The letters (in Dutch) illustrate that Co was very often invited to symposia and events to present his work and that for the sake of his health he often had to refuse.
He also had quite a few demands when presenting on such occasions and he charged a fee of 100 Dutch guilders (roughly 50 euro/USD) for a lecture.
Apparently, the general interest in the application of science to solve crime was as big in 1925 as it is today!
Nowadays, the CLHC together with the IIS organizes the successful Frontiers of Forensic Science lecture series that frequently attract over 100 attendants.
Several Spui 25 sessions on forensic science have been organized and well attended and forensic scientists within the CLHC are frequently asked to present their work to the general public and science community.
All presentations on forensic science in Amsterdam are nowadays given free of charge!