November 27, 1919] 



NATURE 



343 



ApHKi.iA OK Planets and Comets. — Mr. C. D. 

 Perrine examines the grouping of these aphelia in 

 Proc. Nat. Acad. Sci., U.S.A., September, igig. The 

 grouping of aphelia of the minor planets about a 

 strongly marlced maximum in longitude 195° has been 

 pointed out before. It is shown that the aphelia of 

 the forty-five short-period comets are grouped in the 

 same manner. It is further remarked as a coincidence 

 (it can scarcely be more) that the aphelia of the eight 

 major planets are all situated in the same half of the 

 ecliptic, their centre of mean position being in the 

 longitude of the apex of solar motion. The aphelia of 

 the long-period comets appear to be grouped about two 

 maxima, the most strongly marked being near longi- 

 tude 90°, the other near longitude 270°. Mr. Perrine 

 notes that these are respectively the^ longitudes of the 

 antapex and apex, and deduces a theory that the 

 comets are captured from interstellar space. The 

 ■obvious difficulty presents itself that the great majoritv 

 of such objects would enter the sun's domain with 

 independent velocities of the order of several miles 

 per second, and their orbits would, in consequence, be 

 strongly hyperbolic. Mr. Perrine escapes from this 

 difficulty by suggesting that practically all these hyper- 

 bolic comets would pass too far frorii the sun for us 

 to see them ; we should only see those the independent 

 velocity of which was practically zero. These last 

 would, however, be only a very small fraction (perhaps 

 one in ten thousand) of the comets entering the sun's 

 domain, so the number of these would have to be 

 immensely large to supply the number of parabolic 

 comets that we see. The latter number is two or 

 three a year, so the former number would need to be 

 reckoned bv millions everv centurv. 



THK HRiriSH SC1K\'CE EXHIHITION, 

 GLASGOW. 



AN exhibition on similar lines to those of the British 

 ■^^- Science Guild's Exhibition of last summer is 

 now being held by the Corporation of Cilasgow, 

 with the assistance of a scientific advisorx committee. 

 The Kelvin Hall, in which the cxhibition'is held, was 

 erected for the purpose of holding a series of indus- 

 trial exhibitions, and the Corporation has a special 

 department for their organisation. The exhibits are 

 housed in a single building and on one level, so that 

 there is ample space for their display, and power i.s 

 available for setting machinery in motion and allow- 

 ing demonstrations of high-temperature operations. 

 The exhibits are, therefore, seen under very favour- 

 able conditions, and the response to the invitation to 

 exhibit has been very gratifying. Owing to an un- 

 fortunate combination of circumstances, .several firms 

 which were represented in London have been unable 

 to appear, and the absence of some of the leading 

 instrument firms is noticeable ; but manv of the 

 London exhibits reappear, in some cases in an en- 

 l:'rried form, whilst there have been many additions, 

 icially in regard to engineering and shipbuilding. 

 A very large area is covered, and an inspection of 

 the exhibition convinces a visitor that the objects 

 shown were well worth bringing together. The 

 ' normous progress made during the war and since 'the 

 •irinistice in the manufacture of products for which 

 \\r were entirelv dependent on importation is evident, 



1^ is the ingenuity displayed in the design of new 

 insiruments and machines, both for warlike and for 

 P' .iceful use. The relaxation of restrictions in regard 

 to secrecv has made it possible to show many improve- 

 ments which had been kept secret for .Tiilitar\ 

 reasons, .so that there is a most interesting series of 

 Instruments illustrating recent developments in wire- 



NO. 2613. VOL. I04I 



less telegraphy and telephony, and a very extensive 

 display of modern improvements in aircraft, as shown 

 by the work of firms in the Clyde area. 



Steam turbines and oil engines are well represented, 

 as well as such interesting inventions in marine en- 

 gineering as variable-speed gearing and hydraulic 

 transmitters. Many systems of high-temperature 

 welding, especially with the electric arc, are shown in 

 operation, and examples of varied uses of this process 

 are shown, including the junction of the vertical 

 framinti and the roof principals in a steel-frame 

 building. The coal industrv is represented by a full- 

 sized model of a coal seam with electric coal-cutters 

 at work, and there are also exhibits illustrating the 

 utilisation of the iron ores and oil-fuel supplies of this 

 country. 



The chemical exhibits are, in the main, the same as 

 those which were shown in London, whilst the metal- 

 lurgical industries naturally receive special attention. 

 The Health Department of the city shows a large and 

 instructive collection of preparations illustrating the 

 relation between micro-organisms and disease, as well 

 as diagrams relating to the smoke nuisance. Several 

 Government Departments and universities are repre- 

 sented bv stands, at some of which demonstrations are 

 carried on. A kineinatograph hall is used for showing 

 films of scientific interest in connection with engineer- 

 ing, shipbuilding, and metallurgy, as well as with bac- 

 teriology. The educational value of the exhibition is 

 very great, and a most remarkable picture is presented 

 of the capacitv of British manufacturers to accomplish 

 good work when advantage of scientific guidance is 

 taken. 



The opening ceremonv was performed on Monday, 

 November 17, bv Sir Charles Parsons, the Lord Pro- 

 vost of Glasgow presiding, and testimony was then 

 given as to the importance of science to industrial 

 progress. The exhibition has the advantage of fol- 

 lowing closelv on a most successful housing exhibi- 

 tion, also held by the Corporation, and visited by 

 enormous numbers of people, so that there is every 

 reason to expect results which will be beneficial to 

 science and to industry alike bv bringing the two into 

 closer contact, and in educating the public as to (he 

 necessitv for a close co-operation between them. The 

 exhibition remains open until December 6. 



A NEW ASTRONOMICAL MODEL. 



THE illustrious scholar Gerbert (a.d. 940-1003), 

 afterwards Pope under the name of Sylvester II., 

 was apparently the first of the schoolmen who illus- 

 trated his theoretical lessons on astronomy by the 

 use of globes, which he constructed with his own 

 hands. About the year a.d. 1700 George Graham in- 

 vented a machine to show the movem<Mits _ of the 

 earth and planets about the sun, a copy of which was 

 made for Charles Boyle, i;he Earl of "Orrery. Hence 

 the name of an apparatus very useful for illustrating 

 lessons in astrorioinv, although Sir John Hersche! did 

 call orreries "very childish toys." But surely the 

 difficulty in teaching astronomy is to make the yoijng 

 pupil think in three dimensions. What are we going 

 to do when the relativists would have us imagine 

 phenomena in four dimensions? 



Some fortv vears ago the prospectuses of schools 

 gencrallv advertised among the subjects taught "the 

 use of the globes and deportment." Presumably the 

 orderly arrangement of the solar svstem was. to be 

 reflected in the conduct of the pupils. The "use of 

 the globes " seems to have disappeared from the 

 apparatus of oedagogv, although the teaching of geo- 

 graphv and the elementary notions of astronomy are 

 verv much facilitated by their employment. But 



