To stop grave robbing.

Between the 18-19 century grave robbing was a mayor part of some people's lives. A person could make a years wage for the right type of body. It had to be fresh and in most part whole. Young and old it did not matter. The medical community wanted them all for schooling up and coming doctors.

It was just the main cities that had problems with grave robbers, but most towns as well, as their graveyards would have less protection. A grave robbers life was a hard one. First of all it was in the most part all nightshifts, then you had to dig for the body. Break into the coffin, remove the body and refill the grave. All without being seen or heard doing it. Then you had to transport the body without getting caught. But if it was not for the doctors needing the bodies and paying well, none of it would have happened.

So to try and stop grave robbing going on a number of things were done ( will post more on others later).

One of these was an iron cast coffin. Made of iron and weighing over 1 ton it was used to protect the person's coffin. The wooden coffin was placed inside the iron one at the grave side. Then the iron coffin was lifted up and placed in the grave, then covered over. After 7 days it was deemed the body would no longer be fit for use, and the iron coffin dug up. The wooden coffin then would be removed from the iron one and placed in the grave. The grave would then be refilled. The iron coffin would then be taken away.

So the grave robbers knew which grave to go to, someone use to follow the dead person to the graveyard. Check to see how the person was laid to rest, and report back. 

To date no-one really knows how many bodies were removed after death. But there was at least 5 grave robbing gangs in Edinburgh, that are known about. How many more went unknown we shall never know.