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is a sensitive fast-responding measuring instrument that uses a single fine filament of wire suspended in a strong magnetic field to measure small currents. In use, a strong light source is used to illuminate the fine filament, and the optical system magnifies the movement of the filament allowing it
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to detect pulses of electric current, which could be observed and transcribed into a message. The speed at which pulses could be detected by the galvanometer was limited by its mechanical inertia, and by the inductance of the multi-turn coil used in the instrument. Clément Adair, a French engineer,
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described the science background and potential utility of a string galvanometer, stating "Mr. Adair as already built an instrument with a wires stretched between poles of a magnet. It was a telegraph receiver." Einthoven developed a sensitive form of string galvanomter that allowed photographic
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Patients are seated with both arms and left leg in separate buckets of saline solution. These buckets act as electrodes to conduct the current from the skin's surface to the filament. The three points of electrode contact on these limbs produces what is known as
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recording of the impulses associated with the heartbeat. He was a leader in applying the string galvanometer to physiology and medicine, leading to today's electrocardiography. Einthoven was awarded the 1924
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Augustus Waller had discovered electrical activity from the heart and produced the first electrocardiogram in 1887. But his equipment was slow. Physiologists worked to find a better instrument. In 1901,
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book in 1902. The first human electrocardiogram was recorded in 1887; however, it was not until 1901 that a quantifiable result was obtained from the string galvanometer. In 1908, the physicians
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filament of a few centimeters length (see picture on the right) and negligible mass that conducted the electrical currents from the heart. This filament was acted upon by powerful
252:'Willem Einthoven and the Birth of Clinical Electrocardiography a Hundred Years Ago', S. Serge Barold, Cardiac Electrophysiology Review, Springer Netherlands January 2003
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to provide the conductive pathway for the current. By tightening or loosening the filament it is possible to very accurately regulate the sensitivity of the galvanometer.
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The filament was originally made by drawing out a filament of glass from a crucible of molten glass. To produce a sufficiently thin and long filament an
223:'Einthoven's String GalvanometerThe First Electrocardiograph', Moises Rivera-Ruiz et al, Tex. Heart Inst. J. © 2008 by the Texas Heart Institute
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positioned either side of it, which caused sideways displacement of the filament in proportion to the current carried due to the
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The original machine required water cooling for the powerful electromagnets, required 5 operators and weighed some 600 lb.
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was shot across the room so that it dragged the filament from the molten glass. The filament so produced was then coated with
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to measure the heart’s electrical activity, but this device was unable to produce results of a diagnostic level.
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described the dynamic properties of an instrument that could measure the wave shape of an electrical impulse, an
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in the early 20th century, publishing the first registration of its use to record an electrocardiogram in a
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to be observed or recorded by photography. The principle of the string galvanometer remained in use for
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teamed to become the first of their profession to apply electrocardiography in medical diagnosis.
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replaced the coil with a much faster wire or "string" producing the first string galvanometer.
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An early commercial ECG machine, built in 1911 by the
Cambridge Scientific Instrument Company
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For most telegraphic purposes it was sufficient to detect the existence of a pulse. In 1892
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Previous to the string galvanometer, scientists were using a machine called the capillary
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until the advent of electronic vacuum-tube amplifiers in the 1920s.
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Submarine cable telegraph systems of the late 19th century used a
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Einthoven's galvanometer consisted of a silver-coated
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Instruments of
Science: An Historical Encyclopdedia
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37:History
138:silver
119:quartz
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134:arrow
289:NIH
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