Glass Plate Photomicrographs Produced from a Nobert Test Plate

Description:

Friedrich Adolph Nobert (1806-1881), a scientific instrument maker in Barth on the southern Baltic coast, began his career as a watchmaker. By 1845 he had devised a small circular dividing engine for ruling closely spaced lines on glass. Nobert used his engine to produce test plates, microscope slides used to find the resolution of microscopes. Indeed, some of his test plates had rulings beyond the limit of optical resolution, although Nobert did not know this.

In 1867, F. A. P. Barnard, president of Columbia University in New York, acquired an example of a Nobert test plate with nineteen bands, in which the lines of the first band were 1/1000, those of the second band 1/1500, and those of the third band 1/2000 of a Paris line apart. The divisions decreased in this pattern, with the lines of the 19th band being 1/10000 of a Paris line apart.

Nobert’s work attracted the attention of J. J. Woodward, an assistant surgeon and lieutenant colonel in the United States Army. In 1868 Woodward arranged to have photographs made of the different bands of a Nobert grating viewed through a microscope. Dr. E. Curtis of the Army Medical Museum made the observations. Woodward concluded that the lines seen using the sixteenth, seventeenth, eighteenth and nineteenth bands were spurious.

In 1869 Woodward received another nineteen-band test plate made on different principles. Curtis was able to resolve these bands. The four glass plate microphotographs are based on this work. Two photographs show the nineteenth band resolved into fifty-seven lines. One has the label: ARMY MEDICAL MUSEUM (/) NOBERT’S TEST PLATE (/) Showing the 19th band resolved into 57 lines 2850. It also is tagged: 85950. The second microphotograph is marked on a label: ARMY MEDICAL MUSEUM (/) NOBERT’S TEST PLATE 3618 (/) Showing the 19th band resolved into 57 lines. The third is marked on a label: ARMY MEDICAL MUSEUM (/) NOBERT’S TEST PLATE 3617 (/) Showing the 16th, 17th, 18th and 19th bands resolved (/) into respectively 48, 51, 54 and 57 lines. Four bands in the photograph are labeled, one 16, one 17, one 18, and one 19. A tag on the fourth photograph reads: 285950. This number also is stamped on the tape around the glass.

For a related object, see MA.322303.

References:

J. J. Woodward, “Remarks on the nineteen-band Test-plate of Nobert,” American Journal of Science, November 1868, 46, pp. 352-354.

J. J. Woodward, “Additional remarks on the Nineteen-band Test-plate of Nobert,” American Journal of Science, September 1869, 48, pp. 169-172.

C. N. Brown, “Diffraction Gratings: Part 1. Origins and Early Use,” Bulleting of the Scientific Instrument Society, June 2015, no. 125, pp. 14-21.

G. L'E. Turner, "The Woodward Photomicrographs of Nobert's Nineteen-Band Test Plate," Journal of the Quekett Microscopical Club, 29, November 1964, pp. 289-295. The materials described are related to but not the same as these glass plate photomicrographs.

Location: Currently not on view

Subject: MathematicsRuling and Dividing Engines

Subject:

See more items in: Medicine and Science: Mathematics

Exhibition:

Exhibition Location:

Credit Line: Transfer from National Bureau of Standards

Data Source: National Museum of American History

Id Number: MA.322471Catalog Number: 322471Accession Number: 247805

Object Name: glass plate photomicrographs, group of

Physical Description: glass (overall material)tape (edges materail)paper (labels material)Measurements: overall: 4.5 cm x 21.5 cm x 11.5 cm; 1 25/32 in x 8 15/32 in x 4 17/32 insingle plate: .5 cm x 8.7 cm x 17.8 cm; 3/16 in x 3 7/16 in x 7 in

Guid: http://n2t.net/ark:/65665/ng49ca746b2-484a-704b-e053-15f76fa0b4fa

Record Id: nmah_1802316

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