Traces of the Development of Science and Technology(2) In 1837,telegraph,postage stamp In 1839,bicycle,hydrogen fuel cell. In 1846,anesthesia for tooth extraction. In 1850 dishwasher In 1861,elevator ÷ln1862,plastic Traces of the Development of Science and Technology(2) ❖ In 1837, telegraph , postage stamp ❖ In 1839 , bicycle, hydrogen fuel cell. ❖ In 1846 , anesthesia for tooth extraction. ❖ In 1850 , dishwasher ❖ In 1861 , elevator ❖ In 1862, plastic