What was the most important invention for humanity in the late 19th century?

Answer 1

Well, "Electricity" wasn't really invented, was it? Nor was it even first experimented with in the 19th century. But important methods of generating and distributing it were.
You could also make an argument for the telephone, motion pictures or the phonograph - methods of converting sound, images and thoughts into electrical signals for transmission or storage, all had huge impact on modern society.

Answer 2

Adhesives Tape and cellophane tape - 1903 Richard drew Air bags - 1950's Ball factor pens - 1938 ladislo Biro Fly swatter - 1905, Dr. Samuel J. Crumbine plane - 1903 via Orville and Wilbur wright Aluminum foil - 1910 Jacuzzi - 1968 Roy jacuzzi Band-help - 1920 Earle Dickson Answering gadget - 1935 willy Muller Novocain - 1905 Alfred einkorn Parking meter - 1932 Carl magee Cotton swabs - 1923 Leo Gerstenzang Lip stick - 1949 hazel bishop Silicone ear plug - 1962 ray and Cecilia benner Bubble gum - 1906 frank fleer man made hearts - date decrease back to 1950's ,Dr. Paul Winchell Lie detector/polygraph attempt- 1921 john Larson Bar codes - 1952 electric powered blanket - 1936 Pacemaker - 1950 john hopps Liquid cleansing soap -1980

Answer 3

Antiseptics

Answer 4

Gotta go with electric power, seeing where we are now. It permitted computing, the Internet, refrigeration (and therefore huge changes in agriculture, land occupancy, and trade), modern medicine, elevators (and therefore skyscrapers), and a whole lot more.

Answer 5

Electricity.

Answer 6

Light bulbs, the internal combustion engine, and self contained bullet cartridges. And bicycles. And cotten candy.

Answer 7

All cheap means of communication, including postal services, telephone, printing press, telegraph, railway, automobile, and radio signal.

Answer 8

transfusion of blood