| 1. | In 1765, he introduced an astronomical instrument fitted with two achromatic lenses.
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| 2. | This lens had the largest aperture of its day for an achromatic lens.
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| 3. | Had he done so, he would almost certainly have invented the achromatic lens.
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| 4. | He suggested using two achromatic lenses of " six inches focus " placed apart.
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| 5. | The 1955 model came with a meniscus lens, later replaced with an achromatic lens.
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| 6. | It is a refractor with double achromatic lenses of 40 cm diameter and has 5m focal length.
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| 7. | The difficulties of fabricating two disks of optical glass required to make a large achromatic lens were formidable.
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| 8. | Achromatic lenses are corrected to bring two wavelengths ( typically red and blue ) into focus in the same plane.
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| 9. | The glass blanks were ground and polished into a 12-inch achromatic lens by Brashear & Co in 1920.
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| 10. | Malcolm used an original design incorporating achromatic lenses like those used in telescopes, and improved the windage and elevation adjustments.
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