Sachgebiete

Beschreibung:

... Illustrated by Linear Plates Connected with the Detail of the new Telegraphic System ... Dedicated, by Permission, to the Right Honourable Lord Hawkesbury. Mit 5 (1 kolor.) gest. Tafeln von S. Neele. London, Printed for T. Egerton, Military Library, near Whitehall, 1808. 8vo. (20,8 x 12,8 cm). IV, 186 S. Neuer Halblederband mit Rückenvergoldung.

Bemerkung:

"Lieutenant-Colonel John Macdonald [1759-1831], F.R.S., who was already favourably known by two Reports on the Diurnal Variation ... publishes two treatises upon his 'Terrestrial Telegraph' ... His contrivance consists of thirteen boards or shutters arranged, like those of Edelcrantz, into three vertical ranks representing hundreds, tens and units. Twelve of the boards are capable of producing 4095 distinct combinations, and the thirteenth or auxiliary board, which is mounted over the centre of the apparatus, doubles that number. A flag or vane is added to the hundred side to distinguish it in whatever direction it may be viewed, and a ball sliding upon the staff which supports it affords the means of again doubling the number, so that, on the whole, 16,380 distinct signals can be obtained." (Mottelay S. 399). - Macdonald diente lange bei der East India Company, bevor er um 1800 nach England zurückkehrte u. sich neben seinem Militärdienst vor allem Fragen des Erdmagnetismus widmete. * Nicht in der Ronalds Libr. - Vgl. Poggendorff II, Sp. 5. - Leicht gebräunt, 2 Blatt mit alt restauriertem Ausriss.