Art, Daniel, Charles, and other Dialists, I believe one could make a dial that could be read to a few seconds, however I'm not sure of why one would want to be able to read a dial at any time to this accuracy or precision. At most one might want such a dial to be able to set a watch or clock, or to convince skeptical friends that it is possible. For these purposes it might only be necessary to read the time on the hour marks to an accuracy of a few seconds. In this case one would need a "pin-hole' only for each hour mark--a much simpler task than one for each second or even each minute. The shadow sharpening technique gives the required precision of plus or minus a few seconds, but now we must turn to the question of the required accuracy.
To get the desired accuracy the "pin-holes' themselves must be very accurately aligned (not true if the free "pin-hole" technique is used and the hole moved back and forth until the shadow of the gnomon is centered, and on the hour mark, at the same time) The Equation of Time, to the second, must also be taken into account. If this is to be accomplished in a direct reading method a large series of "pin-holes" may have be drilled along an analemma for each hour. (There are some direct reading dials that utilize a sliding scale and a single analemma--their use would be more practical.) As for loss of accuracy because of the dates shifting along the analemma, I don't believe this is a problem. I understand that the analemma stays fixed (over the span of a human life) with respect to HOUR ANGLE and DECLINATION, which is how it would be plotted on a dial, and that the change over time is merely a shift in date positions along this curve. Over the weekend, in the brief time that the sun was out in a clear sky, I did try some experiments. A series of close "pin-holes" (mine were 1/16" diameter) along the sun's path did not work, but if they were punched along a diagonal to the path making a "saw-tooth" curve with a one-minute pitch, I got very nice results. However I gave up when I realized that adjusting each pinhole to the required accuracy would be an extremely difficult job, and that I probably did not want to build a sundial stop-watch! Keep watching the shadows! Bill
