Title of Invention: INDICATING DEVICE Abstract: A dispenser for dispensing metered dosages of a substance from a container includes a dispenser housing having a top, a bottom, and a wall defining an elongated cavity open at the top and extending along a longitudinal axis. An indicating device includes a face member defining a viewing window. The face member is snap-fitted to the dispenser housing wall. The indicating device further includes an indicator member having a surface visible through the viewing window. The surface includes dosage indicia. The indicator member is rotatable about an axis substantially perpendicular to the longitudinal axis. An indicator actuator has at least a portion disposed in the cavity. The actuator is adapted to be moved by an actuation of the container, with the actuator adapted to rotate the indicator member upon a predetermined number of actuations of the container. Detailed Description: This application is a continuation-in-part of application Ser. No. 09/008,184, filed Jan. 16, 1998, and entitled Aerosol Dispensing Device, the disclosure of which is hereby incorporated herein by reference. No license, expressed or implied, is intended to be granted to application Ser. No. 09/008,184, or any patents issuing therefrom, by reason of the incorporation by reference herein. BACKGROUND The present invention relates generally to an indicating device, and in particular, to an indicating device for indicating the number of metered dosages of a substance, and in particular a medicament, that have been dispensed by, or remain in, a dispensing device. Delivery systems, and in particular, dispensing devices, have been developed that include a counting or dose indicating device to indicate the number of metered doses of substance that have been dispensed from the delivery system, or to indicate the number of doses remaining therein. For example, patients have certain conditions that can be treated with medicaments dispersed in an aerosol and administered to the patient by inhalation. In one format, the aerosol and medicaments are contained in a container, and dispensed in metered, or measured, dosages with the dispensing device, which can include an actuator boot. In such an arrangement, it can be important for the patient to be able to ascertain the number of metered doses remaining in the container, either by an indication of the number remaining therein or by knowledge of the number already dispensed therefrom, such that the patient is not caught unaware with an empty container when in need of the medicament Thus, it may be important for the dispensing device to, provide an accurate indication of either the number of doses remaining in the container, or the number of doses already dispensed therefrom. Typically, a conventional aerosol container includes a body and a valve stem which can be depressed relative to the body so as to emit the metered dose of aerosol and medicament. The container is usually supplied with a predetermined number of metered doses, e.g., on the order of about 200, such that the counting of the number of valve stem depressions, and corresponding number of dispensed metered doses, can be directly correlated with the number of doses remaining in the container. In operation, the container is typically received within a housing of the dispensing device, wherein the valve is brought into engagement with a support block in the housing. The user administers the medicament by moving the container relative to the housing so as to depress the valve stem and internal valve and thereby release, a metered dose, which is typically administered to the user through a port or mouthpiece extending from the housing. In an alternative delivery system, the metered dose can be first discharged into a chamber, and thereafter administered to the patient. After the metered dose is discharged from the container, the valve stem, which is typically spring loaded, biases the container away from the support block so as to again move the container relative to the housing. In this way, a metered dose of medicament is discharged by each cycle of linear reciprocal movement of the container relative to the housing. Some dispensing devices have indicating devices that convert the linear reciprocal movement of the container relative to the housing into a one-way, or single-cycle, movement of an indicator, wherein the indicator identifies the relative fullness of the container, the number of metered doses remaining therein or the number of doses already administered. Although these dispensing devices with indicators have provided the advantage of generally being able to keep track of the number of dosages, there remains room for improvement. For example, indicating devices of this nature may include complex moving parts which can be difficult to assemble and expensive to manufacture. Such devices may also be susceptible to counting inaccuracies due to the configuration of the indexing or mating parts, or require excessive amounts of space within the housing to accommodate the relatively large or numerous moving parts. Others still may impede or interfere with the airflow and medicament being dispensed from the inhalation device. Alternatively, some devices use electrical circuitry to count or record the dispersements. Such devices can be relatively expensive to manufacture, however, and typically require a power source which may be susceptible to damage in various environments, such as moist conditions. SUMMARY Briefly stated, in one aspect the invention is directed to a dispensing device having an indicating device. The dispensing device dispenses metered dosages of a substance from a container having a valve moveable between a closed position and an open position. The container dispenses a metered dosage when the valve, actuated by a valve stem, is moved to the open position. In an exemplary embodiment, the dispensing device includes a housing adapted to support the container reciprocally moveable within the housing along a longitudinal axis. The housing has a well adapted to receive the valve stem and