i ripped off a patch of sailcloth with my knife , tore a longish strip of calico to use as field dressing , then pushed stebbings 's hand away , wiped off the blood with a fold of my petticoat , sloshed lamp oil over his chest and the sailcloth patch , then pressed the cloth down to form a rudimentary seal , putting his hand back over it in such a way that one end of the patch remained free , while i wound the improvised field dressing round his torso .