Watermarks of the line-engraved stamps 1840-79
The line-engraved stamps had either small crown or large crown watermarks
except for the ½d
which had its own half penny watermark over three stamps
small crown
1840-55
large crown
1855-79
For a summary of watermarks on line-engraved stamps go
here,
for a summary of watermarks on surface-printed stamps go
here
Most catalogues
illustrate the watermarks used during Queen Victoria's reign
I cannot reproduce them here for copyright reasons, hope you understand