Five Class 10 variants were introduced between 1904 and 1910.

Two Class 2 variants were introduced between 1905 and 1910.

Seven Class 16 variants were introduced between 1914 and 1935.

Several important technical innovations were introduced between 1875 and 1914.

The W6 class was introduced between 1951 and 1955 and are still in service today.

An audience was introduced between the practice and subsequent test trials.

No major changes were introduced between 1.0 and 1.1.

Initially, only one aircraft was purchased, but a total of eight were introduced between 1965 and 1985.

The drugs introduced between 1950 and 1965 came to dominate the treatment of hypertension.

These services were to be gradually introduced between 1969/70 and 1970/71 utilising the new 707s.