Pxiichological Invcstiyationa '2!2.'!i 



fastened square to the lino of sight at distances 7", 9", 1 1" and soon up to 41". 

 The curve of the frame aUing which the test hlocks are phiced was actutdJy 

 an e(|uiangular spiral. Colour sense. A series of hars packed closely with 

 coloured wools wound round their centres, and the examinee had to place 

 pegs against such of the hars as had any shade of green wound round them. 



Jmhjment of the Eye: As regards Lcm/th. A Hist har is shifted along until 

 a pointer is considered to hisect it, and a second bar until a pointer is con- 

 sidered to trisect it. A hinged lid in lK)th cases screens a swile on the top 

 of the bar, which lias a central fiducial mark and ^Joth graduations of its 

 whole length on either side. ^4.s- regards Perpendicularity'. A bar rotates 

 alKMit a screened pivot on a horizontjil table; this bar must be set i>erpen- 

 dicular to a line drawn on the table. When set, a lid is raised, and a jiro- 

 traetor rendered visible on which the difference of the setting and of true 

 |>erpeiulicularity can Ihj read off. 



(c) Instruments for measuring Sense of Touch were also exhibited but 

 not used. Some yeare afterwards Galton adopted as aesthesiometer dividera 

 applied to the nape of the neck^ 



(</) Later Galton dealt with the Sense of Smell, and in the Galton 

 Laboratory we still use his method and his very bottles ! The tests consist : 

 ('() in sorting out by smell from a number of bottles those having tlie same 

 contents and {b) in placing in order a number of bottles having various 

 intensities of smell of the same material. 



((') In the test of the Eye and Hair Coloxirs Galton used artificial glajss 

 eyes respectively dark blue, blue, grey, dark grey, brown grey (green, Tight 

 hazel), brown, dark brown, bhick. He also used standard samples of hair : 

 riaxen, light brown, dark brown, black, and three sluules of red : fair red 

 (golden), red, dark red (chestnut auburn). He was certainly among the first to 

 introduce standard sciiles of this kind, and, what is more, to realise the diffi- 

 culty of reproducing them. Such eye and hair .scjiles are common enough now, 

 but were by no means so in 1882, yet the difficulty remains of reproducing 

 them accurately even when manufactured by one firm. The glass eyes of two 

 standard scales are found not to have the same amount of pigment in them, 

 and the spun glass silk used for standard hair scales not always the same 



' Galton temi.s it "judgment of squareness," but I think such a name is better rei<erved for 

 another sort of test which 1 have [H-rsonally used. A nuinb»>r of rectangles, nut diverging widely 

 from squiires in Ixjth directions and containing one true 8(|unre, are given in confuse<l onlcr to the 

 examinee and he is tusked to give the nunil>er of the rectangle he considers square. In the same 

 way a number of ellipses differing slightly from a circle are given, and lie is a.sked to choose 

 the circle; of course in both ciwes without correcting glasses. By giving each member of an 

 audience a slip of paper as he enters, and throwing ellipses and rectangles on the screen by a 

 liuitcrn, I have lx)en able to nuuisure the a.stigmatism of 400 or 500 persons in a few minuU:«, 

 anil thus tind not only the average a.stigniatisni but the fi-efjuency distribution of astigmatism 

 at the same tiuia The meth<xl was suggest<'d to me by the contour of the dome of St Paul's, 

 which always setMns to me to have its major axis vertical, and to look ungraceful, until I rot«t« 

 iiiy head to the horizontal position, when it iK-comes gracefully pro})ortione<l. I found several 

 of my friends thought the minor axis of the dome vertical. This "judgment of squareness" 

 of course involves the error of judgment as well as astigmatism, but the latter is, I think, the 

 chief contributory factor. ' See our p. 222. 



