Self portrait, 1969
Replica of a wind rose from the chart of Jorge de Aguiar, 1492
Replica of an old wind-rose by Pedro Reinel, 1504
Marine sextant
A vernier caliper
Using a vernier caliper
Using a marine sextant
A proof of the Pythagorian theorem
Missing square puzzle
Ambigram JAG
Symbol: Astrolabe
Symbol: Marine sextant