an exhaust port. The well communicates with the port such that the metered dosage of substance is dispensed through the port when the valve stem is moved to the open position. In one embodiment of the indicating device, an indicator assembly includes a worm rotatably mounted in the housing about an axis transverse to the longitudinal axis and responsive to the movement of the reciprocal movement of the container within the housing such that the longitudinal movement of the container relative to the housing causes the worm to rotate about its axis. An indicator member includes dosage indicia visible to a user and a circular gear mounted in the housing about an axis transverse to the axis of the worm and non-parallel to the longitudinal axis. The circular gear engages the worm. In a preferred embodiment, the indicator assembly further includes a ratchet wheel rotatably mounted in the housing and adapted to be responsive to the reciprocal movement of the container relative to the housing along the longitudinal axis. The ratchet wheel is connected to the worm such that rotation of the ratchet causes the worm gear to rotate about its axis. In addition, an actuator member including an arm is preferably mounted within the housing and is adapted to move in response to the movement of the container and operably engage the ratchet wheel so as to rotate the wheel in response to the longitudinal movement of the container relative to the housing. Also in the preferred first embodiment, the indicator member includes an indicator wheel coaxially mounted with the circular gear on an axle defining the axis of rotation of the indicator member. The dosage indicia are applied to a surface of the indicator wheel. In another embodiment of the indicating device, the housing comprises at least one engagement member and the indicator assembly includes a plurality of indicator members, including, at least a first and second indicator member. The plurality of indicator members are coaxially mounted in the housing. At least one of the first and second indicator members includes an advancement member, while at least the other of the first and second indicator members includes a plurality of teeth. In operation, the first indicator member is rotated relative to the second indicator member such that the engagement member selectively engages and biases the advancement member into operable engagement with at least one of the plurality of teeth so as to rotate the second indicator member an incremental amount. In a preferred embodiment, an actuator member is mounted in the housing and is responsive to the movement of the container. The actuator member selectively engages at least one of the plurality of teeth on the first indicator member so as to advance the first indicator member an incremental amount in response to the movement of the container relative to said housing. A spring is preferably disposed in the housing to bias the actuator member into engagement with the container. In another aspect of the invention, the indicator assembly, including the ratchet wheel, worm, actuator member and indicator member of the first embodiment, are mounted within an indicator module which is adapted to be mounted within the dispenser housing. Similarly, with respect to the second embodiment, the indicator assembly, including the plurality of indicator members, advancement member, spring and ratchet member, are supported in the indicator module. The module preferably includes a first and second member which are joined to form an enclosure or housing, and which support any one or more of the ratchet wheel, worm, actuator member and indicator member of the first embodiment therein, or the plurality of indicator members, advancement member, spring and actuator member of the second embodiment. In the second embodiment, the engagement members are also preferably disposed in the module housing. In another aspect of the invention, a key member is mounted to one of the container and the housing and is shaped to be received in a passageway formed in the other of the housing and container. In yet another aspect of the invention, a method is provided for dispensing measured dosages from the container. In one embodiment, the method includes the steps of moving the container along the longitudinal axis so as to move the valve stem, and valve, to the open position wherein a metered dosage is discharged. The longitudinal movement of the container within the housing causes the ratchet gear to rotate a predetermined angular amount, which, in turn, causes the worm to rotate about its axis. The worm then engages the circular worm gear of the indicator member so as to rotate the worm gear about its axis. Alternatively, in a second embodiment, the first indicator member is rotated a predetermined amount in response to the movement of the valve between a closed and open position, or vice versa. Upon a predetermined number of movements of the valve, the first indicator member causes the second indicator member to rotate a predetermined amount. In another aspect of the invention, a method is provided for assembling a dispenser comprising a housing, a container and an indicator module. In yet another aspect of the invention, a kit includes components capable of being assembled as a dispensing device for dispensing metered dosages of a substance from a container. The kit includes a housing, a container having a plurality of metered dosages of the substance and an indicator module having an indicator member. The present invention provides significant advantages over other indicating devices. In particular, with respect to the first embodiment of the indicating, device, the worm provides for a compact drive component that does not occupy excess space within the housing. Moreover, the worm provides for high gear reduction ratios while maintaining a continuous engagement with the circular worm gear. The continuous engagement of the worm and circular gear ensures that the accuracy of the counting device is maintained, while simultaneously simplifying the manufacturing and assembly process. The