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..
1. Dichorionic/Diamniotic (di/di) twins. Di/di twins are the most common type of twins and the lowest risk. Di/di twins can be identical if the egg split very early, but fraternal twins are always di/di. In di/di twins, each twin has their own placenta and their own amniotic sac. Di/di twin pregnancies have increased risks over singleton pregnancies, but this is the best case scenario in twin world. The biggest worries tend to be going into preterm labor and making sure both babies are growing adequately.