512 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



The Chairman. — I see they have in operation in England, a Yankee in- 

 vention, called a pneumatic railway, about a mile in length. It is an air 

 gun airanged to carry packages, by discharging them througji a pneu- 

 matic tube. It is said that the length of this tube, one mile, can be trav- 

 ersed in one minute. Traveling with the wind, neither faster nor slower, 

 nothing is felt of its influence except just a very little when going head 

 foremost, from the air which finds its way in at the end of the tube. The 

 space is too small for reverberation, and there is less noise than would be 

 expected from iron rattling on iron. 



"Harbor Defences, and the Use of Iron-clad Vessels," was selected as 

 the subject for discussion for the next meeting. 



Adjourned. Johx W. Chambers, Secretary pro tern. 



Americax Ixstitute Polytechn 

 The Chairman, S. D. Tillman, Escj., presiding. 



Improved Roads. 



;hnic As30cl\tiox, \ 

 Ajyril 23, 1863. j 



Mr. J. K. Fisher. — During a residence in Naples, some years ago, I 

 speculated on the subject of lava, as a material for roads. It was used to 

 pave the streets of Pompeii, and is still used in Naples — and seems 

 sufficiently hard for the purpose — much harder than many stones used for 

 paving and road making. And it may be molded into blocks while it is in 

 a semi-fluid state, as it flows for miles, and its surface may be roughened 

 according as the mold is made. A railway might be laid to transport the 

 blocks to the shore, or even to Naples; and vessels may transport them to 

 cities where they are wanted. 



After my return, I went with several members of the Institute to see the 

 operation of making plate glass, at Williamsbiirgli. It struck me that the 

 glass was nearly of the consistency of lava as it flows from Vesuvius, and 

 that, could we make artificial lava, we might roll it into plates as they 

 roll glass; and we might make them thick enough to pave with. 



It also occurred to me that a road might in this way be surfaced with 

 cast iron. To do it would require a furnace moving on wheels, at a steady 

 and slow rate; such a rate as would bring the roller into contact with the 

 melted metal upon the road just in time to give ft the requred shape and 

 a sufficient chill. And if a great extent of road were to be covered with 

 a continuous sheet of iron, several furnaces might be required, so arranged 

 upon the moving platform as to relieve each other, and to produce a 

 regular flow of metal. 



In laying either iron or lava in this Avay, it appears to me, it is practi- 

 cable to give any desired roughness to the surface, any figure or pattern 

 that may be best for the foothold of horses. And this roughness may be 

 spread over the whole surface, as in the iron pavement invented by Mr. 

 Tillman, or it may be confined to the horse tracks, leaving the wheel tracks 

 smooth. 



