342 Proceedings of the Royal Society 
take a repartee; he would “ nothing extenuate nor set down ought 
in malice.” 
It was when in the midst of an apparent health and vigour 
which promised more years of public usefulness, that his friends 
who knew him intimately, and the public who knew him by name 
only, were startled and shocked by the news of his sudden death, 
due, as was afterwards ascertained, to rupture of the heart, on the 
25th January of this year, and consequently when he was in the 
seventy-first year of his age. 
Another generation of Edinburgh doctors must be created and 
become extinct, before it will be forgot that the character of an 
excellent practitioner, a valuable servant of the public and the pro- 
fession, an amiable domestic man, a genial friend, and a true 
Christian gentleman, were united in the person of Andrew Wood. 
The following Communications were read : — 
1. On a Particular Case of the Symbolic Cubic. By Dr. 
Gustav Piarr. Communicated by Professor Tait. 
§ 1. The method by which Hamilton has established the sym- 
bolical cubic 
(1) m — + m 2 <£ 2 - <£ 3 = 0 , 
and more particularly the relation 
(2) — m 1 - m 2 <f> + <£ 2 , 
is founded on a generalisation of the result 
(3) rnxfj ~ 1 ( VA/x) = V (<p t \.cfi f [jL ) , 
where <f> represents a linear and vector function, and <£' its conjugate 
according to the definition 
S p<f> cr = S crcfip . 
In the most general case of <pp the expression of this function is 
reducible to a vector sum of three terms of the form aScqp, and the 
directions which is susceptible of representing are generally not 
limited in space. 
We may now conceive a class of cases in which the expression of 
<f>p is reducible to the sum of two terms only, and in which the 
