Metering device for use in transferring a desired volumetric dose of a flowable substance from a storage container

An inhaler for delivering a substance in a finely divided form, said inhaler comprising:

• air intake means by which air is able to be drawn into said inhaler from the atmosphere;
• an inhalation passage communicating with said air intake means, through which said inhalation passage air is able to be drawn using said air intake means;
• a receptacle having inner walls in combination with a metering device located within said receptacle having a first end element and a second end element sealing against the inner walls of said receptacle for defining an intermediate dosing space loaded with a desired volumetric dose of a substance, said metering device and said receptacle being dimensioned so that said metering device has a tendency to remain in said receptacle unless actively urged out of said receptacle;
• indexing means operable for moving said receptacle into a position in, or adjacent to, said inhalation passage;
• and,
• means for urging said metering device, at least partially, out of said receptacle for releasing the dose of the substance contained in said receptacle into said inhalation passage when said receptacle occupies its position in, or adjacent to, said inhalation passage.