536 DR. SCHULTHESS ON THE APPLICATION OF 



tricity to make soft iron magnetic. In the year 1825, Sturgeon mag- 

 netized cylindrical horseshoes of soft iron by means of copper wires 

 wound round them, connecting the ends of the wires with the plates of 

 an electromotor. Professor Van Moll of Utrecht saw this experiment 

 performed in the physical laboratory of tiie London University by Mr. 

 Watkins, and he obtained on repetition those remarkable results de- 

 scribed in Bibl. Univ., cah. 45. p. 19. This new method of communi- 

 cating such great attractive power to iron created in me the desire of 

 repeating the experiments, and principally of taking into consideration 

 the application of this attractive power, which it appears may be 

 infinitely increased, to some useful purpose. I give these experiments 

 to the public in the conviction that a force so easily evolved and so very 

 powerful justifies repeated and varied experiments. In my experiments 

 the electromotors employed were without doubt smaller than any hi- 

 therto used, and these notwithstanding produced the same results : new 

 circumstances and new laws were observed and discovered respecting 

 the manner of increasing the magnetic power evolved by electromotors, 

 of producing. in them currents now similar, and now different, some- 

 times in the same, sometimes in opposite directions, and by the success 

 of these experiments of setting a lever in motion in different ways, and 

 thus finally enriching natural philosophy with a new motive power." 



It is easy to imagine with what avidity I read this notice, partly from 

 joy at seeing my idea, of the practical application of which I still had 

 many doubts, mentioned by another person, and partly somewhat vexed 

 that the priority of my invention, if it really was as useful as my fancy 

 made me think it, was snatched away from me. I therefore read with 

 intense eagerness this paper; but my expectations were in a great mea- 

 sure disappointed ; for it was only at the end that Dal Negro gave some 

 short, and to me not altogether comprehensible hints concerning his ex- 

 periments en the application of the power of electro-magnets to moving 

 machinery, after having described a considerable number of other expe- 

 riments, the principal object of which was to give with the least possible 

 means to a soft-iron horseshoe the greatest possible magnetic power. He 

 took seven different horseshoes, varying from 0*29 to 5 killogramraes* 

 in weight : the cojiper wire with which he enveloped them, in from 37 

 to 61- coils, had a diameter of 8*2 to 8*4 mill. ; the zinc plates of the four 

 different electromotors had surfaces = l, |, 2J, and 4f square feet 

 each ; the dilute acid employed consisted of ^j^y of sulphuric acid and ^ 

 of nitric acid in 1 of water. With these electro-magnets Dal Negro 

 obtained remarkably powerful results. The largest, (weighing 5 kil- 

 log., surrounded with 64 coils of copper wire of 8'4 millim. diameter,) 

 with the armature weighing 2 killog., when connected with the largest 

 electromotor, supported from 1 08 up to 1 1 7 killog. Dal Negro attri- 



* [1 milliniplre =: -03937 English inch. 



1 killogrammc = 2 lbs. 3 oz. 5 dram. — Trans. ] 



