126 The Rev. Thos. P. Kirkman on 



and called 3Bi. The number of equivalent tapes used is 

 r20'8= 1 60. 



16. There are yet questions about primes, belts, and 

 irreducibles that might be easily raised and disposed of in 

 reasonable limits ; but they are forbidden ground. They 

 are too closely connected with the elementary theory of the 

 polyedra, upon the teaching and learning of which, over 30 

 years ago, was imposed, by the highest scientific tribunal, a 

 solemn and dire taboo. This is on record in p. 165, 

 Vol. CLII., 1862, of the Philosophical Transactions, in the 

 very last printed sentence of my complete Theory of the 

 Polyedra, thus: "Thus we have demonstrated, in this second 

 section, that the data of article xxxvi. are sufficient for the 

 entire completion of the tables A, B, C, D (xxxi. . . . xxxvi.) 

 for faees and for summits. All that remains for the com- 

 plete solution of our problem, of classification and enumera- 

 tion of the P-edra Q-acra and of the P-acra Q-edra, is that 

 we show how these data can be obtained and registered, 

 without ambiguity or repetition. We shall consider first the 

 reciprocals of the faces (d) (/) xxxvi., and the edges (jf) 

 xxxvi." 



The taboo is the sudden, loud, and long silence of that 

 close. 



My first two sections are very summary statements of 

 things to be distinguished and well-arranged in large groups> 

 before handling in detail, and not quite easy to a reader of 

 less than a De Morgan's power. De Morgan read them 

 easily, and very early, without a complaint of my obscurity, 

 and, simply and only from the little just printed, so far shaped 

 to himself what was coming, that he could write the letter 

 now before me, dated "Adelaide Road, N.W., April 18, 

 1862," expressing his satisfaction with it, with acute and 

 kind remarks on the success which he foresaw. But then, I 

 am here bound by candour to own that Professor De Morgan, 



