NOTES. 



Page 6, line 10. It is worth while to compare the following passage from 

 Plato's ' Republic,' Book vii. (Jowett's translation) : 



"After plane geometry, we took solids in revolution instead of taking solids in 

 themselves ; whereas after the second dimension the third, which is concerned with 

 cubes and dimensions of depth, ought to have been followed. 



" It is true, Socrates ; but these subjects seem to be as yet hardly explored. 



" Why, yes, T said, and for two reasons ; in the first place, no government patro- 

 nises them, which leads to a want of energy in the study of them, and they are 

 difficult ; in the second place, students cannot learn them unless they have a 

 teacher. But then a teacher is hardly to be found, and even if one could be found, 

 as matters now stand the students of these subjects, who are very conceited, would 

 not mind him ; that, however, would be otherwise if the whole state patronised 

 and honoured them, then they would listen, and there would be continuous and 

 earnest search, and discoveries would be made ; since even now, disregarded as 

 they are by the world, and maimed of their fair proportions, and although none of 

 their votaries can tell the use of them, still these studies force their way by their 

 natural charm, and very likely they may emerge into light." 



P. 11, 1. 44. Compare with this the latter part of Plato's ' Philebus,' on know- 

 ledge and the handicraft arts ; also Prof. Jowett's ' Introduction ' thereto. 



P. 13, 1. 40. See ' Trattato della Pittura,' by Leonardo da Vinci ; also the 

 ' Memoir on the MSS. of L. d. V.,' by Venturi, 1797. 



P. 14, 1. 2. ' The Gentleman and Cabinet Maker's Director,' by Thomas 

 Chippendale, London, 1754. 



' The Cabinet Maker and Upholsterer's Drawing Book,' by Thomas Sheraton, 

 London, 1793. 



P. 14, 1. 32. See Sorby's ' Address to the Microscopical Society,' 1876. 



P. 14, 1. 38. 'Phil. Trans, of the Royal Society,' 1870, p. 333; and 1870, p. 27. 



P. 14, 1. 42. < Phil. Trans.,' 1877, p. 149. 



P. 15, 1. 6. 'On Attraction and Repulsion resulting from Radiation,' 'Phil. 

 Trans.,' 1874, p. 501 ; 1875, p. 519 ; 1876, p. 325. 



P. 15, 1. 9. ' Philosophical Magazine,' April, 1878. 



P. 15, 1. 10. 'Philosophical Magazine,' 1875, Vol. ii., pp. 337, 446: 187 

 Vol. i., p. 321 ; 1878, Vol. i., p. 161. 



P. 15, 1. 20. PoggendorfFs ' Annalen,' Tom. xxxv., p. 337. 



P. 15, 1. 21. ' Royal Society's Proceedings,' 1878. 



P. 15, 1. 28. The Papers on the Telephone are too numerous to specify. 



P. 15, 1. 29. See various Papers in ' Nature,' and elsewhere, during the last 

 twelve months. 



1878. C 



