A Bor that is less than ten Tefachim deep is Patur if an animal falls in and dies, but if the animal is injured he is Chayav.
The structure that a person who is Chayav Sekilah is pushed off of is two floors high.
Although a person can die from falling from a height of ten Tefachim he is pushed off a tall structure because the Torah instructs us to kill him in a way that will minimize his suffering. (1)
If a person builds a house ten Tefachim below the Reshus ha'Rabim he is Patur from constructing a Ma'akeh (a fence).
If he builds a house that is ten Tefachim above the Reshus ha'Rabim he is Chayav to construct a Ma'akeh.
If a Shor falls into a Bor that is six Tefachim deep and dies he is Chayav according to Rebbi Nachman because it is ten Tefachim from the bottom of the stomach of the Shor to the bottom of the Bor.
If an animal rolls into a Bor he is only Chayav if the Bor is at least ten Tefachim deep.
Rebbi Akiva holds that if a person is Chayav for a Bor even though he was not Mafkir it.
According to the opinion that a person is only Chayav for a Bor that he was Mafkir it is possible for two people to be partners in a Bor if they both pick up a clump of dirt at the same time completing the ten Tefachim of the Bor together.
If a person sends a Shali'ach to do an Aveirah the Shali'ach is Chayav because a person cannot be a Shali'ach for an Aveirah.
If one person digs a Bor that is five Tefachim deep and another person increases it to ten Tefachim the second person is Chayav for Misah and they are both Chayav for Nezikin according to Rebbi.
The Rabanan hold that the second person is Chayav for both Misah and Nezikin.
A person is not Chayav for the Bor of his Shor.
If a Shor Pesulei Mukdashim (an ox that was Hekdesh and was redeemed after it had a Mum) fell into a Bor it is Patur because it is forbidden to derive benefit from the carcass. (2)
If one person digs a Bor of ten Tefachim and the next person increases it to twenty and the next person increases it to thirty they are all Chayav.
If one person digs a Bor of ten Tefachim and the next person coated it with lime or drew diagrams in it the second person is Chayav because he narrowed the Bor thereby increasing the vapor.
If a person placed a stone at the mouth of a Bor and completed it to ten Tefachim according to the Rabanan the person who placed the stone is Chayav for both Misah and Nezikin.
According to Rebbi the second person is Chayav for Misah and they are both Chayav for Nezikin.
If one person digs a Bor of nine Tefachim and the next person increases it to ten and then he puts the dirt back it is a Safek if the second person or the first person is Chayav.
If a Bor is eight Tefachim deep and two of the Tefachim are water he is Chayav for Misah because every Tefach of water is the same as two Tefachim without water.
If a Bor is nine Tefachim deep with one Tefach of water or seven Tefachim deep with three Tefachim of water it is a Safek if he is Chayav for Misah. (3)
If one person digs a Bor of ten Tefachim and the next person widens it Rebbi Ashi says that if the animal that fell in died from the vapor the first person is Chayav because the second person diminished the vapor. (4)
If the animal that fell in died from the impact the second person is Chayav because he widened the Bor and made it more likely that an animal will fall in. (5)
If a Bor is the same width as depth it is a Machlokes if it has vapor that can cause damage.
If a Bor is owned by two partners and the first partner uses the Bor and then the second person uses the Bor and does not cover it the second person is Chayav according to the Tana Kama.
Rebbi Eliezer Ben Yakov holds that the second partner is only Chayav if he hands the cover to the second partner and the second partner fails to cover it. (6)
If someone sells a Bor to his friend as soon he gives the cover to his friend he may be Koneh it with a Kinyan Chazakah. (7)
A BIT MORE
1. However, he is not pushed off a taller structure than two flights high so that his body will remain intact.
2. The Pasuk says that the carcass belongs to the Ba'al ha'Bor and therefore if the carcass is forbidden he is not Chayav.
3. Since in the first case there is very little water and in the second case the Bor is not that deep maybe it does not have a Din of a Bor of ten Tefachim.
4. A wide Bor does not have as much vapor as a narrow Bor.
5. According to the second Lashon if the animal fell in from the side that he widened the second person is Chayav but if not the first person is Chayav.
6. The Tana Kama holds Ein Bereirah and that the second partner who filled up the water from the Bor was using the entire Bor and therefore he is responsible to cover it however Rebbi Eliezer Ben Yakov holds that Yesh Bereirah and the second partner was only filling up water from his portion of the Bor and therefore unless he was handed the cover to the Bor from the first partner they are broth equally responsible to cover it.
7. Handing over the cover is the same as saying Lech Chazek u'Keni.
A BOR OF MISAH
If one person digs a Bor of nine Tefachim and the next person increases it to ten Tefachim, the second person is Chayav for Misah according to Rebbi and also for Nezikin according to the Rabanan. Tosfos says however that if the person digs a Bor of eight Tefachim and the second person increases it to nine Tefachim they are both Chayav for Nezikin just as if one person digs a Bor of ten Tefachim and the second person increases it to twenty they are both Chayav for Misah. So too if the first person digs a Bor of ten Tefachim and the second person increases it to eleven they are both Chayav for Misah.
PARTNERS IN A BOR
If a Bor is owned by two partners and the second partner found the Bor uncovered and he failed to cover it the second partner is Chayav. If the first partner found that the Bor was uncovered and had time to hire workers and make a cover for the Bor if an animal falls in before that time the second partner is Chayav and if an animal falls in after that time they are both Chayav because they are both at fault. According to some opinions we also give the second partner enough time to hire workers to make a cover for the Bor. Some hold that if he cannot find wood for a reasonable price to make a cover for the Bor we give him enough time to find wood at a reasonable price. (Shulchan Aruch CM 410:26, 27)