Hartford, Connecticut. October 8-10, 1999
Our Fifth Annual

An illustrated talk on the sundials Larry has found after decades of searching within a 50 mile radius of the conference site.

This dial concentrates sunlight onto an hour number instead of casting a shadow onto one. It consists of a trough in the shape of a half-cylinder lined with reflective slats, a cylindrical Fresnel mirror. The trough accurately focuses sunlight over a wide range of angles onto a ring that completes the arc of the cylinder. The ring has hour numbers on it spaced at 30º angles. The trough is tilted up by the latitude angle and it faces south (in the northern hemisphere). Each slat is tilted away from the wall of the trough by an angle of ¾ theta, where theta is the angle around the cylinder (the bottom, being at angle 0º and the lip at angle 90º). The dial is derived from an old solar energy scheme that used a large fixed mirror and a tracking collector.

Robert, the designer of one of the sundials we will see on Saturday, will present an illustrated tour of some of the sundial sculptures he has produced.

This talk will review a traditional paper sundial which was popular in Edo-era Japan (1603-1867) and which can be purchased today in Japan as the Basho Hidokei. After a brief review of the calendar and time measurement system used in the traditional format of this horizontal altitude dial, a modern version will be considered. An example designed specifically for his or her latitude will be provided to each conference attendee. [Illustrations]

When designing a vertical dial on a wall, one early problem to be solved is the wall's orientation (declination) since that declination determines the layout of the dial itself. This talk describes a method of determining declination with a simple instrument used in conjunction with the azimuth of the sun at a given date, time and location. [Photo]

This talk will refer to the recent Compendium article on Shadow Plane Dials and show models and graphics to reinforce how these dials work. Illustrations will also include 12-gnomon and 12-block sundial models which will appear in a follow-up article. Each conference attendee will assemble his/her own "shadow plane experimenter sundial" from parts that Mac will supply. [Three photos]

Sundials served Christianity through their functions, shapes, and ornamentation. They were used to find the hours of the Divine Office, the date of Easter and festivals, and the way to Rome and Jerusalem. They served pilgrims, held the bones of saints, and encouraged prayer. In return, religion served the needs of time finding and science. Great cathedrals in Europe were transformed into monumental sundials and solar observatories.

Through the NASS outreach program of helping the community with support to popularize sundials, NASS is assisting an energetic teenager, Bryan Aden, complete his Boy Scout project to create a sundial for the Challenger Science Center in Suffern NY. Through design discussions with Dr. Kellogg, Bryan has submitted plans to the Science Center for a sundial and noon mark using a gnomon above the North-facing entrance of the museum. The design and a discussion of the NASS cooperation will be presented.

Kate will show a survey of her sunaligned work beginning with basic horizontal dials and showing an evolution to sculptures that document the equinoxes and solstices.

This talk will describe the announcement and information placed on the Internet for the 1998 Reutte Sundial Competition. Information from K. Schwarzinger, Chairman of the Working Group for Sundials in the Austrian Astronomical Society, will summarize the entries. Two entrants of unique design will be described in detail: 1. a "bifilar" design by R. Soler, Spain, and, 2. my own design of a skylight and window shelter. [Photos]

Susan will talk about the installation of an Equatorial Sundial in Branford, Connecticut. This 13,000 lb. granite sundial was designed and built by Susan Farricielli, owner of a.k.a. prototype, and Gary DiNello, owner of Custom Boating Fabricators. It was realized through the efforts of a community project to create a children's park called "Nature's Garden".

