[97] _On the Nature of Light and Colours_: Lecture 39, in Young’s _Lectures on Natural Philosophy_, Kelland’s Edition, p. 373, and the authorities there quoted. [98] Brewster’s _Optics_: Lardner’s Cabinet Cyclopædia. Herschel, _On Light_: Encyclopædia Metropolitana. [99] Malus, _Sur une Propriété de la Lumière Réfléchie_: Mémoires d’Arcueil. Numerous memoirs by Sir David Brewster, in the Philosophical Transactions. [100] Bartholin, _On Iceland Crystals_: Copenhagen, 1669. _An Accompt of sundry Experiments made and communicated by that Learn’d Mathematician_ Dr. Erasmus Bartholin, _upon a Chrystal like Body sent to him out of Island_: in connection with which Dr. Matthias Paissenius writes:--The observations of the excellent Bartholin upon the Island Chrystal are, indeed, considerable, as well as painful. We have here, also, made some tryals of it upon a piece he presented me with, which confirm his observations. Mean time he found it somewhat scissile and reducible by a knife into thin laminas or plates, which, when single, shew’d the object single, but laid upon one another shew’d it double; the two images appearing the more distant from one another, the greater the number was of those thin plates laid on one another. With submission to better judgements I think it to be a kind of Selenites. Some of our curious men here were of opinion that the Rhomboid figure proper to this stone was the cause of the appearances doubled thereby. But having tryed whether in other transparent bodies of the like figure the like would happen, we found no such thing in them, which made us suspect some peculiarity in the very Body of the stone.--Phil. Trans. for 1670, vol. v. [101] _On the Application of the Laws of Circular Polarization to the Researches of Chemistry_: by M. Biot.--Nouvelles Annales du Muséum d’Histoire Naturelle, vol. iii., and Scientific Memoirs, vol. i. p. 600. _On Circular Polarization_: by Dr. Leeson.--Memoirs of the Chemical Society. [102] In Sir David Brewster’s Treatise _On Optics_, chap, xviii., _On Polarization_, the best arrangements for a polarizing apparatus will be found described. [103] This beautiful application was recently made by Professor Wheatstone, the particulars of which will be found in his interesting communication.--_On a means of determining the apparent Solar Time by the diurnal changes of the Plane of Polarization at the Northern Pole of the Sky_: Report of the Eighteenth Meeting of the British Association.