Description
The phonic wheel was used as a time marker for the electrocardiographic machine. The small electric motor carries disc with five projecting pieces that are evenly spaced round the edge. There are two brass terminals to provide the electric current. By the early 1920s, the Cambridge Standard Electrocardiograph had become an established clinicial tool; however, demands on the use of the machine forced designers to modify the instrument. There were three problems in particular: the instrument was sensitive to vibrations (though this was later disproven), considerable skill and training was required for the successful operation of the machine, and lastly, the instrument was extremely heavy. In order create a more mobile apparatus for use in hospital wards, a trolley-mounted version of the Standard was developed. The instrument’s success as a diagnostic tool eventually led to the re-design of electrocardiograph as a portable instrument that could be carried by a medical practitioner.

08/07/2014
Created by: Allison Ksiazkiewicz on 08/07/2014