If a properly-tempered steel needle be introduced into a magnetizing bobbin connected with a battery of constant current, battery and bobbin comprising the circuit, it acquires a total determined magnetism at the end of a period which appears not to exceed that of its introduction. On slowly with drawing the needle, it is found to retain residual magnetism, which, together with the total magnetism, increases with each repeated introduction until a limit is reached. The needle may be magnetized in the bobbin by three other methods: 1. Establishment: Introduce the needle; establish the current; slowly withdraw the needle. 2. Interruption: With a closed circuit introduce the needle slowly; break the current and withdraw the needle. 3. Instantaneous charge: Introduce the needle; establish and break the current; withdraw the needle. Repetitions of any of these three processes (all things being equal) insure an augmentation of the needle's magnetic moment. The last method is the best, but care must be taken to introduce the needle and current always in the same position, so as not to reverse the poles.