How to make a sundial

There are lots of articles on how to make a sundial. It is really quite complex to manage it for any given time of year or latitude. Why am I asking?

I am reading Marcus Tomalin's book. Telling the Time in British Literature, 1675-1830, Hours of Folly? (Routledge 2020).

In chapter 4 on Sundials, he shows the respect for Archbishop James Ussher, who "was described (metaphorically) as 'the Sun_dial by which all great Scholars set their watches' (Barksdale 1661, 128)"

You can get an idea of how much harder it is to make a sundial than sticking a straw through a paper plate from the article here. (Images do not show well on a phone.)

The state of intellectual achievement, whether in ancient Egypt or the long 18th century, is still very complex even if we disagree about the age of the earth. I think we might have a hard time passing their exams or following their thoughts.

Tomalin also cites Robert Boyle (signing himself as T. E. a layman).

"... as I make use of my Watch to estimate Time, when ever the Sun is absent or clouded, but when he shines clearly forth, I scruple not to correct and adjust my Watch by his Beams cast on a Dial; so, wherever no better Light is to be had, I estimate Truth by my own Reason; but where Divine Revelation can be consulted, I willingly submit my fallible Reason to the sure Informations afforded by Celestial Light."

Ah, Judgment. 

Who can say (on what errand the insolent emu walks between morning and night on the edge of the plain?) Any appeal to 'Divine' renders the argument unprovable.

We are flightless birds, and yet we claim to know the bright wings of the Spirit. Persistence, another name for the faith that names things, may yet provide us wings.

I recommend Marcus's book. It is a delightful recapitulation of the canon of poetry, science, and literature that we grew up with.