or both the front and back face of the body of the slope level. Alternatively, the slope measuring device may be viewable from both sides by placing a single arced tube in a corresponding aperture in the middle of the body of the slope level. In some embodiments, multiple slope measuring devices may be placed on the same face of the body of the slope level. For example, a first slope measuring device capable of measuring slope angles of up to about 90° may be placed on a front face with a second slope measuring device placed on the same face capable of measuring slope angles of up to about 10°. 
         [0069]    The arced tubes that are used in the embodiments described above may be constructed of glass, plastic, or other transparent material. The arced tube can be rigid or may also be flexible. The arced tube may be placed in a groove in the body on either the front face or the back face or both. The portion of the groove behind the arced tube may be shaded or colored to enhance the ability to distinguish and locate the slope indicator. The arced tube may have a circular outer cross-section as well as a circular inner space. In some embodiments, the outer structure may be in the form of a square, while the inner space has a circular cross-section. Further, the arced tube may have a cross-section of other symmetrical shapes as long as the shape does not interfere with the travel of the slope indicator so that the slope indicator can accurately predict the slope of the surface being measured. 
         [0070]    As described above, the embodiments in which the arced tube is embedded in the body of the slope level, the area of the body in proximity to the arced tube as well as the arced tube may be covered by a clear coating to protect the arced tube of the slope measuring device. The clear coating can be thick to aid in insulating the arced tube from impacts and temperature changes. At the same time, the clear coating may help magnify the slope measuring device to facilitate the reading of measurements. For example, the coating can be a clear transparent epoxy, an acrylic, or the like. For instance, if a clear epoxy is used, the epoxy serves to protect the arced tube; while at the same time may also help to magnify the slope measuring device so that the position of the slope indicator in the arced tube can be more easily identified. 
         [0071]      FIG. 7  is a front view of another exemplary embodiment of a slope level. Exemplary slope level  410  comprises a body  411  which, in this example, comprises a box frame  452  of a generally rectangular shape, one side of which is visible in  FIG. 7 . For instance, box frame  452  may comprise aluminum. Of course, the boxed frame  452  may comprise other metal(s), plastics, composites, wood(s), and/or other suitable materials. Although a boxed frame is discussed in these examples, the body  411  may comprise other shapes so long as the body is suitably configured to define one or more planar measurement surfaces. Regardless of whether frame  452  comprises a boxed or other construction, the frame may comprise a single unit or may comprise multiple components (e.g. sides) that are brought into alignment and are suitably attached. 
         [0072]    The body  411  of slope level  410  has a top side  412  and a bottom side  416 , with bottom side  416  defining a planar measurement surface whereby slope can be measured based on the position of bubble  433  within arced tube  432 . Level  410  has a length L and a width W and a front face  414  and a back face (not shown in  FIG. 7 ).  FIG. 7  further illustrates length L 2  corresponding approximately to the portion of level  410  comprising arced tube  432 , and dashed lines A-A and B-B, which are included to indicate the views discussed below in  FIGS. 8-10 . Level  410  further includes conventional horizontal level  482  and vertical levels  484 , which may be optionally included to enhance the utility of the slope level. As discussed above, slope levels such as level  410  may be of any suitable length, width, and/or depth (cross-sectional thickness). 
         [0073]    In some embodiments, the arced tube is filled with a fluid such as a water-based solution of dissolved ionic solids, for example Dynalene HC-30 or potassium formate, while the tubes in the conventional horizontal level  482  and vertical level  484  are filled with 1,3-Propanediol or another suitable fluid. Advantages of 1,3-Propanediol are discussed in detail later below. 
         [0074]    In this example, arced tube  432  is positioned in an aperture or groove  429  that corresponds to the arced tube. In these examples, groove  429  extends through the body of the level so that arced tube  432  is visible from both the front side and the back side of level  410  via openings in the front and back sides of frame  452 . Of course, in other embodiments, the tube may be visible from only one of the front or back face of level  410 . Measurement template  440  comprising measurement indicia  442  is visible at the opening of the body corresponding to groove  429 . As discussed below, template  440  is printed on a clear cover  454 , which is positioned to protect arced tube  432  at the portions of body  411  where body  411  opens to expose groove  429 . 
