If the Tumour appears on the outside, the Abcess may be open'd between the Ribs; but if no external Signs are discern'd, the Surgeon may choose a more convenient place to make the Opening. Thus when the Patient is set upon his Bed, and conveniently supported, the Opening is to be made between the second and third of the Spurious Ribs, within four Fingers breadth of the Spine, and the lower Corner of the _Omoplata_; to this purpose the Skin is to be taken up a-cross, to cut it in its length, the Surgeon holding it on one side, and the Assistant on the other. The Incision is made with a streight Knife two or three Fingers breadth long, and the Fibres of the great Dorsal-Muscle are cut a-cross, that they may not stop the Opening. Then the Surgeon puts the Fore-Finger of his Left-hand into the Incision, to remove the Fibres, and divides the Intercostal Muscles, guiding the Point of the Knife with his Finger to pierce the _Pleuron_, for fear of wounding {228} the Lungs, which sometimes adhere thereto, the Opening being thus finish'd, if the Matter runs well, it must be taken out; but if not, the Fore-Finger must be put into the Wound, to disjoyn those Parts of the Lungs that stick to the _Pleuron_. To let out the Matter, the Patient must be oblig'd to lean on one side, stopping his Mouth and Nose, and puffing up his Cheeks, as if he were to blow vehemently; then if Blood appears, a greater quantity of it may be taken away than if it were Matter, in regard that a Flux of Matter weakens more than that of Blood. It is also worth the while to observe, that in making the Incision, the Intercostal Muscles ought to be cut a-cross, that the side of the Ribs may not be laid bare, by which means the Wound will not so soon become Fistulous. If it be judg'd that purulent Matter is contain'd in both sides of the Breast, it is requisite that the Operation be done on each side; it being well known that the Breast is divided into two Parts by the _Mediastinum_: But in this case the two Holes made by the Incision must not be left open at the same time, for fear of suffocating the Patient. _The Dressing and Bandage._