Crystal Palace International Electric Exhibition 1881-82

16 [11.] 1846. HIGHTON’S GOLD LEAF TELEGRAPH. A small strip of gold leaf inserted in a glass tube passes through, the field of a permanent magnet and forms part of the line circuit. When a current passes through the gold leaf, it moves the latter to the right or left, according to the direction of the current. The alphabet is made by repetitions and com- binations of these movements, as in the Single-Needle Instru- ment. Batteries and commutators were used as in Cooke and Wheatstone’s single-needle system. [12.] 1848. HIGHTON'S NEEDLE TELEGRAPH. Used by the British and Irish Magnetic Telegraph Company. A horseshoe or circular magnet within a circular coil, and worked by a reversing key or commutator, is used. The signals are similar in principal to those of Cooke and Wheatstone's single needle. [13.] 1852. HIGHTON’S NEEDLE TELEGRAPH. Small form with, folding doors. Used by the British and Irish Magnetic Company. Identical in construction with the original form which it superseded. [14.] 1848. HENLEY'S MAGNETO-ELECTRIC DOUBLE- NEEDLE INSTRUMENT. Used by the British, and Irish Magnetic Company. The needles only move on one side of their vertical position, and the signals are made up of the single and combined movements of the two needles. This instrument requires two line wires, and is worked by the magneto-electric cuirent generated by moving the handle or handles. The interior needles are small straight bar magnets, playing between the semi-circular pole pieces of an electro magnet. The needle remains on the side on which it is left by the last current, which passes through the coils, and does not return to its vertical position by gravity, as in Cooke & Wheatstone’s needle instrument. [15.] 1848. HENLEY’S MAGNETO-ELECTRIC SINGLE- NEEDLE INSTRUMENT. Used by the British, and Irish. Magnetic Telegraph. Com- pany. Similar in action to the last-named instrument, but only one needle and one line wire were employed. The alphabet was produced by combinations of short and prolonged deviations of the needle, as in the Morse code.