the timer has reached zero and a check with the volume dispensed as determined by feedback sensor 106 indicates that ampoule 40 is empty by lead nut 94 being in the fully extended position motor 82 is automatically reversed the reversing motion translates lead nut 94 tube 98 and piston 102 back to the fully retracted position once feedback sensor 106 indicates the fully retracted position has been reached motor 82 is turned off and the operation cycle is complete at this point needle assembly 26 and ampoule 40 may be removed from the unit and discarded when the unit has been returned to base member 34 data representing the amount of anaesthetic injected is transmitted via contact strips 114 and socket 38 to the processing device operating the patient database by retrieving this information from syringe 10 an accurate patient record can be obtained by providing automatic updating once the data has been retrieved from electronic control means 46 the memory is cleared and syringe 10 is reset and ready for another operating cycle an alternative embodiment in accordance with the present invention is shown in fig3 a 3b and 3c and in these figures like elements to those of the above described embodiment of fig1 a and 2b are indicated with like reference numerals thus with reference to fig3 a an electronic syringe 200 is provided with an elongate housing 204 of varying circular cross section in this embodiment a drive system is used which differs from the one employed in fig1 a and 2b a drive system 242 comprises a combination lead screw 290 and a motor 282 a piston 202 and lead nut 294 lead nut 294 is fixedly attached with the.