=990. Lever of the 1st order= }
}
=991. Lever of the 2nd order= } See Applications, Section 48.
}
=992. Lever of the 3rd order= }
=993. Wheel and axle;= power gained and speed reduced in proportion to
the diameters of the two sheaves.
=994. Return block;= power multiplied 2 to 1.
=995. Two double sheave blocks;= power multiplied 4 to 1.
=996. Four single blocks;= power same as No. 995.
=997. Three return blocks;= power multiplied 8 to 1.
See Applications, Section 42.
=The inclined plane= is simply a modification of the force of gravity,
which acts vertically.
=The wedge.= See Section 37.
=The screw= is simply a circular inclined plane. See Section 78.
See also Gearing, Sections 40 and 84.