NASTY SANDY CHURNING UP THE COAST

Yes. That's what Cassini 'invented'.

No. He was invited by Louis XIV to built an observatory. He was the official astronomer/astrologer to Louis XIV.

He only worked on the maps for two years - continued by his son Jacques Cassini and eventually finished by his grandson César-François Cassini de Thury in 1789/1793, 80 years after his death.

All this is interesting however none of it change the fact that the romans demanded that they move their city from the coast and they refused to do so ending in them being wipe off the face of the earth.

... and they wanted to burn down the city with the homes of some 700,000 inhabitants.

A strange assertion that is wrong both historically and in terms of the orbital mechanics involved.. Actually the accurate determination of longitude was first enabled by the development of accurate timepieces. The trajectories of the principal first magnitude stars were well known and measured long before the details of the orbits of the moons of Jupiter were known. Measurement of the aximuth and height (over the horizon) of such stars is vastly easier and more accurate than measurements of the orbital details of the moons of Jupiter.

That's true; the UK had a contest to develop the most accurate time pieces to measure longitude. Those time pieces now sits at the museum in Greenwich.

Wrong wrong wrong as the method to determine the longitude by the moons of Jupiter predate the HI clock by a large amount of time HOWEVER the Jupiter method was not practical from ship board and other methods such as using the earth moon position or creating very very very accurate time pieces was then attempted.

The mathematic of the earth moon position method was far too hairy to be use on shipboard and the results was the the H1 time piece follow by in the end the far smaller H3 time piece solve the problem except for the large cost of such time pieces.

It was some decades after the first such time pieces that they became cheap enough for merchant ships to carry them on a routine basic.

On my next visit to England I am planning on going to see the H1, H2 and H3 clocks.

george said "ACCURATE"Cassini/Miraldi method was merely a computed approximation that was almost impossible to calculate from a ship unless it were tied up .

Sorry but the moons of Jupiter was the first practice method of finding longitude on land and the h1 time piece did the same for ship calculations of longitude.

The moons of Jupiter positions in relationship to each other was just another way of getting a time hack in relationship to Paris and his comments concerning stars positions would not had allow such a time hack.

All this is a matter of history that can be look up in any book on the subject so it get annoying when people are playing games over known facts of history.

Though H4 isn't running ( it requires oil for lubrication and will degrade as it runs), it's on display in Greenwich as well. H5 is shown at the Clockmakers' Museum in the Guildhall.

The main word in all my statements was practice means not a possible means of finding longitude. The H1 prove that time pieces could be the practice means of finding longitude at sea and the moons of Jupiter did the same for finding the shore longitudes.


http://en.wikipedia.org/wiki/History_of_longitude

Proposed methods of determining timeThe first publication of a method of determining time by observing the position of the Earth's moon was by Johannes Werner in his In hoc opere haec continentur Nova translatio primi libri geographiae Cl. Ptolomaei, published at Nürnberg in 1514. The method was discussed in detail by Petrus Apianus in his Cosmographicus liber (Landshut 1524).

It appears that Johannes Werner inspired by Amerigo Vespucci's letter written in 1502 where he wrote: ". . . I maintain that I learned [my longitude] . . . by the eclipses and conjunctions of the Moon with the planets; and I have lost many nights of sleep in reconciling my calculations with the precepts of those sages who have devised the manuals and written of the movements, conjunctions, aspects, and eclipses of the two luminaries and of the wandering stars, such as the wise King Don Alfonso in his Tables, Johannes Regiomontanus in his Almanac, and Blanchinus, and the Rabbi Zacuto in his almanac, which is perpetual; and these were composed in different meridians: King Don Alfonso's book in the meridian of Toledo, and Johannes Regiomontanus's in that of Ferrara, and the other two in that of Salamanca."2 The best "clock" to use for reference, is the stars. In the roughly 27.3 solar days of a lunar orbit, the Moon moves a full 360 degrees around the sky, returning to its old position among the stars. This is 13 degrees per day, or just over 0.5 degree per hour. So, while the rotation of the Earth causes the stars and the Moon to appear to move from east to west across the night sky, the Moon, because of its own orbit around the Earth, fights back against this apparent motion, and seems to move eastward (or retrograde) by about 0.5 degree per hour. In other words, the Moon "moves" west only 11.5 degrees per hour."

[edit] Galileo's proposal — Jovian moonsIn 1612, having determined the orbital periods of Jupiter's four brightest satellites (Io, Europa, Ganymede and Callisto), Galileo proposed that with sufficiently accurate knowledge of their orbits one could use their positions as a universal clock, which would make possible the determination of longitude. He worked on this problem from time to time during the remainder of his life.

