NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Longitude on the "Pilgrim" 1835 (Dana)
From: Frank Reed CT
Date: 2004 May 9, 16:18 EDT
From: Frank Reed CT
Date: 2004 May 9, 16:18 EDT
You can read the famous account of a voyage at sea "Two Years Before the Mast"
by Richard Henry Dana online here:
http://onlinebooks.library.upenn.edu/webbin/gutbook/lookup?num=2055
There are a number of navigational references in this book that match closely with what I have found in ships' logbooks from this period. The 1830s were the pivotal decade when chronometers became common but still could not be trusted. Lunars were taken when possible, but all other methods of determining longitude were used. Speaking other ships was critical. Sighting known land was critical. And dead reckoning was reasonaby reliable except when storms intervened or after very lengthy periods without access to the other methods.
Here's bit of relevant biographical background on Dana from the introduction:
"After somewhat varied and troublous school days, young Dana entered Harvard University, where he took high rank in his classes and bid fair to make a reputation as a scholar. But at the beginning of his third year of college a severe attack of measles interrupted his course, and so affected his eyes as to preclude, for a time at least, all idea of study. The state of the family finances was not such as to permit of foreign travel in search of health. Accordingly, prompted by necessity and by a youthful love of adventure, he shipped as a common sailor in the brig, Pilgrim, bound for the California coast. His term of service lasted a trifle over two years--from August, 1834, to September, 1836. The undertaking was one calculated to kill or cure. Fortunately it had the latter effect; and, upon returning to his native place, physically vigorous but intellectually starved, he reentered Harvard and worked with such enthusiasm as to graduate in six months with honor."
The first reference to longitude navigation:
"Sunday, June 26th, when, having a fine, clear day, the captain got a lunar observation, as well as his meridian altitude, which made us in lat. 47° 50' S., lon. 113° 49' W.; Cape Horn bearing, according to my calculations, E. S. E. 1/2 E., and distant eighteen hundred miles."
Typically in logbooks from this era, I find that lunars are attempted once every two weeks or so. A little more often earlier in the period and rapidly less often by the later 1840s.
A few weeks later, trouble with the chronometer! They head for the coast of Brazil to get the longitude:
"but I soon found, by the direction of all eyes, that there was land stretching along on our weather beam. We immediately took in studding-sails and hauled our wind, running in for the land. This was done to determine our longitude; for by the captain's chronometer we were in 25° W., but by his observations we were much farther; and he had been for some time in doubt whether it was his chronometer or his sextant which was out of order. This land-fall settled the matter, and the former instrument was condemned, and, becoming still worse, was never afterwards used."
Later they run into a yankee whaler:
"He ran down for us, and answered our hail as the whale-ship New England, of Poughkeepsie, one hundred and twenty days from New York. Our captain gave our name, and added, ninety-two days from Boston. They then had a little conversation about longitude, in which they found that they could not agree."
That's the trouble with getting the longitude from another vessel. It's fine you if you agree, but if you disagree, you need to hear the other guy's evidence and decide whether you can trust him. By the way, those not familiar with the northeast US may want to get out a map and find Poughkeepsie --maybe a little surprising as a homeport for vessels sailing the Pacific.
Dana finds a friend who is also 'before the mast' and is skilled in many scientific arts:
"The principles of the steam-engine, too, he was familiar with, having been several months on board a steamboat, and made himself master of its secrets. He knew every lunar star in both hemispheres, and was a master of the quadrant and sextant. The men said he could take a meridian altitude of the sun from a tar bucket. Such was the man, who, at forty, was still a dog before the mast, at twelve dollars a month."
So he knew all NINE of the lunars stars... <g>
Here's an interesting passage which compares the relative ease of finding another vessel to get longitude compared with the difficulty of getting a lunar in the stormy southern ocean:
"Beside the pleasure of seeing a ship and human beings in so desolate a place, it was important for us to speak a vessel, to learn whether there was ice to the eastward, and to ascertain the longitude; for we had no chronometer, and had been drifting about so long that we had nearly lost our reckoning; and opportunities for lunar observations are not frequent or sure in such a place as Cape Horn."
And a comment on the best possible determination of longitude: a well-mapped point of land:
"The land was the island of Staten Land, just to the eastward of Cape Horn; and a more desolate-looking spot I never wish to set eyes upon [...] Yet, dismal as it was, it was a pleasant sight to us; not only as being the first land we had seen, but because it told us that we had passed the Cape,-- were in the Atlantic,-- and that, with twenty-four hours of this breeze, we might bid defiance to the Southern Ocean. It told us, too, our latitude and longitude better than any observation; and the captain now knew where we were, as well as if we were off the end of Long Wharf."
