On 25/04/2018 11:55, Metman2012 wrote:
.

I always wanted one of the charred paper crystal ball sun recorders.

Here's one for sale

https://www.metcheck.co.uk/collectio...recorder-25-60

and don't forget the cards

https://www.metcheck.co.uk/collectio...recorder-cards

I notice one went for £750 on ebay this year.

Ouch! That is expensive. I was planning on a DIY version using a 4"
glass ball I ordered up from China on eBay when I get a roundtuit.

Another slightly weather related demo I have always wanted to do is
start a fire from sunlight using a lens made out of clear water ice.
My attempt this winter failed as the hemispherical mould leaked.

--
Regards,
Martin Brown