1 Calories Burned For Walking: 4.6 km/h (13 minutes per km). 2  Calories Burned For Walking: 4 km/h (15 minutes per km). 3  Calories Burned For Walking: 3.15 km/h (19 minutes per km).
The first true hypodermic syringe was created by Alexander Wood in 1853. He modified a regular syringe, which at that time was used for treating birthmarks, by adding a needle. He then used this new device for introducing morphine into the skin of patients who suffered from sleeping disorders.
The Chinese were the first to discover and use a primitive form of vaccination, called variolation. It was carried out as early as the 10th century, and particularly between the 14th and 17th centuries. The aim was to prevent smallpox by exposing healthy people to tissue from the scabs caused by the disease.