MECHANICAL AND USEFUL ARTS. 109 



the pattern, of course, being in connexion with one pole of a battery, 

 and the bobbins or magnets with the other. Thus, as the tinfoil 

 slowly moves round, the parts which are not to be worked, beiug 

 covered with a non-conducting varnish, transmit no current through 

 the brass teeth to the bobbins. The pattern, or exposed portion of 

 the tinfoil, on the contrary, does so, and transforms the bobbins into 

 electro-magnets, which attract and hold the bars opposite their points 

 attached to the threads of the warp, which, as the lever descends, 

 the bars are thus held up for the instant, and, of course, raising their 

 threads below, and allowing the shuttle to be passed between. The 

 first machine, constructed at Turin, was afterwards modified by M. 

 Hipp, at Berne ; and though it demonstrated the possibility of 

 weaving by means of electro-magnetism, it nevertheless left much 

 to be desired with respect to the success of its practical application. 

 It was not until 1859 that success in perfecting the machinery, and 

 in rendering it available for either hand or power-loom weaving, was 

 attained. 



M. Bonelli has patented his improvements, the abridged specifi- 

 cation of which is thus given in the Mechanics' Magazine — 



By a novel construction and arrangement of mechanism, the patentee is en- 

 abled to dispense with the use of Jacquard cards, and of all the apparatus or 

 operations required for the reading and preparing of these cards from an original 

 pattern or design. For this purpose, instead of these cards, a single plate of 

 the same dimensions as one of these cards is employed. This plate bus openings 

 or perforations made in it corresponding in number to the horizontal needles of 

 the Jacquard apparatus. These openings or perforations are stopped or closed 

 when required by small iron rods, which are drawn forward at suitable times by 

 electro-magnets, but when these small rods are not drawn by the electro- 

 magnets, the openings or perforations in the plate will be left open. The insu- 

 lated wires of the coils of the electro-magnets are connected respectively to one 

 of a series of thin metallic plates which come in contact with the pattern, the 

 said pattern being for that purpose painted or drawn upon a flexible metallic 

 sheet with an insulating varnish ; or the design may be composed of a sheet- 

 metal pattern fixed upon an insulating layer or surface. In order to prevent in- 

 duction he winds the insulated wire of the coils of neighbouring electro-magnets 

 in opposite directions, and arranges the magnets so that the positive pole of one 

 magnet shall be next to the negative pole of its neighbour. 



APPARATUS FOR TESTING SILK. 



This apparatus has been invented by M. Froment, for testing the 

 tenacity and elasticity of Silks of different sorts. The dynamometric 

 portion of the apparatus is composed of a small thin and very flexible 

 lamina of steel horizontally fixed in its centre. Its extremities are 

 connected by two small rods to a single shaft rising to some height, 

 and having its upper extremity finely split for the purpose of fixing 

 the thread to be tested. When this thread is subjected to traction, 

 it causes the lamina or spring above described to bend, and this 

 motion is communicated to the hand of a dial-plate. When the 

 thread snaps, this hand remains at the point to which it had been 

 brought by the effect of the traction. The other portion of the appa- 

 ratus by which the traction is effected, is a piece of clock-work which 

 descends by its own weight. It is provided with a pair of pincers, 



