914 Tra nsa ctions of the a merican Institute, 



1. The transmission- of all ratiii . bags between the post-office and 

 the railway stations, and the several district stations. 



2. The conveyance and delivery of all the small parcels of the rail- 

 way and express companies. 



3. The conveyance and delivery of all ordinary packages from the 

 newspaper offices, stores and markets. . 



Nor is the principle of pneumatic transmission applicable to public 

 undertakings alone ; it is equally iTseful 'for private purposes, as by a 

 separate system of branch tubes all' great commercial ' houses on or 

 near the lines can instantaneously transmit their dispatches-or parcels 

 in separate carriages to all parts of the city. 



Dksokiption of the New Tubes. 

 Yet greater practical results have been manifested by the opening 

 of the Pneumatic Dispatch Company's tube on a larger scale, from 

 the company's office in Holborn street, thence southward under Seven 

 Dials, thence in a curve northw^esterly under Tottenham Court road, 

 crossing over the Metropolitan raihvay at Euston road,- thence north- 

 easterly to Euston station, a distance of nearly ttvo miles. This line 

 is formed of a continuous cast-iron tube of the horse shoe section, in 

 nine feet lengths, the internal dimensions being five feet six inches 

 horizontally, by five feet vertically. Those portions of the tube on 

 short curves are constructed of brick work. The carriages, or trucks, 

 are about ten feet in length, resemble in form an ordinary open 

 goods wagon, the ends being raised above the sides, and presenting 

 an outline conforming to that of the interior of the tube. The edges 

 of these trucks are bound with an elastic medium, although a space 

 is left between the truck and the inner face of the tube ; a perfect fit 

 not' being required for working the dispatch. It is found that no 

 inconvenience arises from leakage, while in the case of a close fit the 

 results of friction would prove prejudicial. Each truck will carry 

 about one and a half tons of mail matter. Trains of four trucks are 

 run; making a gross load of noarly ten tons, at a rate of thirty-five to 

 forty miles an hour, with a blowing pressure of only six ounces per 

 square inch. In ordinary steady working, twenty-four trains of about 

 ten tons each are carried through each four hours. The machinery 

 by which the transit of this weight of trucks is effected consists of 

 two engines of twenty -four inch cylinders', twenty, inch stroke, opera- 

 ting a ffrn ^twenty-two feet in diameter. Ordinarily this fan works at 

 one hundred and sixty revolutions, giving a pressure equal to six 



