John Henry Dallmeyer (6 September 183030 December 1883), Anglo-German optician, was born at Loxten,

Westphalia Westphalia (; german: Westfalen ; nds, Westfalen ) is a region of northwestern Germany and one of the three historic parts of the state of North Rhine-Westphalia. It has an area of and 7.9 million inhabitants. The territory of the regio ...

, the son of a landowner. On leaving school at the age of sixteen he was apprenticed to an

Osnabrück Osnabrück (; wep, Ossenbrügge; archaic ''Osnaburg'') is a city in the German state of Lower Saxony. It is situated on the river Hase in a valley penned between the Wiehen Hills and the northern tip of the Teutoburg Forest. With a population ...

optician, and in 1851 he came to London, where he obtained work with an optician, W Hewitt, who shortly afterwards, with his workmen, entered the employment of Andrew Ross, a lens and telescope manufacturer. Dallmeyer's position in this workshop appears to have been an unpleasant one, and led him to take, for a time, employment as French and German correspondent for a commercial firm. After a year he was, however, re-engaged by Ross as scientific adviser, and was entrusted with the testing and finishing of the highest class of optical apparatus. This appointment led to his marriage with Ross's second daughter, Hannah, and to the inheritance, at Ross's death (1859), of a third of his employer's large fortune and the telescope manufacturing portion of the business. Turning from astronomical work to the design and making of

photographic lens A camera lens (also known as photographic lens or photographic objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capab ...

es, he introduced improvements in both portrait and landscape lenses, in object-glasses for the

microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisi ...

and in condensers for the optical lantern. An important invention was the Rapid Rectilinear camera objective. In connection with celestial photography he constructed photo-

heliograph A heliograph () is a semaphore system that signals by flashes of sunlight (generally using Morse code) reflected by a mirror. The flashes are produced by momentarily pivoting the mirror, or by interrupting the beam with a shutter. The heliograp ...

s for the Wilna observatory in 1863, for the

Harvard College Observatory The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, United St ...

in 1864, and, in 1873, several for the British government. Dallmeyer's instruments achieved a wide success in Europe and America, taking the highest awards at various international exhibitions. The Russian government gave him the order of St Stanislaus, and the French government made him chevalier of the

Legion of Honour The National Order of the Legion of Honour (french: Ordre national de la Légion d'honneur), formerly the Royal Order of the Legion of Honour ('), is the highest French order of merit, both military and civil. Established in 1802 by Napoleon ...

. He was for many years upon the councils of both the

Royal Astronomical Society (Whatever shines should be observed) , predecessor = , successor = , formation = , founder = , extinction = , merger = , merged = , type = NG ...

and Royal Photographic Society. About 1880 he was advised to give up the personal supervision of his workshops, and to travel for his health, but he died on board ship, off the coast of New Zealand, on 30 December 1883. His second son, Thomas Rudolphus Dallmeyer assumed control of the business on the failure of his father's health.

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* {{DEFAULTSORT:Dallmeyer, John 1830 births 1883 deaths People from Osnabrück (district) Lens designers Lens manufacturers German scientific instrument makers German emigrants to the United Kingdom