The first reliable spark plug was invented in 1903 by Oliver Lodge. They're aptly named as well; spark plugs are simply insulated plugs that are screwed into an internal combustion engine's cylinder head to deliver the spark that ignites the mixture of air and fuel in the combustion chamber.
Are Irish Twins Technically Twins? Irish twins are not technically twins, meaning two people born from the same gestational period. It's a colloquial way to classify siblings that are born close together. Sometimes the use of the term Irish twins is expanded to describe any siblings that are close in age. Some even stretch the definition to include siblings less than two years apart. Some would call that almost Irish twins or practically Irish twins..
Identical (Monozygotic) Twins. Identical Twins (Flickr: evilpeacock). Identical twins came from a single egg that split into two. Theyâre genetically identical and (obviously) always the same gender. Early first trimester ultrasound scan can identify approximately two-thirds of monozygotic twins.Our own twins were mis-diagnosed at a second-trimester ultrasound as identical (they werenât).raternal twins came from different eggs and are siblings, but not genetically identical. This is the more common type of twin, representing about two-thirds of twin pregnancies. When conceived naturally, fraternal twins indicate that two eggs were released by the motherâs ovaries instead of one.