September ii, 1919J 



NATURE 



from its source by means of a submerged hydrophone, 

 and that the tirne of the arrival of the sound-wave 

 can be recorded with great precision. At the end 

 of the war the sound-ranging stations were being used 

 for the detection of positions at sea required for 

 strategical purposes. The same stations are now 

 being used extensively for the determination of such 

 positions at sea as light-vessels, buoys which indie- tr 

 channels, and obstructions such as sunken ships. By 

 this means ships steaming in fog can be given their 

 positions with accuracy for ranges up to 500 miles. 



Among the manv other important technical systems 

 and devices brought out during the war which will 

 find useful application under peace conditions as aids 

 to navigation I may mention directional wireless, by 

 which ships and aircraft can be given their positions 

 and directed, and on this subject we are to have a 

 paper in Section G. 



Leader-gear, -first used by the Germans to direct 

 their ships through their minefields, and afterwards 

 used by the Allies, consists of an insulated cable laid 

 on the bottom of the sea, earthed at the further end, 

 through which an alternating- current is passed. 

 By means of delicate devices installed on a ship, she 

 is able to follow the cable at any speed with as much 

 precision as a railless electric 'bus can follow its 

 trolley-wire. Cables up to fifty miles long have been 

 used, and this device promises to be invaluable to 

 ships navigating narrow and tortuous channels and 

 entering or leaving harbours in a fog. 



Aircraft. — It may be justly said that the develop- 

 ment in aircraft design and manufacture is one of 

 the astonishing engineering feats of the war. In 

 August, 1914, the British Air Services possessed a 

 total of 272 machines, whereas in October, 1918, just 

 prior to the armistice, the Royal Air Force possessed 

 more than 22,000 effective machines. During the 

 first twelve months of the war the average monthly 

 delivery of aeroplanes to our Flying Service was 50, 

 while during the last twelve months of the war the 

 average deliveries were 2700 per month. So far as 

 aero-engines are concerned, our position in 19 14 was 

 by no means satisfactory. We depended for a large 

 proportion of our supplies on other countries. In the 

 Aerial Derby of 1913, of the eleven machines that 

 started, not one had a British engine. By the end 

 of the war, however, British aero-engines had gained 

 the foremost place in design and manufacture, and 

 were well up to requirements as regards supply. The 

 total horse-power produced in the last twelve months 

 of the war approximated to eight millions of brake- 

 horse-power, a figure quite comparable with the total 

 horse-power of the marine-engine output of the 

 country.' 



Much might be written on the progress in aircraft, 

 but the subject will be treated at length in the sec- 

 tional papers. In view of the recent trans-.'Vtlantic 

 flight, however, I feel that it may be opportune to 

 make the following observations on the comparative 

 utility of aeroplanes and airships for commercial pur- 

 poses. In the case of the aeroplane, the weight per 

 horse-power increases with the size, other things being 

 equal. This increase, however, is met to some extent 

 by a multiplicity of engines, though in the fuselage 

 the increase remains. 



On the other hand, with the airship the advantage 

 increases with the size, as in all ships. The tractive 

 effort per ton of displacement diminishes in inverse 

 proportion to the dimensions, other things, including 

 the speed, being the same. Thus an airship of 750 ft. 

 length and 60 tons displacement may require a trac- 

 tive force of 5 per cent., or 3 tons, at 60 miles per 



1 See Lord Weir's Paper read at the Victory Meeting of the North-East 

 Coast Institution of Engineers and Shipbuilders, July, 1919. 



hour; and one of 1500 ft. in length and 8x60 = 480 

 tons displacement would require only 2^ per cent, x 

 480=12 tons at the same speed, and would carry fuel 

 for double! the distance. 



With the same proportion of weight of hull to dis- 

 placement, the larger airship would stand double the 

 wind-pressure, and would weather storms of greater 

 violence and hailstones of greater size. It would te 

 more durable, the proportional upkeep would be less, 

 and the proportional loss of gas considerably less. 

 In other words, it would lose a less proportion of its 

 buoyancy per day. It is a development in which 

 success depends upon the project being well thought 

 out and the job being thoroughly well done. TTTe 

 equipment of the airsheds with numerous electric 

 haulage winches, and all other appliances to make 

 egress and ingress to the sheds safe from danger and 

 accident, must be ample and efficient. 



The airship appwars to have a great future for 

 special commerce where time is a dominant factor 

 and the demand is sufficient to justify a large air- 

 ship. It has also a great field in the opening up_ of 

 new countries where other means of communication 

 are difficult. The only limitation to size will be the 

 cost of the airship and its sheds, just as in steam- 

 vessels it is the cost of the vessels and the cost of 

 deepening the harbours that limit the size of .Atlantic 

 liners. 



Such developments generally take place slowly, 

 otherwise failures occur — as in the. case of the Great 

 Eastern — and it may be many years before the air- 

 ship is increased from the present maximum of 750 ft. 

 to 1500 ft. with success, but it will assuredly come. 

 If, however, the development is subsidised or assisted 

 by the Government, incidental failures may be faced 

 with equanimity and very rapid development accom- 

 plished.' In peace-time the seaplane, aeroplane, and 

 airship will most certainly have their uses. But, 

 except for special services of high utility, it is ques- 

 tionable whether thev will play more than a minor 

 part as compared with the steamship, railway, and 

 motor transport. 



Electricity. — The supply and use of electricity has 

 developed rapidly in recent years. For lighting it is 

 the rival of gas, though eafh has its advantages. .\s 

 a means of transmitting power over long distances it 

 has no rival, and its efficiency is so high that, when 

 generated on a largo scale and distributed over large 

 areas, it is a cheap and trustworthy source of power 

 for working factories, tramways, suburban railways, 

 and innumerable other purposes, including metal- 

 lurgical and chemical processes. It is rapidly super- 

 seding locally generated steam-power, and _is a rival 

 to the small- and moderate-sized gas and oil engines. 

 It has made practicable the use of water-power 

 through the generation of electricity in bulk at the 

 natural falls, from which the power is transmitted to 

 the consumers, sometimes at great distances. 



Fifteen years ago electricity was generated chiefly 

 by large reciprocating steam-engines, direct-coupled to 

 dynamos or alternators, but of late years steam tur- 

 bines have in most instances replaced them, and are 

 now exclusively used in large generating stations 

 because of their smaller cost and! greater economy in 

 fuel. The size of the turbines may vary from a few 

 thousand horse-power up to about 50,000 h.p. At the 

 end of last year the central electric stations in the 

 United Kingdom contained plant aggregating 

 2,750,000 kilowatts, 79 per cent, of which was driven 

 bv steam turbines. 



Much discussion has taken place as to the most 

 economical size of generating stations, their number, 



2 The literature on this subject includes an article which appeared in 

 Engineerifig on January 3, 1919. 



NO. 2602; VOL. 104] 



