Original sentence: For this reason, induction coils were sometimes called spark coils.One coil, called the primary winding, is made from relatively few (tens or hundreds) turns of coarse wire.The size of induction coils was often specified by the length of spark it could produce; an '8 inch' induction coil was one that could produce an 8 inch arc
Edited sentence: For this reason, induction coils were called spark coils.One coil, called the primary winding, is made from relatively few (tens or hundreds) of turns of coarse wire.The size of induction coils was usually specified by the length of spark it could produce; an '8 inch' induction coil was one that could produce an 8 inch arc