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Equation of Time Back To The Home Page About the VDial: This style has the least confusion when reading the time. The design is such that the shadows do not interfere with the basic feature of telling time. With long term use this one is probably the most friendly to use, and certainly causes the least confusion. It is not automatic in its time correction, but the correction has been reduced to a lesser level of importance. Excellent accuracy is possible. However, it does require setting the pivot at around 9am and 3pm versus noon and 6. It gives a full 12 hours of time. About the CDial: The unique feature of this sundial style is the automatic correction of the "clock to solar time" discrepancy. It also provides a linear time scale that is magnified by the circular design. With the frosted glass, it has all around visibility - but only 10 hours. A metal version is also shown, but it must be mounted higher to be able to view the early and late hours. About the ODial: This design is attractive and simple to build from available hoops. The translucent ring inside the hoop is a good place to mark the times, and the shadow leads to the hour mark on the outside edge. A suitable translucent material may be difficult to settle on, however.
   Almost a full 12 hours can be visible, and the scale is uniform due to the circle with the gnomen on the hoop. The disadvantage of this design is that the scale must be flipped twice a year to avoid its shadow and to view the shadow on the time correction scale. About the Pivot: This allows for a simple adjustment of the position. The pipe couplers allow rotation only and can be tightened. The three axes give somewhat independent adjustment for elevation, direction, and time. True independence only occurs at the spring and fall equinox at a six hour interval. Other times of the year, iteratively setting the adjustments will zero in on the correct settings with little trouble. Just a bendable support can be used, as shown in most of the pictures, but the fittings are a lot easier, especially if it is expected the mount will be bumped or settle.
   With all of these sundials it is recommented that the time be aligned, and the scale marked, to favor evening hours with a loss of morning hours. It depends when you prefer viewing the time.