24 SIXTH REPORT. — 1836. 



dification, and thought the subject highly worthy of the learning 

 and ability so conspicuously displayed by the English mathematicians. 

 He did not consider the ordinary theory of electrical distribution, or 

 the experimental data on which it depended to be so completely free 

 from objection, as to render all doubts of its accuracy unpardonable ; 

 he thinks that the attractive forces between charged and neutral 

 bodies in a free state depend only on the surfaces immediately oj)- 

 posed, without regard to aay hypothetical distribution arising from 

 the peculiar form or disposition of the unopposed parts ; he has cal- 

 culated from very simple elements, the force which should arise be- 

 tween opposed planes and spheres, and bodies of various forms, 

 whether connected or not with other masses, without any reference 

 whatever to the distribution of the charge, and finds the result veri- 

 fied by experiment. 



A Series of Experiments in Electro-magnetism, ivith Reference to its 

 Application as a Moving Power. By the Rev. J. W. M'Gauley. 



Mr. M'Gauley thought it might not be inappropriate to men- 

 tion to the Section what he had done in the application of electro- 

 magnetism to machinery since the last meeting of the British Asso- 

 ciation. He would mention the principal difficulties which remained 

 to be overcome, after the construction of the working model he 

 had exhibited at Dublin. These, he believed, he Aad overcome, and 

 had in his possession a machine of not inconsiderable power. 



1st. Powerful magnets were to be constructed : the ordinary ones 

 were very imperfect, and their effect limited to inconsiderable di- 

 stances ; their size could not be very great, as the helix must be propor- 

 tioned to the iron, to saturate it, and yet cannot extend beyond a 

 certain distance from it, or it will be inefficient, perhaps of inju- 

 rious effect. A number of coiled bars cannot be united so as to form 

 one great magnet : their poles could not be reversed, they would act 

 on each other in a greater or less degree by induction. 



2ndly. The action of several magnets cannot easily be united, since 

 all the poles cannot be reversed at the same time precisely. 



3rdly. If we succeed in uniting their action, that action is not 

 easily applied to machinery : for let B be a bar of iron traversing 

 between the magnets M and M'. 

 Let B be the position of the 

 bar when C R is the position 

 of the crank, B' its position 

 when the crank is at C R', a 

 dead point : if the bar is not 

 ready to leave the magnet M', 

 the inertia of the machinery 

 carries on the crank, and the engine is broken, or the bar torn off, 

 which very often deranges the reversion of the poles, nor can the 

 mechanism applied in other cases to prevent this injurious effect, be 

 here adopted. 



Mr. M'Gauley exhibited a reversing apparatus, different from that 

 noticed last year, in which mercury is not required, and the difficulty 



