646 



advantage of a iiiiicli smaller decierrieiit, and we may ask liou' 

 far in practice advantage and disadvantage are connterbalanced. 



Tlie answer depends on tiie possibility of deriving the full profit 

 from tlie small decrement of the receivei-. Let ns for instance try 

 to receive in Leyden the signals of the present high freqnency al- 

 ternator at Bandoeng. It does not keep its wave of 7,5 kiloni. 

 absolutely- constant, but according to our measurements the wave 

 varies by amounts of 1 to 2 per thousand. If, by diminishing the 

 field intensity, we decrease the string decrement so much as would 

 be desirable when receiving a constant wave, a signal would only 

 be received now and then, that is to say only at those moments, 

 when the \arying wave of the transmitter coincides exactly with 

 the wave to which the siring is put in tune. To different wave- 

 lengths ihe siring does not respond, so that the dots and dashes 

 transmitted are ruit received regularly and Ihe telegram becomes 

 unreadable. We are obliged to increase the string deci'emeiit and 

 so to enable the reception of a greater i-ange of variation of the 

 wave-length of the transmitter. 



On experimenting we obtained the impression that Ihe reception 

 by telephone of Ihe high frecjuency alternator of Bandoeng is 

 disturbed by extraneous noises about as much as the recejition by 

 the galvanometer. In both cases practically as many signals become 

 unreadable by atmospiierics. Bnt we have not yet had the opportunity 

 to carry out exact measurements on this point and it may be noticed, 

 that the diHerence in skill of the various Marconists, who are 

 carrying on the comparative experiments must also be allowed for. 

 if the wave transmitted oscillates still more than is mentioned 

 above, the MarconisI will obtain the better result, but if it is being 

 kept steady, such as actually is the case with many modern trans- 

 mitters, then Ihe advantage will pass to the side of the galvanometer. 

 The dots and dashes on the strip of paper will then be like those 

 of fig. 4 and of the upper part of fig. 6. 



The slower the rate of Iransmission so much the smaller the string 

 decrement may be made; the freedom from disturbances becomes 

 improved proportionately and thus the possibility of receiving with 

 Ihe galvanometer increases. On the other hand the Marconist is not 

 able to take advantage of a more constant transmission wave; it is 

 impossible for the human ear M to perceive the minute variations 

 in pitch, to which a string vibrating with a small decrement is 

 capable of responding noticeably. 



1) Practically also when the Marconist is applying beat reception. 



