Abstract This letter was lately sent by the author himself to the publisher, as it was printed at Paris in French, the substance wh reof is in English, as followes. It is now almost a twelve-month that I declared my self publickly in this matter of transfusion, and after I had grounded my conjectures upon divers reasons, and a number of experiments which I made joyntly with M. Emmerez, I resolv´d to expect in the sequel a further confirmation, by carefully observing all that should happen in the severall trialls, I intended to practise.