A new equatorial type of sundial is under development which illuminates the time by a sharply focused beam of light. The dial is readable to the minute, and is correctable for latitude, longitude within the time zone, daylight savings, and the equation of time. There are several interesting mathematical relationships demonstrated in this dial. One involves how the focal length of the mirror changes as a function of the sun's right ascension. Another involves how the image stays the same width despite a changing focal length. Another is the geometry by which an angle, whose apex lies on the circumference of a circle and faces the circle's interior, subtends an arc of that circle equal to twice that angle. Additionally, there is a novel tilting mechanism utilizing rotating wedges for accurately adjusting for latitude. [Photo]

The navigators' equations for altitude and azimuth are greatly simplified for the case of sunrise and sunset when the altitude of the sun is zero. For specified latitude and solar declination, the time, location and path of the setting sun are easily determined. Corrections are described for the apparent sunset including refraction, semi-diameter and dip. The intent is to answer questions such as: "Why are sunsets so short in the tropics? What is so special about the equator and the arctic circles? What happens on the equinox and solstice? What is the green flash?"

Stone circles are found world-wide, many of which have astronomical alignments and serve as calendars - they are the original observatories, designed to keep time based on the natural cycles of the Sun and Moon. The majority of people today, however, are totally unfamiliar with the annual cycle in the direction to the rising and setting sun. To help the general public experience and understand the cycles exhibited by the Sun and Moon and the course of the seasons, I began creating a stone circle, which I call a Sunwheel, on the U.Mass Amherst campus in 1992. A preliminary Sunwheel has been in place since May 1997, consisting of a dozen 2-3' high boulders in a circle 100' across. Stones mark North, South, East and West, as well as the summer and winter solstice sunrise and sunset directions. This preliminary Sunwheel is an active arena for public outreach and enhancing the K-12 science curriculum, with over 1000 visitors per year since 1997. This presentation describes the Sunwheel - the design, outreach, and fundraising activities, and plans for larger stones in the future.

The NASS Angel is a portable universal vertical direct east/west diametral or analemmatic sundial designed specifically for the conference. This talk outlines the development of the dial and provides its theoretical basis and historical roots in Foster and Parent. Reading local solar time by means of the Angel is reviewed along with tips for handling the times around the Equinoxes and for determining from the time reading if the dial is properly aligned. Each person registered for the conference received a NASS Angel as a souvenir of our gathering. [Illustration]

This talk will describe the design and installation of an interactive analemmatic sundial at a summer day camp. Older campers and counselors participated in locating permanent time and date markers while younger campers decorated temporary markers that could be moved when mowing the field in which the dial was located. The participants' creativity was demonstrated on a cloudy day when the sundial was shown to the entire camp. During a workshop for about 20 fifth graders, they assembled a dipytch dial and were introduced to the "foot sundial". [Photo]

When a person stands on the zodiac of an analemmatic sundial and acts as the gnomon, it is important for the tip of the shadow to be close to the time marker. Since the shadow length varies dramatically with date (declination) and time (altitude), it is important to consider when the dial is most often used and by whom. The typical shadow length should determine the size and layout of the dial. A computer spreadsheet was developed to optimize the design of an interactive analemmatic dial for the Calgary Science Center. For the specific latitude and longitude, the spreadsheet calculates the hour angles and coordinates of the zodiac and the time markers on the ellipse. From the solar altitude and azimuth of specified dates, declination lines are also calculated and plotted for typical gnomon heights. The presentation covers the design of analemmatic dials, describes the development of the spreadsheet, shows the design graphs and records the construction and use of the dial.

This talk will describe the sundial outreach programs I conducted this past summer for the Smithsonian, Morino Institute, and the Girl Scout Council of the Nation's Capital. After laying out two walk-through sundials on the Mall as part of an outdoor Smithsonian exhibition, Under the Sun, I led four workshops on sundials and solar power for under-privileged DC children, ages 4-16. A fifth workshop was organized for adult-child pairs by the Smithsonian Associates. Two-hundred-fifty girl scouts (ages 10-18) participated in a sixth time finding workshop, which was part of a Total Solar Eclipse Camp-In I organized at the National Air and Space Museum.

Many equations are presented in The Compendium for building sundials and solving sundial problems. The average dialist has few recourses to efficiently implement these equations. The presentation will compare some advantages and disadvantages of MatLab, Visual Basic, and Excel spreadsheets. Computing the equation of time and other problems will be illustrated.