A new treatise on the diseases of the chrystalline humour of a human eye: or, of the cataract and glaucoma. With a new a theory of their causes, and an endeavour to demonstrate that there are no membranous cataracts; but that all cataracts are from an alteration of the chrystalline humour itself. With an exact description of a new and more successful method of making the operations necessary to the removal of the several species of these diseases. Humbly address'd to Her Majesty. To which is pre