An ammeter wired in parallel rather than in series would fail to work because current must:

1. Meter placement follows from the quantity being measured. 2. Voltmeters are connected in parallel with the device measured. 3. Ammeters are connected in series with whatever device's current is to be measured. 4. Series connection puts the meter directly in the current path. 5. So the current must pass through the ammeter for it to read correctly. _Source: OpenStax College Physics for AP Courses 2e (CC BY 4.0), Ch 21 'Circuits and DC Instruments', sections 21.1-21.6_