Lunar Distance (navigation) - USS Peacock

USS Peacock

In 1832, Edmund Roberts was sent aboard the U. S. sloop-of-war Peacock, which had to thread the Sunda Strait by dead reckoning when her chronometers proved useless. Roberts does not say where or how the crew began to use the lunar-distance method, but after departing Canton City, makes reference to lunar observations upon arriving at Siam, notes that Muscat naval officers practise the lunar observations, and possess excellent chronometers, and advises, "...what I have stated, will serve to show the absolute necessity of having firstrate chronometers, or the lunar observations carefully attended to; and never omitted to be taken when practicable.