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George Adams Library Telescope
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40087
A Fine George Adams Library Telescope:
English ca. 1780. A Gregorian reflecting telescope (See Historical Section.) signed in script: “G. Adams, Mathematical Instrument Maker to his Majesty Fleet Street London” on the eye-piece tube. This was George Adams Jr. (b 1750, w 1772, d 1795) who took over the business from his father George Adams Sr in 1774, on Fleet Street in London (1,2). His father (w 1734 d 1772) was appointed as instrument maker to King George III in 1760, and the title transferred to his son and the Adams workshop upon his death in 1774. Dating of the instrument is post 1760 since “Maker to his Majesty” is included in the legend. Instruments without this notation are putatively assigned a manufacture date prior to 1760. The 2.75 inch (6.98 cm) diameter telescope is equipped with an externally applied brass focusing rod for the secondary mirror, a dust cap and a neutral density eye-piece filter for sun viewing. The 14 inch main barrel stands on a folding tripod base and is detachable via two wing nuts affixed to a full 360° laterally, articulating mechanism with knurled brass altitude knob. The upright is further removable from the folding tri-form feet to reveal a large screw for anchoring into wood, in the absence of a flat surface. An almost identical telescope, signed by Benjamin Martin, is illustrated in Scientific Instruments by Harriet Wynter and Anthony Turner, Fig. 240 (3). Historical: The Gregorian telescope is a type of reflecting telescope named after the Scottish mathematician and astronomer James Gregory whose design appeared in his 1663 publication Optica Promota (The Advance of Optics). Similar theoretical designs have been found in the writings of Bonaventura Cavalieri (Lo Specchio Ustorio (On Burning Mirrors), 1632) and Marin Mersenne (l"Harmonie Universalle, 1636). Gregory's early attempts to build the telescope failed, since he had no practical skill himself and he could find no optician capable of actually constructing one. It was not until ten years after Gregory's publication, aided by the interest of experimental scientist Robert Hooke, that a working instrument was created in 1673. The design pre-dates the first practical reflecting telescope, the Newtonian telescope, built by Sir Isaac Newton in 1668, and was not successfully built until 5 years after Newton's first reflecting telescope.
The Gregorian telescope consists of two concave mirrors; the primary mirror (a concave paraboloid) collects the light and brings it into focus before the secondary mirror (a concave ellipsoid) then reflects it back through a hole in the center of the primary, and thence out of the bottom end of the instrument where it can be viewed with the aid of the eyepiece (Fig. 1). The Gregorian design solved the problem of viewing the image in a reflector by allowing the observer to stand behind the primary mirror. This design of telescope renders an upright image, making it useful for general terrestrial observations. Unknown at the time, the Gregorian design also functions as a telephoto, in that the optical tube is much shorter than the system's actual focal length.
English ca. 1780. A Gregorian reflecting telescope (See Historical Section.) signed in script: “G. Adams, Mathematical Instrument Maker to his Majesty Fleet Street London” on the eye-piece tube. This was George Adams Jr. (b 1750, w 1772, d 1795) who took over the business from his father George Adams Sr in 1774, on Fleet Street in London (1,2). His father (w 1734 d 1772) was appointed as instrument maker to King George III in 1760, and the title transferred to his son and the Adams workshop upon his death in 1774. Dating of the instrument is post 1760 since “Maker to his Majesty” is included in the legend. Instruments without this notation are putatively assigned a manufacture date prior to 1760. The 2.75 inch (6.98 cm) diameter telescope is equipped with an externally applied brass focusing rod for the secondary mirror, a dust cap and a neutral density eye-piece filter for sun viewing. The 14 inch main barrel stands on a folding tripod base and is detachable via two wing nuts affixed to a full 360° laterally, articulating mechanism with knurled brass altitude knob. The upright is further removable from the folding tri-form feet to reveal a large screw for anchoring into wood, in the absence of a flat surface. An almost identical telescope, signed by Benjamin Martin, is illustrated in Scientific Instruments by Harriet Wynter and Anthony Turner, Fig. 240 (3). Historical: The Gregorian telescope is a type of reflecting telescope named after the Scottish mathematician and astronomer James Gregory whose design appeared in his 1663 publication Optica Promota (The Advance of Optics). Similar theoretical designs have been found in the writings of Bonaventura Cavalieri (Lo Specchio Ustorio (On Burning Mirrors), 1632) and Marin Mersenne (l"Harmonie Universalle, 1636). Gregory's early attempts to build the telescope failed, since he had no practical skill himself and he could find no optician capable of actually constructing one. It was not until ten years after Gregory's publication, aided by the interest of experimental scientist Robert Hooke, that a working instrument was created in 1673. The design pre-dates the first practical reflecting telescope, the Newtonian telescope, built by Sir Isaac Newton in 1668, and was not successfully built until 5 years after Newton's first reflecting telescope.
