February 4. 1909] 



NA TURE 



417 



the machine rears or sinks forward, touches the ground, 

 and loses its required velocity, so that no start is made. 

 Langley experienced great difficulties in this way. Four 

 methods are available. 



(i) Starting on a track which the aeroplane cannot 

 leave until the required velocity is reached. (Langley.) 



(2) Starting on a track employing a small plane angle, 

 and when a velocity has been reached in excess of the 

 minimum for the machine, raise the planes quickly until 

 the angle suits. The excess of speed will give the initial 

 elevation required. (Farman, Delagrange, Perber.) 



(3) Start from a height, preferably down a slope. 

 (\'oisin. Roc.) 



(4) Use a frame which can by the store of energy in 

 springs, or a lifted weight, act as a catapult. (Wright 

 Brothers.) 



In each case the starting device (carriage, sledge, or 

 catapult) may be integral with, or separate from, the 

 machine. Separately, weight is, of course, saved. On 

 the other hand, the machine is useless without the hoisting 

 device. Starting-stages with necessary catapults or other 

 devices have been suggested. The A^ro Club de Franco 

 tests machines from a steel tower in the Galerie des 

 Machines, on the principle given third in the foregoing 

 list. 



With regard to descent, this is intimately related to 

 gliding stability. As we have seen, if the weight is in 

 the right place, oscillations will be damped out, and the 

 descending machine will follow a straight descending line 

 with a uniform velocity. The alighting springs should be 

 capable of storing the energy of impact corresponding to 

 this speed and angle. 



Helicopteres. 



It will have become evident from what has been said 

 that this type of machine is more or less at a discount. 

 Machines have been made by Santos Dumont, Kress, 

 Dufaux, and others, but as yet the results are not very 

 important. The ability to soar is undoubtedly a great 

 advantage, but the loss due to insufficient air supply, the 

 absence of wedge action, and the necessity for further 

 machinery to give lateral propulsion are great drawbacks. 

 Mr. Rankine Kennedy is one of the strongest advocates 

 of this type just now. and is evidently convinced as to its 

 ultimate success. The author has interested himself in 

 the type for a long time, but cannot say that at present 

 he considers it to be superior to the aeroplane. In a paper 

 just presented to the .Aeronautical Society he has discussed 

 the question. 



Ornithopteres. 



Profs. Marey and Pettigrew have shown that the wings 

 of flying animals rotate while reciprocating, so as to 

 provide a forward thrust as well as a downward one. 

 (See " The Problem of Flight," p. jq.) The researchis 

 of Mouillard, Langley, Fitzgerald, and Deprez have also 

 shown how the greater flying birds manage to utilise the 

 pulsations of the wind and its vertical component to soar 

 and glide. Lord Rayleigh has given simple rules in this 

 connection. 



A type not uncommon (on paper) is the rotating machine, 

 in which a number of blades are controlled by a cam, so 

 that on the downstroke they move perpendicular to their 

 planes and on the upstroke parallel to their planes, and 

 thus produce an upward resultant thrust. The mechanical 

 efficiency of such an arrangement cannot be so high as 

 that of an aeroplane. Moy's aerial steamer and centrifugal 

 fan types correspond to this variety. 



Future Work. 

 Reference has been made to the necessity for further 

 research as to the centre of pressure. Information is also 

 wanted as to the resistance and stability of combined 

 planes, the thrust of screw propellers, and the effect of 

 lateral currents on propellers and gliders. The mathe- 

 matical analysis of the equations of motion of the aero- 

 plane in space needs to be advanced. Simpler forms of 

 the equations of stability and trajectory are required. The 

 application of the latest investigations as to resistance 

 (such as M. Eiffel's) and centre of pressure to these equa- 

 tions has yet to be made, and bird flight needs much study 

 by ornithologists trained in applied mechanics. 