Frank R
[X] Mystic, Connecticut
[ ] Chicago, Illinois
by Richard Henry Dana online here:
http://onlinebooks.library.upenn.edu/webbin/gutbook/lookup?num=2055
There are a number of navigational references in this book that match closely with what I have found in ships' logbooks from this period. The 1830s were the pivotal decade when chronometers became common but still could not be trusted. Lunars were taken when possible, but all other methods of determining longitude were used. Speaking other ships was critical. Sighting known land was critical. And dead reckoning was reasonaby reliable except when storms intervened or after very lengthy periods without access to the other methods.
Here's bit of relevant biographical background on Dana from the introduction:
"After somewhat varied and troublous school days, young Dana entered Harvard University, where he took high rank in his classes and bid fair to make a reputation as a scholar. But at the beginning of his third year of college a severe attack of measles interrupted his course, and so affected his eyes as to preclude, for a time at least, all idea of study. The state of the family finances was not such as to permit of foreign travel in search of health. Accordingly, prompted by necessity and by a youthful love of adventure, he shipped as a common sailor in the brig, Pilgrim, bound for the California coast. His term of service lasted a trifle over two years--from August, 1834, to September, 1836. The undertaking was one calculated to kill or cure. Fortunately it had the latter effect; and, upon returning to his native place, physically vigorous but intellectually starved, he reentered Harvard and worked with such enthusiasm as to graduate in six months with honor."
The first reference to longitude navigation:
"Sunday, June 26th, when, having a fine, clear day, the captain got a lunar observation, as well as his meridian altitude, which made us in lat. 47° 50' S., lon. 113° 49' W.; Cape Horn bearing, according to my calculations, E. S. E. 1/2 E., and distant eighteen hundred miles."
Typically in logbooks from this era, I find that lunars are attempted once every two weeks or so. A little more often earlier in the period and rapidly less often by the later 1840s.
A few weeks later, trouble with the chronometer! They head for the coast of Brazil to get the longitude:
"but I soon found, by the direction of all eyes, that there was land stretching along on our weather beam. We immediately took in studding-sails and hauled our wind, running in for the land. This was done to determine our longitude; for by the captain's chronometer we were in 25° W., but by his observations we were much farther; and he had been for some time in doubt whether it was his chronometer or his sextant which was out of order. This land-fall settled the matter, and the former instrument was condemned, and, becoming still worse, was never afterwards used."
Later they run into a yankee whaler:
"He ran down for us, and answered our hail as the whale-ship New England, of Poughkeepsie, one hundred and twenty days from New York. Our captain gave our name, and added, ninety-two days from Boston. They then had a little conversation about longitude, in which they found that they could not agree."
That's the trouble with getting the longitude from another vessel. It's fine you if you agree, but if you disagree, you need to hear the other guy's evidence and decide whether you can trust him. By the way, those not familiar with the northeast US may want to get out a map and find Poughkeepsie --maybe a little surprising as a homeport for vessels sailing the Pacific.
Dana finds a friend who is also 'before the mast' and is skilled in many scientific arts:
"The principles of the steam-engine, too, he was familiar with, having been several months on board a steamboat, and made himself master of its secrets. He knew every lunar star in both hemispheres, and was a master of the quadrant and sextant. The men said he could take a meridian altitude of the sun from a tar bucket. Such was the man, who, at forty, was still a dog before the mast, at twelve dollars a month."
So he knew all NINE of the lunars stars... <g>
Here's an interesting passage which compares the relative ease of finding another vessel to get longitude compared with the difficulty of getting a lunar in the stormy southern ocean:
"Beside the pleasure of seeing a ship and human beings in so desolate a place, it was important for us to speak a vessel, to learn whether there was ice to the eastward, and to ascertain the longitude; for we had no chronometer, and had been drifting about so long that we had nearly lost our reckoning; and opportunities for lunar observations are not frequent or sure in such a place as Cape Horn."
And a comment on the best possible determination of longitude: a well-mapped point of land:
"The land was the island of Staten Land, just to the eastward of Cape Horn; and a more desolate-looking spot I never wish to set eyes upon [...] Yet, dismal as it was, it was a pleasant sight to us; not only as being the first land we had seen, but because it told us that we had passed the Cape,-- were in the Atlantic,-- and that, with twenty-four hours of this breeze, we might bid defiance to the Southern Ocean. It told us, too, our latitude and longitude better than any observation; and the captain now knew where we were, as well as if we were off the end of Long Wharf."
Frank R
[X] Mystic, Connecticut
[ ] Chicago, Illinois