The Gregorian telescope consists of two concave mirrors; the primary mirror (a concave paraboloid) collects the light and brings it into focus before the secondary mirror (a concave ellipsoid) then reflects it back through a hole in the center of the primary, and thence out of the bottom end of the instrument where it can be viewed with the aid of the eyepiece (Fig. 1). The Gregorian design solved the problem of viewing the image in a reflector by allowing the observer to stand behind the primary mirror. This design of telescope renders an upright image, making it useful for general terrestrial observations. Unknown at the time, the Gregorian design also functions as a telephoto, in that the optical tube is much shorter than the system's actual focal length.
Fig. 1: Light processing in the Gregorian Telescope.
Condition:
The condition is extremely fine throughout with complete original lacquer coverage. Very high quality, heavy, precision instrument. It is substantially impressive to display, quite eye-pleasing, and is rarely found in such fine condition. The optical system is excellent and composed of primary and secondary speculum mirrors, in fine condition, which produce clear, and erect images. A late 18th century aesthetic and technological masterpiece.
The Adams Family of Instrument Makers:
George Adams, senior and his two sons, George, junior and Dudley, were prominent instrument makers in London for over 80 years (2). All three, in turn, held the post of Mathematical Instrument Maker to the King. All three wrote and published books on scientific subjects, especially scientific instruments. George (I) was born in London in 1709 and after his apprenticeship set up an instrument making business in 1734. He had five children by his first wife and nine more by his second. The East India Company purchased instruments from him and he was also the official supplier of instruments to the Ordnance Department. He sold a full range of scientific instruments including globes, orreries, microscopes, telescopes, sectors, quadrants, and ring dials, etc. To supply the demand he employed several apprentices including his son George (II).
In 1857 a disastrous fire destroyed most of the business but while it took the better part of a year, he was able to reestablish it. In addition to the instrument making business he authored works on microscopy (1746) and on globes (1766) among others. His Micrographia Illustrata secured a permanent place in the history of the microscope and many of his books went through multiple editions.
Not one to shirk his civic duties, Adams was also the senior churchwarden for St. Brides church. This was a much more important and responsible position than it appears as he had to manage funds equivalent to a half-million pounds per year for the caring of the poor, sick, and elderly of the parish.In 1757 he became instrument maker for the Prince of Wales. When the prince ascended the throne as King George III in 1760, George Adams was appointed instrument maker to the king, a position he held until his death. Several of the instruments in the magnificent George III collection on display at the Science Museum in London were made by him.
When George (I) died in 1772 his wife Ann and son George (II) managed the business for a couple of years after which George (II) took it over. He, too, became official supplier of instruments to the Ordnance Department. This was a lucrative appointment since it came at the time of the American War of Independence. This created a need for a large number of instruments such as gunners quadrants, theodolites, sextants, compasses, telescopes, and others It was estimated that he needed at least ten workmen to supply the Ordnance Department orders alone. One of his apprentices was his 14-year-old brother Dudley.
George (II) made a wide range of instruments including optical, surveying, navigational, astronomical, meteorological, hydraulic, mechanical, electrical, magnetic and pneumatic instruments as well as instruments for drawing. He supplied a large order to Martinus van Marum of Haarlem in Holland. Most of these instruments are now on display at the Tyler Museum and are described in a 1973 book by Gerard L.’E. Turner. Like his father, George (II) authored many books. His two-volume work Essays on the Microscope (1787) was dedicated to the king. The second volume consisted of a set of large and elaborate engraved plates showing microscopes, accessories, and specimens. His Astronomical and Geographical Essays (1789) ran through six editions in England and two in the United States. His successors continued to publish his books even after his death in 1795. His wife Hannah Adams ran the business for most of a year following his death, but in 1796 the remaining stock of instruments and tools was sold at auction.
Dudley Adams (1762-1830) did not take over his brother’s business, but instead set up his own shop at Charing Cross. He, too, obtained the Ordnance Department business and employed some twenty employees during the Napoleonic Wars. He had several patents including a type of spectacles that could be adjusted to fit the wearer. He made telescopes and in 1800 patented a method of making telescopic drawtubes rigid when extended. This made it possible to make telescopes as long as three feet with multiple draw tubes so that they could be folded down to a size to fit in the pocket.For a while he did well in business and was able to purchase an estate in Nutting Grove, about 18 miles from London. However, the social upheaval following the war led to the bankruptcy of his business in 1817. That he was by then living beyond his means was undoubtedly a contributing factor. His assets, including the Nutting Grove estate, his furniture, tools, library, and stock were all sold in a series of auctions. Thus ended the continuity of the Adams family in the instrument business after over 80 years. To earn a living, Dudley then went into medical applications of electricity and called himself a "Professional Medico-Electrician. In 1820 he wrote a book on the subject and treated patients although at that time most physicians were highly skeptical of the efficacy of treatments using electrical instruments. About that time Dudley’s mental and physical health began to deteriorate and he died in 1830.
Bibliography:
1. Clifton, Gloria (1995) Directory of British Scientific Instrument Makers 1550-1851; IBSN [0 302 00634 6] p. 2.
2. Millburn, John R. (2000) Adams of Fleet Street, Instrument Makers to King George III; Aldershot: Ashgate Publishing Ltd.
3. Wynter, Harriet; Turner, Anthony (1975) Scientific Instruments; IBSN [0289704030]; Studio Vista.
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