824 REPORT— 1897. 



9. Demonstration of the Pendidtom Chronoscope aiid Accessory 

 Apparatus. By Dr. E. W. Scripture, Yale University. 



The pendulum chronoscope contains, in the first place, an accurately adjusted 

 double-bob pendulum. This pendulum is held by a catch at the right-hand side. 

 In making an experiment this catch is pressed noiselessly and the pendulum starts 

 its swing. It carries along a light pointer held in position by a delicate spring. 

 At a definite moment it presses a delicate catch which releases the mechanism 

 beneath the base. This mechanism is adjusted to do several things : one of them 

 is to drop a shutter which covers an opening at the back of the chronoscope. The 

 person experimented upon is seated at the back ; owing to the curtain he can see 

 nothing but the covered opening. He finds before him a rubber button like that 

 on a telegraph-key. He is to press this button as soon as he sees the shutter 

 expose the opening. He does so, and another mechanism releases a horizontal bar 

 running behind the scale. The pointer swings between this bar and the scale, and 

 is consequently stopped when the bar snaps against the scale. The zero-point is 

 passed at the moment the shutter starts to fall ; the marks on the scale indicate 

 the number of thousandths that elapse till the button is pressed. The instrument 

 is built with the greatest accuracy. For reaction to light, coloured cards or pieces 

 of transparent celluloid are inserted into a holder just behind the shutter. 



The reactions to light are not disturbed by noises, as the pendulum makes no 

 noise either at release or during its swing, and the shutter makes only a faint 

 Boimd. 



For reactions to sound without further apparatus, the shutter is arranged to 

 strike with a noise. In this case a constant quantity is subtracted from the scale. 

 For these reactions it is generally preferable to insert a telephone with a battery in 

 circuit with the platinum contact about to be described. 



The shutter rests against a platinum point in such a way that its movement 

 can be used to break an electric circuit ; this can be used ibr producing lights, 

 sounds, electric shocks, &c. A strong electro-magnet is placed beneath the base 

 in such a way that it can take the place of the button ; thus the pointer can be 

 caught by the movement of a key in the hands of a distant person. An arrange- 

 ment is also provided whereby the pendulum itself is released electrically. Still 

 further mechanisms are added for various purposes. 



Among the accessory apparatus are a newly invented lamp battery, a simple, 

 cheap and convenient arrangement which changes a high voltage dynamo current 

 into a low voltage current suitable for ordinary battery purposes^e.^., to run 

 tuning forks, telegraph instruments, bells, &c. 



[For a full account of the chronoscope see Scripture, ' New Psychology,' p. ]5o, 

 London, 1897 : and of the lamp batteries see ' Studies from the Yale Psychological 

 Laboratory,' vol. iv., p. 76.] 



10. The Tricolour Lantern for Illustrating the Physiology and Psychology 

 of Colour-vision. By Dr. E. W. Scripture, Yale University. 



By means of special triple slides and accessory apparatus, the fundamental laws 

 of colour-vision can be demonstrated. The newer theory of colour-blindness is 

 illustrated by some specially devised slides. 



[A full description of the lantern is given in the author's ' New Psychology,' 

 p. 348.] 



11. Observations on Visual Contrast. 

 By C. S. Sherrington, M.A., M.D., F.R.S., Liverpool. 



1. On a parti-coloured disc let two concentric circular bands, each composed of 

 the same two colours alternately disposed, be inscribed, and the arrangement of the 

 Component colours be such as to, in one band (A), minimise the contrast of the 



