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His Wellenlehre, published in 1825 jointly with his brother 

 Eduard, is a classic both in physics and physiology. It has been 

 republished in Ostwald's collection Klassiker, etc., by Von Frey (1889). 



It was asserted by Bichat that the pulse is synchronous in all 

 the arteries. Weber showed that this is not so, but that according 

 to the distance from the heart there is a pulse delay of one-sixth 

 to one-seventh of a second. Weber showed the true nature of the 

 pulse wave as " the effect of the oscillation propagated along the 

 coats of the arteries, and in the blood itself, in consequence of 

 the pressure exerted upon the column of blood in the aorta by the 

 heart in its contraction." From the pulse delay he calculated the 

 velocity of propagation of the wave. 



The velocity of the pulse wave was first measured directly by 

 E. H. Weber, although in 1734 Weitbrecht of St. Petersburg had 

 observed that the carotid precedes the radial pulse. Weber, by 

 means of a watch that beat one-third seconds, found that the pulse 

 in the anterior tibial artery was one-sixth to one-seventh of a second 

 later than that in the maxillary. The distance between these two 

 he took as 1*32 metres, and this gave a velocity for the pulse wave 

 of 7'92 to 9 - 24 metres per second. 



The year 1839 is a famous one in the history of physiology, 

 for in March of that year Schwann published his famous Untersuchungen 

 and Schleiden his Beitrdge zur Phylogenesis. The latter occurs in 

 the Midler's Archiv for this year, and in this same volume of the 

 Archiv is Weber's classical paper On the Movement of Lymph 

 Corpuscles in Arteries and the velocity of blood in the capillaries. 

 Poiseuille before this time had described the space in the small 

 arteries that bears his name. Weber and his brother studied the 

 slow rolling movements " of the particles, which had the form of 

 lymph corpuscles," and discusses the peculiarities of the rate and 

 character of their movement. At the end of this communication 

 he describes how in 1837 with his brother Eduard, then prosector 

 in Leipzig, he studied the capillary circulation in a tadpole, " where 

 the circulation is so slow that one can see the corpuscles moving, 

 and compare their velocity with that of the lymph corpuscles at the 

 walls of the vessel." Magnifying the parts 100 times he found the 

 velocity to be ^ P. Lin. per second, " a velocity so slow that if the 

 corpuscles were large enough to be visible, one could scarcely de- 

 tect the movement with the unaided eye." Perhaps some who have 

 looked at the circulation in the web of a frog's foot have hardly 

 realized this fact — 1 inch in 48 seconds for the red, and 1 inch in 

 10 minutes for the lymph corpuscles. He imitated the velocity by 

 mixing two drops of urine with a drop of blood, and observed by 

 means of the microscope the rate of mixture. The movement was 

 so slow as not to be visible to the naked eye. 



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