| Description | Account drawn up by Thomas Stack
Tract divided into 17 sections
Parhelia witnessed in January 1736
Greater detail given about sections 15-17
15th section - Weidler refutes Huygens' method of accounting the halo
16th section - Weidler gives his views about parhelia
17th section - explains the appearance of an inverted iris
Appendix - account of the red lights seen on 5 December 1737
Read to the Royal Society on 22 March 1738 |