A very ingenious gauge for steam boilers, the character of which is indicated by the above caption, has been in operation for some time at the Fulton Works of Messrs. Pease & Murphy, cor. of Cherry and Corlears street, this city. The alarm consists of an electromagnet which can be placed in any place however distant from the steam boiler, and which will ring a bell whenever the water in the boiler falls below a certain line, also when the pressure of steam rises above a certain standard. The magnet which rings the bell is connected by wires to a battery and a column of mercury in a tube placed in the boiler is employed to break and close the galvanic circuit. When the circuit is broken the bell is silent, but when the pressure of the steam forces the mercury in the tube to close the circuit of the separated wires, the electro magnet at once operates a spring hammer that strikes upon a bell as long as the circuit remains closed. The alarm can be placed in the cabin of a steamboat, captains room or any place desired. The one at the Works mentioned is placed in the office, at a considerable distance from the boiler. The invention is a very beautiful one, and while it has everything to recommend it, we are not aware of any objection that can be urged against it.— We have seen the apparatus in operation, and any explanation required was kindly rendered by Mr. Murphy. The apparatus, we believe, can be kept in order at but little cost, the renewal of the battery being all the running expense required, and this cannot be much.