The first bricks may have been made as sandstocks. This from an 1875 Brunswick cottage, might be an example.
|19th century frogless|
It looks like the typical small frog Hoffman brick, with the all capitals and Large 'H' was in use from about 1880. based on the brick below from Robertson's killing house at the City Abattoirs, collected when it was demolished in the 1980s.
|c1910 standard frog|
|Late 20th century, deep screw impressions|
|c1970s barred frog version|