NATURAL PHILOSOPHY. 145 



account might be given of those considerations which lead all who have 

 thought much on the subject to feel sure that the difficulty arises from the 

 restrictions placed upon the means of solution amounting to a little too much 

 dictation to the nature of things. For it must be remembered that the prob- 

 lem is not to square the circle, nor to trisect the angle, but to square the 

 circle or trisect the angle without recourse to any means except those 

 afforded by Euclid's first three postulates. This limitation is frequently 

 omitted ; and persons are led to conclude that mathematicians have never 

 shown how to square a circle, or to trisect an angle, than which nothing can 

 be more untrue. I may take occasion to raise a query in some future com- 

 munication, whether these difficulties would ever have existed if Euclid's 

 ideas of solid geometry had been as well arranged as his ideas of plane 

 geometry. 



The reader may find details on this subject in the articles QUADRATURE 

 and TRISECTION in the Penny Cyclopasdia. But further information will 

 be found in Montucla's Histoire des Recherches sur la Quadrature du Cercle, 

 Paris, 1831, 8vo. (second edition). This work contains, besides the vagaries 

 of the insufficiently informed, an account of the attempts of older days, 

 which ended in useful discovery. In later times the whole subject has 

 lapsed into burlesque ; the few who have made rational attempts being lost 

 in the crowd who have made absurd misconceptions of the problem. To 

 square the circle has become a byword, though many do not know the prob- 

 lem under a change of terms, say the rectification of the circumference. 



And so much for the impossible problems, which have caught so many in- 

 genious minds, and almost always held them tight. For this reason, I should 

 advise any one not to try them. 



SCHOKBEIX'S ELECTRICAL PAPER. 



By a process similar to that used in the preparation of gun-cotton, Schb'n- 

 bein has succeeded in converting paper into a perfectly transparent sub- 

 stance, which, by the slightest friction, becomes extraordinarily electrified, 

 and which he employed in the construction of an electrical machine. 



Such a substance must be in the highest degree acceptable to the experi- 

 mental physicist, and it is so much the more to be regretted that Schdnbein 

 and Bottger have published nothing further on this subject, although elec- 

 trical paper is now offered for sale in Berlin. In most cases the electrical 

 paper can be replaced by thin sheets of gutta percha. 



SIMPLE ELECTRIC MACHINE. 



M. Thore united the ends of a strip of paper about eight inches in width, 

 so as to make a continuous band of it, and stretched it on two wooden pul- 

 leys covered with silk, one of which was rapidly turned around by a handle ; 

 the electricity was developed by pressing a warmed flat-iron upon the paper 

 as it passed over one of the pulleys. He describes the effects as remarkable. 



There is nothing new in the observation of the electricity developed by 

 paper, and many of our machinists have noticed how often the bands of their 



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