Chullin 31 - Shechitah Must Be Done With A Sawing Motion

If one chopped off the head of an animal, the shechitah is invalid because it must be done with a drawn-out, saw-like motion. Therefore, if he cut the head off with one motion, it is valid - provided that the knife was twice as long as the neck, so that he can accomplish the cut without going back and forth. If he used the back-and-forth motion, it is valid, and then the knife can be as small as a scalpel. If he cut off two animal heads in one motion, it is valid, provided that the knife is thrice as long as one neck. Two people can do a shechitah together, as long as they don't press.

Rava examined an arrow for Rav Yonah, found it smooth, and then Rav Yonah slaughtered with it a bird in flight. But perhaps the arrow entered the side of the neck and burrowed between the pipes? - They saw that the feathers around the neck were sliced. But they need to cover the blood of the bird both below and above? - They plowed the whole field over which the bird was flying, and thus the loose earth served for covering below.

Art: Hans Memling - Portrait of a Man with an Arrow