452 



iVA TURE 



[March 12, 190S 



gravitation, wlicn it comes to light, will be of the saine 

 kind. 



In particular, the molecular aspect of reaction in gases 

 is passed under review. Reasons are brought forward for 

 holding that in gases all ultimate reactions are of necessity 

 mono- or bi-molecular. If this be so, the important work 

 now proceeding with regard to the effect of impurities in 

 promoting or inhibiting gaseous reactions must lead to 

 fuller knowledge of the transient molecules or radicals 

 which are formed in the destructive encounter of a pair 

 of the reacting molecules, and are the carriers or inter- 

 mediaries leading finally to poly-molecular change ; while 

 the same transient combinations may be approachable in- 

 dependently from another side as affording the interpreta- 

 tion of the complex banded spectra of emission or absorp- 

 tion in gaseous media. 



The very remarkable and most fruitful and prophetic 

 symbolic theories of molecular structure, especially for the 

 comple.x molecules of organic chemistrv, have not yet 

 proved capable of dynamical interpretation ; it seems neces- 

 sary, however, to admit, on account of the wide range of 

 physical properties that are nearly atomicalh additive, that 

 stereochemical collocations do represent in some real way 

 the actual aggregation of the atoms instead of mere 

 symbolical representation of it. Recent investigation 

 appears to bring out in certain cases a somewhat definite 

 relation between the configuration of the molecule and the 

 crystalline form of its physical aggregations, which, though 

 reasonable, could not have been foreseen a priori ; exact 

 crystallographic measurements may thus in time afford 

 another intimate clue to the molecular structures in related 

 series of compounds. 



.4 .vyrir method of stereoscopic 



PTIOTOGRAPHV. 

 A N' entirely novel suggestion for the production of 

 stereoscopic photographs ' is proposed by Prof. G. 

 Lippmann in the current number of the Comptcs rendus 

 of the Paris Academy of Sciences (March 2). Let a lens 

 be constructed of a material possessing a refractive index n, 

 t\\i segments forming the front and back of the lens having 

 the same centre of curvature and the ratio of the radius 

 of_ curvature of the front segment to that at the back 

 being n— i. The front surface is the receiving lens, and 

 corresponds to the lens of the eye ; the back surface is 

 covered with the sensitive emulsion, and corresponds to 

 the retina. Owing to the chosen relation between the 

 curvatures of the two faces an image of a point is formed 

 by the front surface on the back one. The system is 

 reversible ; a ray of light proceeding from any point of the 

 receiving surface will pass out at the front over exactly 

 the same path as that taken by the incoming light in act- 

 ing on the sensitive film, and this will be true in spite of 

 any imperfection of the lens surfaces. 



Prof. Lippmann now imagines a material such as 

 celluloid moulded back and front, so that the whole surface 

 is covered with microscopic cells, each of which is an 

 elementary cell possessing the properties of the single lens 

 described above. The w-hole film resembles the compound 

 eye of insects. This plate, sensitised, is exposed in full 

 daylight to the objects to be represented, no photogra))hlc 

 lens being required. The result of the operation would be 

 a series of microscopic images fixed each on the " retina " 

 of one of the cells. Seen from the side of the sensitive 

 layer, the whole plate would present a uniformly grey 

 appearance. But seen from the front and illuminated frorn 

 behind the plate (supposed converted into a positive), the 

 photograph would appear, and would possess the following 

 peculiarities. It would appear in true relief, exactlv as in 

 nature, and shifting the eye about would produce' a change 

 ;n the photograph seen, the effect being as if the observer 

 stood in front of a w^indow. By stepping from side to 

 side, in the latter case, fresh portions of the landscape 

 "ould come into view, the whole always being bounded 

 I'v the four sides of the window. In the case of such a 

 |)lafe as that described, the effect would be preciselv similar. 



.As the author remarks in the paper, the technical difficul- 

 ^■'■^ m the prenaration of such a olale would be verv great. 

