Intelligence and Miscellaneous Articles. 155 



The author does not consider that it may be admitted as proved, 

 that the sulphur becomes opake on account of the transition of the 

 oblique prisms into rhombic octohedrons. Pasteur did not find any 

 octohedrons among the fragments of prisms which had been formed 

 from sulphur in solution ; and the author found that, in consequence 

 of the crystallization of the utricles, octohedrons might be contained 

 in the oblique rhombic prisms which are obtained from sulphur by 

 melting. Therefore when octohedrons are found in prisms of sul- 

 phur, they have originated from previously formed utricles, and do 

 not indicate a transition of the oblique rhombic prism into the 

 rhombic octohedron. — Comptes Rendus, vol. xxxiii. pp. 338-540. 



ON THE ELECTRO-MAGNETIC MOTOR OF FESSEL. 

 BY M. PLUCKER. 



It is known that Mr. Page, a physicist in North America, has 

 recently endeavoured to produce a motive power by an extended 

 application of the force which attracts a mass of iron within an elec- 

 tro-magnetic helix. Th. Hankel of Leipzic has made the same 

 attempt, and has established an important practical law, namely, 

 that this force is as the square of the power of the current. M. Fessel 

 has on his part constructed a model of a machine at my request, the 

 value of which I am not for the moment able to appreciate in case 

 it were made on a large scale, but which as a piece of physical ap- 

 paratus explains and clears up the application of the force in question. 



The model of Fessel is formed of two helices placed end to end 

 in a horizontal position. They serve to conduct the current always 

 in the same direction, but in such a way that it traverses alternately 

 each of the two helices, and consequently only one at a time. In 

 the interior of the helices is a bar of iron, which is alternately 

 attracted from the one into the other by constantly maintaining the 

 same polarity, and which thus executes a motion backwards and 

 forwards. To the two extremities of the bar are fixed two slender 

 horizontal shanks of brass, which rest upon two pulleys attached to 

 the two extremities of the apparatus, and which thus support the 

 whole weight of the iron. One of these shanks sets a wheel in 

 motion. A commutator is moved by an excentric by means of a 

 directing-rod, which is placed so as to be able to make the machine 

 move backwards and forwards as in steam-vessels. In one of the 

 machines the commutator has been fixed immediately to the axis. 



Two couples of Grove's cells are sufficient to communicate to this 

 apparatus a great rapidity. With six couples, the rapidity became 

 such that it threatened to break the apparatus; and fearing this, I 

 stopped the passage of the current. 



1 bave just received from him the news that he has nearly com- 

 pli ted the construction of a new apparatus, in which he has replaced 

 the pulleys by oscillating shanks of mclal rod, similar to the os- 

 cillating cylinders of lb. Bibliothi que I iiinrstllc th 



Gt n< vt ■ I '' '•' mber 1851 . 



