A7A' WILLIAM .V//..I//.-.V.S, I-.K.S. 347 



and h:nl previously worked on a similar subject, for his support in 

 nvommending its adoption. The present paper discredited, to 

 some extent, the circuit system, for which it proposed to substitute 

 a " radial system." He was not inclined, however, to accept the 

 verdict of the authors of the paper, who, he believed, had not 

 stated all the elements upon which this question should be judged. 

 The circuit system, when first established between Telegraph 

 Street, the General Post Office, Fleet Street, and ( 'baring Cross, 

 was considered a complete success ; the postal authorities asked 

 several scientific men and gentlemen connected with the Press 

 to observe its results, and they were extremely pleased with them, 

 but since that time there had been a disposition on the part 

 of their engineeers to substitute the radial system. The first 

 objection raised against the circuit system was, that no advantage 

 was derived from it between Telegraph Street and Charing Cross, 

 and that consequently the circuit had been broken up. Plate 29 

 !].! sented the circuit as originally established. Pressure was 

 maintained in one reservoir, and vacuum in another, and the 

 flow of air was always in one direction, carriers being introduced 

 at the points indicated on the diagram through switches of a 

 simple construction. It would be observed that the circuit was 

 a very oblong one, the intermediate stations on both halves being 

 locally united for the convenience of the traffic. The alteration 

 since made consisted in the removal of the arc connecting the two 

 branches ending at Charing Cross, so that the air flowing from the 

 pressure reservoir was discharged into the atmosphere, and the atmo- 

 sphere introduced at Charing Cross flowed to the vacuum reservoir. 

 It so happened, however, that the pressures marked at each station 

 remained at every point of the circuit the same, Charing Cross 

 being just half-way on each branch of the circuit ; and, although 

 he quite agreed that it might be convenient to take away the 

 connecting link, and to work each half with the atmosphere in- 

 serted in circuit, it made no difference whatever in the principle 

 of working. It had been intended originally to extend the circuit 

 to Westminster ; and if that intention had been carried out, the 

 intermediate instruments at Charing Cross would have been in- 

 dispensable. Although the present system was not worked as a 

 circuit, it was worked on the same continuous method, and it 

 would be observed that the postal authorities had adopted another 



