A team led by David Mearns reported on the oldest Mariner's Astrolabe in a recent article of the International Journal of Nautical Archaeology. During a 2013-2014 series of diving expeditions off the coast of Oman they discovered a Portugues solid leaded-gunmetal disk astrolabe. As the authors put it, "A well-documented and dramatic story from one of the earliest Portuguese foyages to India ... involves the loss off two naus [sailing vessels], the Esmeralda and Sao Pedro, which sank in shallow waters off the coase of a remote Omani Island in the Arabian Sea." What has made this legend is that these ships were part of a Portuguese armada to India led by the legendary explorer Vasco da Gama. Mearns tells the story that following the return of da Gamma and the main fleet to Portugal in February 1503, Vicente and Bras Sodre, uncles of da Gama, led their two ships back to patrol the waters off the south-west Indian coast. But Vicente sailed his squadron to the Gulf of Aden where they looted and burnt a handful of Arab ships. "Vicente then took his ships to Al Hallaniyah ...where they found a safe anchorage to shelter from the south-west monsoon...It was in this location, in May 1503, where a sudden and furious wind tore the two naus from their moorings and drove them against the rocky shoreline smashing their wooden hulls and causing the deaths of many crew, including the squadron commander Vcente Sodre"
Recovered from the ocean after 500 years was the 17.5 cm 344 gram metal Sodre astrolabe as well as more than 2000 other metal and ceramic artifacts. The were slowly desalinated over a period of two years. The astrolabe was clearly decorated with the Portuguese royal coat of arms at top and an esfera armilar (armillary sphere) at bottom. But there was no alidade or any visible gradations. Using laser imagery a total of 18 scale marks became visible along the limb of the upper right quadrant with a spacing of 5 degrees. These marks probably extended to make a full 90 degree quadrant. The solid metal Sodre astrolabe is a rarity, for shortly after 1500 a new generation of open ring astrolabes emerged. An illustration of a mariner's astrolabe from the Boria Chart (1529) shows a ring planisphere with angles marked for 180 degrees. The new open design remaind stable in the wind and became the dominant navigation instrument for the next 170 years. Read the full article at https://onlinelibrary.wiley.com/doi/epdf/10.1111/1095-9270.12353 or a short condensed version at World’s Oldest Mariner’s Astrolabe Found | Archaeology | Sci-News.com
Last February in the Panorama Armenian News an article reviewed some of the oldest sundials in Armenia. Piliposyan, Doctor of History at the Preservations Service for Historic-Cultural Reserve-Museums and Historic Environment (SNCOT) related that the oldest sundial may be on the Zvartnots temple dating to the 7th century. Sundials have been preserved on buildings of Dsegh, Tsakhkadzor, Dilijan, Noyemberyan as well as Nagorno Karabakh churches. Sundial also were curved on khachkars [Armenian cross-stones]. In the Panorama article Piliposyan said that apart from serving as clocks, sundials served as a means of communicating with god. He brought the example of the Zvartnots temple sundial found during excavations with enclosed documents calling on prayers to talk to god whatever time it was.
The vertical dials had horizontal gnomons and on the dial face there are typically 12 equally spaced divisions to mark the hours. Frank King commented on the dials that "These are variants of the standard European sundials used for indicating 'unequal [temporal] hours', at least approximately, in medieval times. Several thousand survive in England alone. They divide the daylight period from sunrise to sunset into 12 parts. Unfortunately, these parts are not equal in time and their relationship varies with the time of year....The examples in the photographs seem very nicely made."
