Electricity. — Survey of the Persian Gulf. 229 



Several thin glass tubes (previously tried by metallic coat- 

 ings) were coated outside with copper foil, and about half-filled 

 with the melted substances, having wires dipping into them, 

 similar to small Leyden vials. The resinous coating, how- 

 ever, distributed no charge over the interior of the glass tubes 

 when connected with the machine, which would have been the 

 case with conductors. 



Upon removing the copper coatings and wires, substituting 

 pointed wires bent at right angles, resting against the interior 

 of the glass tube beneath the melted bodies, and suspending 

 them successively from an electrified conductor, placing a 

 metallic rod outside opposite the points, sparks passed in all 

 cases perforating the glass. 



The last cases would indicate that melted resinous bodies 

 are not conductors, and the results obtained in the first in- 

 stance may possibly be referred to heated air about the ap- 

 paratus. T. G. — Journal of Science, Jan. 1825. 



MOTION OF THE ELECTRIC FLUID. 



It has long been received as a fact, that an electrical dis- 

 charge was capable of being transmitted through a very con- 

 siderable distance (say three or four miles) instantaneously, 

 and without any sensible diminution of its intensity. Mr. 

 Barlow, however, by employing wires of various lengths, up 

 to 810 feet, and measuring the energy of the electric action by 

 the deflection produced in a magnetic needle, has found tha? 

 the intensity diminishes very rapidly, and very nearly as the 

 inverse square of the distance. Hence the idea of constructing 

 electrical telegraphs is quite chimerical. He found, also, that 

 the eflFect was greater with a wire of a certain size, than with 

 one smaller, yet that nothing was gained by increasing the 

 diameter of the wire beyond a given limit. 



SURVEY OF THE PERSIAN GULF. 



The surveying vessels. Discovery and Psyche, will leave 

 Bombay about the end of the month to continue the survey of 

 the Persian Gulf; the examination of which has been com- 

 pleted from lias Moosendem, at the entrance, to the island of 

 Bahrein. Until the year 1821, the coast, with the exception, 

 of a small portion containing the pirate ports, was compara- 

 tively unknown. In the vicinity of the Cape it is high, rugged, 

 and intersected by deep estuaries, the two largest of which 

 have been named alter the present governor of Bombay, 

 and connnander-in-chieC, Elphinstone's Inlet, and Colville's 

 Cove. It was this part that obtained from the ancients the 

 denomination of Asabo, or Black Mountains ; without doubt 

 from the colour of the; rocks, which arc principally composed 



of 



