Vierordt was the first to devise an exact method of enumerating the red blood corpuscles. See also his later paper: Zählungen der Blutkörperchen des Menschen, in the same volume, pp. 326-31.

Vierordt invented a sphygmograph which acted on the principle that indirect estimation of blood-pressure could be accomplished by measuring the counter-pressure necessary to obliterate the arterial pulsation. This was the first instrument with which a tracing of the human pulse could be made. The paper is the first record of a study with an instrument of precision of the pulse in health and disease. Vierordt expanded this work into book form: Die Lehre von Arterienpuls, Braunschweig, Vieweg, 1855.

Vierordt estimated, by means of a “hemotachometer” of his own invention, the rate of the blood flow in various arteries, and also the influence of the blood volume, pulse rate and respiratory rate upon it.

Vierordt’s spectral analyses of hemoglobin, bile and urine were of great value. He studied the variations in the spectrum of oxyhemoglobin produced by different dilutions of this substance and was thus able to estimate the hemoglobin content of the blood.