Note sur la vitesse de propagation de l'agent nerveux dans les nerfs rachidiens in Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences, Tome 30, 1850, pp. 204-206

Paris: Gauthier-Villars, 1850. 1st Edition. FIRST EDITION OF AN IMPORTANT NERVE EXPERIMENT BY HELMHOLTZ THAT MARKS THE BEGINNING OF THE FIELD OF ‘NEUROPHYSIOLOGY.' Helmholtz "was the first scientist to make precise measurements of nervous action" (Schmidgen, Origins of Psychophysiological Time Experiments, 1).

"In 1849, while at Konigsberg, Helmholtz measured the speed at which the signal is carried along a nerve fibre. At that time most people believed that nerve signals passed along nerves immeasurably fast. He used a recently dissected sciatic nerve of a frog and the calf muscle to which it attached. He used a galvanometer as a sensitive timing device, attaching a mirror to the needle to reflect a light beam across the room to a scale which gave much greater sensitivity.

"Helmholtz reported transmissions speeds in the range of 24.6 - 38.4 meters per second" (Wikipedia). "Many physiologists had assumed it to be instantaneous, or comparable to the speed of light, but Helmholtz clocked the nervous impulse at less than 100 miles an hour. Clearly the case for regarding animal - and human - nervous systems as scientifically intelligible mechanisms was strong.

"Amongst historians of physiology, it is understood that Hermann von Helmholtz's work on the propagation speed of nervous stimuli constitutes the beginning of a branch of research that, in the following years and decades, became known as 'nerve and muscle physics' and, in more recent times, has been labeled 'neurophysiology'" (Boden, Mind as Machine, 1).

ALSO IN THIS VOLUME: The first edition of Foucault's determination of the velocity of light, here proving that light travels more slowly in water than in air. CONDITION & DETAILS: Complete volume. Ex-libris bearing only a deaccessioned stamp on the back of the title page and slight ghosting at the spine where a spine level has been removed. 4to (11 x 8 inches; 275 x 200mm). [6], 886, [2]. Bound in clean full blue cloth, gilt-lettered at the spine. Solidly and tightly bound. Very occasional toning, otherwise clean and bright throughout.