March 6, 19 19] 



NATURE 



t up to the end of November there were only 

 ine days in 1918 on which no airship flight took 

 lace in the British Isles. 

 Having- thus indicated the suitability of the 

 f airship for commercial purposes, the paper goes 

 on to discuss the developments which have taken 

 place during the last four years in the design of 

 - both airshij>s and aeroplanes, and it is considered 

 ^that the development of the airship has been even 

 I more marked than that of the aeroplane when 

 f regarded from the point of view of weight-carry- 

 ing. Considerable emphasis is laid on the fact 

 that for a given increase in the gross weight of 

 an aeroplane a more than proportional increase is 

 iHcessary in the weight of the structure itself if 

 the same factor of safety is to be maintained; 

 whereas in the case of the airship the strength of 

 the structure is maintained if the structural 

 \\ eight is directly proportional to the gross weight. 

 This difference is explained by the fact that the 

 lilt of similar aeroplanes is proportional to the 

 square of their linear dimensions, whereas the 

 lift of similar airships varies as the cube of the 

 dimensions. If, therefore, the size of aeroplanes 

 is increased very greatly, while still adhering to 

 the present materials and constructional methods, 

 a point would be reached where the machine could 

 only just lift its own weight, with no reserve for 

 carrying useful load. With the airship, however, 

 the useful load increases continuously, no matter 

 iiMW large the ship. 



It therefore appears that, while airships of great 

 carrying capacity are theoretically possible on the 

 present lines of design, it is impossible to build 

 aeroplanes to carry anything like the same loads 

 unless methods of design can be radically altered. 

 A comparison of this kind is not necessarily an 

 argument in favour of the airship, as it may be 

 ultimately found better to carry a given load by a 

 number of aeroplanes of reasonable dimensions 

 rather than by a single huge airship. 



Numerical illustrations are given of the improve- 

 ment since 1914 in the cases of aeroplanes and 

 rii^l^id airships, and a rough indication of the 

 results arrived at is given in the table below : — 



Type of aircmft 



1914 Avro 



M,i8 D.H. loA 

 (14 Zeppelin (average) 

 Zeppelin (L.70) 



'reposed 10,000,000 cu. ft. 

 rigid airship 



Speed (milts Horse- Useful load 



per hour) power (tons) 



..70 80 0-27 



.. 125 810 1-45 



.. 50 800 8-5 



78 2100 388 



86 6000 



170 



I he table shows the possibilities of the airship 

 a weight-carrier in a marked manner, but it is 

 somewhat difficult to make a comparison of merit 

 when the size and the speed of flight are so vari- 

 able for the various aircraft. If it be assumed 

 that the horse-power varies as the cube of the 

 sneed (an assumption which is true for the airship, 

 1 approximately correct for the aeroplane), 

 s possible to compare roughly the performances 



WV' 

 notmg the value of , for the various 



horse-power 



raft, where W is the useful load in tons, and 

 NO. 2575, VOL. 103] 



V the speed in miles per hour. For the five 

 machines above considered, the values are : — 



These figures indicate clearly that, from the 

 point of view of fuel consumption, the large air- 

 ship is much more efficient than the aeroplane for 

 carrying great loads at a moderate speed. It is 

 possible, however, that this superiority may In 

 practice be outweighed by the greater cost of up- 

 keep of the airship, and, in particular, by the cost 

 of the large housing sheds which are at present 

 necessary, with their attendant need of a large 

 personnel to handle the ships. The aeroplane will, 

 of course, always be the better machine where 

 small loads are to be carried at the highest pos- 

 sible speeds, and it is quite likely that a com- 

 bination of aeroplane and airship services will 

 often prove the best practical solution. For in- 

 stance, as suggested in the paper under dis- 

 cussion, a rigid airship service might run between 

 Lisbon and New York, passengers being taken to 

 Lisbon from Paris, Rome, etc., by aeroplane. The 

 aeroplane would thus compete with the express 

 train, and the airship with the ocean liner, and 

 a gain of not less than 50 per cent, in the time of 

 transit would be realised in both cases. 



In conclusion, the Air Ministry appears very 

 optimistic as to the possibilities of the rigid air- 

 ship in commerce, and produces excellent reason- 

 ing to support its optimism. One note of warning 

 is sounded, and cannot be sounded too often, 

 namely, that progress in point of size of aircraft 

 must be made gradually. A premature attempt 

 to build a very large aeroplane or airship is 

 doomed to failure, and would do much to prejudice 

 future development. If, however, progress is 

 attempted in easy stages, giving time to overcome 

 difficulties gradually, and to apply experience so 

 gained to the next stage of development, there Is 

 every reason to hope that vast improvement will 

 result in both aeroplanes and airships, and that 

 the success of commercial aviation will be assured. 



DR. F. DU CANE GODMAN, F.R.S. 



THE death of Dr. Frederick Du Cane Godman 

 on February 19 removes a familiar figure 

 from the meetings of our scientific societies. Few 

 men had greater opportunities of benefiting the 

 science of their choice ; none made a better use of 

 them. 



There is something characteristically British in 

 the development of Godman 's life-work out of 

 the associations and friendships of his student 

 days at the university. For it was at Cambridge 

 in Godman 's time and with Godman 's help that 

 the Ornithological L'nion and its journal, the Ibis, 

 were founded, and at Cambridge that his fruitful 

 friendship with Osbert Salvin was begun. Of 

 that friendship, which closed with the death of 

 Salvin in 1898, he wrote in his introduction to 



