Napoleon Cybulski (1854–1919) was also the founder of world endocrinology and the discoverer of catecholamines. He invented the photohemotachometer (a device with which he was the first in the world to measure and describe the rapidity of blood current in the femoral and carotid arteries) and the microcalorimeter (which made it possible to calculate the minimum amount of heat released during muscle work).