         [0075]    Turning to  FIG. 8 , a partial side view of the interior of slope level  410  along length L 2  as shown in  FIG. 7  is illustrated. In this view, the front side of frame  452  and the front portion of clear cover  454  are not illustrated so that interior features of level  410  can be shown in closer detail. A small portion of the rear portion  452 ′ of the frame is shown. Arced tube  432  is shown positioned in groove  429  formed in body  411 . Furthermore, body  411  is shown to comprise filler material  450 . Filler material  450  may comprise wood, a composite resin, plastic, or the like. Filler material  450  may comprise a solid or substantially solid unit of material(s) as shown in  FIG. 8  and/or may include voids as illustrated below in  FIGS. 9-10 . Filler material  450  may extend the length of the level in some embodiments, and in other embodiments may correspond to the portion of the level where arced tube  432  is positioned. As will be discussed below, rear side clear cover  454 ′ is shown as extending along the rear portion  452 ′ of the frame between the rear side and filler material  450 . 
         [0076]    In this example, filler material  450  is used to define the interior portion of groove  429  that supports arced tube  432 . For instance, arced tube  432  may be attached or adhered to the top or bottom of groove  429  as defined by filler material  450 . In this example, filler material  450  defines a groove  429  that is slightly larger than arced tube  432  such that a gap exists between the top of arced tube and the top of groove  429 . It will be understood that the amount of clearance between groove  429  and arced tube  432  may be varied. As shown, filler material  450  is formed so that the side of arced tube  432  is visible through a corresponding opening in the side of frame  452 . 
         [0077]    Arced tube  432  includes first end  436  and second end  438 . First and second ends  436  and  438  may each comprise a respective end cap  456  and  458 . For instance, in one embodiment, arced tube  432  comprises a sealed tube and end caps  456  and  458  comprise shock-absorbing material to reduce or minimize mechanical effects on arced tube  432 . For instance, end caps  456  and  458  may comprise transparent or substantially transparent materials such as silicone, rubber, or other suitable materials. Filler material  450  and end caps  456 / 458  may be configured so that the filler material interfaces with a first portion of each end cap, with the other portion of each end cap configured so that the end of arced tube sits in or on the end cap. The end caps  456 / 458  may be any suitable size, and may extend partially or fully across groove  429  between the front and rear clear covers. The use of cushioning/shock absorbing end caps may be advantageous when a glass tube is used for arced tube  432 . Although plastics, composites, and other materials may be used for arced tube  432 , in some embodiments, a shaped tube of glass sealed at each end with a suitable liquid and bubble  433  therein may provide for a more accurate reading over a range of conditions. Any suitable type of glass may be used, including, but not limited to, UV-filtering (ultraviolet filtering) glass. 
         [0078]      FIGS. 9 and 10  are each another view of exemplary slope level  410 .  FIG. 9  shows a cross-sectional view of slope level  410  taken along line B-B shown in  FIG. 7 , while  FIG. 10  shows a cross-sectional view of slope level  410  taken along line A-A shown in  FIG. 7 . Additionally, in  FIG. 9 , the level is shown slightly rotated and in a partial perspective view with bottom side  416  and the front face  414  of the level visible. Visible from the front face  414  of the level are the front side of body  411  as formed by frame  452 . Additionally, the openings corresponding to groove/aperture  429  in the front side of body  411 /frame  452  and the back side of the frame ( 452 ′) are shown. This example further shows arced tube  432  as defining inner space  439  which may comprise liquid and a suitable indicator bubble (not shown). 
         [0079]    As shown in  FIGS. 9-10 , in this example, clear cover  454  extends along the side of frame  452  in between the frame and filler material  450 . In this example, arced tube  432  is visible from the back side of level  410 , as well. For instance, the rear portion  452 ′ of the frame also includes an opening corresponding to groove  429 . Back side clear cover  454 ′ extends along the back side of frame  452  between the frame and filler material  450 . The position of back side clear cover  454 ′ is also shown in  FIG. 8 . 
