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 John Churchman, late land surveyor for the district of the counties of Delaware and Chester, and for part of Lancaster and Berks, Pennsylvania.
Series: Eighteenth century -- reel 1619, no. 02.
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
Notes: The variation chart was also issued separately and dedicated to George Washington.

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

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

Evans 22406

Microfilm. Woodbridge, CT Research Publications, Inc., 1986. 1 reel ; 35mm. (The Eighteenth Century ; reel 1619, no. 02).