use of a circular gear having an axis non-parallel, and preferably transverse or perpendicular to the longitudinal movement of the container within the housing, also provides several advantages. Importantly, the gear can be easily mounted to the housing with an inexpensive and easy-to-install axle. Thus, the circular gear provides for a compact single-cycle device that fits easily into the housing, and which maintains continuous engagement with the worm gear for improved and accurate indexing of the indicator member. Moreover, the components are arranged so as to not interfere with or otherwise impede the air flow from the valve stem to the exhaust port of the housing. In addition, the indicator wheel, which is preferably coaxially mounted with the worm gear, provides an ideal planar surface for displaying the dosage indicia. The indicia can be easily viewed by the user through the viewing window. The second embodiment of the indicating device provides similar advantages. In particular, the plurality of indicator members can be mounted in a compact arrangement to provide accuracy and reliability under various operating conditions but which does not impede or obstruct the airflow to the user. Moreover, the various parts are relatively inexpensive to manufacture and assemble. The indicia, which are visible to the user through the viewing window, are easy to read and readily accessible to the user. The indicator module, with any of the various embodiments of indicating assemblies disposed therein, also presents several advantages. In particular, the self-contained unit can be separately manufactured and installed as needed in any number of conventional types of dispensing devices with minimal modification thereof. Moreover, the module can be easily installed without interfering with or otherwise impeding the air flow from the valve stem to the exhaust port and ultimately to the user. The key member also presents several advantages. In particular, differently configured key members and passageways can be installed between containers holding different substances such as medicaments and corresponding delivery system housings so as to prevent the user from interchanging various containers and housings so as to thereby alter the number of doses being counted. The key member and passageway can also prevent a user from using the wrong delivery system for a particular container having a particular substance, such as a medicament. The present invention, together with further objects and advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a dispensing device with a Viewing window revealing dosage indicia. FIG. 2 is a perspective view of one embodiment of the dispensing device with a portion of the housing cut away. FIG. 3 is a perspective view of one embodiment of the indicator assembly. FIG. 4 is a perspective view of an alternative embodiment of the dispensing device. FIG. 5 is a perspective view of the dispensing device shown in FIG. 4 with a portion of the housing cut away. FIG. 6 is a perspective view of a container, a dispenser housing and one embodiment of an indicator module with a portion of the housing cut away. FIG. 7 is an exploded perspective view of a container, a dispenser housing and one embodiment of the indicator module with a portion of the housing cut away. FIG. 8 is an exploded perspective view of one embodiment of the indicator module. FIG. 9 is an exploded perspective view of the indicator module from the opposite side as shown in FIG. 8. FIG. 10 is an exploded perspective view of a container, and an alternative embodiment of the dispenser housing and the indicator module. FIG. 11 is a perspective view of the alternative embodiment of the indicator module shown in FIG. 10. FIG. 12 is a section cut of a housing and an indicator module mounted therein. FIG. 13 is a top view of one embodiment of the indicator module. FIG. 14 is a rear view of the indicator module shown in FIG. 13. FIG. 15 is a cross-sectional view of the indicator module taken along line 15-15 of FIG. 13. FIG. 16 is a cross-sectional view of the indicator module taken along line 16-16 of FIG. 13. FIG. 17 is a cross-sectional view of the indicator module taken along line 17-17 of FIG. 13. FIG. 18 is a cross-sectional view of the indicator module taken along line 18-18 of FIG. 13. FIG. 19 is a perspective view of an alternative embodiment of the module. FIG. 20 is a cross-sectional view of the indicator module taken along line 20-20 of FIG. 14. FIG. 21 is an exploded view of a container, a key member and an indicator module. FIG. 22 is a top view of the key member. FIG. 23 is a Cross-sectional view of the key member taken along line 23-23 of FIG. 22. FIG. 24 is a perspective view of a container and an alternative embodiment of the indicator module mounted in a dispenser housing with a portion of the housing cut away. FIG. 25 is an exploded perspective view of an alternative embodiment of an indicator module, key member and indicator assembly. FIG. 26 is a top perspective view of a first member of one embodiment of the indicator module housing. FIG. 27 is a bottom perspective view of the member shown in FIG. 26. FIG. 28 is a perspective view of one embodiment of an indicator member. FIG. 29 is an opposite perspective view of the indicator member shown in FIG. 28. FIG. 30 is a top perspective view of a second member of one embodiment of the indicator module with an axle installed therein. FIG. 31 is a perspective view of an actuator member. FIG. 32 is a perspective view of a container with an alternative embodiment of a key member installed thereon positioned above one embodiment of an indicator module. FIG. 33 is a perspective view of an alternative embodiment of the key member. FIG. 34 is an exploded perspective view of an alternative embodiment of a key member being applied to a container. FIG. 35 is a cross-sectional view of an indicator module showing an advancement member of a first indicator member, an engagement member and a second indicator member. FIG. 36 is a cross-sectional view of the advancement member of the first indicator