Notice of Dr. Scoresby^s Magnetical Investigations. 35 



the results are arranged in a lucid and philosophic manner. We 

 have no space to enter into the details of the experiments, but the 

 results are of such interest that we cannot better occupy our pages 

 than in communicating them to our readers. 



The relative powers of the magnetized bars and their combi- 

 nations, were principally determined by their power of deflecting 

 the needle of a given compass. Lest, however, this method 

 should be considered as deficient in accuracy, a sufficient num- 

 ber of comparisons were made between it and the method of tor- 

 sion, to show that it was to be relied upon, when used in the 

 manner and under the circumstances adopted by Dr. Scoresby. 



It appears from the investigations in these volumes ; 



1. That the magnetic capacity of iron is ia proportion to its 

 ductility, a property existing in the highest degree in the purest 

 iron. 



2. That steel made from the purest iron possesses the highest 

 magnetical properties. 



3. That any single bar or plate of magnetized steel is more 

 powerful or energetic proportionally, than two or more corres- 

 ponding and equal bars ; that is to say, that its magnetic force is 

 greater than the half of that exerted by two acting together, and 

 so on. 



4. That a combination of bars or plates in contact with each 

 other, is more powerful than any single bar of the same weight, 

 but that the gaiu of power by each additional plate diminishes 

 progressively. 



5. That continual additions to a powerful combination of bars 

 or plates, cease to be beneficial beyond a limited extent, in conse- 

 quence of the impracticability of obtaining a large series of bars 

 or plates exactly alike. 



6. That the gain in power of any combination of bars or plates 

 over equal masses in a solid bar, is greater when the plates, in- 

 stead of being in contact with each other, are separated ; and 

 this augmentation improves as the spaces between them are en- 

 larged. 



7. That by the separation of the plates or bars, a larger num- 

 ber of them may be combined to advantage. 



8. That temper has a great influence on the relative powers of 

 combinations of steel plates, but that different degrees of temper 

 have different degrees of advantage, in bars or plates of different 

 sizes. 



