The year 1870 in science and technology included many events, some of which are listed below.

Ecology

• Introduced rabbits reach the New South Wales border in Australia.

Mathematics

• Felix Klein constructs a model for hyperbolic geometry establishing its self-consistency and the logical independence of Euclid's fifth postulate. (Note: Eugenio Beltrami had previously given such a model in 1868.)

Medicine

• Louis Pasteur and Robert Koch establish the germ theory of disease.

Meteorology

• November 1 - In the United States, the newly-created Weather Bureau (later renamed the National Weather Service) makes its first official meteorological forecast: "High winds at Chicago and Milwaukee... and along the Lakes".

Physics

• Rudolph Clausius proves the scalar virial theorem.

Technology

• February 26 - In New York City, the first pneumatic-subway is opened.
• Collotype black and white photographic process invented.
• The Magic Lantern movie projector is invented by Henry R. Heyl.
• The stock ticker is invented by Thomas Alva Edison.
• First known use of weapons for the anti-aircraft role at Paris during the Franco-Prussian War.

Awards

• Copley Medal: James Joule
• Wolaston Medal for geology: Gerard Paul Deshayes

Births

• March 17 - Horace Donisthorpe (d. 1951), British entomologist.

Deaths

• Charles Xavier Thomas de Colmar, inventor of the first mass-produced calculator