''1. * * * * 2. In this Act, unless there is anything repugnant in the subject or Definitions context,— (a) accident means an explosion of a boiler or steam-pipe or any damage to a boiler or steam-pipe which is calculated to weaken the strength thereof so as to render it liable to explode ; (b) “ boi,er ” nieans any closed vessel exceeding five gallons in capacity which is used expressly for generating steam under pressure, and includes any mounting or other fitting attached to such vessel, which is wholly or partly under pressure when steam is shut off ; (c) Chief Inspector ” and “ Inspector ” mean, respectively, a person appointed to be a Chief Inspector and an Inspector under this Act ; . (d) “ owner ” includes any person using a boiler as agent of the owner thereof and any person using a boiler which he has hired or obtained on loan from the owner thereof ; (