Sundial

Description

This stack was written as an introduction to sundialling which grew out of an interest in timepieces, typically those of the middle ages. The program was written on a Macintosh SE so the graphics may be a bit too small for some machines. Below is a brief listing of how to use this program and what it can do.

The main card consists of six fields for inputting your current latitude and longitude in degrees, minutes, and seconds. Any empty fields will default to zero. If you wish to calculate hour lines for your local mean time (explained below) in the continental United States be sure to select the correct time zone for your area. If you do not live in the continental United States or would rather calculate hour lines for your local apparent time, choose the "Local Apparent Time" button. The "Calculate" button begins the calculations for the data on the screen.

When completed, the screen shows how a horizontal sundial would appear if viewed from the top and facing true north. An indicator of the latitude and longitude is also repeated. The hour lines are laid out from 7:00 AM to 5:00 PM. Back on the main card are the hour line angles tabulated in a field. The angles are in degrees measured from the gnomon, the triangular piece which creates the shadow and lies along the true north-south line.

More detailed information on equations and building of sundials is on the next card. Graphs detailing time zones, meridians, and the equation of time follow on subsequent cards.

Requirements

HyperCard or HyperCard Player.

Author

bhb@phy.duke.edu

Status

Freeware

• Download Sundial [MacBinary 19 Kb]
• Download Sundial [BinHex 25 Kb]

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