As I've been leas to believe, earlier films were slower and most likely higher in silver content. So perhaps similar experience?
The same essay I referenced earlier in My Leica and I states that the writer "generally work with a panchromatic film of medium speed (21º Scheiner) or a super speed film (27º Scheiner)".
As the book was published in Europe, my first assumption was that he was using European Scheiner (I had no idea there were two versions!), which this chart from 1952 gives as 8 ASA and 32 ASA respectively:
While the ASA/ISO was revised up in later years, 1952 was still the original Weston speeds, and as a long time user of Weston meters, I can confirm that 5 Weston in 1952 is definitely equivalent to 8 ISO today. So... yeah. That's slow. Too slow, really.
However, if he was using American Schneider, that puts us at 32 ISO and 125 ISO respectively - perhaps a bit more reasonable. Considering the one photo he has in the book was shot with Kodak Panatomic, a 32 ISO film, it could well be either.
Through the book, there's a lot of use of AGFA's Isopan F (40 ISO), Isopan FF (25 ISO), and Isochrom (40 ISO), and Perutz's Perpantic (about 40 ISO by today's standard.) There's also a couple of shots that used AGFA's Isopan SS, a 100 ISO film, so it was definitely possible to hit the triple digits in film speed then - but it looks like most were hovering around the 25-50 ISO mark.
Also, a side note, there's one shot taken of the Vienna Symphony orchestra using ambient light with a Telyt 200/4.5 on Isopan SS. and it is
sharp. We're truly spoiled by modern film emulsions!