magnetic variation

I therefore returned to the camp and helped Dovers take observations for longitude and magnetic variation.

The latitude, chronometric differences of longitude, and magnetic variation, were determined on shore at this southern point.

By an azimuth of the sun's centre taken this morning, the magnetic variation was observed to be about 20 minutes west.

He took the "lay" of the place with a pocket-compass, allowing two seconds for magnetic variation.

The magnetic variation ascertained at this camp was 12 30′ east.