When one wheel only is to be taken off, and the other scotched, the props may be placed vertically; but practice alone will point out the proper position of props in all situations.
The point of the lever must not be withdrawn, until it is evident that the prop is well placed.
Article 3.
LIFTING JACK.
The lifting jack forms part of the equipment of every battery, and battering train. It may be applied to many of the purposes for which a long lever is used; but it is commonly employed to raise the wheels of carriages from the ground when they are to be greased, or exchanged, and to extricate them from ruts and holes.
The wheel opposite to that which is to be raised must be scotched.
On soft ground a piece of board must be placed under the foot of the jack, to prevent its sinking.
There are three kinds of lifting jacks in the service—