ccxxiv GENERAL SUMMARY OF SCIENTIFIC AND 



extension of the pneumatic system to other branch offices in the 

 same city, when the traffic is large enough to warrant its applica- 

 tion, is contemplated, and, when the value of the system has been 

 more definitely ascertained, will doubtless be carried into efiect. 



The London Engineer^ commenting upon this topic, affirms in sub- 

 stance that the excellence in both economy and rapidity of the pneu- 

 matic over the electric telegraph, when used for sending messages 

 over comparatively short lines, has been fully demonstrated by the 

 experience made with the system in the cities of London, Paris, 

 Brussels, Berlin, and other EurojDean cities; the system, wherever 

 introduced, being constantly enlarged, while in no instance has it 

 been abandoned. In London, we are told by the same informant, 

 there are now twenty-four distinct tubes of an aggregate length of 

 nearly eighteen miles ; and additions are now in progress which 

 will increase this mileage one third. In London lead is preferred 

 for the tubes, while in Paris iron is successfully used. In point of 

 economy, the experience with the pneumatic system in London es- 

 tablished the fact that during the past year the expense w^as barely 

 two thirds of the amount w^hich would have been required to pay 

 the salaries only of the clerks needed under the old wure system, ir- 

 respective of the cost of wires and instruments. The utility of the 

 IDueumatic system for the transmission of letters to and from central 

 to branch post-offices is obvious ; while its perfect solution of the 

 problem of local transmission should make us far less tolerant of the 

 pole nuisance in our cities than we have heretofore been. 



From the English journals we learn of the proposition to extend 

 telegraphic communication across the African continent to the Cape. 

 There is at the present time telegraphic communication from Alexan- 

 dria to Khartoum, a distance of eleven hundred miles ; and surveys 

 for its further extension into the interior have already been made. 

 The proposed route would lead under the Victoria Nyassa and Tan- 

 ganyika Lakes, and thence down the Shire and Zambesi Rivers to 

 the sea, where a short ocean line would connect it wdth Delagoa Bay 

 or Port Natal. It is claimed, though upon what ground does not ap- 

 pear to be very clear, that the undertaking, if it could be established 

 and kept in w^orking order, would prove to be exceedingly lucrative, 

 and also as must be admitted that it would aid in many ways in 

 opening up Africa to civilization and commerce. Apropos of the 

 preceding, we may add that Mr. Donald Mackenzie with a party left 

 England in the month of July, for the purpose of testing the feasi- 

 bility of that gentleman's project (mentioned in our last yearly Rec- 

 ord) of flooding the Sahara. The immediate purpose of the expedi- 

 tion was announced to be to make the necessary surveys prelimina- 

 ry to the turning of the w^aters of the Atlantic into the great sink or 

 basin which is believed to extend from the valley of the Bella to 

 Timbuctoo. Mr. Mackenzie, it is said, is very confident that a canal 



