Clysters, or Injections, or Lavemens, are liquid remedies introduced into the larger intestines, by the rectum. The most usual clystering machines are those consisting simply of the bladder of a hog, sheep or ox, to which an ivory pipe is fastened with pack-thread. A more convenient and durable sort is prepared of India-rubber, instead of a bladder ; though the French and Germans employ, in preference, a long pewter syringe by which the liquor may, with more ease and expedition, be drawn in, and likewise more forcibly expelled, than from a bladder. Both methods, however, are in many instances liable to great objections, especially the former, which cannot be administered without the assistance of another person, even though the patient should possess sufficient strength and dexterity to perform the operation. Hence we cannot, in justice to Mr. Savigny, of King-street, Covent-garden, omit to mention his newly invented machine for lave-mens; which, for simplicity of construction, facility in using it, cleanliness and durability, far surpasses every former contrivance. This machine is ingeniously adapted both for private use, and to ad-mit of assistance. One of its essential advantages is, that the in-jection may be received into the body, without the least intervention of air; because the cylinder containing the liquid is provided with a piston, which, by gently pressing it down upon the fluid, till it appears on the top of the ivory pipe, expels the air, and thus prevents its introduction into the bowels :— the whole apparatus, in a mahogany case, is sold by Mr. SaVig-ny, tor one guinea and a half.

Clysters form a very important class of medicines, which, if properly understood and applied, might be effectually substituted for many remedies swallowed by the mouth, to the detriment of the stomach, as well as the whole ani-mal economy. For Nature never intended, that the receptacle of nourishment should become the laboratory of drugs; the local effects of which, sooner or later, cannot fail to impair digestion, and lay the foundation of more serious evils than those deluded patients vainly imagined to remove. We shall however, in this place, expa tiate upon the impropriety and absurdity of these practices, which which more properly belong to the article Quack-Medicines.

Clysters not only serve to evacuate the contents of the belly, in cases of obstinate costiveness, but also to convey into the system medicinal preparations of great activity. Thus opium, the Peruvian bark, are. when they cannot be taken by the mouth, may be given in much larger doses, and with less dan--ger: nay, the most nutritive and strengthening liquids may, in this manner, be administered to persons unable to swallow, so that their lives may be supported for many months, and even years, by means of clysters alone. In short, it may without hesitation be affirmed, that injections are more conformable to the intricate functions of the animal body, and doubtless-safer, than the introduction of medicines by the stomach.

Although clysters should never be administered too hot, or too' cold, yet there are certain complaints accompanied with such debility of the larger intestines, and the abdominal muscles, as renders the application of cool liquids sometimes necessary : such cases, however, must be determined by the experienced practitioner. In general, therefore, these remedies are given in a tepid or lukewarm state, that is, from the 80th to the 96th degree of FaHRENHEIT'S scale. The quantity used for adults, is from half a pint to one pint ; and for children, according to their" age, from two or three spoonfuls to half a pint.

Anodyne Clyster. - Take of either linseed-tea, or new milk, from half a pint to three quarters of a pint, and add from 40 to 60 drops of laudanum.

Laxative Clyster. - Milk and water, six- ounces each ; sweet oil, or fresh butter, two ounces ; and a stronger dose be required, one ounce of GlAUBER'S salt, or two table spoonfuls of common salt. In inflammatory or putrid disorders, however, it will be more proper to inject a clyster composed of two-thirds of thin gruel, and one-third of strong vinegar.

For the various forms and ingredients of clysters, to answer different purposes, we refer to the articles, Col:c, Costiveness,Dysentery, Flatulency, Hysterics, Urine, Worms, etc.