premise: A scrum machine, or scrummaging machine, is a padded, weighty device against which a pack of rugby football forwards can practice scrummaging and rucking. The purpose of the scrum machine is to provide teams with a safe tool with which to improve the strength and skills of their players.
hypothesis: At least one specific type of machine was successfully developed to make practicing rugby safer. 
reason: The scrum machine is a safe tool developed to make rugby practice safer.