Analysis of information sources in references of the Wikipedia article "Sans-serif" in English language version.
Figgins 1828 [is] one of two known copies, but with the first known appearance of the world's second sans-serif type, not in the other copy
[T]he Figgins 'Sans-serif' types (so called) are well worth looking at. In fact it might be said to be that with these types the Figgins typefoundry brought the design into typography, since the original Caslon Egyptian appeared only briefly in a specimen and has never been seen in commercial use. One size of the Figgins Sans-serif appears in a specimen dated 1828 (the unique known copy is in the University Library, Amsterdam).…It is a self-confident design, which in the larger sizes abandons the monoline structure of the Caslon letter for a thick-thin modulation which would remain a standard model through the 19th century, and can still be seen in the ATF Franklin Gothic. Note that there is no lower-case. That would come, after 1830, with the innovative condensed 'Grotesque' of the Thorowgood foundry, which provided a model for type that would get large sizes into the lines of posters. It gave an alternative name to the design, and both the new features – the condensed proportions and the addition of lower-case – broke the link with Roman inscriptional capitals…But the antiquarian associations of the design were still there, at least in the smaller sizes, as the specimen of the Pearl size (four and three quarters points) of Figgins's type shows. It uses the text of the Latin inscription prepared for the rebuilt London Bridge, which was opened on 1 August 1831.
[T]he Figgins 'Sans-serif' types (so called) are well worth looking at. In fact it might be said to be that with these types the Figgins typefoundry brought the design into typography, since the original Caslon Egyptian appeared only briefly in a specimen and has never been seen in commercial use. One size of the Figgins Sans-serif appears in a specimen dated 1828 (the unique known copy is in the University Library, Amsterdam).…It is a self-confident design, which in the larger sizes abandons the monoline structure of the Caslon letter for a thick-thin modulation which would remain a standard model through the 19th century, and can still be seen in the ATF Franklin Gothic. Note that there is no lower-case. That would come, after 1830, with the innovative condensed 'Grotesque' of the Thorowgood foundry, which provided a model for type that would get large sizes into the lines of posters. It gave an alternative name to the design, and both the new features – the condensed proportions and the addition of lower-case – broke the link with Roman inscriptional capitals…But the antiquarian associations of the design were still there, at least in the smaller sizes, as the specimen of the Pearl size (four and three quarters points) of Figgins's type shows. It uses the text of the Latin inscription prepared for the rebuilt London Bridge, which was opened on 1 August 1831.