NO. 2049, VOL. 79] 



Relation to War and Commerce.^ 

 The sudden development of aerial navigation led to a 

 popular panic which was quite baseless. At present the 

 dirigible balloon is extremely vulnerable, cannot carry 

 more than a few pounds' weight of projectiles, and has 

 great difficulty in hitting a mark. In espionage it may 

 be useful. Aeroplanes may perhaps be presently available 

 for attacking vital points and despatch work, but it will 

 be long before they will be steady in a wind. 



Commercially, the outlook is worse. Although the 

 energy required for aerial transport is not much greater 

 than in terrestrial and marine locomotion, the danger and 

 unpunctuality will take many years to eliminate. Wind 

 occasionally (not frequently) will have serious effects on 

 direction and time of passage. Eventually the airship and 

 flying machine will affect society, but the author thinks 

 it will not be for some years to come. 



Finally, the author wishes to point out the deplorable, 

 backwardness of English invention in this direction. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



CAMBRIDGE. — The following programme for the Darwin 

 centenary celebrations, subject to alteration in detail, will 

 be issued at an early date : — 



Tuesday, June 22. — 8.30 p.m. to 11 p.m., reception of 

 delegates and other invited guests by the Chancellor in 

 the Fitzwilliam Museum. B^ kind permission of the 

 master and fellows, the gardens of Peterhouse will be 

 accessible from the museum. 



Wednesday, June 23. — 10.30 a.m., presentation of 

 addresses by delegates in the Senate house ; 2.30 p.m. to 

 3.45 p.m., visits to colleges; 4 p.m., garden-party given 

 by the master and fellows of Christ's College in the college 

 grounds; 7 p.m., banquet in the new examination hall; 

 10 p.m. to 12 p.m., the Vice-Chancellor and fellows of 

 Pembroke College " At Home " in the college hall and 

 gardens. 



Thursday, June 24. — 11 a.m., honorary degrees con- 

 ferred in the Senate house; 12 a.m.. Rede lecture in the 

 Senate house by Sir Archibald Geikie, president of the 

 Royal Society. 



A Darwin exhibition will be held in Christ's College on 

 the lines of the Milton exhibition of last year. The 

 syndics of the University Press have agreed to present to 

 each invited guest a copy of the first draft of " The Origin 

 of Species," which is being prepared for press and edited 

 by Mr. Francis Darwin. This is the draft of which Mr. 

 Darwin speaks in his autobiography : — " In June, i843,_ I 

 first allowed myself the satisfaction of writing a very brief 

 abstract of my theory in pencil in thirty-five pages." 



It is proposed to prepare an illustrated programme^ of 

 the commemoration containing some account of Darwin's 

 Cambridge days, under the editorship of the registrary, 

 the senior secretary to the celebration committee. 



Of the seventeen colleges, fifteen have now published 

 the results of their entrance scholarship examinations. ^ 

 The number of scholarships has slightly increased, and in 

 natural sciences seven and a half more scholarships have 

 been awarded this year than last. The mathematical 

 scholarships are fewer by the same number ; the half re- 

 presents a scholarship which has been awarded partly for 

 natural sciences and partly for some other subject. There 

 is also an increase of four'in the history scholarships. Out 

 of the 201 scholarships, 74 have been awarded for classics, 

 43A for natural sciences, and 33^ for mathematics. Only 

 eight candidates availed themselves of their privilege of 

 resigning their emoluments whilst retaining the status of 

 d scholar. 



The soecial board for biology and geology has aopomted 

 Mr. J. Stanley Gardiner, of Gonville and Caius College, to 

 be a manager- of the Balfour fund until June 14, iqii, in 

 succession to Dr. Harmer, who has resigned. 



Mr. David Sharp has resigned the curatorship in zoology 

 from March 25, iqoQ, and Mr. Hugh Scott, of Trinity 

 College, has been appointed in his stead for one year from 

 March 23, igog. 



1 See .irticle by Prof. Newcomb in the Xinetcentlt Century, September 



