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pre-1775 refracting telescopes

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Day, John, 1743 c.20
Coll. Willach

Photo

photo - whole telescope

Basic Info

Maker: Day, John

Year: 1743 c.20

Year Range: -

Year Notes:

Manufacturing Location: England

Signature: I.DAY

Signature Notes:

Inscriptions:

No stand present.

Collection: Coll. Willach

Accession #: RW ??? [1781] [2013 19] [2023]

Sources:

Project investigation

Public Notes:

One of John Day's only surviving telescopes. Three lens eyepiece with missing objective.

Length (open):

Length (closed):

F-ratio:

Exit pupil:

Object status:

Optical Basics

Objective type: unconfirmed

Optical style

Physical style

Functional style

Materials: pasteboard, gold tooling, glass, wood, vellum

Optical/Lab Data

Drawtube data:

Drawtube notes:

Objective Data

Eyepieces

Notes:

Additional Photos/Documents

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Dioptrice is made possible by the generous support of the National Science Foundation, the National Endowment for the Humanities, the Program in the History and Philosophy of Science at the University of Notre Dame, and the Adler Planetarium & Astronomy Museum.

+ Include in full text search:	Maker Manufacturing Location Description Signature Accession Public notes
+ Look for Blank Fields:	Maker Signature Year Manufacturing Location Inscriptions Provenance Drawtube Notes Public Notes Private Notes Objective Focal Length Eyepiece Focal Length Objective Notes Eyepiece Notes Magnification
+ Look for Non-Blank Fields:	Maker Signature Year Manufacturing Location Inscriptions Provenance Drawtube Notes Public Notes Private Notes Objective Focal Length Eyepiece Focal Length Objective Notes Eyepiece Notes Magnification
+ Year range:	1600 - 2014
+ Focal length range (mm):	0 - 2000
+ Free aperture range (mm):	0 - 2000
+ Full aperture range (mm):	1600 - 2014
+ Open length range (mm):	0 - 2000
+ Closed length range (mm):	0 - 2000
+ Categories:	Art Collection Book or Manuscript Instrument Collection
+ Materials:	organics bamboo black ivory bone boxwood ebony fish skin horn ivory lacquer leather lignum vitae mahogany paper parchment pasteboard rayskin shagreen sharkskin tortoiseshell vellum wood metal brass copper gilt gold leaf gold tooling iron platinum tooling silver silver tooling unknown glass glass rock crystal speculum other marble paint stone
+ Collection:
+ Objective type:	(all refractors) (all reflectors) (clear selection) N/A cassegrain doublet (crown forward) doublet (flint forward) doublet (unknown) gregorian herschelian newtonian singlet triplet unconfirmed unknown reflector

organics

metal

glass

other

Objective Data

Eyepieces