Analysis of information sources in references of the Wikipedia article "Navigation" in English language version.
{{cite web}}: CS1 maint: archived copy as title (link)Nautical Almanac 1849-1851.
Chronometers were not regularly supplied to the Royal Navy until about 1825
...what I have stated, will serve to show the absolute necessity of having first rate chronometers, or the lunar observations carefully attended to; and never omitted to be taken when practicable.
{{cite web}}: CS1 maint: archived copy as title (link)