March 2, 191 1] 



NATURE 



17 



strain at two places where the strain was specially 

 great owing to resistances to the well-established 

 f 01 ward march of the overthrusting foot of the Hima- 

 layan range. 



All this is perfectly clearly put, the argument is 

 logically arranged, and the conclusion is perfectly 

 orthodox; but yet we must confess that in reading 

 Mr. Middlemiss's description we were struck by many 

 indications of the absence of direct connection be- 

 tween earthquake and geological structure. The 

 principal focus of maximum Intensity extends from 

 the sub-Himalayan area across the great boundary 



(fault, which is by far the grandest structural feature 



'of the region ; and the subsidiary focus in the Dehra 

 Dun shows no tendency to a concentration of violence 

 along any particular line or connection with any 

 known structural feature, and from this area some 

 observations are recorded which seem to be of im- 

 portance so far as the origin of earthquakes is con- 

 cerned. An old line of levelling from Saharanpur to 

 Mussooree was gone over again after the earthquake 



' with the result that although the relative levels of 

 the extremities of the line were unchanged, it was 

 found that the intervening bench marks in the Dehra 

 Dun and the Siwaliks showed an elevation of from 



■4 to 5 inches. As no alteration in the relative level 

 of Dehra Dun and Mussooree had been noticed when 

 this section was re-levelled in May, 1904, it is prac- 





in which spark-dischargers are used, a spark is 

 caused to bridge the gap by the application of a 

 direct-current or alternating-current supply, and it is 

 arranged that the discharge thus produced should 

 form part of a circuit in which high-frequency oscilla- 

 tions may be set up. This circuit must contain a 

 capacity and inductance, and the charge and discharge 

 of the capacity taking place through it will be of an 

 oscillatory nature if the resistance of the cricuit be 



/4 ,,7hAro I onH vi represent 



where L and K 



not greater than . / 



the inductance and capacity of the circuit. When the 

 resistance is greater than this value, the discharge is 

 not of an oscillatory nature, and is therefore unsuit- 

 able for. the production of waves for wireless tele- 

 graphy. 



In early methods of working the gap was placed 

 directly between the aerial and an earth-plate, and 

 the discharge produced by connecting an induction 

 coil across the gap. The oscillating circuit consisted 

 of the spark-gap and the capacity and inductance of 

 the aerial, and the energy that could be radiated was 

 small owing to the very small capacity of the aerial. 

 The receiving circuit consisted of an aerial connected 

 to earth through a coherer, which formed part of a 

 relay circuit actuating a Morse printing instrument. 



The improvement constituting the subject-matter of 

 the patent under discussion consists in providing for 

 the oscillatory discharge across the gap a closed cir- 

 cuit of large capacity, and therefore capable of taking 



tically certain that 

 the change took 

 place at the time 

 of the earthquake. Now if the results are examined 

 it may be noticed that elevation was not confined to 

 one station, as might be expected had it been due to 

 shifting of the opposite sides of a fault, but is rather 

 a general bulging upwards, such as might be pro- 

 duced by a sudden increase in volume of the material 

 underlying the region of greater violence of shock. 



These, however, are matters of inference and inter- 

 pretation, and whatever may be the ultimate trend of 

 thought as concerns them, the memoir under review 

 will stand as an important contribution to knowledge 

 which will have to be studied and reckoned with by 

 all who attempt to deal with the vexed question of 

 the nature and origin of earthquakes. 



, WIRELESS TELEGRAPHY SYSTEMS. 



'T'HE action brought by Mr. Marconi and Marconi's 

 ( ■*■ Wireless Telegraph Co., Ltd., against the 

 f British Radio-Telegraph and Telephone Co., Ltd., for 

 infringement of patent No. 7777 of 1900, concerning 

 improvements in apparatus for wireless telegraphy, 

 , has been concluded, and Mr. Justice Parker delivered 

 I judgment on February 21 in favour of the plaintiffs. 



The patent in question refers to an arrangement 



I of the sending and receiving circuits in such a manner 



I as to make telegraphy possible over increased dis- 



. tances by means of spark methods. In the methods 



NO. 2157, VOL. 86] 



From " The Kangra Earthquake of April 4 1905." 



Up a considerable amount of energy, and suitably 

 linking this circuit to the transmitting aerial by 

 means of a transformer, the primary of which is in- 

 serted in the closed circuit, and the secondary of which 

 is connected in the aerial. By this means oscilla- 

 tions of great energy are able to be set up in the 

 closed circuit, and if the aerial circuit be tuned to 

 have the same frequency of oscillation as this circuit, 

 and be loosely coupled to it by the transformer, long 

 trains of waves of a single frequency will be radiated 

 by the aerial, which is, in virtue of its open circuit, 

 a good radiator of the energy gradually supplied to 

 it by the good oscillator formed by the closed circuit. 



A similar idea underlies the arrangement adopted 

 for the receiving circuit, in which a good absorber 

 consisting of an open circuit containing the aerial is 

 linked by a transformer to a poor radiator, and con- 

 sequently a good accumulator of energy consisting of 

 a closed circuit. 



The apparatus of the British Radio-Telegraph Co. 

 is substantially similar to that described above, with 

 the exception that the oscillating and radiating cir- 

 cuits at the transmitting end, and the receiving and 

 storing circuits at the receiving end, are connected by 

 means of a single-coil transformer or auto-trans- 

 former Instead of a two-coil transformer, as is used 

 in the Marconi arrangement. 



A considerable portion of the proceedings was occu- 

 pied In the discussion whether the use of a single-coil 

 transformer In the place of a two-coil transformer 

 constituted an infringement or not, and the judgment 



