Maps showing magnetic declination on Cook's voyages

Heading: (Cook, James)
Author: Anonymous
Title: Untitled atlas of 8 maps showing the variations of the compass due to magnetic influence on James Cook's second and third voyages
Place Published: [Paris]
Publisher:
Date Published: [c.1785]
Description:

8 folding copper-engraved maps, seven of them bearing the title "Carte des Déclinaisons et Inclinaisons de l'Aiguille Aimantée redigée d'après la table des observations Magnétiques faites par les Voyageurs depuis l'Année 1775." Of these, the maps numbered 1 & 2 form a map of the Atlantic Ocean; map 3 is of the Indian Ocean; and the maps numbered 4, 5, 6 & 7 together comprise a map of the Pacific Ocean - all of these maps include surrounding coasts and land masses. Map 8 is quite large, featuring the northern and southern hemispheres, titled "Carte Magnétique des Deux Hemisphères." (4to) 29x23.5 cm (11½x9¼"), period calf-backed pastepaper boards.

Rare series of maps, presenting information not commonly available. The atlas has been attributed in the past to La Perouse and to Buffon, but Warren Heckrotte was convinced those attributions were not valid, and that the basis of the maps was information gleaned from Cook's voyages.

He comments on the atlas, which he purchased from PBA Galleries in 2002: "The first seven maps show the value of the declination and inclination where measured. The distribution of data follows Cook's tracks from some of his second voyage and all it seems of his third voyage. The world map does not provide an explanation for its title. There is a distribution of small crosses which follow Cook's tracks but not as densely as on the other maps; no explanation for the marks is provided. North and a little west of Hudson Bay there is a note: Ici l'on suppose le P™le Magnetique... This was catalogued under La Perouse (copying Bonham's attribution), but it has nothing to do with La Perouse. The distribution of magnetic data follows Cook's tracks from some of his second voyage and all it seems to me of his third voyage. The navigational data from Cook's third voyage was published by Bayley in 1782; this included magnetic data. As far as I know this atlas is not listed in any bibliography of publications related to Cook, although it is of course not a primary source."
Condition Report: Wear to covers, spine ends chipped; the first six maps detached; a few folds with short splits or small holes, very good overall.