A magnifying glass (called a hand lens in laboratory contexts) is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle (see image). A magnifying glass can be used to focus light, such as to concentrate the sun's radiation to create a hot spot at the focus for fire starting.
A hand lens can be used to start a fire. 
( z1 possible :ARG1 ( z2 use :ARG1 ( z3 lens :mod ( z4 hand ) ) :ARG2 ( z5 start :ARG0 z3 :ARG1 ( z6 fire ) ) ) )