member as it is first engaged by the engagement member in the indicator module housing. FIG. 37 is a cross-sectional view of the advancement member as it is biased by the engagement member into engagement with the second indicator member so as to rotate the second indicator member. FIG. 38 is a cross-sectional view of the advancement member as it is released by the engagement member and disengages from the second indicator member. FIG. 39 is an exploded perspective view of an alternative embodiment of an indicator module and indicator assembly. FIG. 40 is an enlarged side view of an actuator member in a disengaged position adjacent a first indicator member. FIG. 41 is a side view of the actuator member engaging the first indicator member with the non-return being biased outwardly. FIG. 42 is a perspective side view of an alternative embodiment of an indicator member. FIG. 43 is an opposite perspective side view of the indicator member of FIG. 42. FIG. 44 is a cross-sectional view of an advancement member on a first indicator member, a second indicator member and an engagement member. FIG. 45 is a cross-sectional view of the advancement member as it is first engaged by the engagement member. FIG. 46 is a cross-sectional view of the advancement member as it is biased by the engagement member into engagement with the indicator member. FIG. 47 is a cross-sectional view of the advancement member as it is further biased by the engagement member into engagement with the second indicator member. FIG. 48 is a perspective view of an alternative embodiment of an indicator assembly disposed on a lower member of the module housing. DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS Referring to the drawings, and in particular FIGS. 1, 4, 6, 7 and 24, a delivery system, configured as a dispensing device, or dispenser, is shown as including a housing 10, or actuator boot, and a container 100 disposed therein. The housing 10 has a longitudinally extending cavity 12 shaped to receive the container. A top portion of the housing is generally open such that the container can be inserted in the housing through opening 14 and be installed therein with a bottom end 102 of the container protruding from the housing and exposed to the user for actuation. It should be understood that the term “delivery system,” as used herein, is meant to include a system or apparatus for delivering a substance from a container, reservoir, or similar repository, to a user, and includes but is not limited to the disclosed dispensing device, which delivers the substance to the user in the form of an aerosol that is inhaled by the user. The term “dispensing device,” as used herein, is meant to include devices that extrude, spray or otherwise feed out or deliver a substance in convenient units, and includes, but is not limited to, the disclosed inhalation device which delivers metered dosages of a substance in aerosol form for inhalation by the user. The term “longitudinal” as used herein is intended to indicate the direction of the reciprocal movement of the container relative to the housing. The terms “top,” “bottom,” “upwardly” and “downwardly” are intended to indicate directions when viewing the inhalation devices as shown in the Figures, but with the understanding that the container is inverted such that the top surface thereof is located adjacent the bottom of the housing and vice versa. As shown in FIGS. 5, 6 and 7, a cylindrical support block 16 having a well 18 is formed in a bottom portion 22 of the housing. An orifice 20 penetrates the support block to communicate with a bottom portion of the well. A mouthpiece 24, intended for insertion into the mouth of a patient, forms an exhaust port 26 that communicates with the orifice and-well. The mouthpiece 24 extends laterally from the housing so as to facilitate insertion of the mouthpiece into the mouth of the patient. The container 100 is formed as a cylindrical canister 104 having a 106 hub disposed on a top surface 108 thereof. A valve stem 110 extends longitudinally from the hub. The valve stem extends coaxially from the canister and is biased outwardly therefrom by a spring (not shown) mounted within the canister. The container 100 is mounted in the housing by press fitting the valve stem 110 in the well 18 of the support block It should be understood that the container can be configured in a variety of shapes and sizes, and that the substance contained therein can be released by any number of valve systems that are well known in the art. It should also be understood-that the valve system can be actuated by a variety of actuators, including, but not limited-to, various pumps, levers, actuator boots, buttons and the like. In such embodiments, the valve system can be actuated by an actuator moveable relative to the container and housing such that the container remains stationary relative to the housing. In a preferred embodiment, the container 100 is filled with a substance which is dispensed therefrom in specific metered doses by depressing or moving the valve stem 110 from an extended closed position to a depressed open position, which in turn opens the valve or valve system. Preferably the substance is a medicament, although it should be understood that the container could be used to hold a variety of non-medicinal substances, including; but not limited to, various liquids, foams or aerosols that can be delivered by various delivery systems, and/or dispensing devices. A medicament is defined as a substance that can be used in therapy, such as for various therapeutic treatments, including the treatment of diseases (e.g., respiratory ailments) and for the relief of pain, and should be understood to include medicines and medicinal substances in general. A single metered dose is dispensed from the container by each reciprocal, longitudinal movement of the valve stem and attendant opening and dosing of the valve. The medicament is typically delivered to the user, or patient, through their mouth and/or nose in the form of an aerosol, spray or liquid. In operation, the opening of the valve stem and