NATURAL PHILOSOPHY. Ill 



The points in favor of the magneto-electric light are strong and 

 clear in relation to the increase of light. In cases where the light 

 is from lamp flames fed by oil, no increase of light at or near the 

 focus or foci of the apparatus is possible beyond a certain degree, be- 

 cause of the size of the flames; but in the electric lamp any amount 

 of lio~ht mav be accumulated at the focus and sent abroad, at of 



^3 * 



course an increased expense. In consequence of the evolution of 

 the light in so limited a focal space, it may be directed seaward, di- 

 verging either more or less, or in a vertical or horizontal direction, 

 at pleasure, with the utmost facility. The enormous shadow under 

 the light produced by the oil-flame burner, which absorbs and renders 

 useless the descending rays to a very large extent, does not occur in 

 the magneto-electric lamp ; all the light proceeding in that direction 

 is turned to account; and the optical part of the arrangement, 

 whether dioptric or reflecting, might be very small in comparison 

 with those in ordinary use. 



COLLIER AND BAKER'S IMPROVEMENTS IN THE ELECTRIC LIGHT. 



At a recent meeting of the Franklin Institute, Mr. A. L. Fleury 

 called attention to a magneto-electric machine invented by Messrs. 

 Collier & Baker, of Binghampton, as being the best adapted for all 

 purposes for which a large quantity of dynamic as well as static 

 electricity is required, and as especially applicable for the production 

 of the electric light. 



The invention consists, first, in certain means of controlling the 

 positions of the electrodes, by which they are kept properly in con- 

 tact with each other, as they wear away by the disengagement of the 

 particles, without the difficulty experienced in keeping up a proper 

 degree of separation between them. To produce a light in this way/ 

 has generally been supposed to be impracticable ; but the inventors, 

 by long-continued experiment, have found that by employing an elec- 

 tric current of very low intensity, but large quantity, they are ena- 

 bled to use the points in contact. The difficulty of keeping the 

 carbon electrodes pointed has resulted from particles of carbon being 

 carried over by the current of electricity from the positive to the neg- 

 ative pole of the electrodes. With a view to obviate this (viz., the 

 depositing of particles from the positive on to the negative pole), the 

 invention also consists, secondly, in frequently reversing the direction 

 of the current. To obtain this change of direction, the current of 

 electricity evolved from a magneto-electric machine is used without 

 the intervention of a frotteur or brake-plate, or else the current 

 from a galvanic battery can be used there being arranged in the 

 circuit a brake-plate or pole-changer, which is rotated by electricity, 

 by clock-work, or by any suitable mechanical means to produce a 

 frequent change in the direction of the current. This invention, dis- 

 pensing with expensive machinery, is a valuable contribution to 

 applied science, and will do much towards rendering this most bril- 

 liant light available. 



In the production of electric light, preference has generally been 

 given by scientific men to the employment of carbon electrodes, and 

 these mostly in the shape of pointed pencil?, as giving the most bril- 