To be successful, this method required the observation of the moons from the deck of a moving ship. To this end, Galileo proposed the celatone, a device in the form of a helmet with a telescope mounted so as to accommodate the motion of the observer on the ship.[6] This was later replaced with the idea of a pair of nested hemispheric shells separated by a bath of oil. This would provide a platform that would allow the observer to remain stationary as the ship rolled beneath him, in the manner of a gimballed platform. To provide for the determination of time from the observed moons' positions, a Jovilabe was offered — this was an analogue computer that calculated time from the positions and that got its name from its similarities to an astrolabe.[7] The practical problems were severe and the method was never used at sea. However, it was used for longitude determination on land.

[edit] Halley's proposals — lunar occultations and appulses, magnetic deviationAround 1683, Edmund Halley proposed using a telescope to observe the time of occultations or appulses of a star by the moon as a means of determining time while at sea.[8] He had accumulated observations of the moon's position and of certain stars to this end, and had deduced the means of correcting errors in predictions of the moon's position.

Upon succeeding John Flamsteed in the post of Astronomer Royal, Halley had undertaken the task of observing both stellar positions and the path of the moon, with the intention of supplementing existing knowledge and advancing his proposal for determining longitude at sea.[8] By this time, he had abandoned the use of occultations in preference for appulses exclusively. No reason was given by Halley for abandoning occultations, however, there are few bright stars occulted by the moon and the task of documenting the dim stars' positions and training navigators to recognize them would be daunting. Appulses with brighter stars would be more practical.

While he had tested the method at sea, it was never widely used or considered as a viable method. His observations did contribute to the lunar distance method.

Halley also hoped that careful observations of magnetic deviations could provide a determination of longitude. The magnetic field of the Earth was not well understood at the time. Mariners had observed that magnetic north deviated from geographic north in many locations. Halley and others hoped that the pattern of deviation, if consistent, could be used to determine longitude. If the measured deviation matched that recorded on a chart, the position would be known. Halley used his voyages on the pink Paramour to study the magnetic variance and was able to provide maps showing the halleyan or isogonic lines. This method was eventually to fail as the localized variations from general magnetic trends make the method unreliable.

[edit] Maskelyne's proposal — lunar distance methodFor details on the use of the lunar distance method, see Method of lunar distances.
The first publication of a method of determining time by observing the position of the Earth's moon was by Johannes Werner in his In hoc opere haec continentur Nova translatio primi libri geographiae Cl. Ptolomaei, published at Nürnberg in 1514. The method was discussed in detail by Petrus Apianus in his Cosmographicus liber (Landshut 1524).

A Frenchman, the Sieur de St. Pierre, brought the technique to the attention of King Charles II of England in 1674.[9] Being enthusiastic for the proposed technique, the king contacted his royal commissioners, who included Robert Hooke. They in turn consulted the astronomer John Flamsteed. Flamsteed supported the feasibility of the method but lamented the lack of detailed knowledge of the stellar positions and the moon's movement. King Charles responded by accepting Flamsteed's suggestion of the establishment of an observatory and appointed Flamsteed as the first Astronomer Royal. With the creation of the Royal Observatory, Greenwich and a program for measuring the positions of the stars with high precision, the process of developing a working method of lunar distances was under way.[10] To further the astronomers' ability to predict the moon's motion, Isaac Newton's theory of gravitation could be applied to the motion of the moon.

Tobias Mayer, the German astronomer, had been working on the lunar distance method in order to determine accurately positions on land. He had corresponded with Leonhard Euler, who contributed information and equations to describe the motions of the moon.[11] With these studies, Mayer had produced a set of tables predicting the position of the Moon more accurately than ever before. These were sent to the Board of Longitude for evaluation and consideration for the Longitude Prize. With these tables and after his own experiments at sea trying out the lunar distance method, Nevil Maskelyne proposed annual publication of lunar distance predictions in an official nautical almanac for the purpose of finding longitude at sea to within half a degree.

Being very enthusiastic for the lunar distance method, Maskelyne and his team of human computers worked feverishly through the year 1766, preparing tables for the new Nautical Almanac and Astronomical Ephemeris. Published first with data for the year 1767, it included daily tables of the positions of the Sun, Moon, and planets and other astronomical data, as well as tables of lunar distances giving the distance of the Moon from the Sun and nine stars suitable for lunar observations (ten stars for the first few years).[12] [13] This publication later became the standard almanac for mariners worldwide, and since it was based on the Royal Observatory, it led to the international adoption of Greenwich Mean Time as an international standard.

