DISCOVERY 



75 



from the cable. He eliminated those noises by means 

 of a small receiving frame placed near the magnetos. 

 This small frame was so wound that, when it was placed 

 in series with the more distant receiving frame, the 

 currents induced in these two frames by the variable 

 magnetic fields of the magnetos were annulled. 



The receiving frames are placed on the aeroplane 

 much as they would be on the ship, and, to perfect 

 reception through the telephones, the tuning, as in 

 the case of the apparatus on board ships at sea, can 

 be rendered sharper by mounting the apparatus on a 

 resonator. When the aeroplane or airship has its 



Fig. 2.— VERTICAI, OSCILLATING 1 .<AM:: ^MMBIXED WITH 



HORIZDNT.\L I'RAME. 

 This suspension, with a universal joint, enables an obser\"er to determine 

 the position, as regards direction, of the source from which the electric 

 waves emanate. 



axis paraDel to the guiding-cable the longitudinal 

 frame receives the maximum of waves, and the trans- 

 verse the minimum. The opposite is true when the 

 aeroplane is moving at right angles to the cable, that 

 is to say, the longitudinal frame receives less and 

 less as the aeroplane inclines towards the guiding- 

 cable and none at all when the machine becomes 

 perpendicular to it, and the transverse receives more 

 and more as the axis of the aeroplane tends to be at 

 right angles to the guiding-cable and a maximum when 

 it is travelling perpendicularly to it. 



The longitudinal and transversal frames may be 



replaced bj- two vertical frames placed at 45^ to the 

 axis of the fuselage of the aeroplane. The horizontal 

 frame receives when the aeroplane is influenced by the 

 variable magnetic field of the guiding-cable, that is to 

 say, when it is either near, or at a certain distance from, 

 the cable, but reception is annulled with great clear- 

 ness when the aeroplane passes right over the hne. 

 IncUnation towards the left or right is obtained by 

 placing the longitudinal and transversal frames in 

 series successively and in two opposite ways. Instead 

 of using the lateral frames, simply or in series, one can, 

 when wishing to know when one is passing from the 

 left to the right or from the right to the left of the cable, 

 place the longitudinal and horizontal frames in series 

 successively and in two opposite ways. Landing at 

 aerodromes is effected b\- placing the transversal 

 and horizontal frames in series in two successive and 

 opposite ways. This same placing in series will indicate 

 when the machine is flying horizontally, the ascending 

 of the cable on the side of a mountain or its descent 

 into a vaUey. And thus an aeroplane or a dirigible 

 can rise or descend, following the same angle, without 

 the necessity of visibility. 



Some results obtained by M. Loth may now be given. 

 With the horizontal frame there was contact at a 

 height of about three kilometres. Contact with the 

 vertical frames took place at an altitude of two and a 

 half kilometres. At a height of two kilometres one 

 could hear on the whole of the receiving apparatus, 

 and it was possible to guide the aeroplane without 

 being troubled either b\' the noise on board or by the 

 magnetos. At a height of one and a half kilometres 

 reception of the waves was perfectly clear and ev-en 

 fairly loud. At an altitude of one kilometre it was 

 loud. At 600 metres one could hear quite well even 

 when the receivers were removed from the ears. At 

 an altitude of two kilometres contact was obtained 

 when over ground which was two kilometres distant 

 from the cable ; at a kilometre and a half the zone 

 to which the waves from the guiding-cable extended 

 was much greater ; whilst at a kilometre the range 

 was several kilometres. On the earth the range 

 attained fifteen kilometres. 



It must be remembered that these are minimum 

 results obtained with a chance cable of barely three 

 kilometres in length and one making no fewer than 

 eight turns. The longest straight portion is only half 

 a kilometre. There can be no doubt that the results 

 would be more striking if a normal cable of great length 

 and without sharp twists were used. The intensity of 

 the current in the cable varied from 4'2 to 28 amperes. 



In practice it is suggested that aeroplanes following 

 the cable in one direction would fly at from 900 to 

 1,000 metres altitude, with freedom to manoeuvre 

 either to the right or the left, whilst those flying in 



