If you don't mind doing some cross referencing and calculating, you can download this book from Archive.org:
Most of the popular films and plates available in 1924 are listed with speed numbers that don't correlate well to anything we use today. However, there is also a guide number listed for each product that can be plugged into the exposure tables elsewhere in the text to get sunny 16 exposure values. It's been awhile since I looked any of these up, but the fastest panchromatic emulsion I checked would have been about ISO 25. Most of the panchromatic emulsions were ISO 10 or less.