[edit] Harrison's proposal — marine chronometerMain articles: John Harrison and Marine chronometer

Chronometer of Jeremy Thacker.Another proposed solution was to use a mechanical timepiece, to be carried on a ship, that would maintain the correct time at a reference location. The concept of using a clock can be attributed to Gemma Frisius. Attempts had been made on land using pendulum clocks, with some success. In particular, Huygens had made accurate pendulum clocks that made it possible to determine longitude on land. He also proposed the use of a balance spring to regulate clocks. There is some dispute as to whether he or Robert Hooke first proposed this idea.[14] However, many, including Isaac Newton, were pessimistic that a clock of the required accuracy could ever be developed. At that time, there were no clocks that could maintain accurate time while being subjected to the conditions of a moving ship. The rolling, pitching and yawing, coupled with the pounding of wind and waves, would knock existing clocks out of the correct time.

In spite of this pessimism, a group felt that the answer lay in chronometry -- developing an improved time piece that would work even on extended voyages at sea. A suitable timepiece was eventually built by John Harrison, a Yorkshire carpenter, with his marine chronometer; that timepiece was later known as H-4.

Harrison built five, two of which were tested at sea. His first, H-1, was not tested under the conditions that were required by the Board of Longitude. Instead, the Admiralty required that it travel to Lisbon and back. It performed excellently, but the perfectionist in Harrison prevented him from sending it on the required trial to the West Indies. He instead embarked on the construction of H-2. This chronometer never went to sea, and was immediately followed by H-3. Still not satisfied with his own work, Harrison produced H-4, which did get its sea trial and satisfied all the requirements for the Longitude Prize. However, he was not awarded the prize and was forced to fight for his reward.

Though the British Parliament rewarded John Harrison for his marine chronometer in 1773, his chronometers were not to become standard. Chronometers such as those by Thomas Earnshaw were suitable for general nautical use by the end of the 18th century. However, they remained very expensive and the lunar distance method continued to be used for some decades.

[edit] Lunars or chronometers?The lunar distance method was initially labour intensive because of the time-consuming complexity of the calculations for the Moon's position. Early trials of the method could involve four hours of effort.[10] However, the publication of the Nautical Almanac starting in 1767 provided tables of pre-calculated distances of the Moon from various celestial objects at three-hour intervals for every day of the year, making the process practical by reducing the time for calculations to less than 30 minutes and as little as ten minutes with some efficient tabular methods.[15] Lunar distances were widely used at sea from 1767 to about 1850.

Between 1800 and 1850 (earlier in British and French navigation practice, later in American, Russian, and other maritime countries), affordable, reliable marine chronometers became available, replacing the method of lunars as soon as they reached the market in large numbers. It became possible to buy two or more relatively inexpensive chronometers, serving as checks on each other, rather than acquiring a single (and expensive) sextant of sufficient quality for lunar distance navigation.[16]

By 1850, the vast majority of ocean-going navigators worldwide had ceased using the method of lunar distances. Nonetheless, expert navigators continued to learn lunars as late as 1905, though for most this was a textbook exercise since they were a requirement for certain licenses. They also continued in use in land exploration and mapping where chronometers could not be kept secure in harsh conditions. The British Nautical Almanac published lunar distance tables until 1906 and the instructions until 1924.[17] Such tables last appeared in the 1912 USNO Nautical Almanac, though an appendix explaining how to generate single values of lunar distances was published as late as the early 1930s.[13] The presence of lunar distance tables in these publications until the early 20th century does not imply common usage until that time period but was simply a necessity due to a few remaining (soon to be obsolete) licensing requirements. The development of wireless telegraph time signals in the early 20th century, used in combination with marine chronometers, put a final end to the use of lunar distance tables.

[edit] Modern solutions

Seems like good thinking to me. (Pilkey, a few pages back)

yes indeed. Its especially an issue for the winter season storms like this NorEaster were going to have. The equilibrium sand pile will be worn further and further inland and beaches (already considered engineered "infrastructure" will need to be replaced several times this next year. Thats a shame cause the first beach nourishment projects will all be wasterby seasonal erosion.
Sand in the stream, is replenished naturally by long shore drift during the late spring and summer, and be eroded during the fall and winter storms.

Theres a cute little book about the Crown;s search for a means to accurately determine Longitude, the name of the book was ,ahem, LONGITUDE

I've read a cute little book which said that 18 people helped george "in the ancient art of celestial navigation"

Nonsense. The measurement of the azimuth and height of the well tabulated orbits of the principal stars was the FIRST technique used to estimate both latitude and longitude of both fixed positions on land and of the estimated positions of ships at sea. The sensitivity of the measurements of the relative positions of the moons of Jupiter was far greater and less accurate. An accurate measurement of the local time was a necessary component of BOTH techniques.

