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.
In 1929, the first dental specialty board, the American Board of Orthodontics, was born. On a side note, the first synthetic (nylon)-bristle toothbrush was invented in 1938. Around this time, stainless steel became widely available, but using it for braces was considered somewhat controversial.