John Dollond
Encyclopedia
John Dollond was an English
optician
, known for his successful optics business and his patenting and commercialization of achromatic doublet
s.
Dollond was the son of a Huguenot
refugee, a silk
-weaver at Spitalfields
, London
, where he was born. He followed his father's trade, but found time to acquire a knowledge of Latin
, Greek
, mathematics
, physics
, anatomy
and other subjects. In 1752 he abandoned silk-weaving and joined his eldest son, Peter Dollond
(1730–1820), who in 1750 had started in business as a maker of optical instruments; this business is now Dollond & Aitchison
. His reputation grew rapidly, and in 1761 he was appointed optician to the king.
In 1758 he published an "Account of some experiments concerning the different refrangibility of light" (Phil. Trans.
, 1758), describing the experiments that led him to the achievement with which his name is specially associated, the discovery of a means of constructing achromatic lens
es by the combination of crown
and flint glass
es, which reduces chromatic aberration
(color defects). Leonhard Euler
in 1747 had suggested that achromatism might be obtained by the combination of glass and water lenses. Relying on statements made by Sir Isaac Newton
, Dollond disputed this possibility (Phil. Trans., 1753), but subsequently, after the Swedish
physicist, Samuel Klingenstierna
(1698–1765), had pointed out that Newton's law of dispersion did not harmonize with certain observed facts, he began experiments to settle the question.
Early in 1757 he succeeded in producing refraction without colour by the aid of glass and water lenses, and a few months later he made a successful attempt to get the same result by a combination of glasses of different qualities (see History of telescopes
). For this achievement the Royal Society
awarded him the Copley Medal
in 1758, and three years later elected him one of its fellows. Dollond also published two papers on apparatus for measuring small angles (Phil. Trans., 1753, 1754).
. However, it is well known that he was not the first to make achromatic lenses. Optician George Bass
, following the instructions of Chester Moore Hall
, made and sold such lenses as early as 1733. In the late 1750s, Bass told Dollond about Hall's design; Dollond saw the potential and was able to reproduce them.
Dollond appears to have known of the prior work and refrained from enforcing his patent. After his death, his son, Peter, did take action to enforce the patent. A number of his competitors, including Bass, Benjamin Martin, Robert Rew and Jesse Ramsden
, took action. Dollond's patent was upheld, as the court found that the patent was valid due to Dollond's exploitation of the invention while prior inventors did not. Several of the opticians were ruined by the expense of the legal proceedings and closed their shops as a result. The patent remained valid until it expired in 1772. Following the expiry of the patent, the price of achromatic doublets in England dropped in half. More details on this invention are in History of the telescope.
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
optician
Optician
An optician is a person who is trained to fill prescriptions for eye correction in the field of medicine, also known as a dispensing optician or optician, dispensing...
, known for his successful optics business and his patenting and commercialization of achromatic doublet
Achromatic lens
An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths into focus in the same plane....
s.
Biography
Huguenot
The Huguenots were members of the Protestant Reformed Church of France during the 16th and 17th centuries. Since the 17th century, people who formerly would have been called Huguenots have instead simply been called French Protestants, a title suggested by their German co-religionists, the...
refugee, a silk
Silk
Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...
-weaver at Spitalfields
Spitalfields
Spitalfields is a former parish in the borough of Tower Hamlets, in the East End of London, near to Liverpool Street station and Brick Lane. The area straddles Commercial Street and is home to many markets, including the historic Old Spitalfields Market, founded in the 17th century, Sunday...
, London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
, where he was born. He followed his father's trade, but found time to acquire a knowledge of Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
, Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
, mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
, physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
, anatomy
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
and other subjects. In 1752 he abandoned silk-weaving and joined his eldest son, Peter Dollond
Peter Dollond
Peter Dollond was an English maker of optical instruments, the son of John Dollond. He is known for his successful optics business, and for the invention of the apochromat.-Biography:...
(1730–1820), who in 1750 had started in business as a maker of optical instruments; this business is now Dollond & Aitchison
Dollond & Aitchison
Dollond & Aitchison are one of the oldest opticians in the United Kingdom, having been established in 1750.- History :On 21 April, 1750, Peter Dollond opened a small optical business in Vine Street, near Hatton Garden in London. He was joined by his father John Dollond in 1752. The Dollonds became...
. His reputation grew rapidly, and in 1761 he was appointed optician to the king.
In 1758 he published an "Account of some experiments concerning the different refrangibility of light" (Phil. Trans.