As several others here have already noted, considerable effort was required to produce a clock with small (and predictable) errors that would function reliably on the always moving deck of a ship (or boat) at sea. That was a necessary element for the accurate determination of both Latitude and Longitude, though using Polaris mate the sensitivity of the Latitude measurementto clock time almost negligible.

Probably more than that, Walter.

Interestingly, now, in the age of GPS, the art of celestial navigation or even position finding ashore, is fast dissappearing. I date myself by noting that I even had to learn how to quickly and accurately get a celestial fix, in an aircraft, using a periscope sextant and abbreviated celestial tables for the favored stars. The big challenges there were doing it in the confined space of a cockpit; high cloud cover; and accurately locating the target star in the very small periscope field of view. Dropping your pencil in the dark cockpit, while holding the control stick with your knees didn't help either.

I can't even imagine that. I've used a sextant on dry land and it was hard enough as it is!

Cycloptichorn

This is always a fascinating subject to me. Latitude has not been a problem for experienced navigators, and that's been true for literally thousands of years. It didn't even require an instrument as sophisticated as an astrolabe, either. The Norse used a notched stick. In 985, Bjarni Herjolfsson left Iceland to sail to Greenland--apparently his father, Herjolf Bardsson, had left him sailing directions. He was caught in a Nor'easter shortly after leaving Iceland, and was driven to the southwest for days. When the storm finally blew out, he was locked in a fog, so he hove to. (Mariners until quite recently in history would heave to at night or in a fog, weather allowing, because they could't find longitude.) When the fog cleared, he bagn pulling west (he wouldn't put up the sail until he knew where land was). He finally sighted land, roughly, at the Avalon Peninsula of Newfoundland. He began sailing north northwest, coasting up Newfoundland, and then Labrador. When he reached Cape Chidley at the northern end of Labrador, his notched stick told him that was his latitude. He turned east, and not only made landfall in Greenland, he sailed into Herjolfsness, and beached his ship at his father's steading.

Being wrong could be lethal, too. La Salle had been to the mouth of the Mississippi, but didn't know the longitude, nor had a means of finding it. He set off to find it from the sea. He found his latitude correctly, but unknowingly was already west of his destination when he made the decision to sail west looking for the river. He landed at the island which would become Galveston, Texas. Finally, he took a party and began marching east looking for the river. His men murdered him before they reached the river, and then marched back to the encampment to starve to death with the rest of the party. (EDIT: Some of the sailors, when it came out that La Salle had been murdered, said screw this, and sailed away in a ship's launch, which is how we know what happened to La Salle.)

In 1750, George Anson left England with his squadron with which he was to harry the Spanish Pacific coast of South America. One frigate turned back and sailed to the Cape. One liner was lost rounding Cape Horn. One supply ship made it round the Horn, and then wrecked on the coast of what is now Chile. Anson, in Centurion, with men dying of scurvy every day, made his latitutde, but there was disagreement about whether they were east or west of Juan Fernandez. The majority of his officers believed they were west of the island, so Anson reluctantly agreed to sail east. When the look out told them he could see snow-capped mountains, they knew they were wrong, and turned about to sail west. By the time they reached Juan Fernandez, more that two hundred men, half the crew, had died of scurvy. His latitiude was good enough, though, that they drifted right into the roadstead . Men continued to die, even as they gathered fruit and vegetables on the island. When Gloucester came in, her crew was so reduced from death and sickness that they lay in sight of the island for days, with insufficient healthy crew to pull into shore. Anson's crew on shore had too few healthy men to pull out to Gloucester and tow her in. They took "green stuff" out to the ship, but it was days, and dozens of deaths before they were able to bring Gloucester into the roadstead and bring her crew ashore. The case with Pearl (a converted Eastindiaman used as a frigate) and the sloop Tryall. The one remaining supply ship came in, without scurvy because of the supplies they still carried. I've read estimates that Anson lost 1400 men to scurvy, but i think that is too high. But he lost between 800 and 1000 men to scurvy, of that i have no doubt. Decent chronometers could have dramatically reduced the death toll.

Chronometers were usually kept aboard sailing ships on the orlop deck, down in the bowels of the hold, where there was the least motion.

The periscope sextants are fairly small, gyro stsabilized and mounted on the cockpit frame with an eyepiece and a rotary dial for lining up with the selected star, and automatically recording azimuth and elevation. It might not have been as hard as you imagine, though doing anything in the small cockpits could be difficult. Using the relief tube to take a piss at high altitude was harder, particularly in winter over the ocean - we had to wear early model wet suits.

Also the external relief tube venturi used to freeze up at high altitude (it's 40 deg below zero at 20,000 ft.) - usually when you got to max flow. One could always tell when that happened on a dark night, - when your hand holding the tube suddenly got warm.