502 EEPORT— 1880. 



field possible, but also to the other, of no less moment, that nearly the entire 

 motion of the revolvin<^ armature should be either one of approach to or of 

 withdrawal from the poles of the field-magnets. [Various methods of accom- 

 phshing this object were described and illustrated by drawing models.] Electro- 

 motive engines with field-magnets of more than two poles are more perfect 

 in their action than others with field-magnets of two poles only, mainlj' be- 

 cause in the former the line of attraction, as exercised between the two sj'stems 

 of poles is at angles varying from 80 to 1 degrees from the motion of the poles 

 of the armature, whUe in the latter the line of attraction very nearly coincides 

 with the line of motion. The relative positions to each other of the axes of the 

 systems of field-magnets and the magnets constituting the armature, and the ratio 

 of power of the two systems, are both matters awaiting careful investigation from 

 men of science, and further researches in this most important and interesting field 

 of work must lead to immediate progress. With regard to the former question 

 we have as j'et only the vague, unsatisfactory hypothesis of ' fines of force,' and 

 the latter point appears to have escaped altogether the notice of both inventors 

 and investigators. 



11. On a New Mode of Illuminating Microscopic Objects. 

 By Philip Brahaji, F.C.8. 



12. On an Iiistrument for the Detection of Polarised Light. 

 By Philip Bkaham, F.C.S. 



