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XX.— ON AN APPARATUS POE OBTAINING TELEGRAPHI- 

 CALLY THE READINGS OF METEOROLOGICAL IN- 

 STRUMENTS PLACED AT A DISTANCE PROM THE 

 OBSERVER. (Plates III. and lY.) Br J. JOLY. 



[Read, February 19, 1883.] 



The contrivance described in this Paper is one whicli may be 

 attached or adapted to the various thermometers, the barometer, 

 rain-gauge, and to some others of the instruments installed, say, in 

 a mountain station, enabling their readings to be taken from a 

 conveniently-placed observatory. 



It is submitted that the arrangements are not of a costly 

 nature, or more complicated mechanically than those daily in use 

 in every telegraph office. The proposal for a distributor, as de- 

 scribed in the latter part of the Paper, is advanced with more 

 diffidence, as it has not yet been practically tested. 



A brief generalization of the method proposed will be of 

 assistance in subsequently considering the details of the appa- 

 ratus. 



To take the case of a thermometer : its stem is left open, a fine 

 wire being arranged to move freely upwards or downwards within 

 it. An electro-magnet forms part of the contrivance — which we 

 will suppose is some miles distant from the observer. The 

 electro-magnet is, however, in circuit with the home station, and 

 matters are so arranged between it and the movable wire, that 

 each time a current is sent from the home station to the electro- 

 magnet the wire is advanced doivnwards by a certain amount. 

 Say this advance is the ywo^ of an inch. If fifty makes and 

 breaks are effected in the home station, the wire in the instrument 

 will have moved downwards by half an inch. Suppose, now, that 

 a return circuit connects the mercury in the thermometer with the 

 home station, so that, as soon as the descending wire meets the 

 mercury where it stands in the tube of the thermometer, the cur- 

 rent supplying the electro-magnet will be returned by the circuit, 

 causing a galvanometer in the home station to deflect. The mo- 



