The Royal Society began requiring an oath of secrecy from the members who attended meetings

October 25, 1674

Birch, History, vol. III, p. 137, 15 October 1674 (O.S.) in London:

It being reprefented, that the permitting of such, as are not of the Soeiety, to be present at the meetings thereof, is both troublesome and prejudicial to the same, it was ordered, that the repeal of that stature, which allows such an admission, and which is the second of the fourth chapter, containing the statutes about the ordinary meetings of the Society, shall be propounded at the next meeting of the council.

It being likewise represented, that the liberty of divulging what is brought in to the meetings of the Society is also prejudicial to the same, and renders divers of the members thereof very shy of presenting to them what they have discovered, invented, or contrived; it was moved, that a form of a statute might be prepared, injoining secrecy to the members of the Society in such matters, as shall be brought in, and by the president or vice-president declared to be kept secret, as the communicators desire.

A form to this end was proposed as follows:

"Every fellow of the Royal Society shall make a solemn promise before the the same, not to discover, directly or indirectly, to any person, not being of the Society, such observations, experiments, or other communications, as shall be brought in to the meetings of the  same, and there by the president or one of the vice-presidents declared to be kept secret, at the desire of the communicator."