April 24, 1913] 



NATURE 



ib'g 



held that there was subject-matter in such an omission. 

 A process had been proposed for preparing dyes called 

 anisolines (A) from rhodamines (r) by first forming a 

 potassium salt (ist step=/), and then transforming 

 this salt into anjsoline (2nd step = F). Thus the known 

 process was : — ■ 



A=F[/(r)]. 



Now it was shown that the potassium salt did not 

 exist, i.e. j(r) was imaginary ; the patent in question 

 obtained anisoline direct from rhodamine, A = /(r), and 

 this was held to be an invention. 



I may note two final points. When a patent is 

 granted, the criterion of ingenuity is not applied, as 

 this is left for the Court to determine. However, if 

 there is absolutely no ingenuity possible, the Law 

 Officer may refuse to grant a patent. His criterion 

 of rejection is, therefore, not j(x) = f(a), as > n the 

 Court, but f(x) = f(a). 



A patent is invalid for " insufficiency of description " 

 if it casts on the public the burden of experiment 

 beyond a certain point. This may be expressed by 

 saying that in this case the equation I = <£(a) is in- 

 determinate. Harold E. Potts. 



University Club, Liverpool, April 2. 



A University in the Tropics. 



The importance and value of the establishment of a 

 university in the tropics can only be appreciated fully 

 by those who, trained in the universities of Europe, 

 are suddenly brought face to face with the unfamiliar 

 conditions obtaining in a tropical country. That the 

 proposition may be thoroughly considered and even- 

 tually realised must be the wish of all interested in 

 the development of our tropical possessions. 



The question of a site for an imperial tropical uni- 

 versity is one upon which divergent views may be 

 expected ; few men know the equatorial belt with 

 uniform intimacy, and are liable in consequence to be 

 prejudiced in favour of one part or another. Admit- 

 ting my own imperfect knowledge, I would like to 

 bring forward the claims of British East Africa as 

 an eminently suitable situation for such a university. 



Dissected by the equator, it cannot be equalled for 

 position in British territory. Rising from sea-level to 

 plateaus more than 8000 ft. in altitude, with a moun- 

 tain rising more than 17,000 ft., far above the snow- 

 line ; with heavy rainfall in one part and almost rain- 

 less deserts in another ; with healthy districts and 

 parts uninhabitable by man in consequence of deadly 

 disease ; with soils varying from coral through sands 

 to loams and clays ; with standard crops from cocoa- 

 nuts, rubber, and cotton, to coffee, maize, and wheat ; 

 with a large native population possessing many 

 different languages and customs ; with a flora and 

 fauna as diversified as climate and altitude, and prob- 

 ably as varied as is to be found in any country ; with 

 a geological structure presenting some of the most 

 interesting features in the world — British East Africa, 

 the onlv British territory through which the equator 

 passes, is surely uniquely situated for the seat of an 

 imperial tropical university for the study and advance- 

 ment of our knowledge of medical, agricultural, 

 botanical, zoological, anthropological, ethnological, 

 and other branches of science. 



The capital of the country, Nairobi, is situate 

 within 100 miles of the equator, is in a healthy dis- 

 trict, is twenty-four hours by rail from the coast 

 tropical belt, and the same distance from the Victoria 

 Nyanza and Uganda, both full of the most diverse 

 subjects of scientific interest. 



The proximitv of India is another great advantage 

 in this respect. Practically all the natural conditions 

 obtaining- there — even acquaintance with the natives 



NO. 2269, VOL. 91] 



and their languages— may here be studied while resid- 

 ing in a climate resembling an English summer. 



If any more suitable position for an imperial tropical 

 university can be found than Nairobi, then the British 

 Empire is indeed most fortunate, but a glance at the 

 map does not suggest the possibility of such a collec- 

 tion of favourable factors occurring elsewhere. The 

 passage is seventeen days, with choice of five steam- 

 ship lines. U. H. Kirkham. 



Government Laboratory, Nairobi, February 24. 



The Twinkling of Stars. 



In three papers in The Journal of Pliysiology I have 

 described a number of new visual phenomena which 

 show that the photochemical stimulus is situated ex- 

 ternally to the cones, and that the foveal region is 

 sensitised from the periphery of the retina. The 

 result of this is that at one moment the foveal region 

 may be the most sensitive part of the whole retina, 

 and at another blind. The twinkling of stars may- 

 be imitated in the dark-room. If a small light be 

 looked at in a dark-room, as, for instance, that 

 coming through the smallest diaphragm cf my colour 

 perception lantern, which represents a 5+ in. bull's-eye 

 railway light at a thousand yards when seen at a 

 distance of 20 ft., care being taken not to move the 

 eye, the light will appear to twinkle like a star. It 

 will be noticed that pale bluish-violet circles start at 

 the periphery of the field of vision, and, gradually 

 contracting, reach the centre. On reaching the centre 

 the light brightens. If the circles stop the light 

 disappears. The colour of the circle is the same for 

 white light or any colour. 



There is another simple experiment which shows 

 how the centre of the retina is sensitised from the 

 periphery. On opening one eye on awaking in the 

 morning and looking at the ceiling, the central portion 

 is seen as an irregular, circular, rhomboidal, or star- 

 shaped black spot. On closing the eye again a bluish- 

 violet circle appears at the periphery or middle of the 

 field of vision, contracts, and then, after breaking 

 up into a star-shaped figure and becoming brighter, 

 disappears, to be followed by another contracting 

 circle. If the eye be opened when the star figure 

 has formed in the centre it will appear as a bright 

 rose-coloured star much brighter than any other part 

 of the field of vision. If, however, we wait until the 

 star has broken up and disappeared before opening 

 the eye, it will be found that only a black spot is 

 seen in the centre. F. W. Edridge-Greex. 



London, April 14. 



Gain of Definition obtained by Moving a Telescope. 



A slight adaptation of the explanation offered by 

 your correspondent Mr. G. W. Butler (April 10, 

 p. 137) appears to furnish a more natural solution 

 of the problem. When an object at rest is seen 

 against a background which it closely resembles there 

 is nothing to differentiate between the object and the 

 slight irregularities of the background. So soon as 

 the object moves, such a differentiation becomes pos- 

 sible, the moving irregularities being now attributed 

 to their real origin. It seems unnecessary to assume 

 a " cumulative impression of contrast." 



The following simple experiment lends support to 

 this explanation. A small opening is cut in a sheet 

 of paper covered with irregular markings, such as 

 ink dots. Against the back of this is held another 

 sheet similarly marked. If now the sheets are ob- 

 served from such a distance that the edges of the 

 opening are invisible, its position cannot be determined 



