In the UK, daylight saving runs for 7 months during the
Summer Time, end of March to end of October,  so I favour
making dials which show daylight saving on the grounds
that:-
a) it is correct for the majority of the year
b) summer is when the sun (occasionally) shines

But I have two dials that adjust for the one hour
difference:-

1) A polar dial with a pointer (nodus) perpendicular to the
dial plate. It shows declination lines for my family's
birthdays, but the vertical hour lines are marked with
daylight saving time at the bottom (sun high), and normal
time at the
top (sun low).  So you look at the time nearest to where
the tip of
the shadow falls.

2) An equatorial dial made from a cylindrical pipe, cut so
that it stands at an angle equal to the latitude. The hour
lines are marked on the inside of the pipe, on the
equatorial plane  It has two gnomons cut out on the
circumference.  The upper one's shadow cuts the hour
markings in the summer when the sun is above the equatorial
plane, the lower one's shadow cuts it in the winter.  The
gnomons are
offset by one hour.
As the angle subtended from the centre of a circle is twice
the angle subtended from the circumference, you can't show
as many hours as when the gnomon is at the centre, but I
have made a prototype with four of these stuck together to
show the full 24 hours.

Mike Shaw

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