         [0080]    Unlike the front and back sides of frame  452  and filler material  450 , which each open to form groove  429 , clear covers  454  and  454 ′ extend to cover groove  429 . Thus, clear covers  454 / 454 ′ serve to protect arced tube  432  from impacts, dislodging, tampering, etc. that could occur if arced tube  432  were positioned in an open groove in body  411 , while still allowing for the arced tube  432  to be viewed. In this example, each clear cover  454 / 454 ′ comprises a substantially planar piece of material that further comprises a portion that extends outward into a shape corresponding to the shape of the opening in the side of frame  452 . Further, in these examples, the outwardly-extending portions extend above the plane by an amount equal or nearly equal to the frame thickness so that, when cover  454  ( 454 ′) is positioned between the side of body  411  and the filler material  450 , the exterior of the clear cover is flush with the side of body  411 . However, in other embodiments, clear cover  454  ( 454 ′) does not necessarily extend outward to be fully flush, or may not extend outward at all. 
         [0081]      FIGS. 9-10  further illustrate measurement template  440  comprising a plurality of measurement indicia  442  which, in this example, indicate degrees. As was noted in the embodiments above, the indicia may indicate pitch, roof pitch, degree of surface slope or pitch, percent of slope, combinations of these measurements or present comparisons between these measurements as well as any other suitable indicator(s) of slope. The indicia may be formed on or in the portion of clear cover  454  ( 454 ′) that covers and protects the tube, and may vary between the front and back sides (e.g., the front side may indicate slope in degrees while the back side indicates pitch). In one embodiment, the measurement indicia are formed in the side of the clear cover that faces toward groove  429  (i.e. on the inward side of the cover). The indicia may be printed, embossed, or otherwise formed so as to be visible at the outward side of the cover (i.e. the side of the clear cover that faces away from groove  429 ). 
         [0082]      FIGS. 9-10  additionally illustrate an exemplary cross-sectional view of filler material  450 . For instance, filler material  450  may comprise a plurality of voids  450   b  defined by members  450   a  formed of plastic, resin, and/or other suitable materials so that the slope level is sturdy but also light. Internal area  451  is represented as empty in  FIG. 9 . For instance, area  451  may comprise filler material (members and/or voids). Alternatively, in some embodiments, area  451  may comprise space for another vial or tube (arced or conventional). 
         [0083]    As was the case with filler material  450 , clear cover  454  ( 454 ′) may extend some or all of the length of the level or may extend only along the portion of the level corresponding to groove/aperture  429 . Additionally, the front side clear cover ( 454 ) and back side clear cover ( 454 ′) may be formed as separate units or as a single unitary component positioned between the sides of frame  452  and filler  450 . In any event, clear cover  454  may comprise any suitable transparent material, such as a clear plastic or resin. 
         [0084]    The use of a gaseous fluid-filled bead in a liquid within the slope measuring device provides an accurate and pinpointed measurement based on where it resides underneath the measuring indicia. Similarly, for a slope indicator of a bubble of gaseous fluid within a liquid, the smaller the bubble the more accurate and pinpointed the measurement can be of the slope of the surface being measured. However, the size of the bubble of gaseous fluid should be such that it merits an easy reading of the slope angle. The gaseous fluid within the bubble may be air, oxygen, fluorine, chlorine, bromine, nitrogen, or hydrogen. Further, the gaseous fluid may be an inert gas such as helium, neon, argon, xenon, radon or the like. By using a bubble of gaseous fluid, the liquid within the arced tube is allowed to expand and contract more readily than if an air-filled bead is used in its place. 
         [0085]    The liquid used within the embodiments shown may include water, antifreeze, alcohol, mineral oil, synthetic organic fluids, silicone-based fluids, or the like. One suitable liquid that may be used is DYNALENE-HC, manufactured by Dynalene Transfer Fluids in Whitehall, Pa. DYNALENE-HC solutions are non-toxic, non-flammable, aqueous based and typically have a freezing point less than −20° C. and a boiling point above 108° C. DYNALENE-HC solutions typically demonstrate densities ranging from 1177 kg/m 3  to 1323.4 kg/m 3  at 50° C. For instance, DYNALENE HC-30 provides useful thermal properties that minimize expansion and contraction with a freezing point of −40° C. and a boiling point of 112° C. with a density of 1260 kg/m 3  at 50° C. In some embodiments, advantageous results may be obtained through use of a liquid comprising potassium formate. For example, a solution of potassium formate in water may be used at concentrations between about ten percent (10%) and seventy percent (70%), although greater or lesser concentrations could also be used. The liquid used within the arced tube may also be colored so as to allow for a more distinctive contrast between the gaseous bubble and the fluid. Alternatively, if a bead is used, the bead may be colored, while the liquid may be more transparent. 
