René Laënnec, reluctant to press his ear to the chest of a young female patient, finds a solution in the stethoscope

French physicist Augustin Jean Fresnel develops a more efficient form of lens for use in lighthouses

Fox Talbot exposes the first photographic negatives, among them a view looking out through an oriel window in Lacock Abbey

US inventor Samuel Morse gives the first public demonstration, in Philadelphia, of his electric telegraph

Fox Talbot patents the 'calotype', introducing the negative-positive process that becomes standard in photography

Samuel Morse and his assistant Alfred Vail complete the first telegraph line, between New York and Baltimore

The self-contained metal cartridge, with a percussion cap in its base, is patented by a Paris gunsmith named Houiller

English photographer Frederick Scott Archer publishes the details of his collodion process, a marked improvement on the earlier calotype negative

German physicist Hermann von Helmholtz invents the ophthalmoscope, making it possible for a doctor to examine the inside of a patient's eye

The hypodermic syringe with a plunger is simultaneously developed in France and in Scotland

US inventor Elisha Otis dramatically demonstrates his new safety elevator, cutting the rope suspending his platform in New York's Crystal Palace

The Haughwout Store, a five-storey building in New York, instals the first Otis safety elevator

US entrepreneur Cyrus W. Field succeeds in laying a telegraph cable across the Atlantic, but it fails after only a month

German chemist Robert Wilhelm Bunsen and technician Peter Desdega perfect the non-luminous gas burner for use in the laboratory

The invention of barbed wire is patented in the USA by Lucien Smith, designed to fence in cattle but also a protection for the wheat fields of the midwest plains

Swedish chemist Alfred Nobel patents dynamite, making the volatile explosive nitroglycerine safer by combining it with kieselguhr

Italian US immigrant Antonio Meucci files a patent in New York for the invention of the telephone

William Crookes invents the radiometer, in which light causes four vanes to rotate in a bulb containing gas at low pressure

Alexander Graham Bell makes the first practical use of his telephone, summoning his assistant from another room with the words 'Mr Watson, come here. I want to see you.'

The US inventor Thomas Edison opens an experimental laboratory at Menlo Park, New Jersey, calling it his 'invention factory'

Alexander Graham Bell demonstrates his new invention, the telephone, at the US Centennial Exhibition in Philadelphia

The human voice is recorded for the first time when Thomas Edison recites 'Mary had a little lamb' into his newly patented phonograph

English physicist Joseph Swan demonstrates a practical electric light bulb, using an incandescent carbon filament in a vacuum

English physicist Joseph Swan receives a patent for bromide paper, which becomes the standard material for printing photographs

Thomas Edison develops a long-lasting carbon filament light bulb (traditionally 40 hours) and is able to light his Menlo Park laboratory with 30 bulbs