PortableSundials.com

Ancient gadgets from Earth
Hi!
I hope you enjoy my treasures. Don't forget to choose your Postage at the bottom of this page before you check out!
Maybe you are a Reenactor - when from? Or Steam Punk - aiming anytime in particular? Perhaps you are fascinated by ingenious objects? Or a Collector, a Hoarder - or want a unique gift for a special person?
Our jewellery is amazing, kits are top quality working models - and the rest just endlessly fascinating!
I've tried to group things in a simple way. But maybe you'll just need to browse around to find what you want. NOTE: If it's small enough to be worn as a necklace then it will be on the Jewellery pages. All our Jewellery works! Don't forget to choose your Postage at the bottom of this page before you check out!
Interesting and useful articles. Plus a few odd takes on things. In particular my unique and original FREE sundial!
Also an interesting download "History of Barometers" as a PDF file - I have no idea where I got it from!
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Astrolabes5



Finding the time of celestial event

The time of a celestial event such as sunrise sunset or the culmination of a star is found by setting the astrolabe to the circumstances of the event and reading the time.

Determine the Sun’s position on the ecliptic.

Se the rule to that position on the ecliptic on the front of the astrolabe.

Rotate the rete and rule together until the desired event is in position. For example to find the time of sunrise, rotate the rete and rule until their intersection is right on the easter horizon.

Read the time from the rule’s position on the limb.

The length of the day can be found by finding the time of sunrise and sunset and calculating the difference. Similarly the time until sunrise and sunset can be found as the different with the current time.

If you are in another different latitude for which the astrolabe is made (41º) the obtained results will be erroneous. Despite it you will have learned to handle an instrument that was denominated, with all reason, the mathematical jewel of Middle Age.