To appreciate the Medieval Armenian dials as well as modern interpretations, visit https://www.panorama.am/en/news/2019/02/23/Armenian-sundials/2076856
Register now for the North American Sundial Society 2019 conference to be held in the mile high city of Denver, Colorado. As always there will be an exciting list of presentations and tour of sundials. This year the conference is in June, starting Thursday afternoon at 4:30pm on June 20th continuing through 1pm on Sunday 23rd. THIS IS THE BUSIEST VACATIO WEEKEND OF THE YEAR IN DENVER. So make your registration now at the Hilton Garden Inn - Denver Downtown, 1400 Welton Street Denver CO 80202 (Phone 303-603-8000). NASS has a discound rate of $179/night (plus 15.75% tax). This rate will apply 5 days before and after the conference if rooms are available. Contact the hotel using the "NASS19" discount code. You can also go to the hotel's website set up for the NASS Registration at:
The hotel is 25 miles from the Denver International Airport. Transportation to the hotel is possible using the RTD Train from the airport to Union Station and then the Free Mall Ride Bus on 16th Street. There is always taxi service and Uber.
Full NASS registration until April 14th is $310-$322 depending upon dinner selection. After April 14th the cost increases to $335-$347. Download the attached registration form for full details. If you have a presentation or a table display, please contact Fred Sawyer.
It's rare that a sundialist casts a shadow on UK education, but that's exactly what Dr. Frank King did the other day in a BBC interview (https://www.bbc.co.uk/news/uk-england-cambridgeshire-47133011). Dr. King, a Fellow in Computer Science at Churchill College, has long been intrigued with time remarking to the BBC in an interview, "Anything from atomic clocks to the most ancient of sundials I can tell you about." He is Keeper of the Clock, responsible for Cambridge University's official timepiece on Great St. Mary's Church. But the number of people interested in sundials is on the wane. As president of the British Sundial Society,(a group like the North American Sundial Society who all truly enjoy time systems and the anciernt and beautiful art of designing sundials) Dr. King notes with sadness that the number of people who "really understand" the science behind sundials "are few and far between..... There seems to be no teaching of spherical triangles, and very little teaching of solid geometry. How many school leavers have heard of Euclid?"
Some could argue that who needs sundials in this age of digital watches, GPS navigation, and fit-bit monitors? The UK Register reports that "[Dr.] King would likely be deeply saddened to know, then, that there are people of adult age out there incapable of reading analogue clocks." But for those interested in promoting STEM in schools and getting students excited in something beyond designing a video game, the study of sundials offers a wonderful perspective. As stated by the BBC, "Dr. King strongly believes the sundial - 'the perfect collaboration of science and art' - has a place in the digital age. But he is concerned that the skills needed to create them may dwindle, and believes education could play a greater role."
The development of an aethetically pleasing sundial involves using digital computer aided design tools that sometimes significantly altering classic designs. Sundials requires artisan skill and craft for the selection of materials, casting, engraving and even 3D printing of dials. A sense of artistic proportion is needed to create pleasing embellishments that still remain true to the underlying mathematics that convey acurate time. Artist, sculpture, craftsman, geometer, mathematician, computer programmer, engraver and metal worker are but a few of the talents encompassing the talents of a dialist.
Back in March of 2012, NASS had an article about an inventive sundialist constructing a 62-LEGO block equatorial dial. That now seems like ancient history. In Beijing China, dialists have built a ring dial 9 1/2 feet in diameter consisting of more than 45,000 LEGO blocks, setting a new Guinness World Record.
The dial was the idea of Mrs. Hou at Playable Design, a company that creates and develops eduational activities using LEGO construction blocks. Astronomical professionals and structural engineers were enlisted to guide this three month construction project. According to an article from the on-line Guiness World Records website, Mrs. Hou (founder of Playable Design), says the giant ring sundial "... is a teaching tool that allows children to learn sciences across disciplines including astronomy, mathematics, history and cosmology. Inspire children to think and ask questions, when they see the ring sundial, but we are all very excited to ber recognized by the Guinness World Records at the same time.... This is an important part of a public education project. For creators and educators like us, the process of learning never stops."
