Under some such compact the horse is given to man. The implied, not written obligation, may not be acknowledged or understood; but, nevertheless, it exists, and the terms of the bond are rigidly exacted. Let us regard this matter in relation to specific ophthalmia. A gentleman possesses five horses; he builds a stable twenty feet long, twelve feet wide, and nine feet high; into this place he crams the five huge lives. We will suppose the place to be good of its kind, to be paved with Dutch clinkers and to be perfectly drained; still each horse stands in a stall four feet wide; in this it has to remain all night and the major portion of the day. In this space it has to relieve its body; the liquid, to be sure, may run off by the drain, but it has to fall upon straw, which imbibes some, and to flow over bricks, which absorb more; the solid excrement is during the day removed by the groom as it falls, but it remains in an open basket to taint the air of the place. We will suppose the horses and their attendants, occasionally, are the sole inhabitants, and the building contains none of those things, living and otherwise, which ladies are pleased to order should "be carried into the stable." [Illustration: THE SPECIES OF EYE WHICH IS GENERALLY SUPPOSED TO BE MOST LIABLE TO OPHTHALMIA.] Will the sane reader assert that the space is large enough for its purposes? The stable never can be sufficiently ventilated: it will smell of impurity--of hay, straw, oats, ammonia, and of various other things. The air feels hot. Can it be wondered at? Ten large lungs have been breathing it for weeks and years, during twenty out of every twenty-four hours. Five huge creatures have been cabined there, living by day, sleeping by night, feeding and performing all the other offices of nature. Is it astonishing that the air feels and smells close? Ought we not rather to wonder that animal life can exist in such an atmosphere? The chief contamination is ammonia; ammonia will not support vitality. The reader has inhaled smelling salts; those are purified carbonate of ammonia; have these not made the eyes water? The ammonia of the stable affects the eye of the horse; it also undermines the constitution; but, by constantly entering upon the lungs and stimulating the eyes, it causes the constitutional disease to first affect the visual organs; in short, specific ophthalmia is generated.