Since the publication of my letter to your Lordship, on the history and construction of our Astrological Clock, I have been requested to make an addition or two to that paper, in order to its being more fully illustrative of the subject. In the first place, perhaps the mere representation of the figure of the balance which is given in the thirty-third volume of the Archæologia, page 28, does not convey a precise notion of its end and aim, and therefore another diagram, representing it as applied to the escapement, would be more explanatory: secondly, it has been suggested that to many readers not familiar with the forms of the mediæval horloge, a general drawing of our table-clock would be an acceptable illustration: and thirdly, Count Krasinski, of a distinguished Polish family, who investigated the story and times of Sigismund the Great, has further strengthened me with circumstantial evidence respecting Queen Bona, the presumed original possessor of the clock. On these grounds, therefore, I again trespass on your Lordship's time.