NavList:

I'm attaching an image of a page from the log of the Ship Friendship en route from Salem, Massachusetts to India taken at the Peabody Essex Museum. There are a couple of ships' logs on display, that of the Friendship from 1797 and another from 1824 approaching Cape Horn on the way to Valparaiso, Chile. The latter contains sketches of Staten Island (named by the Dutch) and the New Year Islands (named by Captain Cook) and now known as Isla de los Estados. None of the viewable pages record a longitude by observation although there are placeholders for it. The 1824 log does have an entry longitude by dead reckoning "LongR 62.45" Both logbooks have entries recording the Variation which seems to have been diligently observed. 

From the Friendship log entry of Dec. 8 1797 it's possible to get a rough idea the position.  "Latt by Meridian Alt 39°20'S" is recorded. The last recorded Variation I read as "by sun evening azimuth 27°24'W". This presumably means that they were measuring the Sun's azimuth at sunset and a reading quoted to 1 minute accuracy must have been using something like a an azimuth compass https://en.wikipedia.org/wiki/Azimuth_compass . The variation in 1797 can be found from the website https://www.ncei.noaa.gov/maps/historical-declination/ which as recently discussed on Navlist in a thread starting here https://navlist.net/Longitude-compass-variation-FrankReed-jun-2025-g57399 then places them around longitude 24d 30'E. This position is to the south of the Cape of Good Hope. At this location the lines of constant variation, orthogones, ran almost north-south in this region so it was ideal for finding longitude.

Other things to note are:

•  the full moon was on Dec. 4 so it's not an ideal time for lunar distances if that's what they were using.
•  the log records Course and Winds using the full set of 32 compass points, Entries "SEbE", "NWbW" and "NWbW" can be seen. The first entry for Dec. 9. is strange. Can anyone make sense of it?

Robin Stuart

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