valve is effected by moving the container 100 reciprocally within the housing 10 along a longitudinal axis, defined by the valve stem and the reciprocal movement of the container, by depressing the exposed bottom end 102 of the canister relative to the housing 10 so as to move the valve stem 110 to the open position as it is supported within the well by the support block. Alternatively, an actuator can be moved to open the valve system of the container, which can remain stationary with respect to a supporting housing, a cap and/or an indicating device mounted thereto. For example, the actuator can be attached to the end of the container in the form of a pump device or the like. Referring to FIGS. 5-7, as the valve stem is moved to the open position, the container dispenses a metered dose of the substance in aerosol form through the well 18 and orifice 20 and into the exhaust port. The substance in aerosol form is then transmitted to the user through the exhaust-port of the mouthpiece by way of either a self-generated or assisted airflow. Alternatively, metered doses of liquids and the like can be dispensed from the container. In other delivery systems, which may also include a dispensing device, the housing and holder for the container are attached to a component having a chamber with an output end. Examples of these kinds of delivery systems and dispensing devices are shown for example in U.S. Pat. No. 5,012,803, issued May 7, 1991, and U.S. Pat. 4,460,412, issued Sep. 11, 1984, the entire disclosures of which are hereby incorporated herein by reference. (No license, expressed or implied, is intended to be granted to either of these patents by reason of the incorporation by reference herein.) In these kinds of delivery systems, the component having the chamber can be adapted to receive the mouthpiece of the housing, or it can be integrally connected with a holder supporting the container. In either embodiment, the metered dose of substance, preferably a medicament, in aerosol is first dispensed from the container into the chamber, and thereafter inhaled by the user. In a preferred embodiment, the container 100 is intended to dispense a predetermined number of metered doses of substance. For example, conventional inhaler containers typically hold on the order of 100 to 200 metered doses. In operation, it is important that the user be aware of the number of metered doses remaining in the container such that the user is not caught unaware with an empty canister when in need of the substance, such as a medicament. Now referring to FIGS. 2 and 3, a dispensing device, configured as an aerosol dispenser, is shown as including a housing, a container mounted therein as described above and an indicator assembly. The indicator assembly includes a ratchet gear 32 coaxially mounted with a worm 40 on an axle 42 in a lower portion of the housing. A plurality of teeth 34 are formed about the periphery of the ratchet gear. The teeth 34 are cut or formed with a tapered surface 36 and engagement surface 38. In a preferred embodiment, the ratchet and worm are formed out of a hard durable plastic. It should be understood, however, that other materials such as metal would also work. The ratchet and worm can be made as separate parts, or molded as a single integral member. In a preferred embodiment, the axle 42 and worm 40 define an axis of rotation transverse, or perpendicular, to the longitudinal axis defined-by the valve stem and reciprocal movement of the container relative to the housing. Opposite ends of the axle 42 are rotatably supported in the housing. Also as shown in FIGS. 2 and 3, an indicator member 50 comprises a circular worm gear 52 and indicator wheel 58 coaxially mounted on an axle. In a preferred embodiment, the axle 56 defines an axis of rotation transverse to the axis defined by the worm and also transverse to the longitudinal axis defined by the reciprocal movement of the container relative to the housing. The axle 56 is rotatably supported in the housing. Teeth 54 are formed around the periphery of the worm gear 52 and are shaped to permanently engage the worm 40. As shown in FIG. 2, the indicator wheel 58 has a planar face 60 which is exposed to the patient through a viewing window 28 formed in the housing. The ratchet gear 32, worm 40, worm gear 52 and indicator wheel 58 provide an ideal arrangement for indicating the number of doses remaining in the container, or the number dispensed therefrom. In particular, relatively high reduction ratios are made possible through use of the ratchet, worm and worm gear without the corresponding requirement of providing extremely fine teeth on one or more of the ratchet gear and worm gear. Moreover, the worm and worm gear interface avoids the associated inaccuracies introduced by the mating, and potential skipping, of conventional spur gears having fine teeth. Furthermore, the installation of the indicator member is effected by the installation of a simple axle which can be supported in a plurality of positions and angular orientations within the housing. Importantly, the high reduction ratio realized with the worm 40 allows for the worm gear 52 to have a relatively small diameter, such that it can be easily mounted within small spaces within the housing. Indeed, as shown in FIGS. 6 and 12, the entire indicator assembly can be mounted behind the support block 16 and below the upper surface 17 thereof such that the assembly does not interfere with the dispensing of the medicament from the orifice or with the airflow generated by the patient in administering the medicament. Referring to FIG. 5, an actuator member 70 is configured as a post member 72 moveably supported in the housing along an axis parallel to the longitudinal, axis defined by the reciprocal movement of the container Within the housing. In an alternative embodiment shown in FIGS. 7-9, the post member includes an upper portion 74, a middle portion 76 and a lower portion 78. A resilient arm member 80 extends from the middle portion of the post member and terminates in a tapered hook member 82 shaped to selectively