1879 *] Correspondence . 317 
made without any such previous knowledge, references to the 
older observations were given in the account communicated to 
the Royal Society of Edinburgh, and Mr. Aitken has courteously 
permitted me to peruse his paper in confirmation of the fadt. I 
will only add that no mention of previous workers appeared in 
the abstracts given by the scientific press which came under my 
notice ; and the inference that Mr. Aitken was not aware of the 
existence of these when his paper was presented to the Society 
appeared to be confirmed by the title he gave it, describing the 
phenomenon as “ A New Variety of Ocular Spedtra.” 
I am happy, however, to make the corredtion which Mr, Aitken 
has pointed out to me. — I am, &c., 
S. P. Thompson. 
University College, Bristol, 
March 13, 1879. 
