fig1 illustrates the cycling characteristics using a convention electromechanical thermostat with heat anticipation provided by a resistance heater . in fig1 the y - axis represents temperature and the x - axis represents time . the room or ambient temperature is represented by the line ( at ). the ambient temperature is the temperature at which the room is controlled and in fig1 this is 70 . 5 degrees . the thermostat set point is at 72 and is indicated by the line designated ( m ). this reflects the fact that the thermostat is set to make contact when the sensed temperature reaches 72 degrees to turn on the heating unit . the temperature represented at the line ( b ) is the breakpoint of the thermostat contacts or that point at which the contacts are designed open to turn the heating unit off . the curve shown in fig1 thus represents the temperature sensed by the sensing element in the thermostat which in a typical electromechanical thermostat may be a bimetal contact . at 72 degrees when the heating unit is turned on in conventional thermal heat anticipation a resistance heater generates a thermal effect that is detected by the bimetal . when this sensed temperature reaches the breakpoint , the contacts open and the heating unit is turned off . when the temperature again drops to the make point ( m ), the contacts close , again turning on the heating unit . the thermostat cycles in this manner maintaining the ambient temperature at the level indicated by ( at ). the difference between set point ( m ) and the room or ambient temperature ( at ) is the thermostatic droop characteristic that will be described in more detail hereafter . one embodiment of the essential mechanical elements of the present invention is shown in fig2 . there is illustrated an electromechanical thermostat 10 having a pair of contacts 12 and 14 . contact 12 is an elongated bimetal which is shown mounted for pivotal movement about 16 . contact 14 has a magnet at 18 . a conventional prior art low power stepper motor is shown at 20 . motor 20 may be powered by a battery supply ( not shown ) in wireless applications such as retrofitting . stepper motor 20 is connected to contact 12 by a mechanical interlock which may be any convenient known means at 22 . contact 12 senses temperature and the uneven expansion rates of the bimetal cause contact 12 to make and break with contact 14 as illustrated by the arrow a . the thermostat of fig2 is also provided with a set point adjustment ( not shown ) which is typically a mechanical adjustment to establish the set point relative positions of contacts 12 and 14 . when thermostat 10 is on and operating to sense and control the on / off cycling of a heating / cooling unit , stepper motor 20 functions to change the position of contact 12 about its pivot 16 in opposite directions as indicated by the arrows numbered 1 and 2 . when contacts 12 and 14 close to turn on the heating / cooling unit , stepper motor 20 through its mechanical interlock 22 with contact 12 begins to rotate contact 12 in the direction of arrow 1 about pivot 16 in incremental steps from the minimum ( closed contact position ) to a maximum as indicated in fig3 a . fig3 a shows the operation whereby the stepper motor changes the position of contact 12 in incremental steps from minimum to the maximum displacement of contact 12 and in an exponential fashion . the y - axis in fig3 a shows the stepper position from minimum to a maximum displacement of contact 12 while the x - axis is a function of time . stepper motor 20 is designed to generate gradually increasing incremental steps to mirror the exponential characteristic of conventional heat anticipation cycling . when contacts 12 and 14 open the direction of rotation or movement of stepper motor 20 is reversed . as illustrated in fig3 b the stepper motor causes incremental displacement in an exponential fashion of contact 12 in the direction indicated by the arrow 2 ( in fig2 ) from a maximum displacement to a minimum during the off cycle of the heating / cooling unit . the y - axis of fig3 b shows the stepper position from maximum to minimum and the x - axis is again a function of time . as described previously with respect to fig3 a the stepper motor causes gradually increasing incremental steps to simulate an exponential heat anticipation function . fig4 illustrates the stepper motor cycling adjustment of the relative positions of contacts 12 and 14 to provide mechanical heat anticipation with the heating / cooling unit operating at a fifty percent duty cycle . the graph of fig4 illustrates displacement as a function of time with the line ( at ) illustrating the displacement of contact 12 between make position ( m ) and break position ( b ). the thermostat set point displacement is also shown in fig4 . the set point is also a function of the relative position of contacts 12 and 14 in fig2 . the set point , or the point at which the contacts make , is adjusted by adjusting the relative position between the contacts . for example , with reference to fig2 set point adjustment could be provided on either contact 12 or contact 14 . if it were on contact 14 , contact 14 like contact 12 may also be pivotally mounted with set point adjustment accomplished by mechanically pivoting contact 14 with respect to contact 12 . set point adjustment could also be accomplished by providing a mechanical adjustment to pivot contact 12 about its pivotal axis 16 . as previously discussed , in prior art electromechanical thermostats there is a difference between the thermostat set point and the room ambient or control temperature which is referred to as thermostat droop . this difference increases as the duty cycle increases because of the increased amount of thermostat anticipation heat during the heating mode . likewise the droop increases as the duty cycle decreases with the unit in the cooling mode . typically the design maximum droop is three degrees f at which point the heating unit is operating at one hundred percent duty cycle . fig5 is a graph showing the linear relationship between the thermostat droop in the prior art electromechanical thermostats