SUNDIAL

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To put the pieces together, just sink the post—so that it's exactly vertical—to a depth of six to nine inches at the chosen spot in your yard or garden, slide the 20—penny nail on the bottom of the dial into the 5/16" fuel line in the top of the post, and slip the two nails on the base of the style into the holes in the face.

If your post was placed vertically, your sundial's face should be horizontal . . . but it's a good idea to check it with a carpenter's level anyway. Once you've made any necessary adjustment, you'll need to orient the original noon line (not the one shown by the style) to due north. You can do this by sighting down the (now imaginary) line toward the North Star at night . . . by using a compass (corrected for the local variation between magnetic and true north) . . . or by turning the dial so that it reads noon when your watch does (provided the wristmounted timepiece is set on standard, not daylight-saving, time).

TIME-OF-YEAR CORRECTION

Because vagaries in the earth's orbit, and in its relationship to the sun, cause the length of the day that we observe to vary through the year, corrections must be made to the sundial reading to maintain its agreement with the 24-hour mean solar day, which mechanical (and electric) watches record the passage of. If your sundial is intended primarily for aesthetic purposes (and you can afford to disregard 15 minutes here or there), you can ignore the equation of time correction. But if you would like to read your solar clock as accurately as possible, you'll need to keep a listing—such as Chart B—or a graphic representation of correction factors somewhere on or near your sundial.

Of course, once you've gone to all the trouble of making an accurate sundial, there'll likely come a day each spring when public decree will cause your solar timepiece to be off by one hour throughout the warmer months. It would be possible to build a dial to register daylight-saving time, but it's far easier just to add in the extra hour yourself . . . and leave the face less cluttered.

After all, one of the greatest beauties of a sundial is its utter mechanical simplici ty. And if anyone tries to make fun of the relic in your yard, just ask the joker if he or she happens to be referring to your solarpowered clock . . . which keeps accurate time, yet has no moving parts to wear out!

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