An explanation of the magnetic atlas, or variation chart, hereunto annexed
Subtitle: projected on a plan entirely new, by which the magnetic variation on any part of the globe may be precisely determined, for any time, past, present, or future: and the variation and latitude being accurately known, the longitude is of consequence truly determined.
By: By John Churchman, late land surveyor for the district of the counties of Delaware and Chester, and for part of Lancaster and Berks, Pennsylvania.
Series: Early American imprints -- no. 22406.
Publisher: Printed by James & Johnson, on the north side of Market-Street, between Third and Fourth-Streets.
Published: 1790
Place of publication: Philadelphia
Language: eng
Format: Microform
Number of pages: 46
Subjects: Geomagnetism.
Notes: The chart was also issued separately.

Signatures: [A]⁴ B-F⁴ G².

Subscribers names come to hand."--p. vi-ix.

"Errata."--p. [6].

Evans 22406.

Microfiche. [New York : Readex Microprint, 1985] 11 x 15 cm. (Early American imprints. First series ; no. 22406).