engage one of the ratchet wheel teeth. The middle portion 76 is defined by upper and lower stop surface 84, 86. A spring 88 is disposed about the lower portion 78 of the post member and engages the lower stop surface 86 so as to bias the actuator member upwardly against the top surface 108 of the canister as shown in FIG. 7. Although a compression spring is shown in the Figures, it should be understood that cantilever, torsion, leaf and tension springs, and the like, would also work to bias the actuator member upwardly into engagement with the container. The springs can be made of metal or plastic. In an alternative embodiment, shown in FIGS. 2 and 3, actuator member 90 includes locking ring 92 and a resilient arm member 94 extending longitudinally downwardly therefrom. A longitudinal slit 96 is formed in the locking ring so as to allow for the locking ring 92 to be expanded and disposed around the hub 106 (shown in FIG. 5) of the canister in a snap fit configuration such that the valve stem of the container extends through opening 98 of the locking ring. A distal end of the resilient arm member terminates in a hook member 95 which is shaped to selectively engage the teeth of the ratchet wheel. In the operation of the embodiment shown in FIGS. 6-9, 13-18 and 20, the container is moved longitudinally within the housing so as to depress the valve stem to the open position so as to open the valve as explained above. As the container is moved downwardly within the housing, the actuator member 70 is moved longitudinally downward such that the hook member 82 engages the ratchet wheel and rotates it a predetermined angular amount corresponding to the pitch of the teeth. When the container is released by the user, the spring (not shown) within the container biases the container upwardly within the housing along the longitudinal axis such that the valve stem 110 is moved to the closed position within the container so as to close the valve. As the container moves upwardly, the resilient arm member 80 is biased laterally outward as a tapered end portion of the hook member 82 slides against the tapered surface 36 of one of the ratchet teeth. As the container and resilient arm member reach the top of the stroke, wherein the valve stem is moved completely to the closed position, the resilient arm member 80 returns to its normal straightened configuration as the hook member 82 slips past the tapered surface of one of the teeth so as to be positioned over the engagement surface 38 of that tooth 34 for the next cycle. Alternatively, the operation of the ratchet wheel can be reversed as shown in FIG. 3. In this embodiment, the resilient arm member 94 is biased outwardly by the tapered surface of one of the ratchet gear teeth on the downstroke. At the bottom of the stroke, the hook member 95 slips into an underlying relationship with the engagement surface of the tooth. When the container is released by the user, the spring (not shown) within the canister biases the container upwardly within the housing along the longitudinal axis such that the valve stem is moved to the closed position within the container. As the container moves upwardly with respect to the housing, the resilient arm member 94 moves longitudinally upward such that the hook member 95 engages the engagement surface 38 of one of the teeth and thereby rotates the ratchet wheel an incremental amount. In the embodiment shown in FIGS. 6-9, 13-18 and 20, it is the force of the spring 88 that moves the arm member 80 upwardly so as to return the actuator member in preparation for another cycle. In the alternative embodiment shown in FIGS. 2 and 3, it is the movement of the container, as it is biased upwardly by the internal spring acting on the valve stem, that causes the locking ring 92 and arm member 94 to move upwardly and thereby rotate the ratchet gear. Referring to FIGS. 8 and 17, a resilient non-return member 200 engages the ratchet gear adjacent the hook member so as to ensure that the rotation of the ratchet gear is unidirectional. Alternatively, the non-return member can be positioned to engage the ratchet gear opposite the actuator arm member. The non-return member includes an end portion adapted to engage the engagement surface of the ratchet gear teeth. As the ratchet gear is rotated by the actuator, the non-return member slides along the tapered surface of one of the teeth of the ratchet wheel and does not interfere with the rotation thereof. The rotation of the ratchet gear causes the worm 40 to rotate a desired predetermined amount. It should be understood that the desired amount of rotation is dependent upon the diameter of the ratchet wheel and the number of teeth positioned thereabout. Rotation of the worm, which permanently engages the teeth of the worm gear, causes the worm gear and indicator wheel to rotate a predetermined incremental amount The amount of rotation of the indicator wheel is dependent upon the pitch of the worm, the number of worm threads and the pitch of the worm gear and the number of worm gear teeth. In a preferred embodiment, the worm has a single thread. For ease of manufacturing, it is desirable to provide as coarse a Pitch on each of the ratchet and worm gears as possible, although the gears are still defined as fine-toothed gears. However, it is also intended that the indicator member make only a single revolution (single-cycle) corresponding to a complete evacuation of medicament from the container. Thus, when a large number of doses (on the order of 200 or more) are contained within the canister, it is important for the ratchet, worm and worm gear to provide a relatively high reduction ratio, such that 200 linear reciprocal movements of the actuator member correspond to one or less revolutions of the indicator member. Because the ratchet gear and worm rotate together, it should be understood that the number of teeth on the ratchet gear and worm gear, and the number of threads of the worm, determine the ultimate reduction ratio between the rotation of the ratchet gear and the rotation of the indicator wheel. For example, when the