Proceedings of the Institution of Electrical Engineers Volume 16 (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: 153 ABSTRACTS. E. L. FRENCH?A EELATION BETWEEN MAGNETISING FORCE AND COEE OF MAGNET. (Electrician and Electrical Engineer, Vol. 5, No. 60, Dec., 1886, iy, 445-46.) It is of interest to know the greatest number of ampere.turns that can be used economically on a given core. The currents for several cores of gradually increasing size were first ascertained; the highest economical currents were then plotted for each magnet, and a final curve was drawn, taking these highest economical currents as abscissae and the diameter of the cores as ordinates. The simplified equation for this curve, giving the relation between the current and the diameter, is y = 9 x ? 26 ai3 + 22 x1 - 0-7 x ? 0-22. Having thus found the current for a given core, it must be multiplied by the number of turns to get the magnetising force. The horseshoe electro-magnets experimented upon varied in diameter from 1-22 cm. to 6-34 cm., the length of each limb being about 20-8 cm. Above each bobbin on the electro-magnets, a small space was left, under the armature, in which a narrow coil of fine wire could be placed. The electro-magnets were excited by an accurately measured current from a dynamo. The narrow coil of fine wire was connected to a galvanometer, so that on reversing the main current the induced current in the narrow coil could be measured. From this the strength of the magnet is arrived at, as it is proportional to the sine of half the angle of deflection. DEBB.AY ? BEPORT OF THE CHEMICAL SECTION OP THE ACADEMY OF SCIENCE ON ME. MOISSAN'S EXPERIMENTS FOR THE SEPAEATION OF FLUORINE. (Comptes Bfndu.s, Vol. 103, No. 19, A'ov. 8, 1880, pp. 850-60.) The question of the separation of fluorine is one which has long occupied the attention of chemists, though up to the present time all ...