UK Readers
Its taken me ages to find a good quality credit card-sized Fresnel lens in the UK, but now I have.
They are available from the British Geological Survey shop. (Mail order as well as visitors).
Sales Desk,
British Geological Survey,
Keyworth,
Nottingham,
NG12 5GG.
Tel: +44 (0)115 936 3241 (9am-4.30pm UK local time)
Fax: +44(0)115 936 3488 (24 hours)
Email:
sales@bgs.ac.uk