You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     A typical toilet includes a tank filled with water and having a flush valve at its bottom. When a control handle is manually operated, water in the tank passes into a toilet bowl that may contain waste, to flush the waste through an upper trap and through a passage leading to a drain pipe. The water-filled upper trap prevents sewer gas from passing into the washroom. A water saver toilet typically reduces the amount of water passed into the bowl in each flushing, and uses a smaller toilet bowl to enable the contents of the bowl to be flushed out using less water. This usually results in a smaller “water spot,” which is the top of the pool of water in the bowl. Many people are uncomfortable with a small water spot in a shallow pool of water in the bowl, because waste may stack up above the water spot. A water saver toilet that provided a larger water spot and deeper pool of water in the bowl, and which enhanced a flushing, would be of value. 
     Flushing water can be saved by allowing the user to choose a partial flush when only liquid waste lies in the toilet bowl, and to choose a full flush when solid waste lie in the bowl. It would be desirable if such dual flush toilet used only a single flush valve to minimize the possibility of a leaking flush valve. Also, any less-than-vigorous flush should occur only during the partial flush when only liquid waste is being flushed, while a vigorous flush with rapidly moving flush water should occur during a full flush when solid waste is to be removed from the bowl. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the invention, a water saver toilet is provided that has a larger water spot in the toilet bowl and that provides a better flushing whether in a partial or full flush mode of operation. The toilet has a trapway leading from the toilet bowl to the drain, wherein the trapway includes both upper and lower traps and a trapway passage between them. The lower trap is constructed to hold sufficient water to close the lower trap prior to each flushing. A source of pressured air is coupled to the trapway passage to pressurize it between flushings. The air pressure in the trapway pushes some upper trap water into the toilet bowl to raise the water level therein and create a larger water spot therein. The pressured air is obtained from a first container lying in the toilet tank and having closed top and side walls and an opening in its bottom. Water in the first container is emptied during a flushing, and the first container then fills with air. As water refills the first container though its bottom opening after a flushing, the air in the first container is compressed. This pressured air is carried though a conduit to the trapway passage to pressurize it. 
     For a partial flushing, a flush handle is operated to open a flush valve that passes water in the first container through a coupling region and through the flush valve, to the toilet bowl. For a full flushing, the handle is operated to open a second valve that passes water that lies in the water tank and above the first container, into the coupling region to pass though the same flush valve. 
     The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially sectional isometric view of a toilet constructed in accordance with the present invention. 
         FIG. 2  is a sectional front view of the toilet tank and other parts of the water supply of the toilet of  FIG. 1 . 
         FIG. 3  is a side elevation view, partly in section, of the toilet bowl and trapway of the toilet of  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows a toilet  10  of the present invention, which includes a pottery section comprising a toilet bowl  12  and a trapway  14  that leads from the toilet bowl to a drain  16 . A water source  20  includes a water tank  22  and a flush valve  24  that discharges water lying in the tank. The discharged water flows through a water tunnel  26  and through openings at the top of the bowl, and into the toilet bowl during a flushing. The trapway  14  includes the usual upper trap  30  that prevents sewer gas from passing into the washroom. The trapway also includes a lower trap  32  and a trapway passage  34 . The water source  20  includes first and second containers  40 ,  42 , and a passage or third container  44 , that all lie in the tank  22 . A refill valve  50  admits water into the tank after each flushing, until the water level in the tank reaches a fill level  52 . The refill valve also flows a trickle of water into the tunnel  26  at the end of a flushing to fill the toilet bowl. The top of the container  40  lies more than an inch below the fill level  52  of the tank. The flush valve  24  lies in the bottom of the tank. A second valve  62  in the form of a simple pivotable lid lies at the top of the third tank or passage  44 . 
     As shown in  FIG. 2 , to flush the toilet (for a partial flushing), a person pivots a handle  130  to raise a beam  70  that operates the flush valve  24 . Water moves down out of openings  72 ,  74  at the bottoms of the first and second containers  40 ,  42  and through a coupling region  80  to flow out though an opening  82  at the bottom of the tank that has been uncovered by opening the flush valve. Water flows out of the tanks until water level  84  in tank  42  is reached and the flush valve  24  closes. At that time the water level in the first container  40  is at  86 . The bottom  88  of the container  40  lies a plurality of millimeters above the tank bottom. The water from the containers moves through the water tunnel ( 26 ,  FIG. 1 ) and into the toilet bowl, and raises the level of water in the toilet bowl. The contents of the toilet bowl moves through the upper trap and down through the trapway passage and lower trap to the drain. The water now filling the trapway creates a syphon that pulls out all water and waste in the toilet bowl and carries it to the drain. 
     Immediately after water has flowed out of the two containers  40 ,  42 , water slowly flows back into the containers to fill them. Such water flows though small holes  92  in the walls  94  of the coupling region and up into the containers  40 ,  42 ,  44 . The second container  42  has an upper end that is vented through a tube  96  to the space at the top of the tank, above the filled water level. The first tank  40  is vented only though a conduit  100 . 
     As the water level rises in the first tank  40 , air trapped in an air trapping region  98  at the closed top of the first tank is compressed, and such compressed air moves into the conduit  100 . The conduit  100  is connected to the trapway  14  shown in  FIG. 3 , to flow pressured air therein at the end of a flushing. Late in the next flushing, when water is no longer syphoned out of the toilet bowl, while a trickle of water continues to flow into the toilet bowl to fill it, a trickle of water flows past the upper trap and keeps the lower trap filled. When water stops flowing into the toilet bowl, pressured air remains in the trapway passage  34 . The lower trap is constructed, as shown in  FIG. 3 , so the top point  110  of the lower trap bottom wall  111 , which lies in the downstream side  112  of the lower trap, is higher than the bottom point  114  of the upper wall  115  of the lower trap, which lies in the upstream side  116  of the lower trap. The difference distance A is more than one centimeter and is preferable a plurality of centimeters. This construction maintains pressured air in the trapway between flushings. If the air pressure in the trapway exceeds the pressure of a height A of water, such as 4 centimeters of water (which equals 0.06 psi), then the pressured air pushes down water to level  114  and the pressured air passes under the lower trap top bottom point  114  until the air pressure in the trapway is equal to the height A of water. 
