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Hello David,

I am sure this is only a sideline to your conclusions about the placement of the year-markings on your calendar-disc, but it It seems to me now that the selection of the 1995-2034 range was a slightly unfortunate marketing choice, which led to it being a bit compromised even before the year-markings were put on it.

I am assuming there are 21 segments on the under-plate carrying both the year-markings and the days of the week markings (fig.1 attached).  If that is the case, I don’t think it could have been made completely accurate for the 1995-2034 period.  MS Excel shows me there are seven years in that period having a common-calendar for the March to December period.  The design can only deal with six of these (assuming there are to be two years listed in each of three segments), so it looks as though one year would inevitably have been in error.

If the manufacturer had selected a 40-year range starting from 1994 or 1996 instead of 1995, the above situation of seven years of common calendars would not have arisen and I think then the disc could have been made completely accurately.  Fig. 2 attached shows markings that were generated in Excel for a 1996-2035 disc, that range not having a “seven-year” problem.

I acknowledge that in the mid-1990’s the manufacturer of this type of calendar maybe faced a rather more tedious process in getting all the design right than the wide availability of software such as MS Excel offers us now.

Regards,

Adrian F

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