Message text written by John Carmichael >Now, what if instead of placing the nodus on the style, I use a tall vertical pointed rod at the dial center for the nodus?<
That would be fine - indeed it would be better since the weight of the nodus will not cause the string gnomon to sag. Incidentally the nodus doesn't have to be at the dial's centre - its position should be chosen to get the solstice lines nicely balanced on the plate The analemma is simply the time for one particular hour corrected for EoT (or for EoT combined with the longitude offset) plotted for all dates using as a scale the date line as determined by the vertical nodus. If you plotted it that way you could choose an EoT scale equivalent to the middle of a leap year cycle and then it would probably be a tad more accurate than one drawn by formula. Mayall p 197-9 describes the graphical method. Patrick