container holds 240 metered doses, an acceptable ratio is realized if the ratchet is made relatively coarse with 10 teeth and the worm gear is provided with 28 teeth. In operation, the dispensing of 10 metered doses will cause the worm to make one complete revolution so as to thereby move the worm gear one tooth. After 240 linear reciprocal movements, the worm gear has been advanced by 24 teeth. Extra teeth are provided so that the starting and ending indicia, indicating a relative fullness or emptiness of the container respectively, are not labeled one on top of the other. In a preferred embodiment, shown in FIGS. 9 and 15, the worm gear 52 has teeth formed around only a portion of its periphery so that a gap is formed between the teeth around the remaining portion of the periphery. In operation, the gears are configured so that the worm 40 disengages from the last tooth of the worm gear as the final prescribed dose of medicament is dispensed. In this position, the indicia on the indicator wheel 58 will indicate to the user that the canister is empty. Therefore, although the user can continue to move the container so as to open the valve, the resultant movement of the actuator 70, ratchet gear 32 and worm will not in turn rotate the indicator member as the gap in the teeth on the worm gear results in the disengagement of the worm and worm gear. In this way, the indicator wheel is prevented from being inadvertently rotated from a full to empty reading and then back again to a full reading, which could confuse the user about the number of doses remaining in the canister. The indicator wheel 58, indicia 66 and viewing window 28 can be arranged in a variety of configurations for viewing by the user. For example, the viewing window 28, 124 can be configured as a rectangular shaped window as shown in FIG. 2 or 10 respectively, as an arcuate shaped window 29 as shown in FIG. 4, wherein approximately ⅓ of the face of the indicator wheel is visible at any time, as a circular shaped window (not shown) or as any other shape allowing the user to view the indicator wheel and the indicia located thereon. In one embodiment, the indicia take the form of a color code, where, for example, a portion of the wheel is colored green to indicate the starting full position, a portion is colored yellow to indicate a medium fullness and a portion is colored red to indicate that the container is empty. Obviously, other colors, shading or alpha-numerical indicia can be provided on the indicator wheel to indicate the relative-fullness or emptiness of the container. In an alternative embodiment, the indicator wheel can be oriented within the housing such that either its planar face or its circumferential surface, with indicia applied thereto, are visible to the user through the exhaust port of the mouthpiece. Referring to FIG. 25, an alternative embodiment of an indicator assembly is shown. The indicator assembly includes three indicator members 550 coaxially mounted on an axle 556 and rotatable thereabout As best shown in FIGS. 28 and 29, each of the indicator members includes an indicator wheel 558 having a circumferential skirt 559 with an outer circumferential surface 560 on which indicia (shown as numbers) are applied, and a ratchet gear 552 coaxially mounted with the indicator wheel. The indicator wheel and ratchet gear have an opening 553 shaped to receive the axle. The ratchet gear 552 includes a plurality of teeth 554 formed around its periphery. The ratchet gear is preferably integrally molded with the indicator wheel, although it should be understood that the gear and wheel can be made separately and thereafter attached one to the other by welding, adhesive and the like. In one embodiment of the indicator member, a resilient advancement member 600 is formed from a portion of the circumferential skirt 559 by providing an elongated cutout 602 in the indicator wheel radially inward from and beneath the skirt. The advancement member 600 includes a laterally extending tooth portion 604 having an engagement surface 606. The three indicator members are coaxially mounted such that the tooth portion 604 of the advancement member of a first indicator member overlies the ratchet gear teeth 554 of the second indicator member, and such that the tooth portion 604 of the advancement member of the second indicator member overlies the ratchet gear teeth 554 of the third indicator member. When only three indicator members are used (as shown in FIG. 25), the third indicator member does not require an advancement member, although for the sake of simplicity in manufacturing, a modular indicator member with the same indicia applied thereto and the same advancement member formed thereon is preferably used for each of the first, second and third indicator members. It should be understood by one of skill in the art that one or more indicator members may be used to provide an indication of dosages used or available, and that the three indicator members shown in the Figures is meant to be illustrative, rather than limiting. In addition, it should be understood that a plurality of indicator Members refers to any number of indicator members greater than one. In an alternative embodiment of the indicator member 650, shown in FIGS. 39, 42 and 43, an advancement member 800 is disposed radially inward from a circumferential skirt 659 and includes a first end 657 connected to a planar side portion or hub 655 of the indicator wheel. The advancement member includes a curved resilient portion 708 having a free end with a tooth portion 704 extending laterally outward therefrom so as to extend laterally from beneath the skirt 659 of the indicator wheel such that it overlies the teeth of the ratchet gear of an adjacent indicator member coaxially mounted therewith as shown in FIG. 48. Indicia, preferably in the form of numbers, are applied to the circumferential surface 660 of the skirt. A ratchet gear 652, having a plurality of teeth 654 is coaxially mounted with the indicator wheel. As shown in FIG. 48, three indicator members are coaxially mounted on axle 656. Referring