NavList:

Thanks for your input George. I found nothing specific in the limited access to the journals that was available to me. I submit following for anyone that may be more knowledgeable about these particular instruments and ask (just to satisfy a curiosity) as to how one dates such a piece or indeed how the precession of the equinoxes manifests itself in their construction........ if I am looking at it incorrectly.

Further quoting from the aforementioned book just to pinpoint the ‘date’ to which I earlier referred:

“Circular in shape the instrument had a handle either at the western or northern part of the rim by which it was held up toward the Pole Star. This was viewed through a central hole. The months of the year, divided into days or groups of days, were inscribed around the rim in positions indicating the bearings of the Guards at midnight all through the year, starting with the date at which they lay due east. In a concentric circle of hours, this starting point was marked 12, and the hours ran counter clockwise, indicating the gradual retro-regression of the midnight position.”

The underlined section is the date to which I referred in my last post. This date seemingly changes due to the precession of the equinoxes. (Or does it.......have I got this right?)

On this particular instrument the start date appears to be August 22^nd. Looking at online pictures (NMM in UK) other start dates are evident, three on or about Aug 21^st/ 22^nd  while two others are circa Oct 28^th. Does anyone know if the instruments themselves can be dated from the ‘start date’ mentioned. The six instruments mentioned in this email are all said to be from 17^th century – was that deduced from the start dates or from their construction / lettering etc?

Kinch.

E. G. R. Taylor has quit a few journal articles, do a search for her on JSTOR.com

The date difference might be found in the change from Julian calendar to the Gregorian calendar.
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