         [0086]    In some embodiments, the liquid used in at least one of the tubes can comprise 1,3-Propanediol, also referred to as propane-1,3-diol or trimethylene glycol. 
         [0087]    In some embodiments, the liquid in the tube may consist of 1,3-Propanediol. 
         [0088]    In certain embodiments, the liquid in the tube may consist essentially of 1,3-Propanediol. 
         [0089]    The liquid in the tube may include dye(s) or other suitable additives. 
         [0090]    One example of 1,3-Propandiol is available from Dynalene under the name BIOGLYCOL. BIOGLYCOL is a non-toxic, renewably sourced fluid providing 30% lower viscosity at low temperatures compared to petroleum derived propylene glycol. BIOGLYCOL has a boiling point of 217.4° C., a melting point of −27.7° C., a flash point of 131° C., an autoignition temperature of 405° C., a refractive index of 1,439 and viscosity of 52 at 20° C. 
         [0091]    The liquid may also be SUSTERRA propanediol available from Dupont Tate &amp; Lyle. SUSTERRA is a renewable, non-petroleum derived 1,3-Propanediol. SUSTERRA has a boiling point of 214° C., a freezing point of −24° C., a flashpoint of 131° C., density of 16.833 kg/m 3  at 20° C., an autoignition temperature of 405° C. and a vapor pressure of 0.08 mmHg. 
         [0092]    While 1,3-Propanediol may be used in any type of tube, it may be particularly advantageous for use in one or more tubes in a standard level. Among other advantages, 1,3-Propanediol may be derived from corn products, and a level using corn-derived fluid can be marketed as a “green” (i.e. environmentally-friendly) product. This may result in a significant competitive advantage in the current market, which favors environmentally-friendly products. 1,3-Propanediol could be derived from one or more other sources in some embodiments. Of course, other corn-derived fluids or other “green” fluids could be used in still further embodiments. 
         [0093]    As an example,  FIG. 11  shows a level  510  comprising a horizontal level device  582  and a vertical level device  584 , each respectively comprising a standard tube  590 A and  590 B. In this embodiment, each tube has a total diameter of 8.4 mm, with a wall thickness of 1.2 mm for a resulting internal diameter of 6.0 mm. Other embodiments use an 8 mm diameter tube. In this example, each tube is about 1 and ¼ inches in length. Of course, the dimensions are for purposes of example only, and in other embodiments, the dimensions may diverge from those of this example. The tubes of this example are made of glass, which may advantageously allow for better performance when fluid  532  in each tube comprises 1,3-Propanediol. However, the standard tubes may be plastic or any other suitable material(s). 
         [0094]    In this example, an arced tube is not embedded in or otherwise carried by level  510 . However, in other embodiments, one or more arced tubes may be included in a level, with the arced tube(s) filled with 1,3-Propanediol or any other suitable fluid. For example, in one embodiment, a level comprises at least one standard tube comprising glass and containing 1,3-Propanediol, and at least one arced tube containing potassium formate, Dynalene HC-30, or any other suitable fluid. The arced tube may be plastic, glass, or any other suitable material. 
         [0095]    Level  510  further comprises a body  511  in which tubes  582  and  584  are embedded. In this example, body  511  is of a generally elongated rectangular shape and may, for instance, comprise an I-beam, box frame, or may be of any other suitable construction. Level  510  has a top side  512  and a bottom side  516  with the top side  512  having a planar measurement surface  522  and the bottom side  516  having a planar measurement surface  520 . 
         [0096]    The embodiments of this invention shown in the drawings and described above are exemplary of numerous embodiments that may be made within the scope of the invention. It is contemplated that numerous other configurations of the level may be used and the materials may be selected from numerous materials and dimensions other than those specifically disclosed.