ταῦτα δηλώσω αὐτός τε νοσήσας καὶ αὐτὸς ἰδὼν ἄλλους πάσχοντας → I shall describe those symptoms, since I myself had the disease and witnessed as well what others were suffering
ătămussim, p. ad amussim, v. amussis.
atamussim ADV :: according to a ruler/level, exactly, accurately
atamussim = ad amussim, s. amussis.