as a function of the duty cycle . the room control temperature is plotted along the y - axis with the x - axis representing the duty cycle . in the present invention the droop may be reduced or eliminated by automatically adjusting the relative displacement of the contacts to reduce the offset between the set point and control temperature to zero such as by set point readjustment . to achieve this , as will be described in more detail with reference to fig7 the duty cycle of the heating / cooling unit is monitored , and according to the duty cycle , in the embodiment of fig2 the contact 12 is displaced with reference to contact 14 by stepper motor 20 . fig6 is a graph illustrating the displacement necessary to reduce the droop to zero as a function of duty cycle . for example , at 100 % duty cycle , the displacement must be at a maximum value . as shown in fig6 the relationship between displacement and duty cycle is linear . it is contemplated that the same stepper motor used for heat anticipation also may provide the dedroop adjustment . the droop adjustment is designed for a slow and gradual displacement so that it does not affect the more rapid cyclic displacement necessary for mechanical heat anticipation . a slow response or a long time constant thermal heater is difficult to achieve in small sizes thereby preventing this dedroop function in prior electromechanical thermostats . alternatively , a second stepper motor could be used particularly if the droop adjustment is designed to cause displacement of contact 14 as opposed to contact 12 . it should be understood that the present invention can be used with other prior art electromechanical thermostat configurations in addition to that shown in fig2 . for example , the present invention can be easily incorporated into an electromechanical thermostat of the coiled bimetal type where one end of the bimetal coil is fixed and the other moves and actuates a switch such as a mercury switch . in this application the stepper motor would generate a rotational movement of the spiral bimetal for mechanical heat anticipation and droop control . fig7 illustrates in block diagram form the control incorporated in the present invention . it is understood that the means to implement the specific functions illustrated in block diagram in fig7 would be known by one of ordinary skill in the art . the thermostat switch is illustrated as 30 . this could be any of the conventional types of make / break electromechanical thermostat switches discussed previously . the output of switch 30 is an on / off signal at 32 . this signal controls the operation of a heat / cool unit 34 . while this discussion is with reference to the operation of unit 34 in the heating mode , it is understood that the present invention is also useful in an air conditioning or cooling mode . unit 34 functions to heat or cool the space in a house 36 or other structure . the thermostat of the present invention has a space temperature sensor 38 which , for example , may be a bimetal element with unequal expansion rates as described above . the relationship between the space temperature and a thermostat set point determines the make and break of switch 30 . for example , the thermostat is typically designed to make contact when the sensed space temperature falls to the set point and break contact when the sensed space temperature exceeds the set point by a predetermined value . ( see , for example , fig1 .) the thermostat mechanical heat anticipation control loop is illustrated at 38 . it includes a stepper motor logic control circuit 40 and stepper motor 42 . the on / off signal at 32 is fed to logic control circuit 40 along with a feedback signal at 44 which is indicative of the stepper motor position . the stepper motor position controls the cycling of switch 30 via mechanical displacement as described above . the feedback control loop for reducing or eliminating thermostat droop is shown at 46 . the feedback loop includes a thermostat on / off counter 48 , a stepper motor logic control circuit 50 and stepper motor 52 . as stated above in the implementation of the present invention motors 42 and 52 as illustrated diagrammatically in fig7 can be the same physical motor . the on / off signal from switch 30 is an input to the thermostat on / off counter for measurement of the duty cycle . a signal representative of the duty cycle is an input from counter 48 to logic control circuit 50 . the logic control circuit 50 then generates a signal to slowly control displacement of stepper motor 52 to adjust the thermostat set point to reduce the difference between the set point and control temperature of the system . the mechanical heat anticipation of the present invention also finds application in line voltage electric heat thermostats to improve their cycling characteristics . in this type of thermostat the physical size of the bimetal temperature sensor is often quite large and therefore sluggish in time response to temperature changes . the switch differential from make to break is often large in these thermostats . this condition is caused by the force requirements to make / break the electrical contacts that conduct substantial current . the combination of a slow thermal response sensor , a large thermostat switch differential , and large thermostat current causes excessive heat to be generated within the thermostat to achieve the desired cycling rates with a corresponding large amount of thermostat droop . this problem can be eliminated using the mechanical heat anticipation of the present invention . this would provide a desirable cycle rate to provide comfort with a reasonable amount of droop . the present invention is thus an improved electromechanical thermostat having mechanical as opposed to thermal heat anticipation cycling characteristics . it is particularly useful in wireless thermostat applications where the thermostat uses battery power . the present invention also is an improved electromechanical thermostat with a means to mechnically reduce thermostat droop providing for a consistently comfortable environment under varying load conditions .