The brass, octagonal scarificator with 8, 10, and particularly 12 blades became the standard scarificator sold in England and America.[120] Both unidirectional ("plain") and reversible scarificators were offered through trade catalogs. Smaller octagonal scarificators with four to six blades were sold for cupping parts of the body with limited surface area. _Cupping Procedure_ The art of cupping, it was generally agreed, required a high degree of dexterity that could be maintained only by constant practice. Professional cuppers were concerned with avoiding any appearance of clumsiness, else the patient might come to fear an operation essential to his health. In the hands of an inexperienced physician or surgeon, cupping could be highly painful to the patient, and yet fail to produce the requisite amount of blood. While expert cuppers were usually available in cities, the rural doctor was not trained in the operation. It was to these rural practitioners that the treatises of the professional cuppers were addressed. One cupper, George Frederick Knox, offered in addition personal instruction in cupping procedures. His charge was a guinea for medical students and three guineas for non-medical students for a three month course.[121] Physicians and surgeons took a renewed interest in cupping in the early nineteenth century. Cupping was no longer regarded as merely a useful substitute for bloodletting. Recent physiological research seemed to prove to the advocates of cupping that the effects of slow withdrawal of blood from the capillaries produced a different effect on the constitution than the quick withdrawal of blood from a vein. Thus, Knox was convinced by the results of this research that, while phlebotomy was indicated in cases of high fever, "particular phlegmasiae" specifically required the intervention of cupping.[122] The procedure that the experts followed in wet cupping was as follows. First, the cups were immersed in hot water. Bayfield recommended that one glass be used for every four ounces of blood required. Thus, to abstract 18 to 20 ounces, as was common in cupping on the back or abdomen, four or five glasses were needed. The spot chosen for placement of the cups should be free of bone, but also not overly fatty. Cupping over the belly of a muscle was especially recommended. After the spot was fomented with hot water, the torch was dipped in alcohol, lit, and inserted into the cup for about two seconds. Once the torch was removed, the cup was allowed to sink of its own weight into the skin. During the minute that the skin was allowed to tumefy under the cup, the scarificator was warmed in the palm of the hand in preparation for the most difficult part of the operation. It required great skill to manage torch, scarificator, and cups in such a way as to lift the cup, scarify, and recup before the tumefaction had subsided. Monson Hills (1834) described the manipulations involved thus: