Safety arch (Arch.), a discharging arch. See under Discharge, v. t. --
Safety belt, a belt made of some buoyant material, or which is capable
of being inflated, so as to enable a person to float in water; a life
preserver. -- Safety buoy, a buoy to enable a person to float in water;
a safety belt. -- Safety cage (Mach.), a cage for an elevator or mine
lift, having appliances to prevent it from dropping if the lifting rope
should break. -- Safety lamp. (Mining) See under Lamp. -- Safety match,
a match which can be ignited only on a surface specially prepared for
the purpose. -- Safety pin, a pin made in the form of a clasp, with a
guard covering its point so that it will not prick the wearer. --
Safety plug. See Fusible plug, under Fusible. -- Safety switch. See
Switch. -- Safety touchdown (Football), the act or result of a player's
touching to the ground behind his own goal line a ball which received
its last impulse from a man on his own side; -- distinguished from
touchback. See Touchdown. -- Safety tube (Chem.), a tube to prevent
explosion, or to control delivery of gases by an automatic valvular
connection with the outer air; especially, a bent funnel tube with
bulbs for adding those reagents which produce unpleasant fumes or
violent effervescence. -- Safety valve, a valve which is held shut by a
spring or weight and opens automatically to permit the escape of steam,
or confined gas, water, etc., from a boiler, or other vessel, when the
pressure becomes too great for safety; also, sometimes, a similar valve
opening inward to admit air to a vessel in which the pressure is less
than that of the atmosphere, to prevent collapse.