DISCOVERY 



125 



danger, it is well to bear in mind that aerial transport 

 is yet in its infancy, but can already show a greater 

 percentage of reliability and safety than any other 

 form of transport at a corresponding or even much 

 later stage of development. One has only to take 

 into consideration the almost daily charabanc 

 fatalities so realise the truth of this statement. 



As regards actual figures, for the year ending 

 September 1921, 4,559 Continental aircraft used 

 Croydon. Of this total 1,315 were British, 1,436 

 French, 577 Belgian,'and 295 Dutch. For the same 

 period a total of 10,554 passengers were carried 

 between London and the Continent, 5,424 being carried 

 in British machines, 4,024 by French, 676 by Belgian, 

 and 420 by Dutch companies. During this period the 

 following casualties occurred on British air lines : 

 pilots killed, 3 ; passengers killed, 4 ; third party 

 killed, o ; pilots injured, 3 ; passengers injured, 2 ; 

 third party injured, o. The casualty rates during last 

 summer work out at -03 passengers killed per thousand 

 carried, and -03 passengers injured per thousand 

 carried, whilst a total of 32,200 miles was flown over 

 for every accident which occurred. Other figures 

 show that one accident occurred for every 1,718 

 flights commenced. These figures, which are issued 

 by the Air Ministry, show that air travel cannot be 

 considered as unduly dangerous. 



For the three months ending July 31, 1921, the 

 British services between London and Paris came up 

 to the high standard described as " 100 per cent. 

 efficient," whilst for the six months ending Septem- 

 ber 21, the average " efficiency " was 96 per cent. 



Other European countries interested in civil flying 

 are Belgium, which operates routes to London and 

 Paris, and Denmark, which will enter the field this 

 spring, probably employing German machines. Spain, 

 too, is operating a regular service from Seville to 

 Laraiche in Morocco, and has other services in contem- 

 plation, notably the airship service to South America 

 alread}' mentioned. 



As regards comfort, everyone who has flown realises 

 that air travel is the quickest method of getting from 

 place to place, and speed in transit adds to comfort in 

 travelling by taking away the monotony of long 

 journeys. All machines now used on the airways are 

 fitted with closed cabins carrying from two to twenty 

 people. These cabins are invariably fitted with com- 

 fortable armchairs, and are generally well ventilated 

 with windows which may be opened or closed at will. 

 They are comparatively warm in winter and not 

 unduly stuffy in summer weather. There is none of 

 the jolting and banging experienced in rail and road 

 travel ; there is no dust or cinders to irritate the 

 travellers' eyes ; there is no excessive draught to 

 injure delicate gowns. The sensation of bumping 



sometimes felt when flying low over hilly country on 

 a hot day is the worst that can be experienced, and 

 it is not nearly so bad as a sea voyage in comparatively 

 calm weather. The views seen from the windows of 

 the machine are generally good, and the panorama 

 seen by the traveller is superior to anything of the 

 kind which can possibly be obtained by people who 

 travel by old-fashioned methods. 



All cross-Channel companies provide their passengers 

 with life-belts which automatically inflate from a 

 compressed-air condenser by moving a small lever. 

 This is to guard against danger in the event of a forced 

 landing in the Channel, though all the machines will 

 float a certain length of time on water, and since civil 

 aviation commenced there are only two recorded 

 instances of commercial machines having to descend 

 in the Channel. In addition most aeroplanes have 

 an emergency outlet at the top of the cabin as well 

 as a normal entrance bj' a full-sized door. At least 

 one company has a map of the route inserted inside 

 the cabin on which the exact position of the machine 

 is shown by a pointer which the pilot moves as he 

 flies over the route. It should be borne in mind that 

 there is no necessity to wear special clothing when 

 travelling by air. The most delicate costume will 

 not get injured, and nothing more than a light wrap 

 occasionally in srmimer, and an overcoat in winter, 

 is needed by any traveller. 



What is a Chemical 

 Element ? ' 



The pubUcation of Dr. Aston's monograph on a subject 

 he has made peculiarly his own aft'ords a convenient 

 opportunity for a few reflections upon the change in 

 our conception of a chemical element which recent 

 research work has occasioned. The e.xact idea con- 

 veyed by the word " element " in chemistry and 

 physics in the past has been more easily realised or felt 

 by students than expressed in words. The textbooks 

 told, and still tell, us that an element is a " body 

 which has not been decomposed " ; or, is " something 

 to which we can add, but from which we can take 

 nothing " ; or, a " body which increases in weight wth 

 every chemical change." Such definitions have always 

 been regarded as unsatisfactory because they were 

 provisional ; a time might conceivably come when 

 they would be inapplicable to a given case. They 

 took their stand, as Sir \Mlliam Crookes pointed out, 

 not on any attribute of things to be defined, but on the 



1 Isotopes. By F. W. Aston, D.Sc, F.R.S. (.\mold, gs.) 



