10 SIR J. COCKLE ON MATHEMATICAL HISTORY. 



building-up are more favourable on one side than another ; 

 so that we may get showers of acicular snow when a strong 

 wind prevails. On the same principle the one side of a 

 rope may be covered with hoar frost turning in the direc- 

 tion of the wind ; but the same thing can sometimes be still 

 better seen on a fir all the leaves of which are covered with 

 acicular hoar frost, these needles in the same way all 

 having a direction against the wind. 



The temperature when the crystal figured fell was between 

 — io°-5 C. and -ii°-4 C. 



III. Notes bearing on Mathematical History. By Sir 

 James Cockle, F.R.S., Corresponding Member of tlje 

 Society. 



Read October 1 9 th, 1875. 



I . To the list of Professor Boole^s writings which follows 

 the preface to the Supplementary Volume of his ' Differ- 

 ential Equations ' [2nd (posthumous) ed., 1 865, pp. viii- 

 xi] may be added a paper, entitled " Mr. Boole's theory 

 of the mathematical basis of logic,'' published in the ' Me- 

 chanics' Magazine' (1848, vol. xlix. pp. 254-255). 



2. Mr. Blissard in his " Theory of Generic Equations " 

 (Q. J. of Math. vol. iv. p. 279, vol. v. pp. 58 and 185, 

 see also pp. 184 and 325) has applied "representative no- 

 tation " very extensively. Professor J. R. Young had no- 

 ticed (Mech. Mag. 1847, vol. xlvii. p. 627) that the law 

 of Bernoulli's numbers is expressed by 

 (i+B)"-B„=o, 

 if we write the exponents of B belovr instead of above that 

 symbol. Judging from what purports to be an examination 



