Calculated dates for the construction of the Ancient
Crosses at Sandbach in Cheshire

On the north face of each of the two Ancient Crosses which stand in the Market Square at Sandbach in Cheshire there are ladder calendars.

A ladder calendar for the year 325 AD. is shown in fig 1. It consists of a vertical line joining the position of the shadow from a gnomon point at midwinter at the top of the line with the position of the shadow from the gnomon point at midsummer at the bottom. Horizontal lines are drawn on one side of the line on the first day of each month in winter and spring and on the other side of the line in summer and autmn.

The ladder calendar contains two different sets of information, one is the solar (tropical) calibration. The other set is that of the calendar that was in use at the time that the ladder was made, in this case the Julian calendar calibration.

As the Julian calendar was not synchronised with the solar calendar, by calculating the error between the two sets of information the date of the construction of the cross can be calculated.

Fig 2. shows the ladder on the north face of the larger cross and how the date of the carving was calculated.

Fig 3. shows the ladder on the north face of the smaller cross and the calculation to give its date of construction.

Fig 4. shows how the Julian calendar drifted between BC46. when it was introduced and 1582 AD. when the Gregorian calendar started. I have set the equinox to the 21st of March in the year 325 AD. to agree with the Council of Nicaea.

As the calibrations for both of the crosses are on the north faces a mirror or some reflector must have been used to read them. Fig 5. shows how the Sun elevation angles on the first day of each month at Sandbach, in the year 600 AD. using the Julian calendar, with the Sun at 180 degrees south compare with the ladder on the larger cross.

The calculated date for the larger cross at 601 AD. is about fifty years earlier than the usually accepted date of its errection. The positions of the pictures cut on the sides of the larger cross agree with the dates of the Christian feast days on the calendar.

The calculated date for the smaller cross at 1702 AD. falls between the start of the Gregorian calendar in 1582 AD. and 1752 AD. when England and the colonies started to use it. Between these dates the Julian calendar continued to be used.

The characters who are standing on the rungs of the ladders are the mediaeval representations of the months in which they are standing.