to FIGS. 25 and 39, an actuator member 570, 670, otherwise referred to as a ratchet member, is shown as having an upper portion 574, 674 extending upwardly from a lower portion 578, 678 and a resilient arm member 580, 680 extending outwardly therefrom and terminating in a resilient hook member 582, .682 shaped to selectively engage at least one of the teeth of the ratchet gear of the first indicator member. A spring 588, 688 is disposed around the lower portion of the actuator member and biases the upper portion 574, 674 of the actuator member into engagement with the container. Referring to FIG. 27, a housing 820 is shown as having a pair of engagement members 770 formed integrally with the housing and including ramped surfaces 772. A plurality of non-return members 900 extend from the housing and selectively engage the ratchet gear to ensure unidirectional rotation of the indicator member as shown in FIGS. 35-38. Although the engagement members and non-return members are shown as being formed in or extending from a module housing, as described below, one of skill in the ad should understand that those members or equivalent features could also be formed in or connected to the dispenser housing or actuator boot that supports the container, or disposed on or connected to the container itself. Referring to FIGS. 25 and 35-38, the operation of the indicator assembly shown in FIG. 25 is generally shown. In particular, the Container is moved longitudinally within the housing 10 so as to depress the valve stem 110 to the open position so as to open the valve as explained above. As the container is moved downwardly within the housing, or downwardly with respect to the module housing described below, the actuator member 570 is moved longitudinally downward such that the hook member 582 is biased outwardly by the ratchet gear 552 on a first outer indicator member. At the bottom of the stroke, the hook member 582 slips into an underlying relationship with the teeth on the ratchet gear. When the container is released by the user, the spring (not shown) within the container biases the container upwardly within the housing along the longitudinal axis such that the valve stem 110 and valve are moved to the closed position within the container. As the container moves upwardly, the resilient arm member 580 moves longitudinally upward such that the hook member 582 rotates the first indicator member a predetermined angular or incremented amount corresponding to the pitch of the teeth disposed around the periphery of the ratchet gear. As the container and resilient arm member reach the top of the stroke, wherein the valve stem and valve are moved completely to the closed position, the resilient arm member 580 is positioned over the ratchet gear for the next cycle. Alternatively, the operation of the actuator member and ratchet gear can be reversed as explained above with respect to the embodiment shown in FIGS. 6-9. Referring to FIGS. 39-41 and 44-48, a plurality of resilient arm members 700 are shown as extending from a module housing so as to be aligned with the ratchet gears on each of the indicator members. The arm members 700 each serve as a combined engagement member and non-return member. In particular, as shown in FIGS. 40 and 41, the arm member 700 functions as a non-return member and includes an end portion that is biased away from the teeth on the ratchet gear as the actuator member, or adjacent indicator member with its advancement member, is actuated to advance the ratchet gear. The operation of the actuator member 670 and ratchet gear is similar to the operation of the ratchet gear shown in FIGS. 6-9 as explained above. The arm member 700 snaps back so that the end portion engages one of the teeth of the ratchet gear so as to ensure that the rotation of the ratchet gear is unidirectional. As shown in FIGS. 44-47, the arm member 700 overlying the ratchet gears of the second and third indicator members also serves as an engagement member that selectively engages the advancement members connected to the indicator members. In operation, the reciprocal movement of the container relative to the housing is repeated until the first indicator member 550, 650, and its ratchet gear, are rotated one complete revolution. The predetermined number of reciprocal movements required to advance the first indicator member one revolution is equal to the number of teeth disposed about the periphery of the ratchet gear 552, 652. As the first indicator member is rotated by successive movements of the container relative to the housing, the advancement member 600, 800 of the first indicator member is brought into selective engagement with the engagement member, configured as the ramped surface 772 formed in the housing or as the upwardly extending arm member 700. In particular, the engagement member 700, 772 biases the tooth portion 604, 704 of the advancement member into engagement with one of the teeth 554, 654 of the ratchet gear on the second indicator member. As the first indicator member is further rotated by successive movements of the container relative to the housing, whether it be the dispenser housing for the container or the module housing described below, the advancement member 600 engages one of the teeth on the ratchet wheel of the adjacent indicator member and advances the indicator member a predetermined incremental angular amount corresponding to the pitch of the ratchet gear teeth. The term incremental is meant to refer to the angular amount the indicator member is moved by the advancement of one actuation, which corresponds to the movement of one tooth, regardless of whether the indicating device is indicating the number of doses left (e.g., counting down) or indicating the number of doses administered (e.g., counting up). As the resilient advancement member 600, 800 clears the engagement member 772, 700, it springs away from the ratchet gear such that further advancements of the first indicator-member do not effect a rotation of the second indicator member until the first
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