fire-brigade is brought to bear. Plans have been proposed, both here and in America, for remedying this evil by the use of the telegraph. The instantaneous intelligence that it would communicate to the fire preventive force of the metropolis would result in the saving of an immense amount of property and life. In America, a project has been discussed in the council of New York, for running a telegraph from the fire look-out, on the City Hill, (what an excellent place, in time past, our St. Paul's would be for such a purpose!) to each of the eighteen police-stations, to give intelligence of the whereabouts of every fire; so that on hearing the great bell, a person in any part of the city could ascertain at the station-house where the fire was raging. A large amount of loss to life and the assurance offices would thus be annually saved. To exemplify how usefully the telegraph would come into play, it appears, from the report of Mr. Braidwood, "the fire-king," that, in fewer than 834 serious fires, and 1022 alarms, and the number of lives lost, 29. Apropos of proposals for ameliorating these matters, and for applying the telegraph to these philanthropic purposes, we have—

1846, there were no

THE ELECTRIC FIRE ALARUM.

Mr. G. Petrie, the telegraphist at the London and Blackwall railway, proposes to facilitate the saving of buildings and property from destruction by fire, also to save with certainty, the lives of the inmates of dwelling-houses which may happen to take fire, and to prevent depredations by thieves, by means of elec

tricity; causing the fire itself or the thieves themselves to act necessarily upon apparatus which shall convey audible, visible, and sensible alarm signals to the inmates or to watchmen.

These several alarm signals may be made to operate either by the breaking or by the completing of the electric circuits, according to whichever plan may be most convenient for the particular apparatus employed; and in all cases the electric circuits may be broken or completed either by springs, or by wires and vessels of mercury. The electric circuits are broken or completed by fire in the following manner: either by means of the flame which runs up the walls, or else by means of the heated air which rises to the ceiling. The flame running up the wall, comes in contact with an inflammable cord, which runs horizontally along the wall, and the burning of this cord in any part, lets fall a weight which allows a spring to fly back and break or complete the electric circuit. The hot air which rises to the ceiling operates by causing the expansion of mercury or air, or any other elastic or non-elastic fluid which is contained in tubes and other vessels or by causing the expansion of metallic rods or sheets, or any other suitable solid substances—or by the depression of mercury by the expansion of enclosed air.

THE SMALLEST BATTERY.

MR. E. HIGHTON, C.E., states that he has made a battery which exposes a surface of only one-hundred

part of an inch; it consists but of one cell; it is less than one ten-thousandth part of a cubic inch, and yet it produces electricity more than sufficient to overcome all the resistance in the inventor's brother's patent gold-leaf telegraph, and works the same powerfully. It is, in short, a battery which, although it will go through the eye of a needle, will yet work a telegraph well. Mr. Highton had previously constructed a battery in size less than the one-fortieth of a cubic inch. This battery he found would, for a month together, ring a telegraph bell ten miles off.-Paper read before the Society of Arts.

THE LARGEST TELEGRAPHIC LINE.

NEWHAVEN has been put into telegraphic communication with Toronto, Upper Canada; and messages have been instantaneously exchanged between the two capitals. The route is viâ New York, Albany, Rochester, Buffalo; then crossing the Niagara river, below the Falls, and passing round Lake Ontario to Toronto; the entire distance being nine hundred miles! The experiment was a most successful one, and the distance has been overcome with as much ease and promptness as between Newhaven and Hertford, or thirty miles. The above was, in 1847, the longest distance yet traversed by electricity in a continuous, unbroken line.

T. C. Savill, Printer, 4, Chandos-street, Covent-garden.