"I have been informed that this mill was where Seel, or Seal Mill is now, at the end of Hertford town, towards Stevenage; and that an adjoining meadow is still called Paper-mill Mead. This Seel Mill, so denominated from the adjoining hamlet, was erected in the year 1700; and is noted for being the first that made the finest flour, known by the name of _Hertfordshire White_. It stands upon the river Bean, in the middle of three acres of meadow land, called Paper-mill Mead, so denominated in the charter of King Charles I. to the town of Hertford for the fishery of a certain part of that river. Hence, perhaps, some have thought it was at Stevenage, but there is no water for a mill at or even near that place." The French authorities are particularly unhappy on the subject of the introduction of the art of paper-making in England. According to the _Dictionnaire de la Conversation_, "la première manufacture, établie à _Gertford_ en Angleterre, est de 1588;" while the _Encyclopédie des Gens du Monde_ asserts that "la première patererie de chiffons qu'eu notre pays fut établie en 1312; celle d'Angleterre en 1388." A. GRAYAN. THE PENDULUM DEMONSTRATION. (Vol. iv., pp. 129. 177. 235. 277.) Since my last communication on this subject (Vol. iv., p. 235.) I have been engaged in examining the theory, and the experiments connected with it, somewhat more closely; and, in the meanwhile, I abstain from replying to the last observations of A. E. B. (Vol. iv., p. 277.) A. E. B. says it was "uncourteous" in me to call the theory which he put forward _his_ theory. I beg pardon for the offence. I intended by the expression merely to indicate the particular theory which he advocated. I believe its author is M. Chesles. The theory in question is: "That the variation of the pendulum's plane is due to the excess of velocity with which one extremity of the line of oscillation may be affected more than the other." I ventured to pronounce this to be untenable, and begged A. E. B. to "reduce it to paper." Upon this he remarked: "H. C. K. is surely not so unphilosophical as to imagine that a theory, to be true, must be palpable to the senses. If the element of increase exist at all, however imperceptible in a single oscillation, repetition of effect must eventually make it observable. But I shall even gratify H. C. K., and inform him, that the difference in linear circumference between two such parallels in the latitude of London, would be about 50 feet; so that the northern end of a 10 feet rod, placed horizontally in the meridian, would travel less by that number of feet in twenty-four hours, than the southern end. This, so far from being inadequate, is greatly _in excess_ of the alleged apparent motion in the place of the pendulum's vibration."