Philosophical Transactions of the Royal Society
The Philosophical Transactions of the Royal Society is a scientific journal published by the Royal Society of London. It was established in 1665, making it the first journal in the world exclusively devoted to science, and it has remained in continuous publication ever since, making it the world's...
, 1758), describing the experiments that led him to the achievement with which his name is specially associated, the discovery of a means of constructing achromatic lens
Achromatic lens
An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths into focus in the same plane....
es by the combination of crown
Crown glass (optics)
Crown glass is type of optical glass used in lenses and other optical components. It has relatively low refractive index and low dispersion...
and flint glass
Flint glass
Flint glass is optical glass that has relatively high refractive index and low Abbe number. Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00...
es, which reduces chromatic aberration
Chromatic aberration
In optics, chromatic aberration is a type of distortion in which there is a failure of a lens to focus all colors to the same convergence point. It occurs because lenses have a different refractive index for different wavelengths of light...
(color defects). Leonhard Euler
Leonhard Euler
Leonhard Euler was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion...
in 1747 had suggested that achromatism might be obtained by the combination of glass and water lenses. Relying on statements made by Sir Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
, Dollond disputed this possibility (Phil. Trans., 1753), but subsequently, after the Swedish
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
physicist, Samuel Klingenstierna
Samuel Klingenstierna
Samuel Klingenstierna was a very renowned Swedish mathematician and scientist. He started his career as a lawyer but soon moved to natural philosophy. He was the first to enunciate errors in Newton's theories of refraction, geometrical notes that were used by John Dollond in his experiments...
(1698–1765), had pointed out that Newton's law of dispersion did not harmonize with certain observed facts, he began experiments to settle the question.
Early in 1757 he succeeded in producing refraction without colour by the aid of glass and water lenses, and a few months later he made a successful attempt to get the same result by a combination of glasses of different qualities (see History of telescopes
History of telescopes
The earliest known working telescopes appeared in 1608 and are credited to Hans Lippershey. Among many others who claimed to have made the discovery were Zacharias Janssen, a spectacle-maker in Middelburg, and Jacob Metius of Alkmaar. The design of these early refracting telescopes consisted of a...
). For this achievement the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
awarded him the Copley Medal
Copley Medal
The Copley Medal is an award given by the Royal Society of London for "outstanding achievements in research in any branch of science, and alternates between the physical sciences and the biological sciences"...
in 1758, and three years later elected him one of its fellows. Dollond also published two papers on apparatus for measuring small angles (Phil. Trans., 1753, 1754).
Priority of invention
John Dollond was the first person to patent the achromatic doubletDoublet (lens)
In optics, a doublet is a type of lens made up of two simple lenses paired together. Such an arrangement allows more optical surfaces, thicknesses, and formulations, especially as the space between lenses may be considered an "element." With additional degrees of freedom, optical designers have...
. However, it is well known that he was not the first to make achromatic lenses. Optician George Bass
George Bass (optician)
George Bass was an optician known to have made an achromatic doublet around 1733.The instructions for the constructions were given by Chester Moore Hall. According to Hoyle, Hall wished to keep his work on the achromatic lenses a secret and contracted the manufacture of the crown and flint lenses...
, following the instructions of Chester Moore Hall
Chester Moore Hall
Chester Moore Hall was a British lawyer and inventor who produced the first achromatic lenses in 1729 or 1733 ....
, made and sold such lenses as early as 1733. In the late 1750s, Bass told Dollond about Hall's design; Dollond saw the potential and was able to reproduce them.
Dollond appears to have known of the prior work and refrained from enforcing his patent. After his death, his son, Peter, did take action to enforce the patent. A number of his competitors, including Bass, Benjamin Martin, Robert Rew and Jesse Ramsden
Jesse Ramsden
Jesse Ramsden FRSE was an English astronomical and scientific instrument maker.Ramsden was born at Salterhebble, Halifax, West Riding of Yorkshire, England. After serving his apprenticeship with a cloth-worker in Halifax, he went in 1755 to London, where in 1758 he was apprenticed to a...
, took action. Dollond's patent was upheld, as the court found that the patent was valid due to Dollond's exploitation of the invention while prior inventors did not. Several of the opticians were ruined by the expense of the legal proceedings and closed their shops as a result. The patent remained valid until it expired in 1772. Following the expiry of the patent, the price of achromatic doublets in England dropped in half. More details on this invention are in History of the telescope.