AERONAUTICS 34 i 



Recent experiments having shown that the results of tests on scale models may be 

 applied, in accordance with the known law of correspondence, to full-size machines, the 

 work of the laboratory has become increasingly valuable and rendered superfluous the 

 hazardous and often inconclusive experiments with full-size machines in flight. 



While scientific experiment and research work have played a part of inestimable 

 value in the development of aeronautics in general and of aviation in particular, this 

 development has also called forth a new branch of engineering. In Great Britain the 

 aeronautical engineering profession is represented by the Aeronautical Society, which 

 grants Associate- Fellowship and Fellowship degrees of proficiency. 



While both the aeroplane and the dirigible have made vast progress in recent years, 

 the balloon, from its very nature, has reached the limit of its development and "lost some 

 of its popularity in the face of the advance of the other forms of aerial 

 navigation. From the military point of view it has been supplanted by 

 motor-driven aircraft. For purposes of sport, however, the balloon remains in favour, 

 stimulated to a great extent by the balloon races held in many countries. The follow- 

 ing figures, representing the cubic feet of gas consumed for balloon ascents during the 

 years 1909, 1910 and 1911, in the four principal countries, reflect with fair accuracy the 

 position of ballooning during recent times. 



1909. 1910. 1911. 



Belgium . .; . .'.'=: . : : 7,720,000 7,200,000 7,590,000 



France . . . . . . . 28,600,000 17,400,000 27,290,000 



Germany 44,500,000 76,900,000 72,260,000 



Great Britain . . . . . . 7,690,000 5,860,000 5,650,000 



The chief sporting event of the year^the International Gordon-Bennett Balloon Race, 

 in 1912 produced two new world's records. The race started from Stuttgart on October 

 2yth, and was won by M. Bienaime, a French representative, who landed in Russia 

 after having covered 1,360 miles; M. Leblanc, the second French representative, also 

 beating the former record by covering 1,243 miles. 



Some few years ago, in the face of questionable results and repeated disasters, it was 

 commonly thought that the dirigible, too, had attained the limit of its development and 

 utility. But in recent years progress has been enormous in this direction. 

 It is difficult to explain the reasons of this progress, save on the score of 

 improvements in detail and in structural methods, based largely on accumulated experi- 

 ence. The one factor which, no doubt, has been chiefly responsible for the slow develop- 

 ment of the dirigible has been that of expense. From its very nature, this type of air- 

 craft is enormously costly, not only in the primary cost of materials, but in upkeep and 

 by reason of the elaborate accommodation required for its harbourage. While an aero- 

 plane is practically independent of a fixed base, a dirigible requires vast halls for shelter, 

 since, once on the ground, it becomes, in default of suitable harbourage, the prey of the 

 least gust of wind. Nevertheless, the enormous progress realized with this type of air- 

 craft, and its indubitable advantages, which an aeroplane can never possess, have ren- 

 dered it a military instrument of potent value. 



The three types of dirigibles which have always existed have been developed, each 

 according to its special nature and purpose, to a high degree of efficiency during recent 

 years. Their classification is based on their structural nature: the rigid, in which the 

 hull consists of a rigid wood or metal skeleton, wherein the gas envelopes are contained; 

 the non-rigid, forming in effect an elongated motor-driven balloon, comprising no rigid 

 members or frameworks of any kind; the semi-rigid, a type intermediate between the 

 previous two, in which the lower part of the hull is strengthened by a rigid framework 

 forming the point from which the car is suspended and to which the organs of direction 

 and control are attached. The latter type, however, is tending to disappear and to be- 

 come absorbed in that termed non-rigid. The relative advantages of the three types 

 are expressed in their denominations. The two a'ms pursued by designers are speed 

 and lifting-power. The former object demands considerable structural strength to 

 resist the high air pressure exerted upon the hull at high speeds. The rigid type of craft, 



