ADDENDA. 



Galton in the Appendix to his Memories of my Life gives a bibliography 

 of 179 memoirs, books, articles and papers written by himself. I have been 

 able to increase this by 59 titles, and am only too conscious that others may 

 still have escaped me. It is indeed difficult in the case of a life as long as 

 Galton's to discover all the side channels into which he poured the ideas of 

 a fertile mind in the hope of reaching one or another section of the 

 community, and so irrigating the arid wastes of prejudice. I can only trust 

 that nothing of first-class importance may have escaped my notice. But 

 neither Galton's own collections of memoirs and letters nor those preserved 

 by his relatives cover by any means all that he wrote even in the years with 

 which they deal. Just as I have closed my volumes with nothing I thought 

 remaining but the indexing, I have come across two omitted papers of 

 considerable interest. 



In the case of the first paper — an important one — my excuse must be 

 that while there are two papers by Galton in the xxvith volume of Nature 

 there is only one entry under his name in the Index, and having come across 

 in opening the text one paper, I did not expect and look for a second. Of 

 the other omitted paper I found the abstract given below among my notes, 

 when checking certain entries in the index ; it was marked for incorporation 

 in Chapter XI of Vol. II, but a fitting place not having been found for it 

 there, it had been overlooked and so omitted entirely. 



I fear these two papers may not be the only omissions ; if so, my sole 

 excuse must be that working independently, I have been more comprehensive 

 than earlier bibliographers, including even Galton himself. 



Addendum I. 



"A Rapid-View Instrument for Momentary Attitudes." This paper 

 appeared in Nature, July 13, 1882*. In it Galton suggested a very simple 

 mechanism for obtaining with direct vision an almost instantaneous picture of 

 a moving object. His purpose was twofold, (i) to transmit a brief glimpse of 

 a moving body — thus by aid of it he was able to see the wheel of a bicycle 

 at full speed as a well-defined and apparently stationary object — and (ii) to 

 transmit two or more such glimpses separated by short intervals, and to 

 cause the successive images to appear as simultaneous pictures in separate 

 compartments in the same field of view. 



Tlie power of the eye to be impressed by a glimpse of very brief duration has not, I think, 

 been duly recognised. Its sensitivity is vastly superior to that of a so-called "instantaneous" 

 photographic plate when exposed in a camera, but it is of a different quality, because the 

 impression induced at each instant of time upon the eye lasts barely for the tenth of a second, 

 whereas that upon a photographic plate is cumulative. There is a continual and rapid 



* Vol. xxvi, pp. 249-251. 



