[24] The German word _Kette_ has been translated as "circuit" throughout. Although the equivalence of these words is clear, for example, in Ohm's work of 1826, the context in which _Kette_ is sometimes used in 1820 and 1821 indicates that the concept of a "circuit," in the sense of the wiring external to the source of electricity, has not been established. The wiring is regarded more as something incidental, used to "close" the cell, the cell being considered essentially the whole of the apparatus. This view underlies the many attempts to correlate the Oersted phenomena with cell materials and design, and with the use of such terms as "chemical magnetism" by Erman and others. [25] The reference here is to the Oersted-type experiments described in two papers by authors other than Schweigger on pages 19 to 34 of the volume. [26] Op. cit. (footnote 19), pp. 422-426. [27] One "line" seems to have been about 1/12 inch. [28] J. G. POGGENDORF, "Physisch-chemische Untersuchungen zur näheren Kenntniss des Magnetismus der voltaischen Säule," _Isis von Oken_ (1821), vol. 8, pp. 687-710. Most of Poggendorf's numerical data is also in C. H. PFAFF, _Der Elektromagnetismus_ (Hamburg, 1824), along with some of Pfaff's own work. [29] Reported in _Annales de Chimie et de Physique_ (1820), vol. 15, pp. 222-223. [30] "On the Development of Electro-Magnetism by Heat," _Transactions of the Cambridge Philosophical Society_ (1823), vol. 2, pp. 47-76. [31] "Account of the New Galvano-Magnetic Condenser invented by M. Poggendorf of Berlin," _Edinburgh Philosophical Journal_ (July 1821), vol. 5, pp. 112-113. * * * * * Transcriber's Notes. The following assumed typographical errors have been corrected: Page 125: J. B. [Johann Bartholomacus] Tromsdorff--should be Johann Bartholomäus Trommsdorff? Page 134: "paper of April 2, 1821,[22] is quite"--had "1921." Footnote 13: "_Geschichte der Elektrizität_"--had "Elektrizitat." Footnote 16: "_Journal für Chemie und Physik_"--had "and." One questionable spelling has been retained as follows: Footnote 20: "Sur le Multiplier electro-magnetique..."--should be "Multiplicateur"? * * * * * CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY: PAPER 39 FULTON'S "STEAM BATTERY": BLOCKSHIP AND CATAMARAN _Howard I. Chapelle_ SURVIVING DESIGNS FOR FLOATING BATTERIES 145 CONTROVERSIAL DESCRIPTIONS 147 COPENHAGEN PLANS 150 HISTORY OF DOUBLE-HULL CRAFT 152 SAIL AND INBOARD PLANS 157