     The presence of pressured air in the trapway between flushings has the effect of raising the level of water in the toilet bowl  12 . If there were zero pressure (atmospheric pressure) in the trapway between flushings, then during bowl refill at the end of a flushing, water would flow out of the bowl. The water spot in the bowl would move down until it reached level B at the top point  120  of the lower wall of the upper trap. In a water saver toilet, the bowl may be significantly smaller than previously, and the ability to raise the water level in the bowl is an important advantage. The air pressure in the trapway raises the water level in the bowl to level C. The bowl walls are inclined, especially at the front, which results in a significantly larger water spot  122 . Consumers generally want a large water spot  122  because it indicates that more waste will be completely submersed in water in the bowl and possibly emit less odor. The increase E in water spot level is roughly about equal to height A and to height D. 
     The movement of toilet bowl water from level B to level C has an additional advantage. This additional advantage is that the water  124  in the bowl falls by the distance E just from the drop in air pressure in the trapway  14  as the pressure drops to atmospheric pressure or to a vacuum. Such dropping occurs as water starts filling the bowl, to thereby provide a more vigorous flushing. The pressure of air in the trapway is rapidly lowered during a flushing as the water level in the first container drops. Such lowering of air pressure in the trapway occurs early during a flushing, as the water level in the first container  40  drops, and the first container drains air through conduit  100  out the trapway and may even create a vacuum therein. During a flushing, when the upper trap  30  breaks but is not yet filled by a trickle of water from the refill valve, air passes through the upper trap and through the conduit  100  to refill the top of the container  40  with air. 
     The water source  20  of  FIG. 2  can be operated in a partial flush mode to empty primarily the contents of the first and second containers  40 ,  42  into the water tunnel, and can be operated in a full flush mode. In a full flush, the second valve formed by the lid  62  is opened, in addition to opening the flush valve  24 . When the lid  62  is also opened, water in the third container  44  plus water in the tank  22  that lies above the lid, flows though the third container, or passage, to the coupling region  80  and out through the open flush valve. The greater height of water at  52  that lies above the lid, results in a more vigorous flushing. If the lid  62  does not form a leak-tight seal, this has little effect, because it results in only a slight leakage into the coupling region at the beginning of a flushing, and until the containers  40 ,  32 ,  44  are refilled. A leak in the flush valve  24  can cause loss of a large amount of water. It is possible to provide a large third container and empty its contents in a full flushing by opening a valve that admits air rather than additional water, into the third container. For example, if container  44  holds one liter of water, a valve shown at  128  can be opened to admit air into the third container  44  to flush out the entire liter when flush valve  24  is also open. 
     A variety of manually controlled devices are available to open the flush valve  24 , and sometimes also the lid  62 .  FIG. 2  shows two handles  130 ,  132  with the first  130  depressed for a partial flush and with both handles  130 ,  132  depressed for a full flush. The handles  130 ,  132  connect to beams  70 ,  134  with outer ends attached to chains  140 ,  142 . Chain  140  extends to a rod  143  to lift it and open the flush valve  24 . The other chain  142  extends to the lid  62  to pivot it open. The lid  62  can have a hydrodynamic surface or float that keeps the lid open while water flows past it, until almost all water above the lid  62  has flowed out. One type of flush valve  24  may be the type described in U.S. Pat. No. 3,988,785, which remains open when first opened, until almost all water has been released. 
     Thus, the invention provides an enhanced water saver toilet. The water spot in the toilet bowl in increased and the depth of water in the bowl is increased by providing a trapway that contains pressured air between flushings. The trapway includes upper and lower traps. The lower trap is constructed so it is closed between flushings, by placing the top location ( 110 ) of the lower trap bottom wall, which lies at the downstream side of the lower trap, so it is higher than the bottom location ( 114 ) of the lower trap upper wall, which lies at the upstream side of the lower trap, to contain water in the lower trap between flushings. The difference A in height is more than a centimeter and preferable at least two centimeters to significantly raise the level of water in the toilet bowl. The water supply includes a first container that has closed top and side walls and an opening in its bottom, so when the first container fills with water, air at the top of the container is pressurized and carried though a conduit to the trapway. The water supply can include a vented (though a vented second container) coupling region that connects the first container to a flush valve. Additional water can be supplied by opening a second valve that flows water from a third container, plus any water in the tank above the second valve, to the coupling region to flow out though the flush valve. 
     Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

Summary:
A water saver toilet that produces a larger water spot ( 122 ) in the toilet bowl ( 12 ) and a better flushing, and that enables partial and full flushing. A trapway ( 14 ) that extends from the toilet bowl outlet to a drain ( 16 ), has upper and lower traps ( 30, 32 ) and a trapway passage ( 34 ) that extends between and into the traps. The lower trap is constructed to be sealed by water therein prior to each flushing, and a pressured air source ( 98 ) applies pressured air to the trapway prior to a flushing. The pressured air in the trapway pushes some upper trap water into the toilet bowl to increase the water spot therein. A first container ( 40 ) lies in the water tank, and the water therein can be flushed down from the first container though a coupling region ( 80 ) and though a flush valve ( 24 ), for a partial flushing. A full flushing is achieved by opening a second valve ( 62 ) to pass water lying in the tank around and above the first container, and through the coupling region and the flush valve.