318 Intelligence and Miscellaneous Articles. 



where periodical attendance is sufficient, the signals may be cor- 

 rectly registered on paper, by connecting with the air-tube an in- 

 strument called a pressure register, invented by the projector of 

 the pneumatic telegraph, which has been successfully employed in 

 large gas-light establishments upwards of fourteen years, for regi- 

 stering the variations of the pressure of gas in street mains. The 

 same instrument produces also an increased range of the index scale, 

 by v/hich means the chance of errors from minute divisions is obviated. 



It may be observed, that the introduction of railways has not 

 only created an additional use for telegraphic communications, but 

 the important difficulty which previously existed in the expense of 

 providing a proper line and safe foundation is, at once, removed by 

 the site of the railway itself, possessing as it does, by its police, the 

 most ample security againstinjury, either to the tubes or electric wires. 



There being now three different projects for improvements in tele- 

 graphic communications, viz. the electro- magnetic, the hydraulic, 

 and the pneumatic telegraph, — and assuming that such improve- 

 ments are of importance to the state, as well as to railway proprie- 

 tors and the community at large, it seems desirable that their merits 

 should be thoroughly investigated by competent engineers, and that 

 the joint aid of Government should be solicited, in conjunction with 

 that of railway proprietors, for the purpose of establishing, on a 

 practical scale, the most eligible project. 



The prominent questions for consideration seem to be — the cer- 

 tainty and accuracy of the communications, the first cost, the ex- 

 pense of repair and superintendence, also the time required for trans- 

 mitting intelligence. 



On the question of time, it is quite clear that neither the hydrau- 

 lic nor the pneumatic can compete with the electro-magnetic tele- 

 graph in rapidity. No doubt, on investigation, each project will be 

 found to possess its pecuUar advantages. Thus, in considering the 

 advantage one may have in point of time, another may possess a 

 greater degree of certainty or accuracy in the communications, suf- 

 ficient to outweigh the difference of time, for instance, between 1 

 second and 1 minute, or even between 1 second and 5 or 10 minutes. 



The time occupied in transmitting intelligence by the pneumatic 

 telegraph will depend on the capacity of the air-tube, the degree of 

 compression given, and the distance between the stations ; but should 

 greater dispatch be required than is afforded by one tube, and the 

 cost be of minor importance, several tubes may be employed, each 

 fitted in the manner above described, so that all the figures con- 

 tained in one telegraphic number, may be communicated at once 

 with four tubes. Nine thousand nine hundred and ninety-nine dif- 

 ferent signal numbers may be communicated, referring to so many 

 words or sentences, and these numbers may be multiplied fourfold 

 by letters A, B, C, &c., as indices to distinguish each series. 



The projector of the pneumatic telegraph is not in possession of 

 any results of experiments on a practical scale by the electro-mag- 

 netic or by the hydraulic telegraph, employed at any considerably 

 extended distances, or of their continued operation for any long 

 period of time ; nor can he offer much decisive information, of a 



