/'/ti>t(t!fni/>/iii- RiKearvluH and Portrait nn- HI 7 



very little tlie inetliod ot' procedure, of clianffinpf sometimes Us a|ij)lnaUoiis. 

 Tliero Hie a gootl many iie«(utives or piiiitu also lef'eiiiiij^ to tlie matter, some 

 intelligihie, some needing an interjjretution, wlucii I have been unable to 

 supply. To one series of such, clearly involving distant objects, I have 

 already drawn attention (see p. :n6) ; a gowl deal of the matter refei-s to 

 fairly near objects, and the Hrat experiments — to judge by the photo- 

 graphs — seem to have Ix'en made on a series of shelves or racks at the Kew 

 ()i)servatory. Then (ialton photographed a bronze horse (Carousel) and de- 

 termined the three coordinates of eight to eleven points of it in a variety 

 of ways. It is really wonderful thirty years later to see the amount of 

 lal)our he put into work of this kind. A reader of Nature might conclude 

 that his communications to it were brilliant suggestions written in a few 

 hours. This, I U'lieve, was never the case; he rarely refers to a tithe of his 

 experimental work, the calculations, trials and failures he had made Ix'fore 

 preparing his paper; in many cases a paper was written over and over again 

 before it assinned its final form, and if a reader of the latter thinks the result 

 could have been more eiisily reached by another niethod, it is extremely 

 probable that that method could be found, experimentally tested and silently 

 rejected, in one or other of Galton's preliminary notebook records. If he tried 

 and condemned a method, he scarcely ever stated that he had done so. He 

 assumed that his readere would suppose him to have surveyed the country 

 before plotting the selected path to his goal. 



Galton started with the general problem of studying the perspective of 

 a photograph; he did this by the simple method of photogmphing with his 

 subject some horizontal reticulation, or if needful lx)th a horizontal and a 

 vertical reticulation, and this served as the bjusis for analysing the perepective 

 properties of the photograph. Galton shows that photographic measurements 

 of objects may be tlivided into two classes ; those in which we measure lengths 

 parallel to the focal i)lane of the camera, and those in which we measure other 

 lines, and in this case we may require two photographsof the same object taken 

 simultaneously from difterent aspects. The mathematics of the latter are by 

 no means complicated, and are provided by (talton, but his dominant passion 

 for the study of heredity soon led him to the measurement of animals, and 

 by proper orientation of the animal the principal measurements Galton was 

 seeking can be obtained from a single standardised photograph, provided it 

 is accompanied by suittible reticulations or tiducial lines. 



In one of his many notebooks I find the draft of a paper which starts 

 thus: 



"Architecturiil dniughtiiuieii iire familiar witli the art of tniiislatiiig objects into their per- 

 spective representations, but the converse process of translating perspectives into their objective 

 etjuivalents has never, I believe, been yet brought into practice'. So long as pictures had to be 



' It was not an uncommon problem before even 1890 to ask engineering students to draw 

 a model in {K-rspectivo and then take the measurements of parts of the original model from the 

 perspective drawing. It must bo confessed, however, that it was done with the view of testing 

 dniwing accuracy and possibly suggesting the superiority of plan and elevation drawings. 

 It would certainly have been giKxl experience to have obtained measurements of the parts of 

 machines by double photographs of them accompitiic<l b^- suitable reticulations. 



