John Dollond


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Dollond, John

 

Born June 10, 1706; died Nov. 30, 1761. English optician.

In 1758, Dollond received a patent to produce achromatic objectives for telescopes. The first achromatic objectives were made in England as early as 1733, but they were highly imperfect. Dollond, who at first shared Newton’s opinion that it was impossible to make achromatic objectives, began to study the question in the light of L. Euler’s theory. After lengthy experiments he found a successful combination of lenses with good achromatic properties (a converging [positive] lens of crownglass and a diverging [negative] lens of flintglass). Dollond’s telescopes rapidly became popular.

WORKS

“An Account of Some Experiments Concerning the Different Refrangibility of Light.” Philosophical Transactions of the Royal Society, 1758, vol. 50.
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The telescopes of optician John Dollond were among the best available at the time, and Messier quickly turned this one back to the new comet.
He was joined by his father John Dollond in 1752 and early customers included King George III and the Duke of York.
Hall did not publicize his lens properly, and John Dollond (1706-1761), who prepared an achromatic lens in 1757, often gets the credit.
Achromatic doublet lenses were not invented until the early 18th century, and the first patent for one was issued to John Dollond only around 1758.