See a time-lapse video of the dial's construction at: http://www.guinnessworldrecords.com/news/2018/11/45-000-bricks-used-to-create-largest-lego-brick-ring-sundial-for-gwr-day-546470
The Land Institute is a not for profit organization based in Salina, Kansas, having a goal to create an agriculture system that mimics natural systems in order to produce ample food and reduce or eliminate the negative impacts of industrial agriculture. A mile north of the Institue is their Marty Bender Nature Area where Owen Brown has created an art project "Units of Measurement". According to Jason Beets of the Salina Journal, his project "consists of three sets of sun dials created from praire-colored angled flag poles to symbolically represent the passage of time."
The idea is to meditate on the passage of time. The first set of three poles, called "In the Beginning" is 1,190 feet east of another set of poles called "The Passage of a Second". According to the artiist, this is the distance that the earthrotates in one second. A third site, called "From the Future" is located 723 feet north of "In the Beginning" is placed such that at "... dawn of the summer solstice, the shadows of the sundials at “From the Future” will touch [point to] the sundials at “The Passage of a Second.” Owen said, "I want this installation to make us more aware of where we are, who we are, and how we are ... in relation to the earth, to what we grow, and to what nurtures us."
Interesting art but very poor science. For each cluster of three flag poles, only the one point to North can work as a sundial. And the pole needs to be at an angle from the ground equal to the latitude of 38.855° N. From the photo, the angle is closer to 60°. Fortunately there are no hour lines on the ground to show the incorrect time of the shadow.
If a dialist computes the distances of separation, again our artist fails. We need to meditate on using the radius of the earth at Salina, KS, (a value between the earth's equatorial radius of 6378.137 km and polar radius of 6356.752 km. The parallel circumference distance is 2pi*R*cos(lat), which is 27142 km, the distance Salina KS travels in a day. But what is a day? Here we need to use the sidereal day of 86164.1 seconds (giving one revolution of the earth in inertial space). The distance between "In the Beginning" and "The Passage of a Second" is therefore 27142/86164, resulting in 1,033 ft, not 1,190 ft. By the way, if we had a telescope and somehow watched the events from one site to another, we would see the event 1 microsecond later. Another unit of time to contimplate.
The azimuth of sunrise (when the limb of the sun just peaks over the horizon) at summer solstice is a bit messy to calculate, but turns out to be 62.1° measured clockwise from north. The separation distance between "From the Future" and "In the Beginning" to have the sun's shadow align with "Passage of a Second" is 1,033/tan(62.1), giving only 547 ft, much shorter than the 723 ft designed by the artist. So for a dialist, there are indeed many things to meditate looking upon and calculating shadows at Owen Brown's "Unit of Measurement" in Kansas.
On Wed, Oct 3, 2018 the six-foot-tall Cranmer Sundial and surrounding Plaza were rededicated, celebrating the completion of a $2 million renovation project that started nearly two years ago. The city's Parks and Recreation Department replaced the cracked and sinking terrazzo plaza that was originally laid in the 1930s. They improved the drainage system that was a factor in the plaza's deteriation as well.
In 1941 George Cranmer placed a sundial of Chinese tradition on what was then called Mountain View Park. But in 1966 the original Cranmer Sundial was blown up with dynamite. The community rallied to raise funds and through the Erickson Monument Company, erected a large 6-foot disk equatorial dial of pink granitie on a terrazzo plaza. But the years did not treat the sundial well. When the sundial fell into disrepair the community pulled together again, and through the organization The Park People started "Save Our Sundial" and began fundraising. In all, citizens were able to raise $830,000 for the dial's repair. The Denver City Council committed to the rest of the funding, but the restoration would not be possible without the financial support of the residence of Hilltop community.
At the dedication, City Councilwoman of District 5, Mary Beth Susman said, “To have it restored to what George Cranmer’s vision was ... meaningful to all of us, and to have it restored in such a beautiful way, with the inlay still there, I can’t tell you how moving it is to celebrate this day.” [CBS News]