When, however, an object is singled out of the whole view for particular attention, the _uvea_ then contracts or dilates, which, together with the muscular action of the whole ball, proportions all the humours suitable to the magnitude and distance of the object under examination, and the quantity of light; and to make the eye more capable, the lids are frequently moving, in order to moisten and varnish, as it were, with a liquid pressed from the innermost gland, called _canthus major_, to keep the surface smooth, and assist its transparency. If this intense looking is continued beyond the strength of this noble organ, it relaxes from its proper destined expansion, and the objects are rendered obscure. Darkness is ease and rest to the eye, because it is then out of action; whilst light always keeps it in exercise; And in diseases of the eyes, light should be kept away as much as possible. Here then I shall beg leave to conclude this short description of the wonderful structure of our frame; which when we duly consider, will never fail of filling our breasts with a sense of admiration; and induce us to lift up our souls with reverence and gratitude, to that incomprehensible GREAT CAUSE, by whose wisdom we are formed; and by whose goodness we exist. ------------------------------------------------------------------------ LECTURE II. ON THE NECESSARY MEANS AND MEDICINES REQUISITE TOWARDS RESTORING HEALTH. ------------------------------------------- Having, in the preceding lecture, given a general view of our wonderful structure, I shall, in this, endeavour to lay a foundation of the healing art, in order to assist nature when impaired by the attack of disease, or any unforeseen accidents. But that I may become useful, and yet concise, I will, without loss of time, lead the reader to the principal distinction between health and disease; for without forming a proper judgment of an ailment, there can be no reasonable intention of cure. I shall therefore beg leave to solicit a serious attention to the following important observations, particularly, as they are founded upon the purest principles of _physic_, authenticated by happy success in an extensive practice, and communicated by the dictates of a candid and well disposed heart, that wishes Existence only as a useful member to society. ------------------------------------------- SECT. I. _Of the Pulse._