From: NoReply_Robin-Jouan@fer3.com
To: jacksonmcdonald@hotmail.com
Date: Sat, 22 Nov 2014 10:16:03 -0800
Subject: [NavList] Re: L'Hermione en route to America next summer
In France, Lunar Distance method is said to have been introduced on 1759, using a graphical pattern invented by Abbe Lacaille.
I know that J-J. de Lalande described Lunar Distance method and Maskelyne table use in Connaissance_des_Temps of 1774.
Moreover, in France, marine chronometers of Le Roy then of Berthou were qualified through the scientific voyages of Aurore, Isis and Flore frigates (before 1772).
Nethertheless on 1780, Captain de Latouche did not used Lunar distances for Hermione Atlantic crossing. Indeed, neither Lunar Distances, nor marine chronometers !
Captain de Latouche used only dead reckoning and sun meridian latitude. At last, he knew that his longitude was false (due to a problem with his loch or log) and he maintained the latitude of Boston bay during several days. His longitude error was 295 NM when arriving at Cape Ann !
It was much better during the Hermione return voyage on 1782.
By the way, a contribution will be published about Hermione and Latouche navigation in "Navigation" IFN (Institut Francais de Navigation), N°246, T1 2015.
As for me, I proposed to new-Hermione French Association to do some celestial navigation on-board. But I was not accepted (because too much old !).
New-Hermione has every modern navigation instruments on board. No doubt about that.
Yves Robin-Jouan
