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shown experimentally without the known facts having led to the 

 discovery of their intimate connexion. To this important investi- 

 gation Ohm determined to devote the remainder of his life. The 

 peculiar views which he had adopted in his researches in electricity 

 respecting the interior constitution of bodies and of the molecules of 

 which they consist, appeared to him to throw a new light on the na- 

 ture and co-relations of the forces referred to. Following out these 

 ideas, he established the general properties, form, and arrangement 

 of the molecules; he attributed to them simple and polar powers; he 

 determined their relations to the various external actions, and thus 

 gradually formed a complete system, from which he saw the pheno- 

 mena of light, heat, electricity and magnetism evolve themselves. 



Of this projected work on ' Molecular Physics,' only one volume 

 has appeared, which was published in 1849 under the general title of 

 " Contributions to Molecular Physics," vol. i., and with the special 

 title of " Elements of Analytical Geometry of three dimensions 

 according to the system of oblique-angled co-ordinates." This in- 

 troduction he thought necessary, because the ordinary mathematical 

 methods did not appear to him to apply themselves to his ideas with 

 sufficient simplicity and conciseness. He dedicated this work to 

 the Royal Society of London, " whose approbation," he says, 

 " tempered his courage, which had previously been softened by 

 disheartening treatment, to renewed efforts in the field of science." 



Whilst Ohm was, with incessant industry, carrying out his great 

 undertaking, he was, towards the end of the year 1849, unexpectedly 

 called to fill the vacant place of Conservator of the Physical Collec- 

 tion at Munich. Agreeable as this appointment must have been to 

 him, and in accordance with the new scientific direction he had 

 taken, still the event is to be regretted, as the arrangement of the 

 Museum and the construction of new instruments withdrew his 

 attention from continuing and completing his great work. During 

 this time he published a memoir of great interest on the phenomena 

 of interference in uniaxal crystals. 



In 1852 changes occurred which induced Ohm to relinquish the 

 official position he had gained in Munich and to become Professor 

 of Experimental Physics in the High School of that city. Not con- 

 tented to restrict himself to the customary demonstrations and ex- 

 planations, which would have cost him but little exertion, he pre- 



