Note: Of spherical lenses, there are six varieties, as shown
in section in the figures herewith given: viz., a
plano-concave; b double-concave; c plano-convex; d
double-convex; e converging concavo-convex, or
converging meniscus; f diverging concavo-convex, or
diverging meniscus.
{Crossed lens} (Opt.), a double-convex lens with one radius
equal to six times the other.
{Crystalline lens}. (Anat.) See {Eye}.
{Fresnel lens} (Opt.), a compound lens formed by placing
around a central convex lens rings of glass so curved as
to have the same focus; used, especially in lighthouses,
for concentrating light in a particular direction; -- so
called from the inventor.
{Multiplying} {lens or glass} (Opt.), a lens one side of
which is plane and the other convex, but made up of a
number of plane faces inclined to one another, each of
which presents a separate image of the object viewed
through it, so that the object is, as it were, multiplied.
{Polyzonal lens}. See {Polyzonal}.
Impunity will multiply motives to disobedience.
--Ames.
2. (Math.) To add (any given number or quantity) to itself a
certain number of times; to find the product of by
multiplication; thus 7 multiplied by 8 produces the number
56; to multiply two numbers. See the Note under
{Multiplication}.
3. To increase (the amount of gold or silver) by the arts of
alchemy. [Obs.]
{Multiplying gear} (Mach.), gear for increasing speed.
{Multiplying lens}. (Opt.) See under {Lens}.