 I he chief difficulty would be the fulfilment of the con- 

 NO. 2002, VOL. 'Jj'\ 



liliiuii necessary for the clear definition of each image in 

 each elementary cell ; the ratio of the radii of curvature 

 must be equal to n— 1. Considering the thickness of the 

 film, this dilTiculty would appear to be insuperable, but it 

 Is to be hoped tliat an attempt will be made to put this 

 Idea into practice, liowever imperfectly. 



VNIVEKSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Camrridge. — During the last four years the average 

 income of the botanic garden has been 1708/., to whiih 

 the University chest has contributed 1175/., the rest being 

 made up of money from trust funds and from rents. The 

 botanic garden syndicate now points out that the in- 

 come is no longer sufficient to cover the expenses. The 

 syndicate estimates that in future, if the gardens are to 

 maintain their high position amongst kindred institutions, 

 some additional income must be found, and it is recom- 

 mended that the present grant from the University chest 

 to the botanic garden be increased by the sum of 220/. per 

 annum. 



The next combined examination for sixty-seven entrance 

 scholarships and a large number of exhibitions at Penr- 

 broke, Gonvllle and Caius, King's, Jesus, Christ's, St. 

 [ohn's, and E^mmanuel Colleges will be held on Tuesday, 

 December i, and following days. Mathematics, classics, 

 and natural sciences will be the subjects of examination at 

 all these colleges. Some of the colleges allow candidates 

 who intend to study mechanical sciences to compete for 

 scholarships and exhibitions by taking the papers set in 

 mathematics or natural science. The colleges desire it to 

 be known that anv candidate for a scholarship may signify 

 in writing his wish not to receive the emolument of the 

 same if elected thereto, and that such candidate may be 

 elected to a scholarship which may be honorary only and 

 without emolument, but shall carry with it all other 

 privileges attached to the position of a scholar. The 

 amount thus set free will serve to increase the number of 

 scholarships or exhibitions open to other candidates. 



Glasgow. — .'^mong the honorary degrees to be conferred 

 by the University on April 22 are the following: — LL.D. : 

 Mr. G. T. Beilby, F.R.S., chairman of the governors of 

 Glasgow and West of .Scotland Technical College ; Colonel 

 David Bruce, C.B., F.R.S. ; Dr. J. J. Dobbie, F.R.S., 

 director of the Roval Scottish Museum, Edinburgh ; Mr. 

 R. Kidstnn, F.R.S.'; and Dr. J. C. McVall, county medical 

 officer, .Stirlingshire and Dumbartonshire. 



Dr. R. Stewart MacDoc-gall, on his appointment to 

 the lectureship in botany in Edinburgh University, has 

 resigned his position as biologist on the staff of the Edin- 

 burgh and East of Scotland College of Agriculture. 



Mr. a. L. Bowlev, reader in statistics in the Uni- 

 versity of London, will give a course of ten lectures on 

 elementary applications of mathematics to statistical data 

 at the .School of Economics, at 7 p.m., on Thursdays, 

 March 26 and April 2, resuming after the Easter vacation 

 on May 7, and continuing thereafter for seven consecutive 

 Thursdays. 



The Earl of Roseberv will visit University College on 

 the afternoon of Thursdav, March 26, and will formally 

 open the new libraries and the new south wing, which 

 includes lecture-rooms for the faculty of arts, the depart- 

 ments of geology, hygiene, and experimental psychology, 

 also large extensions of the departments of applied mathe- 

 matics, of mechanical, electrical, and municipal engineer- 

 ing, and accommodation for the new hydraulic laboratory. 



The first volume of the report of the U.S. Commissioner 

 of Education for the year ending June 30, iqofi, has been 

 received from Washington. In addition to chapters 

 summarising the progress made during the year under 

 review in the various departments of American education, 

 the report contains a series of excellent articles on educa- 

 tional administration in various European and other 

 countries. A usefid simim.ary of the different sections of 

 the report is provided in the commissioner's introi'.iction, 



