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B. E. van der Bildt Telescope
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40048
A Reflecting Telescope by B. E. van der Bildt:
Dutch ca. 1805. A Gregorian reflecting telescope signed in script on the eye-piece plate: B. E. van der Bildt. This was Bauke Eisma van der Bildt (II) (1). He was born in Franeker, Netherlands on 4 October 1753, and died there on 24 April 1831. He was the son of the merchant and distiller Bauke Eisma van der Bildt (I) and his wife Renske. He apprenticed to his grandfather Jan van der Bildt (1709-1791), the famous telescope maker of Franeker, in watchmaking, lens grinding, and manufacturing all sorts of optical instruments. In 1787 he moved to Amsterdam, and settled in Buiksloot. There he perfected the production of concave and convex lenses ab inito, through methods of his own development. In 1806 he was appointed professor of physics and astronomy at Franeker University. He held this position until his death in 1831.
Examples of B.E. van der Bildt's telescopes can be found in the Museum Boerhaave, the University Museum in Utrecht and in the Louwman Collection of Historic Telescopes in the Hague. Unlike his grandfather, whose telescopes were signed with “Franeker,” the present instrument is unsigned with respect to its location of manufacture. The telescope may have been manufactured between 1787-1806, the years he moved from, and then returned to Franeker.
The telescope is complete with its original dust cap, eyepiece lenses, and altazimuth tripod mount. The tripod mount is engineered with a precision, fully lateral articulating azimuth movement (360°), with a separate altitude mechanism. The lateral azimuth mechanism is lockable via a knurled thumb screw, and is then finely adjustable by a separate knurled thumb screw. The altitude control is by rackwork on a semi-circular mount, moveable by a threaded rod and control knob. This part of the mechanism is also lockable by an independent, knurled thumb screw.
The optical tube is 4 in. in diameter and 25 in. in length. The eyepiece adds an additional 4.5 in., and is complete with a removable solar filter for sun viewing. The exterior of the main optical tube is mounted with a short refracting telescope, with dust shades, fore and aft, functioning as a range finder for gross location of objects. Focusing of the main telescope is by movement of the secondary mirror by way of a finely threaded rod. A small section of the rod is located on the right side, with the remainder housed internally, leading to the platform mount for the secondary mirror. The entire interior of the main optical tube is blackened, in the classical way, to preclude aberrant light reflection.
Condition:
The condition is very fine throughout, and fully operational. Remarkably, the original dust cap is present. The instrument is of high precision, heavy, and with good stability, making it an ideal telescope for an Antiquarian Library setting. The important, large primary and secondary speculum mirrors are in excellent original condition. Suprisingly, the telescope provides amazing images with strong magnification and clarity.
Bibliography:
1. The New Dutch Biographical Dictionary (NNBW). (Nieuw Nederlandsch Biografisch Woordenboek) 2. Konst, Algemeene (1810) Letterbode, II, 25. 3. van Nieuwenhuis, G. Appendix to the Dictionary of Arts Science, I, 431; nature wordb. XIII, 794. 4. de Crane JW, Biogr. Contributions, 105-111. 5. Boeles, WBS Frieslands Hoogeschool and the Rijks Atheaeum in Franeker, I, 422.
Dutch ca. 1805. A Gregorian reflecting telescope signed in script on the eye-piece plate: B. E. van der Bildt. This was Bauke Eisma van der Bildt (II) (1). He was born in Franeker, Netherlands on 4 October 1753, and died there on 24 April 1831. He was the son of the merchant and distiller Bauke Eisma van der Bildt (I) and his wife Renske. He apprenticed to his grandfather Jan van der Bildt (1709-1791), the famous telescope maker of Franeker, in watchmaking, lens grinding, and manufacturing all sorts of optical instruments. In 1787 he moved to Amsterdam, and settled in Buiksloot. There he perfected the production of concave and convex lenses ab inito, through methods of his own development. In 1806 he was appointed professor of physics and astronomy at Franeker University. He held this position until his death in 1831.
Examples of B.E. van der Bildt's telescopes can be found in the Museum Boerhaave, the University Museum in Utrecht and in the Louwman Collection of Historic Telescopes in the Hague. Unlike his grandfather, whose telescopes were signed with “Franeker,” the present instrument is unsigned with respect to its location of manufacture. The telescope may have been manufactured between 1787-1806, the years he moved from, and then returned to Franeker.
The telescope is complete with its original dust cap, eyepiece lenses, and altazimuth tripod mount. The tripod mount is engineered with a precision, fully lateral articulating azimuth movement (360°), with a separate altitude mechanism. The lateral azimuth mechanism is lockable via a knurled thumb screw, and is then finely adjustable by a separate knurled thumb screw. The altitude control is by rackwork on a semi-circular mount, moveable by a threaded rod and control knob. This part of the mechanism is also lockable by an independent, knurled thumb screw.
The optical tube is 4 in. in diameter and 25 in. in length. The eyepiece adds an additional 4.5 in., and is complete with a removable solar filter for sun viewing. The exterior of the main optical tube is mounted with a short refracting telescope, with dust shades, fore and aft, functioning as a range finder for gross location of objects. Focusing of the main telescope is by movement of the secondary mirror by way of a finely threaded rod. A small section of the rod is located on the right side, with the remainder housed internally, leading to the platform mount for the secondary mirror. The entire interior of the main optical tube is blackened, in the classical way, to preclude aberrant light reflection.
Condition:
The condition is very fine throughout, and fully operational. Remarkably, the original dust cap is present. The instrument is of high precision, heavy, and with good stability, making it an ideal telescope for an Antiquarian Library setting. The important, large primary and secondary speculum mirrors are in excellent original condition. Suprisingly, the telescope provides amazing images with strong magnification and clarity.
Bibliography:
1. The New Dutch Biographical Dictionary (NNBW). (Nieuw Nederlandsch Biografisch Woordenboek) 2. Konst, Algemeene (1810) Letterbode, II, 25. 3. van Nieuwenhuis, G. Appendix to the Dictionary of Arts Science, I, 431; nature wordb. XIII, 794. 4. de Crane JW, Biogr. Contributions, 105-111. 5. Boeles, WBS Frieslands Hoogeschool and the Rijks Atheaeum in Franeker, I, 422.
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