The development of the modern electrocardiographic instrument illustrates how medicine, a branch of the bio¬logic sciences, took advantage of the concepts of physical science and its instrumentation. The invention of the electrocardiographic instrument would not have been possible without the notable orchestrated work of engi¬neers, physicists, physiologists, and researchers. Of parti¬cular importance was the development of the string galvanometer by Ader, a French electrical engineer.
Thus, it seems reasonable to give readers the following historical details. The initial work of Galvani (1791), Muller (1856), Waller (1890–1900), and Ader (1897) initiated Einthoven’s discovery from 1901 to 1903. The rather heavy and cumbersome Einthoven machine was too complicated for routine diagnostic use as it occupied two rooms and required five assistants to operate the instrument. Advances that led to the modern electro¬cardiograph required the perseverance of the Cambridge Scientific Instrument Company and the diligent research work of Sir Thomas Lewis, Frank Wilson, Goldberger, and others.
A. Early Timeline
In about 1760 Luigi Galvani observed that an electrical stimulus applied to a motor nerve caused contraction of the associated muscle. In 1856, Muller, who was working on the dissection of live frogs, observed that when a motor nerve to a frog’s leg was laid over the isolated beating heart, the frog’s leg kicked with each heartbeat. In 1887, Waller observed that the heart’s rhythmic electrical stimuli could be monitored from a person’s skin. Waller’s initial work in electrocardiography was conducted at St. Mary’s Hospital in London. He called the tracing obtained with a Lippmann capillary electrometer an electrogram. The instrument was too large to adopt for clinical use and his recordings prior to 1901 were difficult to understand. Einthoven had attended Waller’s first demonstration of the device at St Mary’s hospital and would go on to further the technology.

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