A silence is not an absence
Much of what we know about who lived and worked at the corner comes from one source: the Rotterdam address book, printed almost every year. It is easy to read it as a census. A name at a door means someone was there; no name means no one was. The second half of that is wrong, and the address book says so itself. When the directory shows no one at an address, what may we conclude?
Less than it looks. At the foot of its street list the book prints a rule for the homes it leaves out, and they are the cheapest ones. The 1917 page gives the fullest form: it sets aside the upper flats of weekly-let dwellings, and the weekly-let dwellings below three guilders' rental value. Other years print a shorter rule that excludes only the weekly-let dwellings whose tenant keeps changing. The note names kinds of dwelling and rent, not the occupation or circumstances of every omitted household.
Even where the book does list a building, the print drifts from it. The unit range printed against a firm changes almost every year, even though the people inside stay where they are. From 1915 to 1918 Van Duffelen & Pelt appears now at one span of units, now at another, though the same households live at 169b and 169c throughout. The 1917 page shown here is one example.
Duffelen & Pelt, v., meubelfabrik., behang. & stoffeerders - Rochussenstraat … … 169a-b
The directory can also lag behind events. Van Duffelen & Pelt had long stopped advertising for work at the corner, yet the directories went on listing the firm there as furniture manufacturers, keeping the old trade at the old address for years after its last traced advertisement at no. 169.
It is still useful as one witness among several.
Where the address book is silent, the population register's household cards supply a named household and dated moves. On the back of Cornelis Pelt's card the corner appears first as Coolhavenkade 169, later as Rochussenstraat 169c, and then comes his move to Snellinckstraat 10a on 22 March 1921.
The cards date the founders' departures from the corner too: Cornelis Pelt on 22 March 1921, and the van Duffelens, for Zeist, on 4 May 1921.
The whole table rests on the rule the book prints against itself: a silence is not an absence.